YSO jets in the Galactic plane from UWISH2 - V. Jets and outflows in M17

NASA Astrophysics Data System (ADS)

Samal, M. R.; Chen, W. P.; Takami, M.; Jose, J.; Froebrich, D.

2018-07-01

Jets and outflows are the first signposts of stellar birth. Emission in the H2 1-0 S(1) line at 2.122- μm is a powerful tracer of shock excitation in these objects. Here we present the analysis of 2.0 × 0.8 deg2 data from the UK Wide-field Infrared Survey for H2 (UWISH2) in the 1-0 S(1) line to identify and characterize the outflows of the M17 complex. We uncover 48 probable outflows, of which 93 per cent are new discoveries. We identified driving source candidates for 60 per cent of outflows. Among the driving source candidate young stellar objects (YSOs), 90 per cent are protostars and the remaining 10 per cent are Class II YSOs. In comparison with results from other surveys, we suggest that H2 emission fades very quickly as the objects evolve from protostars to pre-main-sequence stars. We fit spectral energy distribution (SED) models to 14 candidate outflow-driving sources and conclude that the outflows of our sample are mostly driven by moderate-mass YSOs that are still actively accreting from their protoplanetary disc. We examined the spatial distribution of the outflows with the gas and dust distribution of the complex and observed that the filamentary dark cloud M17SWex, located on the south-western side of the complex, is associated with a greater number of outflows. We find that our results corroborate previous suggestions that, in the M17 complex, M17SWex is the most active site of star formation. Several of our newly identified outflow candidates are excellent targets for follow-up studies to understand better the very early phase of protostellar evolution.

Character and dynamics of the Red Sea and Persian Gulf outflows

NASA Astrophysics Data System (ADS)

Bower, Amy S.; Hunt, Heather D.; Price, James F.

2000-03-01

Historical hydrographic data and a numerical plume model are used to investigate the initial transformation, dynamics, and spreading pathways of Red Sea and Persian Gulf outflow waters where they enter the Indian Ocean. The annual mean transport of these outflows is relatively small (<0.4 Sv), but they have a major impact on the hydrographic properties of the Indian Ocean at the thermocline level because of their high salinity. They are different from other outflows in that they flow over very shallow sills (depth < 200 m) into a highly stratified upper ocean environment and they are located at relatively low latitudes (12°N and 26°N). Furthermore, the Red Sea outflow exhibits strong seasonal variability in transport. The four main results of this study are as follows. First, on the basis of observed temperature-salinity (T-S) characteristics of the outflow source and product waters we estimate that the Red Sea and Persian Gulf outflows are diluted by factors of ˜2.5 and 4, respectively, as they descend from sill depth to their depth of neutral buoyancy. The high-dilution factor for the Persian Gulf outflow results from the combined effects of large initial density difference between the outflow source water and oceanic water and low outflow transport. Second, the combination of low latitude and low outflow transport (and associated low outflow thickness) results in Ekman numbers for both outflows that are O(1). This indicates that they should be thought of as frictional density currents modified by rotation rather than geostrophic density currents modified by friction. Third, different mixing histories along the two channels that direct Red Sea outflow water into the open ocean result in product waters with significantly different densities, which probably contributes to the multilayered structure of the Red Sea product waters. In both outflows, seasonal variations in source water and oceanic properties have some effect on the T-S of the product waters, but they have only a minor impact on equilibrium depth. Fourth, product waters from both outflows are advected away from the sill region in narrow boundary currents, at least during part of the year. At other times, the product water appears more in isolated patches.

Effects of stellar outflows on interstellar sulfur oxide chemistry

NASA Technical Reports Server (NTRS)

Welch, W. J.; Vogel, S.; Terebey, S.; Dreher, J.; Jackson, J.; Carlstrom, J.

1986-01-01

Interferometer Maps with 2" to 6" resolution of a number of regions with active star formation (Orion A, W49, W51, SGRB2) show that the distribution of the molecule SO is very compact around stellar outflow sources. Both SO and SO2 were studied near three outflows, OrionA/IRc2 and two sources in W49. The two molecules have similar distributions and abundances. More than 95% of the emission comes from regions whose extents are only .05 to .2 pc., being larger around the more energetic sources. Their spectra are broad, 30 km/sec or more, suggesting that the oxide production is associated with the flows. The outflows are identified by water masers and by extended bipolar flows in SiO. Maps in other molecules, such as HCO+ and CS, which have similar collisional excitation requirements, have much greater spatial extent. Thus it appears that the SO and SO2 abundances are truly compact and are closely associated with the outflows.

Geochemistry and source waters of rock glacier outflow, Colorado Front Range

USGS Publications Warehouse

Williams, M.W.; Knauf, M.; Caine, N.; Liu, F.; Verplanck, P.L.

2006-01-01

We characterize the seasonal variation in the geochemical and isotopic content of the outflow of the Green Lake 5 rock glacier (RG5), located in the Green Lakes Valley of the Colorado Front Range, USA. Between June and August, the geochemical content of rock glacier outflow does not appear to differ substantially from that of other surface waters in the Green Lakes Valley. Thus, for this alpine ecosystem at this time of year there does not appear to be large differences in water quality among rock glacier outflow, glacier and blockslope discharge, and discharge from small alpine catchments. However, in September concentrations of Mg2+ in the outflow of the rock glacier increased to more than 900 ??eq L-1 compared to values of less than 40 ??eq L-1 at all the other sites, concentrations of Ca2+ were greater than 4,000 ??eq L-1 compared to maximum values of less than 200 ??eq L-1 at all other sites, and concentrations of SO42- reached 7,000 ??eq L-1, compared to maximum concentrations below 120 ??eq L-1 at the other sites. Inverse geochemical modelling suggests that dissolution of pyrite, epidote, chlorite and minor calcite as well as the precipitation of silica and goethite best explain these elevated concentrations of solutes in the outflow of the rock glacier. Three component hydrograph separation using end-member mixing analysis shows that melted snow comprised an average of 30% of RG5 outflow, soil water 32%, and base flow 38%. Snow was the dominant source water in June, soil water was the dominant water source in July, and base flow was the dominant source in September. Enrichment of ?? 18O from - 10??? in the outflow of the rock glacier compared to -20??? in snow and enrichment of deuterium excess from +17.5??? in rock glacier outflow compared to +11??? in snow, suggests that melt of internal ice that had undergone multiple melt/freeze episodes was the dominant source of base flow. Copyright ?? 2005 John Wiley & Sons, Ltd.

Far-Ultraviolet Observations of Outflows from Infrared-Luminous Galaxies

NASA Astrophysics Data System (ADS)

Leitherer, Claus; Chandar, Rupali; Tremonti, Christy A.; Wofford, Aida

2013-03-01

We have obtained ultraviolet spectra between 1150 and 1450 Å of four ultraviolet-bright, infrared-luminous starburst galaxies. Our selected sight-lines towards the starburst nuclei probe the conditions in the starburst-driven outflows. We detect outflowing gas with velocities of up to ˜900 km s-1. It is likely that the outflows are a major source of metal enrichment of the galaxies' halos. The mass outflow rates of several tens of M⊙ yr-1 are similar to the star-formation rates. The outflows may quench star formation and ultimately regulate the starburst.

Comparing the contributions of ionospheric outflow and high-altitude production to O+ loss at Mars

NASA Astrophysics Data System (ADS)

Liemohn, Michael; Curry, Shannon; Fang, Xiaohua; Johnson, Blake; Fraenz, Markus; Ma, Yingjuan

2013-04-01

The Mars total O+ escape rate is highly dependent on both the ionospheric and high-altitude source terms. Because of their different source locations, they appear in velocity space distributions as distinct populations. The Mars Test Particle model is used (with background parameters from the BATS-R-US magnetohydrodynamic code) to simulate the transport of ions in the near-Mars space environment. Because it is a collisionless model, the MTP's inner boundary is placed at 300 km altitude for this study. The MHD values at this altitude are used to define an ionospheric outflow source of ions for the MTP. The resulting loss distributions (in both real and velocity space) from this ionospheric source term are compared against those from high-altitude ionization mechanisms, in particular photoionization, charge exchange, and electron impact ionization, each of which have their own (albeit overlapping) source regions. In subsequent simulations, the MHD values defining the ionospheric outflow are systematically varied to parametrically explore possible ionospheric outflow scenarios. For the nominal MHD ionospheric outflow settings, this source contributes only 10% to the total O+ loss rate, nearly all via the central tail region. There is very little dependence of this percentage on the initial temperature, but a change in the initial density or bulk velocity directly alters this loss through the central tail. However, a density or bulk velocity increase of a factor of 10 makes the ionospheric outflow loss comparable in magnitude to the loss from the combined high-altitude sources. The spatial and velocity space distributions of escaping O+ are examined and compared for the various source terms, identifying features specific to each ion source mechanism. These results are applied to a specific Mars Express orbit and used to interpret high-altitude observations from the ion mass analyzer onboard MEX.

Novel neural pathways for metabolic effects of thyroid hormone.

PubMed

Fliers, Eric; Klieverik, Lars P; Kalsbeek, Andries

2010-04-01

The relation between thyrotoxicosis, the clinical syndrome resulting from exposure to excessive thyroid hormone concentrations, and the sympathetic nervous system remains enigmatic. Nevertheless, beta-adrenergic blockers are widely used to manage severe thyrotoxicosis. Recent experiments show that the effects of thyrotoxicosis on hepatic glucose production and insulin sensitivity can be modulated by selective hepatic sympathetic and parasympathetic denervation. Indeed, thyroid hormone stimulates hepatic glucose production via a sympathetic pathway, a novel central pathway for thyroid hormone action. Rodent studies suggest that similar neural routes exist for thyroid hormone analogues (e.g. thyronamines). Further elucidation of central effects of thyroid hormone on autonomic outflow to metabolic organs, including the thyroid and brown adipose tissue, will add to our understanding of hyperthyroidism. Copyright 2009 Elsevier Ltd. All rights reserved.

The Valley Networks on Mars

NASA Astrophysics Data System (ADS)

Gulick, V. C.

2002-12-01

Despite three decades of exploration, the valley networks on Mars still seem to raise more questions than they answer. Valley systems have formed in the southern highlands, along some regions of the dichotomy boundary and the south rim of Valles Marineris, around the rim of some impact craters, and on the flanks of some volcanoes. They are found on some of the oldest and youngest terrains as well as on intermediate aged surfaces. There is surprisingly little consensus as to the formation and the paleoclimatic implications of the valley networks. Did the valleys require a persistent solar-driven atmospheric hydrological cycle involving precipitation, surface runoff, infiltration and groundwater outflow as they typically do on Earth? Or are they the result of magmatic or impact-driven thermal cycling of ground water involving persistent outflow and subsequent runoff? Are they the result of some other process(es)? Ground-water sapping, surface-water runoff, debris flows, wind erosion, and formation mechanisms involving other fluids have been proposed. Until such basic questions as these are definitively answered, their significance for understanding paleoclimatic change on Mars remains cloudy. I will review what is known about valley networks using data from both past and current missions. I will discuss what we have learned about their morphology, environments in which they formed, their spatial and temporal associations, possible formation mechanisms, relation to outflow channel and gully formation, as well as the possible implications for past climate change on Mars. Finally I will discuss how future, meter to submeter scale imaging and other remote sensing observations may shed new light on the debate over the origin of these enigmatic features.

YSO Jets in the Galactic Plane from UWISH2. IV. Jets and Outflows in Cygnus-X

NASA Astrophysics Data System (ADS)

Makin, S. V.; Froebrich, D.

2018-01-01

We have performed an unbiased search for outflows from young stars in Cygnus-X using 42 deg2 of data from the UKIRT Widefield Infrared Survey for H2 (UWISH2 Survey), to identify shock-excited near-IR H2 emission in the 1–0 S(1) 2.122 μm line. We uncovered 572 outflows, of which 465 are new discoveries, increasing the number of known objects by more than 430%. This large and unbiased sample allows us to statistically determine the typical properties of outflows from young stars. We found 261 bipolar outflows, and 16% of these are parsec scale. The typical bipolar outflow is 0.45 pc in length and has gaps of 0.025–0.1 pc between large knots. The median luminosity in the 1–0 S(1) line is 10‑3 {L}ȯ . The bipolar flows are typically asymmetrical, with the two lobes misaligned by 5°, one lobe 30% shorter than the other, and one lobe twice as bright as the other. Of the remaining outflows, 152 are single-sided and 159 are groups of extended, shock-excited H2 emission without identifiable driving sources. Half of all driving sources have sufficient WISE data to determine their evolutionary status as either protostars (80%) or classical T Tauri stars (20%). One-fifth of the driving sources are variable by more than 0.5 mag in the K-band continuum over several years. Several of the newly identified outflows provide excellent targets for follow-up studies. We particularly encourage the study of the outflows and young stars identified in a bright-rimmed cloud near IRAS 20294+4255, which seems to represent a textbook example of triggered star formation.

An X-ray/SDSS sample. II. AGN-driven outflowing gas plasma properties

NASA Astrophysics Data System (ADS)

Perna, M.; Lanzuisi, G.; Brusa, M.; Cresci, G.; Mignoli, M.

2017-10-01

Aims: Galaxy-scale outflows are currently observed in many active galactic nuclei (AGNs); however, characterisation of them in terms of their (multi-) phase nature, amount of flowing material, and effects on their host galaxy is still unresolved. In particular, ionised gas mass outflow rate and related energetics are still affected by many sources of uncertainty. In this respect, outflowing gas plasma conditions, being largely unknown, play a crucial role. Methods: We have analysed stacked spectra and sub-samples of sources with high signal-to-noise temperature- and density-sensitive emission lines to derive the plasma properties of the outflowing ionised gas component. We did this by taking advantage of the spectroscopic analysis results we obtained while studying the X-ray/SDSS sample of 563 AGNs at z < 0.8 presented in our companion paper. For these sources, we also studied in detail various diagnostic diagrams to infer information about outflowing gas ionisation mechanisms. Results: We derive, for the first time, median values for electron temperature and density of outflowing gas from medium-size samples ( 30 targets) and stacked spectra of AGNs. Evidence of shock excitation are found for outflowing gas. Conclusions: We measure electron temperatures of the order of 1.7 × 104 K and densities of 1200 cm-3 for faint and moderately luminous AGNs (intrinsic X-ray luminosity 40.5 < log (LX) < 44 in the 2-10 keV band). We note that the electron density that is usually assumed (Ne = 100 cm-3) in ejected material might result in relevant overestimates of flow mass rates and energetics and, as a consequence, of the effects of AGN-driven outflows on the host galaxy.

A young bipolar outflow from IRAS15398-3359

NASA Astrophysics Data System (ADS)

Bjerkeli, Per; Jørgensen, Jes K.

2015-08-01

The Class 0 protostar IRAS 15398-3359 is located in the Lupus I cloud at a distance of 155 pc. The source is known to harbour a molecular outflow, but the region has not attracted much interest until recently. IRAS 15398 is known to show interesting chemical signatures and being one of the very nearby, young outflow sources makes it an excellent target for detailed studies of the gas kinematics of different species.We present observations of several molecular species, carried out with the Submillimeter Array and ALMA, towards the IRAS 15398 outflow. The analysis of CO emission show obvious signs of episodic mass ejections, with a dynamical time scale between the knots in the jet, of the order 100 years. This is consistent with recent ALMA results where luminosity outbursts are estimated to occur on similar time-scales. The physical properties of the outflow, such as mass, momentum, momentum rate, mechanical luminosity, kinetic energy and mass-loss rate are estimated at relatively low values. We argue that this source is of a very young age, possibly younger than ~1000 years. This is consistent with recent studies of the kinematics of the inner envelope/disk. The observed line profiles were compared to full 3D radiative transfer models of the source, constructed with the Line Modelling Engine (LIME). The observed line shapes can only be understood when considering several distinctly different physical components, viz. the outflow cavity, the infalling envelope and the surrounding cloud material. This allows us to put quantitative constraints on the kinematics of the material close to the central source.

Uncovering the Protostars in Serpens South with ALMA: Continuum Sources and Their Outflow Activity

NASA Astrophysics Data System (ADS)

Plunkett, Adele; Arce, H.; Corder, S.; Dunham, M.

2017-06-01

Serpens South is an appealing protostellar cluster to study due the combination of several factors: (1) a high protostar fraction that shows evidence for very recent and ongoing star formation; (2) iconic clustered star formation along a filamentary structure; (3) its relative proximity within a few hundred parsecs. An effective study requires the sensitivity, angular and spectral resolution, and mapping capabilities recently provided with ALMA. Here we present a multi-faceted data set acquired from Cycles 1 through 3 with ALMA, including maps of continuum sources and molecular outflows throughout the region, as well as a more focused kinematical study of the protostar that is the strongest continuum source at the cluster center. Together these data span spatial scales over several orders of magnitude, allowing us to investigate the outflow-driving sources and the impact of the outflows on the cluster environment. Currently, we focus on the census of protostars in the cluster center, numbering about 20, including low-flux, low-mass sources never before detected in mm-wavelengths and evidence for multiplicity that was previously unresolved.

Outflows, infall and evolution of a sample of embedded low-mass protostars. The William Herschel Line Legacy (WILL) survey

NASA Astrophysics Data System (ADS)

Mottram, J. C.; van Dishoeck, E. F.; Kristensen, L. E.; Karska, A.; San José-García, I.; Khanna, S.; Herczeg, G. J.; André, Ph.; Bontemps, S.; Cabrit, S.; Carney, M. T.; Drozdovskaya, M. N.; Dunham, M. M.; Evans, N. J.; Fedele, D.; Green, J. D.; Harsono, D.; Johnstone, D.; Jørgensen, J. K.; Könyves, V.; Nisini, B.; Persson, M. V.; Tafalla, M.; Visser, R.; Yıldız, U. A.

2017-04-01

Context. Herschel observations of water and highly excited CO (J > 9) have allowed the physical and chemical conditions in the more active parts of protostellar outflows to be quantified in detail for the first time. However, to date, the studied samples of Class 0/I protostars in nearby star-forming regions have been selected from bright, well-known sources and have not been large enough for statistically significant trends to be firmly established. Aims: We aim to explore the relationships between the outflow, envelope and physical properties of a flux-limited sample of embedded low-mass Class 0/I protostars. Methods: We present spectroscopic observations in H2O, CO and related species with Herschel HIFI and PACS, as well as ground-based follow-up with the JCMT and APEX in CO, HCO+ and isotopologues, of a sample of 49 nearby (d < 500 pc) candidate protostars selected from Spitzer and Herschel photometric surveys of the Gould Belt. This more than doubles the sample of sources observed by the WISH and DIGIT surveys. These data are used to study the outflow and envelope properties of these sources. We also compile their continuum spectral energy distributions (SEDs) from the near-IR to mm wavelengths in order to constrain their physical properties (e.g. Lbol, Tbol and Menv). Results: Water emission is dominated by shocks associated with the outflow, rather than the cooler, slower entrained outflowing gas probed by ground-based CO observations. These shocks become less energetic as sources evolve from Class 0 to Class I. Outflow force, measured from low-J CO, also decreases with source evolutionary stage, while the fraction of mass in the outflow relative to the total envelope (I.e. Mout/Menv) remains broadly constant between Class 0 and I. The median value of 1% is consistent with a core to star formation efficiency on the order of 50% and an outflow duty cycle on the order of 5%. Entrainment efficiency, as probed by FCO/Ṁacc, is also invariant with source properties and evolutionary stage. The median value implies a velocity at the wind launching radius of 6.3 km s-1, which in turn suggests an entrainment efficiency of between 30 and 60% if the wind is launched at 1 AU, or close to 100% if launched further out. L[O I] is strongly correlated with Lbol but not with Menv, in contrast to low-J CO, which is more closely correlated with the latter than the former. This suggests that [O I] traces the present-day accretion activity of the source while CO traces time-averaged accretion over the dynamical timescale of the outflow. H2O is more strongly correlated with Menv than Lbol, but the difference is smaller than low-J CO, consistent with water emission primarily tracing actively shocked material between the wind, traced by [O I], and the entrained molecular outflow, traced by low-J CO. L[O I] does not vary from Class 0 to Class I, unlike CO and H2O. This is likely due to the ratio of atomic to molecular gas in the wind increasing as the source evolves, balancing out the decrease in mass accretion rate. Infall signatures are detected in HCO+ and H2O in a few sources, but still remain surprisingly illusive in single-dish observations. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

Water in star-forming regions with Herschel (WISH). V. The physical conditions in low-mass protostellar outflows revealed by multi-transition water observations

NASA Astrophysics Data System (ADS)

Mottram, J. C.; Kristensen, L. E.; van Dishoeck, E. F.; Bruderer, S.; San José-García, I.; Karska, A.; Visser, R.; Santangelo, G.; Benz, A. O.; Bergin, E. A.; Caselli, P.; Herpin, F.; Hogerheijde, M. R.; Johnstone, D.; van Kempen, T. A.; Liseau, R.; Nisini, B.; Tafalla, M.; van der Tak, F. F. S.; Wyrowski, F.

2014-12-01

Context. Outflows are an important part of the star formation process as both the result of ongoing active accretion and one of the main sources of mechanical feedback on small scales. Water is the ideal tracer of these effects because it is present in high abundance for the conditions expected in various parts of the protostar, particularly the outflow. Aims: We constrain and quantify the physical conditions probed by water in the outflow-jet system for Class 0 and I sources. Methods: We present velocity-resolved Herschel HIFI spectra of multiple water-transitions observed towards 29 nearby Class 0/I protostars as part of the WISH guaranteed time key programme. The lines are decomposed into different Gaussian components, with each component related to one of three parts of the protostellar system; quiescent envelope, cavity shock and spot shocks in the jet and at the base of the outflow. We then use non-LTE radex models to constrain the excitation conditions present in the two outflow-related components. Results: Water emission at the source position is optically thick but effectively thin, with line ratios that do not vary with velocity, in contrast to CO. The physical conditions of the cavity and spot shocks are similar, with post-shock H2 densities of order 105 - 108 cm-3 and H2O column densities of order 1016 - 1018 cm-2. H2O emission originates in compact emitting regions: for the spot shocks these correspond to point sources with radii of order 10-200 AU, while for the cavity shocks these come from a thin layer along the outflow cavity wall with thickness of order 1-30 AU. Conclusions: Water emission at the source position traces two distinct kinematic components in the outflow; J shocks at the base of the outflow or in the jet, and C shocks in a thin layer in the cavity wall. The similarity of the physical conditions is in contrast to off-source determinations which show similar densities but lower column densities and larger filling factors. We propose that this is due to the differences in shock properties and geometry between these positions. Class I sources have similar excitation conditions to Class 0 sources, but generally smaller line-widths and emitting region sizes. We suggest that it is the velocity of the wind driving the outflow, rather than the decrease in envelope density or mass, that is the cause of the decrease in H2O intensity between Class 0 and I sources. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.Appendices are available in electronic form at http://www.aanda.orgReduced spectra are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/572/A21

Exploring the engines of molecular outflows

NASA Astrophysics Data System (ADS)

Testi, Leonardo

1995-03-01

Water vapour masers and CO outflows are well known to be associated with the youngest phases of evolution of massive stellar objects. Nevertheless, up to now there is a lack of high resolution multiwavelength study of the regions containing these objects. Using the VLA, the CSO and the TIRGO equipped with the new Near-Infrared (NIR) camera ARNICA, we have begun a systematic study of water maser/CO outflow regions. These new high resolution and high sensitivity data have proved to be very useful in probing the star formation activity and the connection between infrared and radio sources. Here we report the results obtained in a preliminary sub- sample of objects. The NIR data showed that both the maser spots and the large- scale outflows tend to be associated to the most embedded and probably younger sources of the infrared clusters. Infrared emission lines observed with narrow band filters show the presence of jet-like structures in most of the sources observed. Water masers, jet-like and Herbig-Haro-like infrared structures, and CO outflows enable to probe ejection phenomena at all spacial scales ranging from 0.01 to 1 parsec.

THE NATURE AND FREQUENCY OF OUTFLOWS FROM STARS IN THE CENTRAL ORION NEBULA CLUSTER

DOE Office of Scientific and Technical Information (OSTI.GOV)

O’Dell, C. R.; Ferland, G. J.; Henney, W. J.

Recent Hubble Space Telescope images have allowed the determination with unprecedented accuracy of motions and changes of shocks within the inner Orion Nebula. These originate from collimated outflows from very young stars, some within the ionized portion of the nebula and others within the host molecular cloud. We have doubled the number of Herbig–Haro objects known within the inner Orion Nebula. We find that the best-known Herbig–Haro shocks originate from relatively few stars, with the optically visible X-ray source COUP 666 driving many of them. While some isolated shocks are driven by single collimated outflows, many groups of shocks aremore » the result of a single stellar source having jets oriented in multiple directions at similar times. This explains the feature that shocks aligned in opposite directions in the plane of the sky are usually blueshifted because the redshifted outflows pass into the optically thick photon-dominated region behind the nebula. There are two regions from which optical outflows originate for which there are no candidate sources in the SIMBAD database.« less

Interactions between gravity waves and cold air outflows in a stably stratified uniform flow

NASA Technical Reports Server (NTRS)

Lin, Yuh-Lang; Wang, Ting-An; Weglarz, Ronald P.

1993-01-01

Interactions between gravity waves and cold air outflows in a stably stratified uniform flow forced by various combinations of prescribed heat sinks and sources are studied using a hydrostatic two-dimensional nonlinear numerical model. The formation time for the development of a stagnation point or reversed flow at the surface is not always directly proportional to the Froude number when wave reflections exist from upper levels. A density current is able to form by the wave-otuflow interaction, even though the Froude number is greater than a critical value. This is the result of the wave-outflow interaction shifting the flow response to a different location in the characteristic parameter space. A density current is able to form or be destroyed due to the wave-outflow interaction between a traveling gravity wave and cold air outflow. This is proved by performing experiments with a steady-state heat sink and an additional transient heat source. In a quiescent fluid, a region of cold air, convergence, and upward motion is formed after the collision between two outflows produced by two prescribed heat sinks. After the collision, the individual cold air outflows lose their own identity and merge into a single, stationary, cold air outflow region. Gravity waves tend to suppress this new stationary cold air outflow after the collision. The region of upward motion associated with the collision is confined to a very shallow layer. In a moving airstream, a density current produced by a heat sink may be suppressed or enhanced nonlinearly by an adjacent heat sink due to the wave-outflow interaction.

X-ray diving in the center of Sh2-129: looking for the driving source of Ou4

NASA Astrophysics Data System (ADS)

Grosso, Nicolas

2012-10-01

The outflow phenomenon is associated both with the early and the last phase of the stellar evolution. Recently, a unique bipolar outflow with an angular size of 1.2 degrees was discovered in the blister HII region Sh2-129. Ou4, nicknamed "The Giant Squid", is to our knowledge the bipolar outflow with the largest angular size ever found. We propose joint XMM-Newton/EPIC (35 ks) and Chandra/HRC-I (16 ks) observations to look for the driving source of Ou4 and to clarify the nature of this object.

Si Isotopes of Brownleeite

NASA Technical Reports Server (NTRS)

Nakamura-Messenger, K.; Messenger, Scott R.; Ito, M.; Keller, L. P.; Clemett, S. J.; Jones, J. H.; Tatsuoka, H.; Zolensky, M. E.; Tatsuoka, H.

2010-01-01

Brownleeite is a manganese silicide, ideally stoichiometric MnSi, not previously observed in nature until its discovery within an interplanetary dust particle (IDP) that likely originated from a comet [1]. Three discrete brownleeite grains in the IDP L2055 I3 (4 microns in size, hereafter IDP I3) were identified with maximum dimensions of 100, 250 and 600 nm and fully analyzed using scanning-transmission electron microscopy (STEM) [1]. One of the grains (100 nm in size) was poikilitically enclosed by low-Fe, Mn-enriched (LIME) olivine. LIME olivine is epitaxial to the brownleeite with the brownleeite (200) parallel to the olivine c* [1]. LIME olivine is an enigmatic phase first reported from chondritic porous IDPs and some unequilibrated ordinary chondrites [ 2], that is commonly observed in chondritic-porous IDPs. Recently, LIME olivine has been also found in comet Wild-2 (Stardust) samples [3], indicating that LIME olivine is a common mineral component of comets. LIME olivine has been proposed to form as a high temperature condensate in the protosolar nebula [2]. Brownleeite grains also likely formed as high-temperature condensates either in the early Solar System or in the outflow of an evolved star or supernova explosion [1]. The isotopic composition of the brownleeite grains may strongly constrain their ultimate source. To test this hypothesis, we performed isotopic analyses of the brownleeite and the associated LIME olivine, using the NASA/JSC NanoSIMS 50L ion microprobe.

Outflow structure and velocity field of Orion source. I. ALMA imaging of SiO isotopologue maser and thermal emission

NASA Astrophysics Data System (ADS)

Niederhofer, F.; Humphreys, E. M. L.; Goddi, C.

2012-12-01

Using Science Verification data from the Atacama Large Millimeter/Submillimeter Array (ALMA), we have identified and imaged five rotational transitions (J = 5-4 and J = 6-5) of the three silicon monoxide isotopologues 28SiO v = 0, 1, 2 and 29SiO v = 0 and 28Si18O v = 0 in the frequency range from 214 to 246 GHz towards the Orion BN/KL region. The emission of the ground-state 28SiO, 29SiO and 28Si18O shows an extended bipolar shape in the northeast-southwest direction at the position of Radio Source I, indicating that these isotopologues trace an outflow ( 18 km s-1, PA 50°, 5000 AU in diameter) that is driven by this embedded high-mass young stellar object (YSO). Whereas on small scales (10-1000 AU) the outflow from Source I has a well-ordered spatial and velocity structure, as probed by Very Long Baseline Interferometry (VLBI) imaging of SiO masers, the large scales (500-5000 AU) probed by thermal SiO with ALMA reveal a complex structure and velocity field, most likely related to the effects of the environment of the BN/KL region on the outflow emanating from Source I. The emission of the vibrationally-excited species peaks at the position of Source I. This emission is compact and not resolved at an angular resolution of 1farcs5 ( 600 AU at a distance of 420 pc). 2D Gaussian fitting to individual velocity channels locates emission peaks within radii of 100 AU, i.e. they trace the innermost part of the outflow. A narrow spectral profile and spatial distribution of the v = 1 J = 5-4 line similar to the masing v = 1 J = 1-0 transition, provide evidence for the most highly rotationally excited (frequency > 200 GHz) SiO maser emission associated with Source I known to date. The maser emission will enable studies of the Source I disk-outflow interface with future ALMA longest baselines.

The VLA Nascent Disk And Multiplicity Survey of Perseus Protostars (VANDAM). III. Extended Radio Emission from Protostars in Perseus

NASA Astrophysics Data System (ADS)

Tychoniec, Łukasz; Tobin, John J.; Karska, Agata; Chandler, Claire; Dunham, Michael M.; Li, Zhi-Yun; Looney, Leslie W.; Segura-Cox, Dominique; Harris, Robert J.; Melis, Carl; Sadavoy, Sarah I.

2018-01-01

Centimeter continuum emission from protostars offers insight into the innermost part of the outflows, as shock-ionized gas produces free–free emission. We observed a complete population of Class 0 and I protostars in the Perseus molecular cloud at 4.1 and 6.4 cm with resolution and sensitivity superior to previous surveys. From a total of 71 detections, eight sources exhibit resolved emission at 4.1 cm and/or 6.4 cm. In this paper, we focus on this subsample, analyzing their spectral indices along the jet and their alignment with respect to the large-scale molecular outflow. Spectral indices for fluxes integrated toward the position of the protostar are consistent with free–free thermal emission. The value of the spectral index along a radio jet decreases with distance from the protostar. For six sources, emission is well aligned with the outflow central axis, showing that we observe the ionized base of the jet. This is not the case for two sources, where we note misalignment of the emission with respect to the large-scale outflow. This might indicate that the emission does not originate in the radio jet, but rather in an ionized outflow cavity wall or disk surface. For five of the sources, the spectral indices along the jet decrease well below the thermal free–free limit of ‑0.1 with > 2σ significance. This is indicative of synchrotron emission, meaning that high-energy electrons are being produced in the outflows close to the disk. This result can have far-reaching implications for the chemical composition of the embedded disks.

Submillimeter array observations of NGC 2264-C: molecular outflows and driving sources

NASA Astrophysics Data System (ADS)

Cunningham, Nichol; Lumsden, Stuart L.; Cyganowski, Claudia J.; Maud, Luke T.; Purcell, Cormac

2016-05-01

We present 1.3 mm Submillimeter Array (SMA) observations at ˜3 arcsec resolution towards the brightest section of the intermediate/massive star-forming cluster NGC 2264-C. The millimetre continuum emission reveals ten 1.3 mm continuum peaks, of which four are new detections. The observed frequency range includes the known molecular jet/outflow tracer SiO (5-4), thus providing the first high-resolution observations of SiO towards NGC 2264-C. We also detect molecular lines of 12 additional species towards this region, including CH3CN, CH3OH, SO, H2CO, DCN, HC3N, and 12CO. The SiO (5-4) emission reveals the presence of two collimated, high-velocity (up to 30 km s-1 with respect to the systemic velocity) bipolar outflows in NGC 2264-C. In addition, the outflows are traced by emission from 12CO, SO, H2CO, and CH3OH. We find an evolutionary spread between cores residing in the same parent cloud. The two unambiguous outflows are driven by the brightest mm continuum cores, which are IR-dark, molecular line weak, and likely the youngest cores in the region. Furthermore, towards the Red MSX Source AFGL 989-IRS1, the IR-bright and most evolved source in NGC 2264-C, we observe no molecular outflow emission. A molecular line rich ridge feature, with no obvious directly associated continuum source, lies on the edge of a low-density cavity and may be formed from a wind driven by AFGL 989-IRS1. In addition, 229 GHz class I maser emission is detected towards this feature.

The nature of ULX source M101 X-1: optically thick outflow from a stellar mass black hole

NASA Astrophysics Data System (ADS)

Shen, Rong-Feng; Barniol Duran, Rodolfo; Nakar, Ehud; Piran, Tsvi

2015-02-01

The nature of ultraluminous X-ray sources (ULXs) has long been plagued by an ambiguity about whether the central compact objects are intermediate-mass (IMBH, ≳103 M⊙) or stellar-mass (a few tens M⊙) black holes (BHs). The high-luminosity (≃1039 erg s-1) and supersoft spectrum (T ≃ 0.1 keV) during the high state of the ULX source X-1 in the galaxy M101 suggest a large emission radius (≳109 cm), consistent with being an IMBH accreting at a sub-Eddington rate. However, recent kinematic measurement of the binary orbit of this source and identification of the secondary as a Wolf-Rayet star suggest a stellar-mass BH primary with a super-Eddington accretion. If that is the case, a hot, optically thick outflow from the BH can account for the large emission radius and the soft spectrum. By considering the interplay of photons' absorption and scattering opacities, we determine the radius and mass density of the emission region of the outflow and constrain the outflow mass-loss rate. The analysis presented here can be potentially applied to other ULXs with thermally dominated spectra, and to other super-Eddington accreting sources.

Analysis of Asian Outflow over the Western Pacific using Observations from Trace-P

NASA Technical Reports Server (NTRS)

Jacob, Daniel J.

2004-01-01

Our analysis of the TRACE-P data focused on answering the following questions: 1) How do anthropogenic sources in Asia contribute to chemical outflow over the western Pacific in spring? 2) How does biomass burning in southeast Asia contribute to this outflow? 3) How can the TRACE-P observations be used to better quantify the sources of environmentally important gases in eastern Asia? Our strategy drew on a combination of data analysis and global 3-D modeling, as described below. We also contributed to the planning and execution of TRACE-P through service as mission scientist and by providing chemical model forecasts in the field.

The Role of Cosmic-Ray Pressure in Accelerating Galactic Outflows

NASA Astrophysics Data System (ADS)

Simpson, Christine M.; Pakmor, Rüdiger; Marinacci, Federico; Pfrommer, Christoph; Springel, Volker; Glover, Simon C. O.; Clark, Paul C.; Smith, Rowan J.

2016-08-01

We study the formation of galactic outflows from supernova (SN) explosions with the moving-mesh code AREPO in a stratified column of gas with a surface density similar to the Milky Way disk at the solar circle. We compare different simulation models for SN placement and energy feedback, including cosmic rays (CRs), and find that models that place SNe in dense gas and account for CR diffusion are able to drive outflows with similar mass loading as obtained from a random placement of SNe with no CRs. Despite this similarity, CR-driven outflows differ in several other key properties including their overall clumpiness and velocity. Moreover, the forces driving these outflows originate in different sources of pressure, with the CR diffusion model relying on non-thermal pressure gradients to create an outflow driven by internal pressure and the random-placement model depending on kinetic pressure gradients to propel a ballistic outflow. CRs therefore appear to be non-negligible physics in the formation of outflows from the interstellar medium.

THE ROLE OF COSMIC-RAY PRESSURE IN ACCELERATING GALACTIC OUTFLOWS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Simpson, Christine M.; Pakmor, Rüdiger; Pfrommer, Christoph

We study the formation of galactic outflows from supernova (SN) explosions with the moving-mesh code AREPO in a stratified column of gas with a surface density similar to the Milky Way disk at the solar circle. We compare different simulation models for SN placement and energy feedback, including cosmic rays (CRs), and find that models that place SNe in dense gas and account for CR diffusion are able to drive outflows with similar mass loading as obtained from a random placement of SNe with no CRs. Despite this similarity, CR-driven outflows differ in several other key properties including their overallmore » clumpiness and velocity. Moreover, the forces driving these outflows originate in different sources of pressure, with the CR diffusion model relying on non-thermal pressure gradients to create an outflow driven by internal pressure and the random-placement model depending on kinetic pressure gradients to propel a ballistic outflow. CRs therefore appear to be non-negligible physics in the formation of outflows from the interstellar medium.« less

Searching for outflows in ultraluminous X-ray sources through high-resolution X-ray spectroscopy

NASA Astrophysics Data System (ADS)

Kosec, P.; Pinto, C.; Fabian, A. C.; Walton, D. J.

2018-02-01

Ultraluminous X-ray sources (ULXs) are non-nuclear point sources exceeding the Eddington luminosity of a 10 M⊙ black hole. Modern consensus for a majority of the ULX population is that they are powered by stellar-mass black holes or neutron stars accreting well above the Eddington limit. Theoretical models of super-Eddington accretion predict existence of powerful outflows of moderately ionized gas at mildly relativistic velocities. So far, these winds have been found in three systems: NGC 1313 X-1, NGC 5408 X-1 and NGC 55 ULX. In this work, we create a sample of all ULXs with usable archival high-resolution X-ray data, with 10 sources in total, in which we aim to find more signatures of outflows. We perform Gaussian line scans to find any narrow spectral signatures, and physical wind model scans where possible. We tentatively identify an outflow in NGC 5204 X-1, blueshifted to 0.34c, which produces emission features with a total significance of at least 3σ. Next we compare ULXs with similar hardness ratios. Holmberg IX X-1 shows absorption features that could be associated with a photoionized outflowing absorber, similar to that seen in NGC 1313 X-1. The spectrum of Holmberg II X-1 possesses features similar to NGC 5408 X-1 and NGC 6946 X-1 shows O VIII rest-frame emission. All other sources from the sample also show tentative evidence of spectral features in their high-resolution spectra. Further observations with the XMM-Newton and Chandra gratings will place stronger constraints. Future missions like XARM and Athena will be able to detect them at larger distances and increase our sample.

A highly embedded protostar in SFO 18: IRAS 05417+0907

NASA Astrophysics Data System (ADS)

Saha, Piyali; Gopinathan, Maheswar; Puravankara, Manoj; Sharma, Neha; Soam, Archana

2018-04-01

Bright-rimmed clouds, located at the periphery of relatively evolved HIT regions, are considered to be the sites of star formation possibly triggered by the implosion caused due to the ionizing radiation from nearby massive stars. SFO 18 is one such region showing a bright-rim on the side facing the 0-type star, A Ori. A point source, IRAS 05417+0907, is detected towards the high density region of the cloud. A molecular outflow has been found to be associated with the source. The outflow is directed towards a Herbig-Haro object, HH 175. From the Spitzer and WISE observations, we show evidence of a physical connection between the molecular outflow, IRAS 05417+0907 and the HH object. The spectral energy distribution constructed using multi-wavelength data shows that the point source is most likely a highly embedded protostar.

3D AMR hydrosimulations of a compact source scenario for the Galactic Centre cloud G2

NASA Astrophysics Data System (ADS)

Ballone, A.; Schartmann, M.; Burkert, A.; Gillessen, S.; Plewa, P. M.; Genzel, R.; Pfuhl, O.; Eisenhauer, F.; Habibi, M.; Ott, T.; George, E. M.

2018-06-01

The nature of the gaseous and dusty cloud G2 in the Galactic Centre is still under debate. We present three-dimensional hydrodynamical adaptive mesh refinement (AMR) simulations of G2, modeled as an outflow from a "compact source" moving on the observed orbit. The construction of mock position-velocity (PV) diagrams enables a direct comparison with observations and allow us to conclude that the observational properties of the gaseous component of G2 could be matched by a massive (\\dot{M}_w=5× 10^{-7} M_{⊙} yr^{-1}) and slow (50 km s-1) outflow, as observed for T Tauri stars. In order for this to be true, only the material at larger (>100 AU) distances from the source must be actually emitting, otherwise G2 would appear too compact compared to the observed PV diagrams. On the other hand, the presence of a central dusty source might be able to explain the compactness of G2's dust component. In the present scenario, 5-10 years after pericentre the compact source should decouple from the previously ejected material, due to the hydrodynamic interaction of the latter with the surrounding hot and dense atmosphere. In this case, a new outflow should form, ahead of the previous one, which would be the smoking gun evidence for an outflow scenario.

Formation of Glass with Embedded Metal and Sulfides from Shock-accelerated Crystalline Dust in Superbubbles

NASA Astrophysics Data System (ADS)

Westphal, A. J.; Bradley, J. P.

2004-12-01

Interplanetary dust particles (IDPs) contain enigmatic submicron components called GEMS (glass with embedded metal and sulfides). The compositions and structures of GEMS indicate that they have been processed by exposure to ionizing radiation, but details of the actual irradiation environment(s) have remained elusive. Here we propose a mechanism and astrophysical site for GEMS formation that explains for the first time the following key properties of GEMS: they are stoichiometrically enriched in oxygen and systematically depleted in S, Mg, Ca, and Fe (relative to solar abundances); most have normal (solar) oxygen isotopic compositions; they exhibit a strikingly narrow size distribution (0.1-0.5 μm diameter); and some of them contain ``relict'' crystals within their silicate glass matrices. We show that the compositions, size distribution, and survival of relict crystals are inconsistent with amorphization by particles accelerated by diffusive shock acceleration. Instead, we propose that GEMS are formed from crystalline grains that condense in stellar outflows from massive stars in OB associations, are accelerated in encounters with frequent supernova shocks inside the associated superbubble (SB), and are implanted with atoms from the hot gas in the SB interior. We thus reverse the usual roles of target and projectile. Rather than being bombarded at rest by energetic ions, grains are accelerated and bombarded by a nearly monovelocity beam of atoms as viewed in their rest frame. Meyer, Drury, and Ellison have proposed that Galactic cosmic rays (GCRs) originate from ions sputtered from such accelerated dust grains. We suggest that GEMS are surviving members of a population of fast grains that constitute the long-sought source material for GCRs. Thus, representatives of the GCR source material may have been awaiting discovery in cosmic dust labs for the last 30 yr.

The terrestrial plasma source - A new perspective in solar-terrestrial processes from Dynamics Explorer

NASA Technical Reports Server (NTRS)

Chappell, Charles R.

1988-01-01

The geospace environment has been viewed as a mixing bowl for plasmas of both solar and terrestrial origin. The present perspective on the nature of the supply mechanisms has undergone a radical evolution over the past decade, particularly during the five years of the Dynamics Explorer mission. During this period, the terrestrial source has increased in importance in both magnitude and character of ionospheric outflow. These outflows include the classical polar wind, the cleft ion fountain, the auroral ion fountain, and the polar cap. The earth can be envisioned as a multifaceted fountain which ejects particles from different spatial locations spread around the globe. These particles exhibit a range of masses from 1 to 32 amu and a range of energies from 1 eV to 10 keV. The total flux of this ionospheric outflow is very large: adequate to supply the entire magnetospheric particle population. And the implications of the outflow are significant across a broad spectrum of solar-terrestrial processes ranging from sources of magnetospheric plasmas, to influences on ionospheric density and temperature structure, to energy transfer in phenomena such as stable auroral red arcs. The Dynamics Explorer mission has made a major contribution in the characterization of the terrestrial plasma source.

A precessing jet in the NGC2264G outflow

NASA Astrophysics Data System (ADS)

McCoey, Carolyn; Teixeira, P. S.; Fich, M.; Lada, C. J.

2007-05-01

We present new infrared imaging of the NGC 2264 G protostellar outflow region, obtained with the Spitzer Space Telescope. A jet in the red (eastern) outflow lobe is clearly detected in all four IRAC bands and, for the first time, is shown to continuously extend over the entire length of the red outflow lobe, as traced by CO observations. The jet also extends to a deeply embedded Class 0 source, VLA2, confirming previous suggestions that it is the driving source of the outflow. The images show that the easternmost part of the jet exhibits what appears to be multiple changes of direction. We consider two possible explanations for the jet morphology: (i) deflection of the jet off the walls of the outflow lobes as proposed by Fich & Lada (1997) and (ii) precession. The jet structure shown in the IRAC images can be largely, although not entirely, explained by a slowly precessing jet (period 8000 yr) that lies mostly on the plane of the sky. In either case it appears that the observed and inferred changes in the jet direction are sufficient to broaden the NGC 2264 G outflow to an extent comparable to that observed in the CO emission. P. S. T. acknowledges support from the scholarship SFRH/BD/13984/2003 awarded by the Fundaçao para a Ciencia e Tecnologia (Portugal). Both M. F. and C. M. are supported by a Natural Sciences and Engineering Research Council of Canada (NSERC) Discovery Grant.

Herschel GASPS spectral observations of T Tauri stars in Taurus. Unraveling far-infrared line emission from jets and discs

NASA Astrophysics Data System (ADS)

Alonso-Martínez, M.; Riviere-Marichalar, P.; Meeus, G.; Kamp, I.; Fang, M.; Podio, L.; Dent, W. R. F.; Eiroa, C.

2017-07-01

Context. At early stages of stellar evolution young stars show powerful jets and/or outflows that interact with protoplanetary discs and their surroundings. Despite the scarce knowledge about the interaction of jets and/or outflows with discs, spectroscopic studies based on Herschel and ISO data suggests that gas shocked by jets and/or outflows can be traced by far-IR (FIR) emission in certain sources. Aims: We want to provide a consistent catalogue of selected atomic ([OI] and [CII]) and molecular (CO, H2O, and OH) line fluxes observed in the FIR, separate and characterize the contribution from the jet and the disc to the observed line emission, and place the observations in an evolutionary picture. Methods: The atomic and molecular FIR (60-190 μm) line emission of protoplanetary discs around 76 T Tauri stars located in Taurus are analysed. The observations were carried out within the Herschel key programme Gas in Protoplanetary Systems (GASPS). The spectra were obtained with the Photodetector Array Camera and Spectrometer (PACS). The sample is first divided in outflow and non-outflow sources according to literature tabulations. With the aid of archival stellar/disc and jet/outflow tracers and model predictions (PDRs and shocks), correlations are explored to constrain the physical mechanisms behind the observed line emission. Results: Outflow sources exhibit brighter atomic and molecular emission lines and higher detection rates than non-outflow sources. The line detection fractions decrease with SED evolutionary status (from Class I to Class III). We find correlations between [OI] 63.18 μm and [OI] 6300 Å, o-H2O 78.74 μm, CO 144.78 μm, OH 79.12+79.18 μm, and the continuum flux at 24 μm. The atomic line ratios can be explain either by fast (Vshock > 50 km s-1) dissociative J-shocks at low densities (n 103 cm-3) occurring along the jet and/or PDR emission (G0 > 102, n 103-106 cm-3). To account for the [CII] absolute fluxes, PDR emission or UV irradiation of shocks is needed. In comparison, the molecular emission is more compact and the line ratios are better explained with slow (Vshock < 40 km s-1) C-type shocks with high pre-shock densities (104-106 cm-3), with the exception of OH lines, that are better described by J-type shocks. Disc models alone fail to reproduce the observed molecular line fluxes, but a contribution to the line fluxes from UV-illuminated discs and/or outflow cavities is expected. Far-IR lines dominate disc cooling at early stages and weaken as the star+disc system evolves from Class I to Class III, with an increasing relative disc contribution to the line fluxes. Conclusions: Models which take into account jets, discs, and their mutual interaction are needed to disentangle the different components and study their evolution. The much higher detection rate of emission lines in outflow sources and the compatibility of line ratios with shock model predictions supports the idea of a dominant contribution from the jet/outflow to the line emission, in particular at earlier stages of the stellar evolution as the brightness of FIR lines depends in large part on the specific evolutionary stage. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

Formation and spatial distribution of hypervelocity stars in AGN outflows

NASA Astrophysics Data System (ADS)

Wang, Xiawei; Loeb, Abraham

2018-05-01

We study star formation within outflows driven by active galactic nuclei (AGN) as a new source of hypervelocity stars (HVSs). Recent observations revealed active star formation inside a galactic outflow at a rate of ∼ 15M⊙yr-1 . We verify that the shells swept up by an AGN outflow are capable of cooling and fragmentation into cold clumps embedded in a hot tenuous gas via thermal instabilities. We show that cold clumps of ∼ 103 M⊙ are formed within ∼ 105 yrs. As a result, stars are produced along outflow's path, endowed with the outflow speed at their formation site. These HVSs travel through the galactic halo and eventually escape into the intergalactic medium. The expected instantaneous rate of star formation inside the outflow is ∼ 4 - 5 orders of magnitude greater than the average rate associated with previously proposed mechanisms for producing HVSs, such as the Hills mechanism and three-body interaction between a star and a black hole binary. We predict the spatial distribution of HVSs formed in AGN outflows for future observational probe.

Required, tissue-specific roles for Fgf8 in outflow tract formation and remodeling.

PubMed

Park, Eon Joo; Ogden, Lisa A; Talbot, Amy; Evans, Sylvia; Cai, Chen-Leng; Black, Brian L; Frank, Deborah U; Moon, Anne M

2006-06-01

Fibroblast growth factor 8 (Fgf8) is a secreted signaling protein expressed in numerous temporospatial domains that are potentially relevant to cardiovascular development. However, the pathogenesis of complex cardiac and outflow tract defects observed in Fgf8-deficient mice, and the specific source(s) of Fgf8 required for outflow tract formation and subsequent remodeling are unknown. A detailed examination of the timing and location of Fgf8 production revealed previously unappreciated expression in a subset of primary heart field cells; Fgf8 is also expressed throughout the anterior heart field (AHF) mesoderm and in pharyngeal endoderm at the crescent and early somite stages. We used conditional mutagenesis to examine the requirements for Fgf8 function in these different expression domains during heart and outflow tract morphogenesis. Formation of the primary heart tube and the addition of right ventricular and outflow tract myocardium depend on autocrine Fgf8 signaling in cardiac crescent mesoderm. Loss of Fgf8 in this domain resulted in decreased expression of the Fgf8 target gene Erm, and aberrant production of Isl1 and its target Mef2c in the anterior heart field, thus linking Fgf8 signaling with transcription factor networks that regulate survival and proliferation of the anterior heart field. We further found that mesodermal- and endodermal-derived Fgf8 perform specific functions during outflow tract remodeling: mesodermal Fgf8 is required for correct alignment of the outflow tract and ventricles, whereas activity of Fgf8 emanating from pharyngeal endoderm regulates outflow tract septation. These findings provide a novel insight into how the formation and remodeling of primary and anterior heart field-derived structures rely on Fgf8 signals from discrete temporospatial domains.

Correction to "Asian chemical Outflow to the Pacific in Spring: Origins, Pathways, and Budgets" by Isabelle Bey et al.

NASA Technical Reports Server (NTRS)

Bey, Isabelle; Jacob, Daniel J.; Logan, Jennifer A.; Yantosca, Robert M.

2003-01-01

We analyze the Asian outflow of CO, ozone, and nitrogen oxides (NOx) to the Pacific in spring by using the GEOS-CHEM global three-dimensional model of tropospheric chemistry and simulating the Pacific Exploratory Mission-West (PEM-West B) aircraft mission in February-March 1994. The GEOS-CHEM model uses assimilated meteorological fields from the NASA Goddard Earth Observing System (GEOS). It reproduces relatively well the main features of tropospheric ozone, CO, and reactive nitrogen species observed in PEM-West B, including latitudinal and vertical gradients of the Asian pollution outflow over the western Pacific although simulated concentrations of CO tend to be too low (possibly because biogenic sources are underestimated). We use CO as a long-lived tracer to diagnose the processes contributing to the outflow. The highest concentrations in the outflow are in the boundary layer (0-2 km), but the strongest outflow fluxes are in the lower free troposphere (2-5 km) and reflect episodic lifting of pollution over central and eastern China ahead of eastward moving cold fronts. This frontal lifting, followed by westerly transport in the lower free troposphere, is the principal process responsible for export of both anthropogenic and biomass burning pollution from Asia. Anthropogenic emissions from Europe and biomass burning emissions from Africa make also major contributions to the Asian outflow over the western Pacific; European sources dominate in the lower troposphere north of 40 degrees N, while African sources are important in the upper troposphere at low latitudes. For the period of PEM-West B (February-March) we estimate that fossil fuel combustion and biomass burning make comparable contributions to the budgets of CO, ozone, and NO, in the Asian outflow. We find that 13% of NO, emitted in Asia is exported as NO, or PAN, a smaller fraction than for the United States because of higher aerosol concentrations that promote heterogeneous conversion of NOx to HNO3. Production and export of ozone from Asia in spring is much greater than from the United States because of the higher photochemical activity.

A Sleeping Giant Awakened: Reignition of AGN Activity, Reborn Star Formation, and a Multiphase Outflow in one of the Largest Radio Galaxies Known

NASA Astrophysics Data System (ADS)

Tremblay, Grant; O'Dea, Christopher; Labiano, Alvaro; Baum, Stefi; McDermid, Richard; Combes, Francoise; Garcia-Burillo, Santiago; Davis, Timothy

2014-08-01

3C 236 is the second largest known radio galaxy and one of the largest objects in the known Universe. Its central AGN has recently reignited after a 10 Myr dormancy period, giving rise to a very young and compact radio source and a 1000 km/sec outflow of warm ionized and atomic HI gas. We propose GMOS-N IFU observations to resolve this outflow, determine its driver, and estimate the relative coupling efficiencies between the warm ionized, atomic, and cold molecular gas phases. We will assemble a much-needed spatially resolved Balmer decrement (extinction map) across the dramatic double dust lanes of this source, enabling high spatial resolution star formation rate, efficiency, and gas excitation and velocity maps. These will address several mysteries related to the very high star formation efficiency and the unique nature of the multiphase outflow in this source. 3C 236 is such a remarkable galaxy that whatever the results of the proposed observations, they will have wide-ranging implications for the triggering of star formation and AGN activity, their possibly coupled co-evolution, and the feedback effects of the latter on the former.

The circum-Chryse region as a possible example of a hydrologic cycle on Mars: Geologic observations and theoretical evaluation

NASA Technical Reports Server (NTRS)

Moore, Jeffrey M.; Clow, Gary D.; Davis, Wanda L.; Gulick, Virginia C.; Janke, David R.; Mckay, Christopher P.; Stoker, Carol R.; Zent, Aaron P.

1995-01-01

The transection and superposition relationships among channels, chaos, surface materials units, and other features in the circum-Chryse region of Mars were used to evaluate relative age relationships and evolution of flood events. Channels and chaos in contact (with one another) were treated as single discrete flood-carved systems. Some outflow channel systems form networks and are inferred to have been created by multiple flood events. Within some outflow channel networks, several separate individual channel systems can be traced to a specific chaos which acted as flood-source area to that specific flood channel. Individual flood-carved systems were related to widespread materials units or other surface features that served as stratigraphic horizons. Chryse outflow channels are inferred to have formed over most of the perceivable history of Mars. Outflow channels are inferred to become younger with increasing proximity to the Chryse basin. The relationship of subsequent outflow channel sources to the sources of earlier floods is inferred to disfavor episodic flooding due to the progresssive tapping of a juvenile near-surface water supply. Instead, we propose the circum-Chryse region as a candidate site of past hydrological recycling. The discharge rates necessary to carve the circum-Chryse outflow channels would have inevitably formed temporary standing bodies of H2O on the Martian surface where the flood-waters stagnated and pooled (the Chryse basin is topographically enclosed). These observations and inferences have led us to formulate and evaluate two hypotheses. Our numerical evaluations indicate that of these two hypotheses formulated, the groundwater seep cycle seems by far the more viable. Further observations from forthcoming missions may permit the determination of which mechanisms may have operated to recycle the Chryse flood-waters.

Another piece of the puzzle: The fast H I outflow in Mrk 231

NASA Astrophysics Data System (ADS)

Morganti, Raffaella; Veilleux, Sylvain; Oosterloo, Tom; Teng, Stacy H.; Rupke, David

2016-09-01

We present the detection, performed with the Westerbork Synthesis Radio Telescope (WSRT) and the Karl Jansky Very Large Array (VLA), of a fast H I 21 cm outflow in the ultra-luminous infrared galaxy Mrk 231. The outflow is observed as shallow H I absorption blueshifted ~1300 km s-1 with respect to the systemic velocity and located against the inner kpc of the radio source. The outflowing gas has an estimated column density between 5 and 15 × 1018Tspin cm-2. We derive the Tspin to lie in the range 400-2000 K and the corresponding H I densities are nHI ~ 10-100 cm-3. Our results complement previous findings and confirm the multiphase nature of the outflow in Mrk 231. Although effects of the interaction between the radio plasma and the surrounding medium cannot be ruled out, the energetics and the lack of a clear kpc-scale jet suggest that the most likely origin of the H I outflow is a wide-angle nuclear wind, as earlier proposed to explain the neutral outflow traced by Na I and molecular gas in this source. Our results suggest that an H I component is present in fast outflows regardless of the acceleration mechanism (wind vs. jet driven) and that it must be connected with common properties of the pre-interaction gas involved. Considering the observed similarity of their column densities, the H I outflow likely represents the inner part of the broad wind identified on larger scales in atomic Na I. The mass outflow rate of the H I outflow (between 8 and 18 M⊙ yr-1) does not appear to be as large as that observed in molecular gas, partly owing to the smaller sizes of the outflowing region sampled by the H I absorption. These characteristics are commonly seen in other cases of outflows driven by the active galactic nucleus (AGN) suggesting that the H I may represent a short intermediate phase in the rapid cooling of the gas. The results further confirm H I as a good tracer for AGN-driven outflows not only in powerful radio sources. We also obtained deeper continuum images than previously available. They confirm the complex structure of the radio continuum originating both from the AGN and star formation. At the resolution obtained with the VLA (~1'') we do not see a kpc-scale jet. Instead, we detect a plateau of emission, likely due to star formation, surrounding the bright nuclear region. We also detect a poorly collimated bridge which may represent the channel feeding the southern lobe. The unprecedented depth of the low-resolution WSRT image reveals radio emission extending 50'' (43 kpc) to the south and 20'' (17 kpc) to the north. The continuum images and the average spectra (FITS files) are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/593/A30

A green roof experimental site in the Mediterranean climate: the storm water quality issue.

PubMed

Gnecco, Ilaria; Palla, Anna; Lanza, Luca G; La Barbera, Paolo

2013-01-01

Since 2007, the University of Genoa has been carrying out a monitoring programme to investigate the hydrologic response of green roofs in the Mediterranean climate by installing a green roof experimental site. In order to assess the influence of green roofs on the storm water runoff quality, water chemistry data have been included in the monitoring programme since 2010, providing rainfall and outflow data. For atmospheric source, the bulk deposition is collected to evaluate the role of the overall atmospheric deposition in storm water runoff quality. For subsurface outflow, a maximum of 24 composite samples are taken on an event basis, thus aiming at a full characterization of the outflow hydrograph. Water chemistry data reveal that the pollutant loads associated with green roof outflow is low; in particular, solids and metal concentrations are lower than values generally observed in storm water runoff from traditional rooftops. The concentration values of chemical oxygen demand, total dissolved solids, Fe, Ca and K measured in the subsurface outflow are significantly higher than those observed in the bulk deposition (p < 0.05). With respect to the atmospheric deposition, the green roof behaviour as a sink/source of pollutants is investigated based on both concentration and mass.

Lunar and Planetary Science XXXV: Ancient Mars Water and Landforms

NASA Technical Reports Server (NTRS)

2004-01-01

Titles in this section include: 1) Giant Lowland Polygons: Relics of an Ancient Martian Ocean? 2) Lake Shorelines: Earth Analogs for Hypothesized Martian Coastal Features; 3) Complex Evolution of Paleolacustrine Systems on Mars: An Example from the Holden Crater; 4) Geomorphology and Hydraulics of Ma'adim Vallis, Mars, During a Noachian/Hesperian Boundary Paleoflood; 5) Geologic Evolution of Dao Vallis, Mars; 6) Advances in Reconstructing the Geologic History of the Chryse Region Outflow Channels on Mars; 7) Ravi Vallis, Mars - Paleoflood Origin and Genesis of Secondary Chaos Zones; 8) Walla Walla Vallis and Wallula Crater: Two Recently Discovered Martian Features Record Aqueous History; 9) Tharsis Recharge: a Source of Groundwater for Martian Outflow Channels; 10) Factors Controlling Water Volumes and Release Rates in Martian Outflow Channels; 11) Significance of Confined Cavernous Systems for Outflow Channel Water Sources, Reactivation Mechanisms and Chaos Formation; 12) Systematic Differences in Topography of Martian and Terrestrial Drainage Basins; 13) Waves on Seas of Mars and Titan: Wind-Tunnel Experiments on Wind-Wave Generation in Extraterrestrial Atmospheres.

Role of Non-Precipitation Sources in Regulating the River Hydrology of a Himalayan Catchment

NASA Astrophysics Data System (ADS)

Grover, S.; Tayal, S.; Beldring, S.

2017-12-01

Hydrology of mountain catchments in Himalayas is strongly regulated by snow/ ice melt. Chenab basin of Himalayas is a snow and glacier fed basin, which makes it perennial and an important source of sustenance for downstream community. It is important to understand the variability in contribution from various sources to the water balance of catchment. Indirect assessment techniques are important to make such an assessment about the runoff patterns especially in data-scarce basins like Chenab. To analyze runoff patterns and contribution from different sources, we applied combination of semi-distributed HBV model and water balance approach for the period between 1971-2007. It was found that the contribution from non-precipitation sources to the total outflow in this region ranged from 30-70% with approximately 30% from glacier ice melt, and base-flow contributing around 20% to annual water-balance. Least precipitation year of 1977 shows maximum contribution from other sources, but also recorded the least outflow in catchment. Seasonal variation of the contribution from glacier ice melt was also estimated and in the months of May and June around 44% of the contribution to the outflow is from glacier melt only. Hydrological balance of the basin is positive during winters with outflow being very less than the inflow of water through precipitation or melt. Melt season starts in March but peaks during May and June with cryospheric contribution being almost twice the base flow contribution. Melting starts receding slowly after September, with its contribution to the outflow declining much below the baseflow contribution in October and November, when base-flow provides around 65% of water to the basin's outflow. Long term (1951-2010) temperature and precipitation data for the higher reaches of the basin indicates a warming trend (0.02 0C yr-1) and a decline in annual precipitation. But on a basin scale, precipitation is increasing and the non-precipitation contribution from snow/ ice melt and base flow is declining. This further emphasizes the fact that climate change is affecting the precipitation regime and liquid precipitation is taking a dominant position in an otherwise snow/ ice fed catchment. Thus, in Chenab basin, non-precipitation contribution is important to drive its water balance.

A Molecular-line Study of the Interstellar Bullet Engine IRAS05506+2414

NASA Astrophysics Data System (ADS)

Sahai, Raghvendra; Lee, Chin-Fei; Sánchez Contreras, Carmen; Patel, Nimesh; Morris, Mark R.; Claussen, Mark

2017-12-01

We present interferometric and single-dish molecular line observations of the interstellar bullet-outflow source IRAS 05506+2414, whose wide-angle bullet spray is similar to the Orion BN/KL explosive outflow and likely arises from an entirely different mechanism than the classical accretion-disk-driven bipolar flows in young stellar objects. The bullet-outflow source is associated with a large pseudo-disk and three molecular outflows—a high-velocity outflow (HVO), a medium-velocity outflow (MVO), and a slow, extended outflow (SEO). The size (mass) of the pseudo-disk is 10,350 au × 6400 au (0.64-0.17 M ⊙) from a model-fit assuming infall and rotation, we derive a central stellar mass of 8-19 M ⊙. The HVO (MVO) has an angular size ˜5180 (˜3330) au and a projected outflow velocity of ˜140 km s-1 (˜30 km s-1). The SEO size (outflow speed) is ˜0.9 pc (˜6 km s-1). The HVO’s axis is aligned with (orthogonal to) that of the SEO (pseudo-disk). The velocity structure of the MVO is unresolved. The scalar momenta in the HVO and SEO are very similar, suggesting that the SEO has resulted from the HVO interacting with ambient-cloud material. The bullet spray shares a common axis with the pseudo-disk and has an age comparable to that of MVO (few hundred years), suggesting that these three structures are intimately linked. We discuss several models for the outflows in IRAS 05506+2414 (including dynamical decay of a stellar cluster, chance encounter of a runaway star with a dense cloud, and close passage of two protostars), and conclude that second-epoch imaging to derive proper motions of the bullets and nearby stars can help to discriminate between them.

The two-way relationship between ionospheric outflow and the ring current

DOE Office of Scientific and Technical Information (OSTI.GOV)

Welling, Daniel T.; Jordanova, Vania Koleva; Glocer, Alex

It is now well established that the ionosphere, because it acts as a significant source of plasma, plays a critical role in ring current dynamics. However, because the ring current deposits energy into the ionosphere, the inverse may also be true: the ring current can play a critical role in the dynamics of ionospheric outflow. This study uses a set of coupled, first-principles-based numerical models to test the dependence of ionospheric outflow on ring current-driven region 2 field-aligned currents (FACs). A moderate magnetospheric storm event is modeled with the Space Weather Modeling Framework using a global MHD code (Block Adaptivemore » Tree Solar wind Roe-type Upwind Scheme, BATS-R-US), a polar wind model (Polar Wind Outflow Model), and a bounce-averaged kinetic ring current model (ring current atmosphere interaction model with self-consistent magnetic field, RAM-SCB). Initially, each code is two-way coupled to all others except for RAM-SCB, which receives inputs from the other models but is not allowed to feed back pressure into the MHD model. The simulation is repeated with pressure coupling activated, which drives strong pressure gradients and region 2 FACs in BATS-R-US. It is found that the region 2 FACs increase heavy ion outflow by up to 6 times over the non-coupled results. The additional outflow further energizes the ring current, establishing an ionosphere-magnetosphere mass feedback loop. This study further demonstrates that ionospheric outflow is not merely a plasma source for the magnetosphere but an integral part in the nonlinear ionosphere-magnetosphere-ring current system.« less

The two-way relationship between ionospheric outflow and the ring current

DOE PAGES

Welling, Daniel T.; Jordanova, Vania Koleva; Glocer, Alex; ...

2015-06-01

It is now well established that the ionosphere, because it acts as a significant source of plasma, plays a critical role in ring current dynamics. However, because the ring current deposits energy into the ionosphere, the inverse may also be true: the ring current can play a critical role in the dynamics of ionospheric outflow. This study uses a set of coupled, first-principles-based numerical models to test the dependence of ionospheric outflow on ring current-driven region 2 field-aligned currents (FACs). A moderate magnetospheric storm event is modeled with the Space Weather Modeling Framework using a global MHD code (Block Adaptivemore » Tree Solar wind Roe-type Upwind Scheme, BATS-R-US), a polar wind model (Polar Wind Outflow Model), and a bounce-averaged kinetic ring current model (ring current atmosphere interaction model with self-consistent magnetic field, RAM-SCB). Initially, each code is two-way coupled to all others except for RAM-SCB, which receives inputs from the other models but is not allowed to feed back pressure into the MHD model. The simulation is repeated with pressure coupling activated, which drives strong pressure gradients and region 2 FACs in BATS-R-US. It is found that the region 2 FACs increase heavy ion outflow by up to 6 times over the non-coupled results. The additional outflow further energizes the ring current, establishing an ionosphere-magnetosphere mass feedback loop. This study further demonstrates that ionospheric outflow is not merely a plasma source for the magnetosphere but an integral part in the nonlinear ionosphere-magnetosphere-ring current system.« less

Nutrients in waters on the inner shelf between Cape Charles and Cape Hatteras

NASA Technical Reports Server (NTRS)

Wong, G. T. F.; Todd, J. F.

1981-01-01

The distribution of nutrients in the shelf waters of the southern tip of the Middle Atlantic Bight was investigated. It is concluded that the outflow of freshwater from the Chesapeake Bay is a potential source of nutrients to the adjacent shelf waters. However, a quantitative estimation of its importance cannot yet be made because (1) there are other sources of nutrients to the study area and these sources cannot yet be quantified and (2) the concentrations of nutrients in the outflow from Chesapeake Bay exhibit significant short-term and long-term temporal variabilities.

THE ORION FINGERS: NEAR-IR SPECTRAL IMAGING OF AN EXPLOSIVE OUTFLOW

DOE Office of Scientific and Technical Information (OSTI.GOV)

Youngblood, Allison; Bally, John; Ginsburg, Adam, E-mail: allison.youngblood@colorado.edu

2016-06-01

We present near-IR (1.1–2.4 μ m) position–position–velocity cubes of the 500 year old Orion BN/KL explosive outflow with spatial resolution 1″ and spectral resolution 86 km s{sup −1}. We construct integrated intensity maps free of continuum sources of 15 H{sub 2} and [Fe ii] lines while preserving kinematic information of individual outflow features. Included in the detected H{sub 2} lines are the 1-0 S(1) and 1-0 Q(3) transitions, allowing extinction measurements across the outflow. Additionally, we present dereddened flux ratios for over two dozen outflow features to allow for the characterization of the true excitation conditions of the BN/KL outflow. All of themore » ratios show the dominance of the shock excitation of the H{sub 2} emission, although some features exhibit signs of fluorescent excitation from stellar radiation or J-type shocks. We also detect tracers of the PDR/ionization front north of the Trapezium stars in [O i] and [Fe ii] and analyze other observed outflows not associated with the BN/KL outflow.« less

DISCOVERY OF RELATIVISTIC OUTFLOW IN THE SEYFERT GALAXY Ark 564

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gupta, A.; Mathur, S.; Krongold, Y.

2013-07-20

We present Chandra High Energy Transmission Grating Spectra of the narrow-line Seyfert-1 galaxy Ark 564. The spectrum shows numerous absorption lines which are well modeled with low-velocity outflow components usually observed in Seyfert galaxies. There are, however, some residual absorption lines which are not accounted for by low-velocity outflows. Here, we present identifications of the strongest lines as K{alpha} transitions of O VII (two lines) and O VI at outflow velocities of {approx}0.1c. These lines are detected at 6.9{sigma}, 6.2{sigma}, and 4.7{sigma}, respectively, and cannot be due to chance statistical fluctuations. Photoionization models with ultra-high velocity components improve the spectralmore » fit significantly, providing further support for the presence of relativistic outflow in this source. Without knowing the location of the absorber, its mass and energy outflow rates cannot be well constrained; we find E-dot (outflow)/L{sub bol} lower limit of {>=}0.006% assuming a bi-conical wind geometry. This is the first time that absorption lines with ultra-high velocities are unambiguously detected in the soft X-ray band. The presence of outflows with relativistic velocities in active galactic nuclei (AGNs) with Seyfert-type luminosities is hard to understand and provides valuable constraints to models of AGN outflows. Radiation pressure is unlikely to be the driving mechanism for such outflows and magnetohydrodynamic may be involved.« less

Bipolar outflows and Jets From Young Stars

NASA Astrophysics Data System (ADS)

Bally, J.

2000-05-01

Stars produce powerful jets and winds during their birth. These primary outflows power shock waves (Herbig-Haro objects) and entrain surrounding gas to produce molecular outflows. Many outflows reach parsec-scale dimensions whose dynamical ages can become comparable to the accretion age of the source star. Thus, these giant outflows provide fossil records of the mass loss histories of their parent stars. Jet symmetries provide tantalizing clues about the violent history of stellar accretion and dynamical interactions with nearby companions. These flows inject sufficient energy and momentum into the surrounding medium to alter the physical and chemical state of the gas, generate turbulence, disrupt the parent cloud, and self-regulate the rate of star formation. Recent observations have revealed a new class of externally irradiated jets which are rendered visible by the light of nearby massive stars. Some of these jets appear to be millions of years old, indicating that outflow activity can persist for much longer than previously thought. Stellar jets provide ideal laboratories for the investigation of accretion powered outflows and associated shocks since their time-dependent behavior can be observed with a rich variety of spectral line diagnostics.

Massive Outflows Associated with ATLASGAL Clumps

NASA Astrophysics Data System (ADS)

Yang, A. Y.; Thompson, M. A.; Urquhart, J. S.; Tian, W. W.

2018-03-01

We have undertaken the largest survey for outflows within the Galactic plane using simultaneously observed {}13{CO} and {{{C}}}18{{O}} data. Out of a total of 919 ATLASGAL clumps, 325 have data suitable to identify outflows, and 225 (69% ± 3%) show high-velocity outflows. The clumps with detected outflows show significantly higher clump masses ({M}clump}), bolometric luminosities ({L}bol}), luminosity-to-mass ratios ({L}bol}/{M}clump}), and peak H2 column densities ({N}{{{H}}2}) compared to those without outflows. Outflow activity has been detected within the youngest quiescent clump (i.e., 70 μ {{m}} weak) in this sample, and we find that the outflow detection rate increases with {M}clump}, {L}bol}, {L}bol}/{M}clump}, and {N}{{{H}}2}, approaching 90% in some cases (UC H II regions = 93% ± 3%; masers = 86% ± 4%; HC H II regions = 100%). This high detection rate suggests that outflows are ubiquitous phenomena of massive star formation (MSF). The mean outflow mass entrainment rate implies a mean accretion rate of ∼ {10}-4 {M}ȯ {yr}}-1, in full agreement with the accretion rate predicted by theoretical models of MSF. Outflow properties are tightly correlated with {M}clump}, {L}bol}, and {L}bol}/{M}clump} and show the strongest relation with the bolometric clump luminosity. This suggests that outflows might be driven by the most massive and luminous source within the clump. The correlations are similar for both low-mass and high-mass outflows over 7 orders of magnitude, indicating that they may share a similar outflow mechanism. Outflow energy is comparable to the turbulent energy within the clump; however, we find no evidence that outflows increase the level of clump turbulence as the clumps evolve. This implies that the origin of turbulence within clumps is fixed before the onset of star formation.

Synoptic Observations of The Terrestrial Polar Wind

NASA Astrophysics Data System (ADS)

Pollock, C. J.; Jahn, J.-M.; Moore, T. E.; Valek, P.; Wiig, J.

High altitude passes of NASA"s Polar spacecraft, during intevals when the Plasma Source Investigation (PSI) was operating to neutralize the spacecraft charge, are uti- lized to study the relatively low energy outflow of plasma from Earth's polar iono- sphere into the magnetosphere. Four years (1996 - 2000) of data from the Themal Ion Dynamics Experiment (TIDE) are analyzed to determine typical polar wind outflow parameters and their variability. These outflows, which are typically but not always present, are usually of high mach number, are strongly collimated along the outgoing field aligned direction and display significant temporal variability. Multi-species out- flows are distinguished from those of a single-species based on the energy signature. Preliminary results show that single species outflow is the rule and that observation of multi-species outflow is often associated with geomagnetic storms.

Geometrically Thick Obscuration by Radiation-driven Outflow from Magnetized Tori of Active Galactic Nuclei

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chan, Chi-Ho; Krolik, Julian H.

2017-07-01

Near-Eddington radiation from active galactic nuclei (AGNs) has significant dynamical influence on the surrounding dusty gas, plausibly furnishing AGNs with geometrically thick obscuration. We investigate this paradigm with radiative magnetohydrodynamics simulations. The simulations solve the magnetohydrodynamics equations simultaneously with the infrared (IR) and ultraviolet (UV) radiative transfer (RT) equations; no approximate closure is used for RT. We find that our torus, when given a suitable sub-Keplerian angular momentum profile, spontaneously evolves toward a state in which its opening angle, density distribution, and flow pattern change only slowly. This “steady” state lasts for as long as there is gas resupply towardmore » the inner edge. The torus is best described as a midplane inflow and a high-latitude outflow. The outflow is launched from the torus inner edge by UV radiation and expands in solid angle as it ascends; IR radiation continues to drive the wide-angle outflow outside the central hole. The dusty outflow obscures the central source in soft X-rays, the IR, and the UV over three-quarters of solid angle, and each decade in column density covers roughly equal solid angle around the central source; these obscuration properties are similar to what observations imply.« less

Maja Valles, Mars: A Multi-Source Fluvio-Volcanic Outflow Channel System

NASA Astrophysics Data System (ADS)

Keske, A.; Christensen, P. R.

2017-12-01

The resemblance of martian outflow channels to the channeled scablands of the Pacific Northwest has led to general consensus that they were eroded by large-scale flooding. However, the observation that many of these channels are coated in lava issuing from the same source as the water source has motivated the alternative hypothesis that the channels were carved by fluid, turbulent lava. Maja Valles is a circum-Chryse outflow channel whose origin was placed in the late Hesperian by Baker and Kochel (1979), with more recent studies of crater density variations suggesting that its formation history involved multiple resurfacing events (Chapman et al., 2003). In this study, we have found that while Maja Valles indeed host a suite of standard fluvial landforms, its northern portion is thinly coated with lava that has buried much of the older channel landforms and overprinted them with effusive flow features, such as polygons and bathtub rings. Adjacent to crater pedestals and streamlined islands are patches of dark, relatively pristine material pooled in local topographic lows that we have interpreted as ponds of lava remaining from one or more fluid lava flows that flooded the channel system and subsequently drained, leaving marks of the local lava high stand. Despite the presence of fluvial landforms throughout the valles, lava flow features exist in the northern reaches of the system alone, 500-1200 km from the channels' source. The flows can instead be traced to a collection of vents in Lunae Plaum, west of the valles. In previously studied fluvio-volcanic outflow systems, such as Athabasca Valles, the sources of the volcanic activity and fluvial activity have been indistinguishable. In contrast, Maja Valles features numerous fluvio-volcanic landforms bearing similarity to those identified in other channel systems, yet the source of its lava flows is distinct from the source of its channels. Furthermore, in the absence of any channels between the source of the lava flows and their intersection with the channels of Maja Valles, it is clear that the lava flows did not achieve the turbulence necessary to thermomechanically erode large channels, despite indications that they were very fluid. These findings weaken arguments that lava erosion has played a major role in the formation of martian outflow channels in general.

THE MULTIPHASE STRUCTURE AND POWER SOURCES OF GALACTIC WINDS IN MAJOR MERGERS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rupke, David S. N.; Veilleux, Sylvain, E-mail: drupke@gmail.com

2013-05-01

Massive, galaxy-scale outflows are known to be ubiquitous in major mergers of disk galaxies in the local universe. In this paper, we explore the multiphase structure and power sources of galactic winds in six ultraluminous infrared galaxies (ULIRGs) at z < 0.06 using deep integral field spectroscopy with the Gemini Multi-Object Spectrograph (GMOS) on Gemini North. We probe the neutral, ionized, and dusty gas phases using Na I D, strong emission lines ([O I], H{alpha}, and [N II]), and continuum colors, respectively. We separate outflow motions from those due to rotation and tidal perturbations, and find that all of themore » galaxies in our sample host high-velocity flows on kiloparsec scales. The properties of these outflows are consistent with multiphase (ionized, neutral, and dusty) collimated bipolar winds emerging along the minor axis of the nuclear disk to scales of 1-2 kpc. In two cases, these collimated winds take the form of bipolar superbubbles, identified by clear kinematic signatures. Less collimated (but still high-velocity) flows are also present on scales up to 5 kpc in most systems. The three galaxies in our sample with obscured QSOs host higher velocity outflows than those in the three galaxies with no evidence for an active galactic nucleus. The peak outflow velocity in each of the QSOs is in the range 1450-3350 km s{sup -1}, and the highest velocities (2000-3000 km s{sup -1}) are seen only in ionized gas. The outflow energy and momentum in the QSOs are difficult to produce from a starburst alone, but are consistent with the QSO contributing significantly to the driving of the flow. Finally, when all gas phases are accounted for, the outflows are massive enough to provide negative feedback to star formation.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bally, John; Ginsburg, Adam; Probst, Ron

We present observations of near-infrared 2.12 μm molecular hydrogen outflows emerging from 1.1 mm dust continuum clumps in the North America and Pelican Nebula (NAP) complex selected from the Bolocam Galactic Plane Survey (BGPS). Hundreds of individual shocks powered by over 50 outflows from young stars are identified, indicating that the dusty molecular clumps surrounding the NGC 7000/IC 5070/W80 H II region are among the most active sites of ongoing star formation in the solar vicinity. A spectacular X-shaped outflow, MHO 3400, emerges from a young star system embedded in a dense clump more than a parsec from the ionizationmore » front associated with the Pelican Nebula (IC 5070). Suspected to be a binary, the source drives a pair of outflows with orientations differing by 80°. Each flow exhibits S-shaped symmetry and multiple shocks indicating a pulsed and precessing jet. The 'Gulf of Mexico', located south of the North America Nebula (NGC 7000), contains a dense cluster of molecular hydrogen objects (MHOs), Herbig-Haro (HH) objects, and over 300 young stellar objects (YSOs), indicating a recent burst of star formation. The largest outflow detected thus far in the North America and Pelican Nebula complex, the 1.6 parsec long MHO 3417 flow, emerges from a 500 M {sub ☉} BGPS clump and may be powered by a forming massive star. Several prominent outflows such as MHO 3427 appear to be powered by highly embedded YSOs only visible at λ > 70 μm. An 'activity index' formed by dividing the number of shocks by the mass of the cloud containing their source stars is used to estimate the relative evolutionary states of Bolocam clumps. Outflows can be used as indicators of the evolutionary state of clumps detected in millimeter and submillimeter dust continuum surveys.« less

PLASMOID EJECTIONS AND LOOP CONTRACTIONS IN AN ERUPTIVE M7.7 SOLAR FLARE: EVIDENCE OF PARTICLE ACCELERATION AND HEATING IN MAGNETIC RECONNECTION OUTFLOWS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu Wei; Chen Qingrong; Petrosian, Vahe

2013-04-20

Where particle acceleration and plasma heating take place in relation to magnetic reconnection is a fundamental question for solar flares. We report analysis of an M7.7 flare on 2012 July 19 observed by SDO/AIA and RHESSI. Bi-directional outflows in forms of plasmoid ejections and contracting cusp-shaped loops originate between an erupting flux rope and underlying flare loops at speeds of typically 200-300 km s{sup -1} up to 1050 km s{sup -1}. These outflows are associated with spatially separated double coronal X-ray sources with centroid separation decreasing with energy. The highest temperature is located near the nonthermal X-ray loop-top source wellmore » below the original heights of contracting cusps near the inferred reconnection site. These observations suggest that the primary loci of particle acceleration and plasma heating are in the reconnection outflow regions, rather than the reconnection site itself. In addition, there is an initial ascent of the X-ray and EUV loop-top source prior to its recently recognized descent, which we ascribe to the interplay among multiple processes including the upward development of reconnection and the downward contractions of reconnected loops. The impulsive phase onset is delayed by 10 minutes from the start of the descent, but coincides with the rapid speed increases of the upward plasmoids, the individual loop shrinkages, and the overall loop-top descent, suggestive of an intimate relation of the energy release rate and reconnection outflow speed.« less

Image digitising and analysis of outflows from young stars

NASA Astrophysics Data System (ADS)

Zealey, W. J.; Mader, S. L.

1997-08-01

We present IIIaJ, IIIaF and IVN band images of Herbig-Haro objects digitised from the ESO/SERC Southern Sky Survey plates. These form part of a digital image database of southern HH objects, which allows the identification of emission and reflection nebulosity and the location of the obscured sources of outflows.

COPS-GREAT: CO in ProtoStars with GREAT

NASA Astrophysics Data System (ADS)

Kristensen, Lars

2013-10-01

Low-mass embedded protostars drive strong bipolar jets, which shock the surrounding gas on 100-1000 AU scales and entrain colder gas in outflows on 10,000 AU and larger scales. The aim of this proposal is to analyze the transition between shocks and entrainment and to quantify the mass in each component. We plan to do this by observing the CO 13-12 line with GREAT in five sources. Outflows from young protostars are a major source of feedback on both protostellar and cloud scales. However, our understanding of how they entrain or impact the protostellar envelope is still in its infancy. High-J CO observations are required to analyze in detail the transition where the outflowing gas goes from being colder (T ~ 100 K) entrained outflowing gas to being directly excited by the shocks causing the entrainment. These observations will allow us to quantify the amount of currently shocked gas with respect to the entrained gas, as well as examine shock properties as a function of velocity, and thereby quantify the feedback from a protostar on its natal material.

COPS-GREAT2: CO in ProtoStars with GREAT

NASA Astrophysics Data System (ADS)

Yildiz, Umut

Low-mass embedded protostars drive strong bipolar jets, which shock the surrounding gas on 100-1000 AU scales and entrain colder gas in outflows on 10,000 AU and larger scales. The aim of this proposal is to analyze the transition between shocks and entrainment and to quantify the mass in each component. We plan to do this by observing the CO 11-10 line with GREAT in nine sources. Outflows from young protostars are a major source of feedback on both protostellar and cloud scales. However, our understanding of how they entrain or impact the protostellar envelope is still in its infancy. High-J CO observations are required to analyze in detail the transition where the outflowing gas goes from being colder (T 100 K) entrained outflowing gas to being directly excited by the shocks causing the entrainment. These observations will allow us to quantify the amount of currently shocked gas with respect to the entrained gas, as well as examine shock properties as a function of velocity, and thereby quantify the feedback from a protostar on its natal material.

A flattened cloud core in NGC 2024

NASA Technical Reports Server (NTRS)

Ho, Paul T. P.; Peng, Yun-Lou; Torrelles, Jose M.; Gomez, Jose F.; Rodriguez, Luis F.; Canto, Jorge

1993-01-01

The (J, K) (1, 1) and (2, 2) NH3 lines were mapped toward a molecular cloud core in NGC 2024 using the VLA in its C/D-configuration. This region is associated with one of the most highly collimated molecular outflows. We find that the molecular condensations associated with the far-infrared sources FIR 5, FIR 6, and FIR 7 have kinetic temperatures of about 40 K. We also find line broadening toward FIR 6 and FIR 7. This suggests that these condensations may not be protostars heated by gravitational energy released during collapse but that they have an internal heating source. A flattened structure of ammonia emission is found extending parallel to the unipolar CO outflow structure, but displaced systematically to the east. If the NH3 emission traces the denser gas environment, there is no evidence that a dense gas structure is confining the molecular outflow. Instead, the location of the high-velocity outflow along the surface of the NH3 structure suggests that a wind is sweeping material from the surface of this elongated cloud core.

Do Radio Jets Contribute to Driving Ionized Gas Outflows in Moderate Luminosity Type 2 AGN?

NASA Astrophysics Data System (ADS)

Fowler, Julia; Sajina, Anna; Lacy, Mark

2016-01-01

This poster examines the role of AGN-driven feedback in low to intermediate power radio galaxies. We begin with [OIII] measurements of ionized gas outflows in 29 moderate AGN-luminosity z~0.3-0.7 dust-obscured Type 2 AGN. We aim to examine the relative role of the AGN itself, of star-formation and of nascent radio jets in driving these outflows. The strength of the AGN and star formation are based on the [OIII] luminosities, and the far-IR luminosities respectively. For the radio jets, we present multi-frequency radio (X, S, and L-bands) JVLA imaging of our sample, which allows us both to constrain the overall radio power, but also look for signatures of young radio sources, including Giga-hertz Peaked Spectrum (GPS) sources, as well as small-scale jets. While radio jet-driven outflows are well known for powerful radio-loud galaxies, this study allows us to constrain the degree to which this mechanism is significant at more modest radio luminosities of L5GHz~10^22-25 W/Hz.

The Dual Role of Starbursts and Active Galactic Nuclei in Driving Extreme Molecular Outflows

NASA Astrophysics Data System (ADS)

Gowardhan, Avani; Spoon, Henrik; Riechers, Dominik A.; González-Alfonso, Eduardo; Farrah, Duncan; Fischer, Jacqueline; Darling, Jeremy; Fergulio, Chiara; Afonso, Jose; Bizzocchi, Luca

2018-05-01

We report molecular gas observations of IRAS 20100‑4156 and IRAS 03158+4227, two local ultraluminous infrared galaxies (ULIRGs) hosting some of the fastest and most massive molecular outflows known. Using Atacama Large Millimeter Array and Plateau de Bure Interferometer observations, we spatially resolve the CO (1‑0) emission from the outflowing molecular gas in both and find maximum outflow velocities of v max ∼ 1600 and ∼1700 km s‑1 for IRAS 20100‑4156 and IRAS 03158+4227, respectively. We find total gas mass outflow rates of {\\dot{M}}OF}∼ 670 and ∼350 M ⊙ yr‑1, respectively, corresponding to molecular gas depletion timescales {τ }OF}dep}∼ 11 and ∼16 Myr. This is nearly 3 times shorter than the depletion timescales implied by star formation, {τ }SFR}dep}∼ 33 and ∼46 Myr, respectively. To determine the outflow driving mechanism, we compare the starburst luminosity (L *) and active galactic nucleus (AGN) luminosity (L AGN) to the outflowing energy and momentum fluxes, using mid-infrared spectral decomposition to discern L AGN. Comparison to other molecular outflows in ULIRGs reveals that outflow properties correlate similarly with L * and L IR as with L AGN, indicating that AGN luminosity alone may not be a good tracer of feedback strength and that a combination of AGN and starburst activity may be driving the most powerful molecular outflows. We also detect the OH 1.667 GHz maser line from both sources and demonstrate its utility in detecting molecular outflows.

APEX-CHAMP+ high-J CO observations of low-mass young stellar objects. IV. Mechanical and radiative feedback

NASA Astrophysics Data System (ADS)

Yıldız, U. A.; Kristensen, L. E.; van Dishoeck, E. F.; Hogerheijde, M. R.; Karska, A.; Belloche, A.; Endo, A.; Frieswijk, W.; Güsten, R.; van Kempen, T. A.; Leurini, S.; Nagy, Z.; Pérez-Beaupuits, J. P.; Risacher, C.; van der Marel, N.; van Weeren, R. J.; Wyrowski, F.

2015-04-01

Context. During the embedded stage of star formation, bipolar molecular outflows and UV radiation from the protostar are important feedback processes. Both processes reflect the accretion onto the forming star and affect subsequent collapse or fragmentation of the cloud. Aims: Our aim is to quantify the feedback, mechanical and radiative, for a large sample of low-mass sources in a consistent manner. The outflow activity is compared to radiative feedback in the form of UV heating by the accreting protostar to search for correlations and evolutionary trends. Methods: Large-scale maps of 26 young stellar objects, which are part of the Herschel WISH key program are obtained using the CHAMP+ instrument on the Atacama Pathfinder EXperiment (12CO and 13CO 6-5; Eup ~ 100 K), and the HARP-B instrument on the James Clerk Maxwell Telescope (12CO and 13CO 3-2; Eup ~ 30 K). The maps have high spatial resolution, particularly the CO 6-5 maps taken with a 9″ beam, resolving the morphology of the outflows. The maps are used to determine outflow parameters and the results are compared with higher-J CO lines obtained with Herschel. Envelope models are used to quantify the amount of UV-heated gas and its temperature from 13CO 6-5 observations. Results: All sources in our sample show outflow activity, with the spatial extent decreasing from the Class 0 to the Class I stage. Consistent with previous studies, the outflow force, FCO, is larger for Class 0 sources than for Class I sources, even if their luminosities are comparable. The outflowing gas typically extends to much greater distances than the power-law envelope and therefore influences the surrounding cloud material directly. Comparison of the CO 6-5 results with HIFI H2O and PACS high-J CO lines, both tracing currently shocked gas, shows that the two components are linked, even though the transitions do not probe the same gas. The link does not extend down to CO 3-2. The conclusion is that CO 6-5 depends on the shock characteristics (density and velocity), whereas CO 3-2 is more sensitive to conditions in the surrounding environment (density). The radiative feedback is responsible for increasing the gas temperature by a factor of two, up to 30-50 K, on scales of a few thousand AU, particularly along the direction of the outflow. The mass of the UV heated gas exceeds the mass contained in the entrained outflow in the inner ~3000 AU and is therefore at least as important on small scales. Appendix A is available in electronic form at http://www.aanda.orgThe CHAMP+ maps (data cubes) are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/576/A109

Quasar outflows and AGN feedback in the extreme UV: HST/COS observations of HE 0238-1904

NASA Astrophysics Data System (ADS)

Arav, Nahum; Borguet, Benoit; Chamberlain, Carter; Edmonds, Doug; Danforth, Charles

2013-12-01

Spectroscopic observations of quasar outflows at rest-frame 500-1000 Å have immense diagnostic power. We present analyses of such data, where absorption troughs from O IV and O IV* allow us to obtain the distance of the outflows from the AGN and troughs from Ne VIII and Mg X reveal the warm absorber phase of the outflow. Their inferred column densities, combined with those of O VI, N IV and H I, yield two important results. (1) The outflow shows two ionization phases, where the high-ionization phase carries the bulk of the material. This is similar to the situation seen in X-ray warm absorber studies. Furthermore, the low-ionization phase is inferred to have a volume filling factor of 10-5-10-6. (2) We determine a distance of 3000 pc from the outflow to the central source using the O IV*/O IV column density ratio and the knowledge of the ionization parameter. Since this is a typical high-ionization outflow, we can determine robust values for the outflow's mass flux and kinetic luminosity of 40 M⊙ yr-1 and 1045 erg s-1, respectively, where the latter is roughly equal to 1 per cent of the bolometric luminosity. Such a large kinetic luminosity and mass flow rate measured in a typical high-ionization wind suggest that quasar outflows are a major contributor to AGN feedback mechanisms.

The circum-Chryse region as a possible example of a hydrologic cycle on Mars: geologic observations and theoretical evaluation.

PubMed

Moore, J M; Clow, G D; Davis, W L; Gulick, V C; Janke, D R; McKay, C P; Stoker, C R; Zent, A P

1995-03-25

The transection and superposition relationships among channels, chaos, surface materials units, and other features in the circum-Chryse region of Mars were used to evaluate relative age relationships and evolution of flood events. Channels and chaos in contact (with one another) were treated as single discrete flood-carved systems. Some outflow channel systems form networks and are inferred to have been created by multiple flood events. Within some outflow channel networks, several separate individual channel systems can be traced to a specific chaos which acted as flood-source area to that specific flood channel. Individual flood-carved systems were related to widespread materials units or other surface features that served as stratigraphic horizons. Chryse outflow channels are inferred to have formed over most of the perceivable history of Mars. Outflow channels are inferred to become younger with increasing proximity to the Chryse basin. In addition, outflow channels closer to the basin show a greater diversity in age. The relationship of subsequent outflow channel sources to the sources of earlier floods is inferred to disfavor episodic flooding due to the progressive tapping of a juvenile near-surface water supply. Instead, we propose the circum-Chryse region as a candidate site of past hydrological recycling. The discharge rates necessary to carve the circum-Chryse outflow channels would have inevitably formed temporary standing bodies of H2O on the Martian surface where the flood-waters stagnated and pooled (the Chryse basin is topographically enclosed). These observations and inferences have led us to formulate and evaluate two hypotheses: (1) large amounts of the sublimated H2O off the Chryse basin flood lakes precipitated (snowed) onto the flood-source highlands and this H2O was incorporated into the near surface, recharging the H2O sources, making possible subsequent deluges; and (2) ponded flood-water in Chryse basin drained back down an anti basinward dipping subsurface layer accessed long the southern edge of the lake, recharging the flood-source aquifers. H2O not redeposited in the flood-source region was largely lost to the hydrologic cycle. This loss progressively lowered the vitality of the cycle, probably by now killing it. Our numerical evaluations indicate that of the two hypotheses we formulated, the groundwater seep cycle seems by far the more viable. Optimally, approximately 3/4 of the original mass of an ice-covered cylindrical lake (albedo 0.5, 1 km deep, 100-km radius, draining along its rim for one quarter of its circumference into substrata with a permeability of 3000 darcies) can be modeled to have moved underground (on timescales of the order of 10(3) years) before the competing mechanisms of sublimation and freeze down choked off further water removal. Once underground, this water can travel distances equal to the separation between Chryse basin and flood-source sites in geologically short (approximately 10(6) year-scale) times. Conversely, we calculate that optimally only approximately 40% of the H2O carried from Chryse can condense at the highlands, and most of the precipitate would either collect at the base of the highlands/lowlands scarp or sublimate at rates greater than it would accumulate over the flood-source sites. Further observations from forthcoming missions may permit the determination of which mechanisms may have operated to recycle the Chryse flood-waters.

The Circum-Chryse Region as a Possible Example of a Hydrologic Cycle on Mars: Geologic Observations and Theoretical Evaluation

NASA Technical Reports Server (NTRS)

Moore, Jeffrey M.; Clow, Gary D.; Davis, Wanda L.; Gulick, Virginia C.; Janke, David R.; McKay, Christopher P.; Stoker, Carol R.; Zent, Aaron P.

1995-01-01

The transection and superposition relationships among channels, chaos, surface materials units, and other features in the circum-Chryse region of Mars were used to evaluate relative age relationships and evolution of flood events. Channels and chaos in contact (with one another) were treated as single discrete flood-carved systems. Some outflow channel systems form networks and are inferred to have been created by multiple flood events. Within some outflow channel networks, several separate individual channel systems can be traced to a specific chaos which acted as flood-source area to that specific flood channel. Individual flood-carved systems were related to widespread materials units or other surface features that served as stratigraphic horizons. Chryse outflow channels are inferred to have formed over most of the perceivable history of Mars. Outflow channels are inferred to become younger with increasing proximity to the Chryse basin. In addition, outflow channels closer to the basin show a greater diversity in age. The relationship of subsequent outflow channel sources to the sources of earlier floods is inferred to disfavor episodic flooding due to the progressive tapping of a juvenile near-surface water supply. Instead, we propose the circum-Chryse region as a candidate site of past hydrological recycling. The discharge rates necessary to carve the circum-Chryse outflow channels would have inevitably formed temporary standing bodies of H2O on the Martian surface where the flood-waters stagnated and pooled (the Chryse basin is topographically enclosed). These observations and inferences have led us to formulate and evaluate two hypotheses: (1) large amounts of the sublimated H2O off the Chryse basin flood lakes precipitated (snowed) onto the flood-source highlands and this H2O was incorporated into the near surface, recharging the H2O sources, making possible subsequent deluges; and (2) ponded flood-water in Chryse basin drained back down an anti basinward dipping subsurface layer accessed along the southern edge of the lake, recharging the flood-source aquifers. H2O not redeposited in the flood-source region was largely lost to the hydrologic cycle. This loss progressively lowered the vitality of the cycle, probably by now killing it. Our numerical evaluations indicate that of the two hypotheses we formulated, the groundwater seep cycle seems by far the more viable. Optimally, approximately 3/4 of the original mass of an ice-covered cylindrical lake (albedo 0.5, 1 km deep, 100-km radius, draining along its rim for one quarter of its circumference into substrata with a permeability of 3000 darcies) can be modeled to have moved underground (on timescales of the order of 10(exp 3) years) before the competing mechanisms of sublimation and freeze down choked off further water removal. Once underground, this water can travel distances equal to the separation between Chryse basin and flood-source sites in geologically short (approximately 10(exp 6) year-scale) times. Conversely, we calculate that optimally only approximately 40% of the H2O carried from Chryse can condense at the highlands, and most of the precipitate would either collect at the base of the highlands/lowlands scrap or sublimate at rates greater than it would accumulate over the flood-source sites. Further observations from forthcoming missions may permit the determination of which mechanisms may have operated to recycle the Chryse flood-waters.

The circum-Chryse region as a possible example of a hydrologic cycle on Mars: Geologic observations and theoretical evaluation

NASA Technical Reports Server (NTRS)

Moore, Jeffrey M.; Clow, Gary D.; Davis, Wanda L.; Gulick, Virginia C.; Janke, David R.; McKay, Christopher P.; Stoker, Carol R.; Zent, Aaron P.

1995-01-01

The transection and superposition relationships among channels, chaos, surface materials units, and other features in the circum-Chryse region of Mars were used to evaluate relative age relationships and evolution of flood events. Channels and chaos in contact (with one another) were treated as single discrete flood-carved systems. Some outflow channel systems form networks and are inferred to have been created by multiple flood events. Within some outflow channel networks, several separate individual channel systems can be traced to a specific chaos which acted as flood-source area to that specific flood channel. Individual flood-carved systems were related to widespread materials units or other surface features that served as stratigraphic horizons. Chryse outflow channels are inferred to have formed over most of the perceivable history of Mars. Outflow channels are inferred to become younger with increasing proximity to the Chryse basin. In addition, outflow channels closer to the basin show a greater diversity in age. The relationship of subsequent outflow channel sources to the sources of earlier floods is inferred to disfavor episodic flooding due to the progressive tapping of a juvenile near-surface water supply. Instead, we propose the circum-Chryse region as a candidate site of past hydrological recycling. The discharge rates necessary to carve the circum-Chryse outflow channels would have inevitably formed temporary standing bodies of H2O on the Martian surface where the flood-waters stagnated and pooled (the Chryse basin is topographically enclosed). These observations and inferences have led us to formulate and evaluate two hypotheses: (1) large amounts of the sublimated H2O off the Chryse basin flood lakes precipitated (snowed) onto the flood-source highlands and this H2O was incorporated into the near surface, recharging the H2O sources, making possible subsequent deluges; and (2) ponded flood-water in Chryse basin drained back down an anti basinward dipping subsurface layer accessed along the southern edge of the lake, recharging the flood-source aquifers. H2O not redeposited in the flood-source region was largely lost to the hydrologic cycle. This loss progressively lowered the vitality of the cycle, probably by now killing it. Our numerical evaluations indicate that of the two hypotheses we formulated, the groundwater seep cycle seems by far the more viable. Optimally, approx. 3/4 of the original mass of an ice-covered cylindrical lake (albedo 0.5, 1 km deep, 100-km radius, draining along its rim for one quarter of its circumference into substrata with a permeability of 3000 darcies) can be modeled to have moved underground (on timescales of the order of 10(exp 3) years) before the competing mechanisms of sublimation and freeze down choked off further water removal. Once underground, this water can travel distances equal to the separation between Chryse basin and flood-source sites in geologically short (approx. 10(exp 6) year-scale) times. Conversely, we calculate that optimally only approx. 40% of the H2O carried from Chryse can condense at the highlands, and most of the precipitate would either collect at the base of the highlands/lowlands scarp or sublimate at rates greater than it would accumulate over the flood-source sites. Further observations from forthcoming missions may permit the determination of which mechanisms may have operated to recycle the Chryse flood-waters.

Large-Scale Outflows in Seyfert Galaxies

NASA Astrophysics Data System (ADS)

Colbert, E. J. M.; Baum, S. A.

1995-12-01

\\catcode`\\@=11 \\ialign{m @th#1hfil ##hfil \\crcr#2\\crcr\\sim\\crcr}}} \\catcode`\\@=12 Highly collimated outflows extend out to Mpc scales in many radio-loud active galaxies. In Seyfert galaxies, which are radio-quiet, the outflows extend out to kpc scales and do not appear to be as highly collimated. In order to study the nature of large-scale (>~1 kpc) outflows in Seyferts, we have conducted optical, radio and X-ray surveys of a distance-limited sample of 22 edge-on Seyfert galaxies. Results of the optical emission-line imaging and spectroscopic survey imply that large-scale outflows are present in >~{{1} /{4}} of all Seyferts. The radio (VLA) and X-ray (ROSAT) surveys show that large-scale radio and X-ray emission is present at about the same frequency. Kinetic luminosities of the outflows in Seyferts are comparable to those in starburst-driven superwinds. Large-scale radio sources in Seyferts appear diffuse, but do not resemble radio halos found in some edge-on starburst galaxies (e.g. M82). We discuss the feasibility of the outflows being powered by the active nucleus (e.g. a jet) or a circumnuclear starburst.

SOA VOLATILITY EVOLUTION: FORMATION AND OXIDATION OVER THE LIFECYCLE OF PM2.5

EPA Science Inventory

Secondary Organic Aerosols are a major, possibly dominant, source of organic PM_2.5 that remain enigmatic. Enormous progress has been made in the past 15 years regarding SOA formation, starting with recognition that most SOA products are semivolatile, continuing to a...

The Evolution of Quasar C IV and Si IV Broad Absorption Lines over Multi-year Timescales

NASA Astrophysics Data System (ADS)

Gibson, Robert R.; Brandt, W. N.; Gallagher, S. C.; Hewett, Paul C.; Schneider, Donald P.

2010-04-01

We investigate the variability of C IV λ1549 broad absorption line (BAL) troughs over rest-frame timescales of up to ≈7 yr in 14 quasars at redshifts z >~ 2.1. For nine sources at sufficiently high redshift, we also compare the C IV and Si IV λ1400 absorption variation. We compare shorter and longer term variability using spectra from up to four different epochs per source and find complex patterns of variation in the sample overall. The scatter in the change of absorption equivalent width (EW), ΔEW, increases with the time between observations. BALs do not, in general, strengthen or weaken monotonically, and variation observed over shorter (lsimmonths) timescales is not predictive of multi-year variation. We find no evidence for asymmetry in the distribution of ΔEW that would indicate that BALs form and decay on different timescales, and we constrain the typical BAL lifetime to be gsim30 yr. The BAL absorption for one source, LBQS 0022+0150, has weakened and may now be classified as a mini-BAL. Another source, 1235+1453, shows evidence of variable, blue continuum emission that is relatively unabsorbed by the BAL outflow. C IV and Si IV BAL shape changes are related in at least some sources. Given their high velocities, BAL outflows apparently traverse large spatial regions and may interact with parsec-scale structures such as an obscuring torus. Assuming BAL outflows are launched from a rotating accretion disk, notable azimuthal symmetry is required in the outflow to explain the relatively small changes observed in velocity structure over times up to 7 yr.

The magnetic field structure around protostars. Submillimetre polarimetry of VLA 1623 and S 106-IR/FIR.

NASA Astrophysics Data System (ADS)

Holland, W. S.; Greaves, J. S.; Ward-Thompson, D.; Andre, P.

1996-05-01

We present 800μm polarization observations of the young low-mass candidate protostar VLA 1623, and of the high-mass young stellar object S 106-IR and its companion candidate protostar S 106-FIR. The polarized emission due to aligned dust grains has been used to derive the magnetic field direction around both sources. In the case of VLA 1623 we find that the field direction is almost exactly perpendicular to the extremely well-collimated CO outflow. This suggests that the large-scale magnetic field in the cloud cannot be responsible for the collimation of the outflow. However, the data may be consistent with a recent magneto-hydrodynamic model where the field follows stream lines through the central plane of a `cored apple' accretion structure. In S 106 our observations indicate a magnetic field along the dust lane connecting the IR/FIR sources, and perpendicular to the bipolar HII region. A model consistent both with these data, and previous Zeeman measurements, is presented, in which the large-scale magnetic field is poloidal, but is either twisted into a toroidal morphology, or highly `pinched-in', in the flattened dust lane. We also present a synopsis of recent submillimetre polarimetry observations of young disk/outflow sources. For high-mass objects, the data are consistent with super-critical collapse models, and there is evidence for varying degrees of field compression. There is also a correlation of net field orientation with source distance, which is explained by the inclusion of varying amounts of ambient cloud material within the telescope beam. For the few low-mass objects for which data is available, the polarization is less affected by ambient material, and there is some evidence that different outflow models may apply in different sources.

Enigmatic mounds in 'Subglacial Meltwater Corridors' on the Canadian Shield: a record of channelised, subglacial meltwater drainage during Laurentide deglaciation

NASA Astrophysics Data System (ADS)

Haiblen, Anna; Ward, Brent; Normandeau, Philippe; Campbell, Janet

2017-04-01

Esker networks have traditionally been invoked to represent the channelised subglacial drainage system in shield terrains. However, eskers are only one landform found within 'subglacial meltwater corridors' (SMCs) on the Canadian Shield. SMCs are tracts where till has been eroded, bedrock is exposed, and glaciofluvial sediments have been deposited. SMCs are regularly spaced, parallel deglacial ice-flow directions, have undulating longitudinal profiles, and cross modern drainage divides. Our lidar- and field-based mapping near Lac de Gras, Northwest Territories, west of the Keewatin Ice Divide (KID), reveals that eskers are not present in the majority of SMCs. Instead, enigmatic mounds are commonly the dominant landform type. Enigmatic mounds typically occur in groups of 20 to 200. They are commonly composed of sandy diamicton that is coarser grained and better sorted than regional till. This diamicton is occasionally draped with well-sorted, stratified glaciofluvial sediments. Some enigmatic mounds have a single highpoint (individual mounds) while others have a complex, irregular form (complex mounds). Individual mounds have an average long-axis length of 43 m and an average height of < 2 m, however, their size is highly variable: the largest mounds are 170 m long and 15 m high. Complex mounds are typically larger than individual mounds. Our morphometric analysis shows that individual mounds have a mean length-to-width ratio of 1.8. The average mound elongation direction parallels the final ice flow that affected the area. However, where meltwater- and ice-flow directions differ, mound long-axis orientations typically cluster about meltwater flow directions. We have also observed SMCs and enigmatic mounds in the South Rae region of Northwest Territories, 450 km SE of Lac de Gras. Multiple types of enigmatic mounds are present in this area: some are similar to those near Lac de Gras, some are composed of till, and some are composed of sorted and stratified sediments. SMCs likely formed late during deglaciation because the enigmatic mounds and eskers that they contain do not appear to have been significantly affected by ice flow following their deposition. We suggest that transient, sheet-type subglacial meltwater flow events resulted in erosion and transport of basal till. Meltwater was likely sourced from supraglacial lakes that formed and drained catastrophically when the ablation zone of the Laurentide Ice Sheet affected the area. The enigmatic mounds that we have observed near Lac de Gras may have been deposited from a slurry-type flow. Eskers likely formed later, after a channelised drainage system was established. It is possible that SMCs are the Quaternary landscape record of lake-drainage events similar to those that occur in Southwest Greenland today. The hydraulic conditions required to create enigmatic mounds are different to those required for esker formation. Thus, SMCs, not just the eskers that they sometimes contain, should be considered when parameters are developed for numerical models relating to subglacial drainage systems in shield terrains. Determining the genesis of landforms found within SMCs will improve our understanding of hydraulic conditions in the subglacial, channelised drainage system during ice-sheet retreat and decay.

Impact of green roofs on stormwater quality in a South Australian urban environment.

PubMed

Razzaghmanesh, M; Beecham, S; Kazemi, F

2014-02-01

Green roofs are an increasingly important component of water sensitive urban design systems and can potentially improve the quality of urban runoff. However, there is evidence that they can occasionally act as a source rather than a sink for pollutants. In this study, the water quality of the outflow from both intensive and extensive green roof systems were studied in the city of Adelaide, South Australia over a period of nine months. The aim was to examine the effects of different green roof configurations on stormwater quality and to compare this with runoff from aluminium and asphalt roofs as control surfaces. The contaminant concentrations in runoff from both intensive and extensive green roofs generally decreased during the study period. A comparison between the two types of green roof showed that except for some events for EC, TDS and chloride, the values of the parameters such as pH, turbidity, nitrate, phosphate and potassium in intensive green roof outflows were higher than in the outflows from the extensive green roofs. These concentrations were compared to local, state, national and international water quality guidelines in order to investigate the potential for outflow runoff from green roofs to be reused for potable and non-potable purposes. The study found that green roof outflow can provide an alternative water source for non-potable purposes such as urban landscape irrigation and toilet flushing. © 2013.

Global-scale Ionospheric Outflow: Major Processes and Unresolved Problems

NASA Astrophysics Data System (ADS)

Liemohn, M. W.; Welling, D. T.; Ilie, R.; Khazanov, G. V.; Jahn, J. M.; Zou, S.; Ganushkina, N. Y.; Valek, P. W.; Elliott, H. A.; Gilchrist, B. E.; Hoegy, W. R.; Glocer, A.

2016-12-01

Outflow from the ionosphere is a major source of plasma to the magnetosphere. Its presence, especially that of ions heavier than He+, mass loads the magnetosphere and changes reconnection rates, current system configurations, plasma wave excitation and wave-particle interactions. It even impacts the propagation of information. We present a brief overview of the major processes and scientific history of this field. There are still major gaps, however, in our understanding of the global-scale nature of ionospheric outflow. We discuss these unresolved problems highlighting the leading questions still outstanding on this topic. First and foremost, since the measurements of ionospheric outflow have largely come from individual satellites and sounding rockets, the processes are best known on the local level, while the spatial distribution of outflow has never been simultaneously measured on more global scales. The spatial coherence and correlation of outflow across time and space have not been quantified. Furthermore, the composition of the outflow is often only measured at a coarse level of H+, He+, and O+, neglecting other species such as N+ or moleculars. However, resolving O+ from N+, as is customary in planetary research, aids in revealing the physics and altitude dependence of the energization processes in the ionosphere. Similarly, fine-resolution velocity space measurements of ionospheric outflow have been limited, yet such observations can also reveal energization processes driving the outflow. A final unresolved issue to mention is magnetically conjugate outflow and the full extent of hemispherically asymmetric outflow fluxes or fluence. Each of these open questions have substantial ramifications for magnetospheric physics; their resolution could yield sweeping changes in our understanding of nonlinear feedback and cross-scale physical interactions, magnetosphere-ionosphere coupling, and geospace system-level science.

Broad [C II] Line Wings as Tracer of Molecular and Multi-phase Outflows in Infrared Bright Galaxies

NASA Astrophysics Data System (ADS)

Janssen, A. W.; Christopher, N.; Sturm, E.; Veilleux, S.; Contursi, A.; González-Alfonso, E.; Fischer, J.; Davies, R.; Verma, A.; Graciá-Carpio, J.; Genzel, R.; Lutz, D.; Sternberg, A.; Tacconi, L.; Burtscher, L.; Poglitsch, A.

2016-05-01

We report a tentative correlation between the outflow characteristics derived from OH absorption at 119 μm and [C II] emission at 158 μm in a sample of 22 local and bright ultraluminous infrared galaxies (ULIRGs). For this sample, we investigate whether [C II] broad wings are a good tracer of molecular outflows, and how the two tracers are connected. Fourteen objects in our sample have a broad wing component as traced by [C II], and all of these also show OH119 absorption indicative of an outflow (in one case an inflow). The other eight cases, where no broad [C II] component was found, are predominantly objects with no OH outflow or a low-velocity (≤100 km s-1) OH outflow. The FWHM of the broad [C II] component shows a trend with the OH119 blueshifted velocity, although with significant scatter. Moreover, and despite large uncertainties, the outflow masses derived from OH and broad [C II] show a 1:1 relation. The main conclusion is therefore that broad [C II] wings can be used to trace molecular outflows. This may be particularly relevant at high redshift, where the usual tracers of molecular gas (like low-J CO lines) become hard to observe. Additionally, observations of blueshifted Na I D λλ 5890, 5896 absorption are available for 10 of our sources. Outflow velocities of Na I D show a trend with OH velocity and broad [C II] FWHM. These observations suggest that the atomic and molecular gas phases of the outflow are connected.

Superposed epoch analysis of O+ auroral outflow during sawtooth events and substorms

NASA Astrophysics Data System (ADS)

Nowrouzi, N.; Kistler, L. M.; Lund, E. J.; Cai, X.

2017-12-01

Sawtooth events are repeated injection of energetic particles at geosynchronous orbit. Studies have shown that 94% of sawtooth events occurred during magnetic storm times. The main factor that causes a sawtooth event is still an open question. Simulations have suggested that heavy ions like O+ may play a role in triggering the injections. One of the sources of the O+ in the Earth's magnetosphere is the nightside aurora. O+ ions coming from the nightside auroral region have direct access to the near-earth magnetotail. A model (Brambles et al. 2013) for interplanetary coronal mass ejection driven sawtooth events found that nightside O+ outflow caused the subsequent teeth of the sawtooth event through a feedback mechanism. This work is a superposed epoch analysis to test whether the observed auroral outflow supports this model. Using FAST spacecraft data from 1997-2007, we examine the auroral O+ outflow as a function of time relative to an injection onset. Then we determine whether the profile of outflow flux of O+ during sawtooth events is different from the outflow observed during isolated substorms. The auroral region boundaries are estimated using the method of (Andersson et al. 2004). Subsequently the O+ outflow flux inside these boundaries are calculated and binned as a function of superposed epoch time for substorms and sawtooth "teeth". In this way, we will determine if sawtooth events do in fact have greater O+ outflow, and if that outflow is predominantly from the nightside, as suggested by the model results.

Quasar Outflows and AGN Feedback in the Extreme UV: HST/COS Observations of QSO HE0238-1904

NASA Astrophysics Data System (ADS)

Arav, Nahum; Borguet, B.; Chamberlain, C.; Edmonds, D.; Danforth, C.

2014-01-01

Spectroscopic observations of quasar outflows at rest-frame 500-1000 Angstrom have immense diagnostic power. We present analyses of such data, where absorption troughs from three important ions are measured: first, O IV and O IV* that allow us to obtain the distance of high ionization outflows from the AGN; second, Ne VIII and Mg X that are sensitive to the very high ionization phase of the outflow. Their inferred column densities, combined with those of troughs from O VI, N IV, and H I, yield two important results: 1) The outflow shows two ionization phases, where the high ionization phase carries the bulk of the material. This is similar to the situation seen in x-ray warm absorber studies. Furthermore, the low ionization phase is inferred to have a volume filling factor of 10^(-5)-10^(-6). 2) From the O IV to O IV* column density ratio, and the knowledge of the ionization parameter, we determine a distance of 3000 pc. from the outflow to the central source. Since this is a typical high ionization outflow, we can determine robust values for the mass flux and kinetic luminosity of the outflow: 40 solar masses per year and 10^45 ergs/s, respectively, where the latter is roughly equal to 1% of the bolometric luminosity. Such a large kinetic luminosity and mass flow rate measured in a typical high ionization wind suggests that quasar outflows are a major contributor to AGN feedback mechanisms.

An evaluation of simulated particulate sulfate over East Asia through global model intercomparison

NASA Astrophysics Data System (ADS)

Goto, Daisuke; Nakajima, Teruyuki; Dai, Tie; Takemura, Toshihiko; Kajino, Mizuo; Matsui, Hitoshi; Takami, Akinori; Hatakeyama, Shiro; Sugimoto, Nobuo; Shimizu, Atsushi; Ohara, Toshimasa

2015-06-01

Sulfate aerosols simulated by an aerosol module coupled to the Nonhydrostatic Icosahedral Atmospheric Model (NICAM) at a spatial resolution (220 km) widely used by global climate models were evaluated by a comparison with in situ observations and the same aerosol module coupled to the Model for Interdisciplinary Research on Climate (MIROC) over East Asia for January, April, July, and October 2006. The results indicated that a horizontal gradient of sulfate from the source over China to the outflow over Korea-Japan was present in both the simulations and the observations. At the observation sites, the correlation coefficients of the sulfate concentrations between the simulations and the observations were high (NICAM: 0.49-0.89, MIROC: 0.61-0.77), whereas the simulated sulfate concentrations were lower than those obtained by the observation with the normalized mean bias of NICAM being -68 to -54% (all), -77 to -63% (source), and -67 to -30% (outflow) and that of MIROC being -61 to -28% (all), -77 to -63% (source), and -60 to +2% (outflow). Both NICAM and MIROC strongly underpredict surface SO2 over China source regions and Korea-Japan outflow regions, but the MIROC SO2 is much higher than NICAM SO2 over both regions. These differences between the models were mainly explained by differences in the sulfate formation within clouds and the dry deposition of SO2. These results indicated that the uncertainty of the meteorological and cloud fields as well as the vertical transport patterns between the different host climate models has a substantial impact on the simulated sulfate distribution.

Chemical Characteristics of Continental Outflow from Asia to the Troposphere Over the Western Pacific Ocean during February - March 1994: Results from PEM-West B

NASA Technical Reports Server (NTRS)

Talbot, R. W.; Dibb, J. E.; Lefer, B. L.; Bradshaw, J. D.; Sandholm, S. T.; Blake, D. R.; Blake, N. J.; Sachse, G. W.; Sachse, G. W.; Heikes, B. G.;

Detectable radio flares following gravitational waves from mergers of binary neutron stars.

PubMed

Nakar, Ehud; Piran, Tsvi

2011-09-28

Mergers of neutron-star/neutron-star binaries are strong sources of gravitational waves. They can also launch subrelativistic and mildly relativistic outflows and are often assumed to be the sources of short γ-ray bursts. An electromagnetic signature that persisted for weeks to months after the event would strengthen any future claim of a detection of gravitational waves. Here we present results of calculations showing that the interaction of mildly relativistic outflows with the surrounding medium produces radio flares with peak emission at 1.4 gigahertz that persist at detectable (submillijansky) levels for weeks, out to a redshift of 0.1. Slower subrelativistic outflows produce flares detectable for years at 150 megahertz, as well as at 1.4 gigahertz, from slightly shorter distances. The radio transient RT 19870422 (ref. 11) has the properties predicted by our model, and its most probable origin is the merger of a compact neutron-star/neutron-star binary. The lack of radio detections usually associated with short γ-ray bursts does not constrain the radio transients that we discuss here (from mildly relativistic and subrelativistic outflows) because short γ-ray burst redshifts are typically >0.1 and the appropriate timescales (longer than weeks) have not been sampled.

Understanding "Lord of the Flies": A Student Casebook to Issues, Sources, and Historical Documents.

ERIC Educational Resources Information Center

Olsen, Kirstin

A seemingly simple tale of schoolboys marooned on an island, the novel "Lord of the Flies" is an enigmatic and provocative piece of literature. This casebook probes the many layers of meaning in the novel, examining its literary, philosophical, historical, scientific, and religious significance. The casebook integrates analysis and…

Simulated O VI Doppler dimming measurements of coronal outflow velocities

NASA Technical Reports Server (NTRS)

Strachan, Leonard; Gardner, L. D.; Kohl, John L.

1992-01-01

The possibility of determining O(5+) outflow velocities by using a Doppler dimming analysis of the resonantly scattered intensities of O VI lambda 1031.9 and lambda 1037.6 is addressed. The technique is sensitive to outflow velocities, W, in the range W greater than 30 and less than 250 km/s and can be used for probing regions of the inner solar corona, where significant coronal heating and solar wind acceleration may be occurring. These velocity measurements, when combined with measurements of other plasma parameters (temperatures and densities of ions and electrons) can be used to estimate the energy and mass flux of O(5+). In particular, it may be possible to locate where the flow changes from subsonic to supersonic and to identify source regions for the high and low speed solar wind. The velocity diagnostic technique is discussed with emphasis placed on the requirements needed for accurate outflow velocity determinations. Model determinations of outflow velocities based on simulated Doppler observations are presented.

Unification of X-ray Winds in Seyfert Galaxies: From Ultra-fast Outflows to Warm Absorbers

NASA Astrophysics Data System (ADS)

Tombesi, Francesco; Cappi, M.; Reeves, J.; Nemmen, R.; Braito, V.; Gaspari, M.; Reynolds, C. S.

2013-04-01

The existence of ionized X-ray absorbing layers of gas along the line of sight to the nuclei of Seyfert galaxies is a well established observational fact. This material is systematically outflowing and shows a large range in parameters. However, its actual nature and dynamics are still not clear. In order to gain insights into these important issues we performed a literature search for papers reporting the parameters of the soft X-ray warm absorbers (WAs) in 35 type 1 Seyferts and compared their properties to those of the ultra-fast outflows (UFOs) detected in the same sample. The fraction of sources with WAs is >60%, consistent with previous studies. The fraction of sources with UFOs is >34%, >67% of which also show WAs. The large dynamic range obtained when considering all the absorbers together allows us, for the first time, to investigate general relations among them. In particular, we find significant correlations indicating that the closer the absorber is to the central black hole, the higher the ionization, column, outflow velocity and consequently the mechanical power. The absorbers continuously populate the whole parameter space, with the WAs and the UFOs lying always at the two ends of the distribution. This strongly suggest that these absorbers, often considered of different types, could actually represent parts of a single large-scale stratified outflow observed at different locations from the black hole. The observed parameters and correlations are consistent with both radiation pressure through Compton scattering and MHD processes contributing to the outflow acceleration, the latter playing a major role. Most of the absorbers, especially the UFOs, have a sufficiently high mechanical power to significantly contribute to the AGN feedback.

Identifying Unidentified Fermi-LAT Objects (UFOs) at High-Latitude

NASA Astrophysics Data System (ADS)

Cheung, Chi Teddy

2009-09-01

We propose a Chandra study of 8 high Galactic latitude gamma-ray sources in the Fermi-LAT bright source list. These sources are currently unidentified, i.e., they are not clearly associated with established classes of gamma-ray emitters like blazars and pulsars. The proposed observations will determine the basic properties (fluxes, positions, hardness ratio/spectra) of all X-ray sources down to a 0.3-10 keV flux limit of 1.5e-14 erg/cm2/s within the Fermi-LAT localization circles. This will enable further follow-up at other wavelengths, with the ultimate goal to reveal the nature of these enigmatic gamma-ray sources.

The COS revolution of AGN outflow science

NASA Astrophysics Data System (ADS)

Arav, Nahum

2016-10-01

HST/COS has opened a new discovery space for quasar outflow science. Specifically, it provides high quality FUV spectra covering the diagnostic-rich 500A-1050A rest-frame of medium redshift objects. We have published three refereed papers based on the analysis of such data that were supported by our concluded COS archive program, in which we reported: a) a new population of very high ionization outflows, b) robust cases of two-ionization-phase outflows, which are the missing link between UV AGN outflows and x-ray warm absorbers, and most importantly c) spectral diagnostics that allowed us to determine the distance of the outflows from the central source. The latter is a cardinal issue in the field as many researchers believe that most outflows are situated close to the accretion disk ( 0.01 pc) while the few reliable measurements show distances of 10-10,000 pc. Therefore, every empirical distance measurement is of importance. Our archive based publication also demonstrates that quasar outflows have sufficient energy to match theoretical predictions for AGN feedback influencing galaxy evolution.We propose to continue this successful archive program. Thus far we've analyzed about 300 COS G130M and G160M orbits of AGN observations. There are roughly 900 additional orbits that satisfy our criteria and will be available within a year. Based on our published survey, we expect that these 900 orbits will yield about 20-30 additional very-high ionization outflows and 4-6 cases of distance and kinetic luminosity determinations, all in cosmologically important luminous-quasars.

HELICAL MAGNETIC FIELDS IN THE NGC 1333 IRAS 4A PROTOSTELLAR OUTFLOWS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ching, Tao-Chung; Lai, Shih-Ping; Zhang, Qizhou

We present Submillimeter Array polarization observations of the CO J = 3–2 line toward NGC 1333 IRAS 4A. The CO Stokes I maps at an angular resolution of ∼1″ reveal two bipolar outflows from the binary sources of NGC 1333 IRAS 4A. The kinematic features of the CO emission can be modeled by wind-driven outflows at ∼20° inclined from the plane of the sky. Close to the protostars the CO polarization, at an angular resolution of ∼2.″3, has a position angle approximately parallel to the magnetic field direction inferred from the dust polarizations. The CO polarization direction appears to vary smoothly frommore » an hourglass field around the core to an arc-like morphology wrapping around the outflow, suggesting a helical structure of magnetic fields that inherits the poloidal fields at the launching point and consists of toroidal fields at a farther distance of outflow. The helical magnetic field is consistent with the theoretical expectations for launching and collimating outflows from a magnetized rotating disk. Considering that the CO polarized emission is mainly contributed from the low-velocity and low-resolution data, the helical magnetic field is likely a product of the wind–envelope interaction in the wind-driven outflows. The CO data reveal a PA of ∼30° deflection in the outflows. The variation in the CO polarization angle seems to correlate with the deflections. We speculate that the helical magnetic field contributes to ∼10° deflection of the outflows by means of Lorentz force.« less

Nature and characteristics of the flows that carved the Simud and Tiu outflow channels, Mars

USGS Publications Warehouse

Rodriguez, J.A.P.; Tanaka, K.L.; Miyamoto, H.; Sasaki, S.

2006-01-01

Geomorphic and topographic relations of higher and lower levels of dissection within the Simud and Tiu Valles outflow channels on Mars reveal new insights into their formational histories. We find that the water floods that carved the higher channel floors were primarily sourced from Hydaspis Chaos. The floods apparently branched into distributaries downstream that promoted rapid freezing and sublimation of water and limited discharge into the lowlands. In contrast, we suggest that the lower outflow channels were carved by debris flows from Hydraotes Chaos. Surges within individual debris flows possessed variable volatile contents and led to the deposition of smooth deposits marked by low relief longitudinal ridges. Lower outflow channel discharges resulted in widespread deposition within the Simud/Tiu Valles as well as within the northern plains of Mars. Copyright 2006 by the American Geophysical Union.

Anthropogenic aerosols as a source of ancient dissolved organic matter in glaciers

USGS Publications Warehouse

Stubbins, Aron; Hood, Eran; Raymond, Peter A.; Aiken, George R.; Sleighter, Rachel L.; Hernes, Peter J.; Butman, David; Hatcher, Patrick G.; Striegl, Robert G.; Schuster, Paul F.; Abdulla, Hussain A.N.; Vermilyea, Andrew W.; Scott, Durelle T.; Spencer, Robert G.M.

2012-01-01

Glacier-derived dissolved organic matter represents a quantitatively significant source of ancient, yet highly bioavailable carbon to downstream ecosystems. This finding runs counter to logical perceptions of age–reactivity relationships, in which the least reactive material withstands degradation the longest and is therefore the oldest. The remnants of ancient peatlands and forests overrun by glaciers have been invoked as the source of this organic matter. Here, we examine the radiocarbon age and chemical composition of dissolved organic matter in snow, glacier surface water, ice and glacier outflow samples from Alaska to determine the origin of the organic matter. Low levels of compounds derived from vascular plants indicate that the organic matter does not originate from forests or peatlands. Instead, we show that the organic matter on the surface of the glaciers is radiocarbon depleted, consistent with an anthropogenic aerosol source. Fluorescence spectrophotometry measurements reveal the presence of protein-like compounds of microbial or aerosol origin. In addition, ultrahigh-resolution mass spectrometry measurements document the presence of combustion products found in anthropogenic aerosols. Based on the presence of these compounds, we suggest that aerosols derived from fossil fuel burning are a source of pre-aged organic matter to glacier surfaces. Furthermore, we show that the molecular signature of the organic matter is conserved in snow, glacier water and outflow, suggesting that the anthropogenic carbon is exported relatively unchanged in glacier outflows.

Signatures of Slow Solar Wind Streams from Active Regions in the Inner Corona

NASA Astrophysics Data System (ADS)

Slemzin, V.; Harra, L.; Urnov, A.; Kuzin, S.; Goryaev, F.; Berghmans, D.

2013-08-01

The identification of solar-wind sources is an important question in solar physics. The existing solar-wind models ( e.g., the Wang-Sheeley-Arge model) provide the approximate locations of the solar wind sources based on magnetic field extrapolations. It has been suggested recently that plasma outflows observed at the edges of active regions may be a source of the slow solar wind. To explore this we analyze an isolated active region (AR) adjacent to small coronal hole (CH) in July/August 2009. On 1 August, Hinode/EUV Imaging Spectrometer observations showed two compact outflow regions in the corona. Coronal rays were observed above the active-region coronal hole (ARCH) region on the eastern limb on 31 July by STEREO-A/EUVI and at the western limb on 7 August by CORONAS- Photon/TESIS telescopes. In both cases the coronal rays were co-aligned with open magnetic-field lines given by the potential field source surface model, which expanded into the streamer. The solar-wind parameters measured by STEREO-B, ACE, Wind, and STEREO-A confirmed the identification of the ARCH as a source region of the slow solar wind. The results of the study support the suggestion that coronal rays can represent signatures of outflows from ARs propagating in the inner corona along open field lines into the heliosphere.

Estimation of cold plasma outflow during geomagnetic storms

NASA Astrophysics Data System (ADS)

Haaland, S.; Eriksson, A.; André, M.; Maes, L.; Baddeley, L.; Barakat, A.; Chappell, R.; Eccles, V.; Johnsen, C.; Lybekk, B.; Li, K.; Pedersen, A.; Schunk, R.; Welling, D.

2015-12-01

Low-energy ions of ionospheric origin constitute a significant contributor to the magnetospheric plasma population. Measuring cold ions is difficult though. Observations have to be done at sufficiently high altitudes and typically in regions of space where spacecraft attain a positive charge due to solar illumination. Cold ions are therefore shielded from the satellite particle detectors. Furthermore, spacecraft can only cover key regions of ion outflow during segments of their orbit, so additional complications arise if continuous longtime observations, such as during a geomagnetic storm, are needed. In this paper we suggest a new approach, based on a combination of synoptic observations and a novel technique to estimate the flux and total outflow during the various phases of geomagnetic storms. Our results indicate large variations in both outflow rates and transport throughout the storm. Prior to the storm main phase, outflow rates are moderate, and the cold ions are mainly emanating from moderately sized polar cap regions. Throughout the main phase of the storm, outflow rates increase and the polar cap source regions expand. Furthermore, faster transport, resulting from enhanced convection, leads to a much larger supply of cold ions to the near-Earth region during geomagnetic storms.

Estimation of cold plasma outflow during geomagnetic storms

NASA Astrophysics Data System (ADS)

Haaland, S.; Eriksson, A. I.; Andre, M.; Maes, L.; Baddeley, L. J.; Barakat, A. R.; Chappell, C. R.; Eccles, V.; Johnsen, C.; Lybekk, B.; Li, K.; Pedersen, A.; Schunk, R. W.; Welling, D. T.

2015-12-01

Low energy ions of ionospheric origin provide a significant contributon to the magnetospheric plasmapopulation. Measuring cold ions is difficult though. Observations have to be done at sufficiently high altitudes and typically in regions of space where spacecraft attain a positive charge due to solar illumination. Cold ions are therefore shielded from the satellite particle detectors. Furthermore, spacecraft can only cover key regions of ion outflow during segments of their orbit, so additional complications arise arise if continuous longtime observations such as the during a geomagnetic storms are needed. In this paper we suggest a new approach, based on a combination of synoptic observations and a novel technique to estimate the flux and total outflow during the various phases of geomagnetic storms. Our results indicate large variations in both outflow rates and transport throughout the storm. Prior to the storm main phase, outflow rates are moderate, and the cold ions are mainly emanating from moderately sized polar cap regions. Throughout the main phase of the storm, outflow rates increase and the polar cap source regions expand. Furthermore, faster transport, resulting from enhanced convection, leads to a much larger supply of cold ions to the near Earth region during gemagnetic storms.

The Orion Fingers: H2 Temperatures and Excitation in an Explosive Outflow

NASA Astrophysics Data System (ADS)

Youngblood, Allison; France, Kevin; Ginsburg, Adam; Hoadley, Keri; Bally, John

2018-04-01

We measure H2 temperatures and column densities across the Orion Becklin-Neugebauer/Kleinmann-Low (BN/KL) explosive outflow from a set of 13 near-infrared (IR) H2 rovibrational emission lines observed with the TripleSpec spectrograph on Apache Point Observatory’s 3.5 m telescope. We find that most of the region is well characterized by a single temperature (∼2000–2500 K), which may be influenced by the limited range of upper-energy levels (6000–20,000 K) probed by our data set. The H2 column density maps indicate that warm H2 comprises 10‑5–10‑3 of the total H2 column density near the center of the outflow. Combining column density measurements for co-spatial H2 and CO at T = 2500 K, we measure a CO/H2 fractional abundance of 2 × 10‑3 and discuss possible reasons why this value is in excess of the canonical 10‑4 value, including dust attenuation, incorrect assumptions on co-spatiality of the H2 and CO emission, and chemical processing in an extreme environment. We model the radiative transfer of H2 in this region with ultraviolet (UV) pumping models to look for signatures of H2 fluorescence from H I Lyα pumping. Dissociative (J-type) shocks and nebular emission from the foreground Orion H II region are considered as possible Lyα sources. From our radiative transfer models, we predict that signatures of Lyα pumping should be detectable in near-IR line ratios given a sufficiently strong source, but such a source is not present in the BN/KL outflow. The data are consistent with shocks as the H2 heating source.

Spatially resolved galactic wind in lensed galaxy RCSGA 032727-132609

NASA Astrophysics Data System (ADS)

Bordoloi, Rongmon; Rigby, Jane R.; Tumlinson, Jason; Bayliss, Matthew B.; Sharon, Keren; Gladders, Michael G.; Wuyts, Eva

2016-05-01

We probe the spatial distribution of outflowing gas along four lines of sight separated by up to 6 kpc in a gravitationally lensed star-forming galaxy at z = 1.70. Using Mg II and Fe II emission and absorption as tracers, we find that the clumps of star formation are driving galactic outflows with velocities of -170 to -250 km s-1. The velocities of Mg II emission are redshifted with respect to the systemic velocities of the galaxy, consistent with being back-scattered. By contrast, the Fe II fluorescent emission lines are either slightly blueshifted or at the systemic velocity of the galaxy. Taken together, the velocity structure of the Mg II and Fe II emission is consistent with arising through scattering in galactic winds. Assuming a thin shell geometry for the outflowing gas, the estimated masses carried out by these outflows are large (≳30-50 M⊙ yr- 1), with mass loading factors several times the star formation rate. Almost 20 per cent to 50 per cent of the blueshifted absorption probably escapes the gravitational potential of the galaxy. In this galaxy, the outflow is `locally sourced', that is, the properties of the outflow in each line of sight are dominated by the properties of the nearest clump of star formation; the wind is not global to the galaxy. The mass outflow rates and the momentum flux carried out by outflows in individual star-forming knots of this object are comparable to that of starburst galaxies in the local Universe.

Spatially Resolved Galactic Wind in Lensed Galaxy RCSGA 032727-132609

NASA Technical Reports Server (NTRS)

Bordoloi, Rongmon; Rigby, Jane R.; Tumlinson, Janson; Bayliss, Matthew B.; Sharon, Keren; Gladders, Michael G.; Wuyts, Eva

2016-01-01

We probe the spatial distribution of outflowing gas along four lines of sight separated by up to 6 kpc in a gravitationally lensed star-forming galaxy at z = 1.70. Using Mg II and Fe II emission and absorption as tracers, we find that the clumps of star formation are driving galactic outflows with velocities of - 170 to - 250 km/s. The velocities of Mg II emission are redshifted with respect to the systemic velocities of the galaxy, consistent with being backscattered. By contrast, the Fe II fluorescent emission lines are either slightly blueshifted or at the systemic velocity of the galaxy. Taken together, the velocity structure of the Mg II and Fe II emission is consistent with arising through scattering in galactic winds. Assuming a thin shell geometry for the outflowing gas, the estimated masses carried out by these outflows are large (approx 30-50 M/yr), with mass loading factors several times the star formation rate. Almost 20 per cent to 50 per cent of the blueshifted absorption probably escapes the gravitational potential of the galaxy. In this galaxy, the outflow is 'locally sourced', that is, the properties of the outflow in each line of sight are dominated by the properties of the nearest clump of star formation; the wind is not global to the galaxy. The mass outflow rates and the momentum flux carried out by outflows in individual star-forming knots of this object are comparable to that of starburst galaxies in the local Universe.

Ion Outflow Observations

NASA Technical Reports Server (NTRS)

Mellot, Mary (Technical Monitor)

2002-01-01

The characteristics of out-flowing ions have been investigated under various circumstances. In particular the upwelling of ions from the cleft region has been studied to attempt to look at source characteristics (e.g., temperature, altitude). High altitude (6-8 Re) data tend to show ions species that have the same velocity and are adiabatically cooled. Such ions, while representative of their source, can not provide an accurate picture. Ion observations from the TIDE detector on the Polar spacecraft show an energy (or equivalently a velocity) spectrum of ions as they undo the geomagnetic mass spectrometer effect due to convection-gravity separation of the different species. Consolidation of this type of data into a complete representation of the source spectrum can be attempted by building a set of maximum-phase-space- density-velocity pairs and attributing the total to the source.

Resolved atomic lines reveal outflows in two ultraluminous X-ray sources.

PubMed

Pinto, Ciro; Middleton, Matthew J; Fabian, Andrew C

2016-05-05

Ultraluminous X-ray sources are extragalactic, off-nucleus, point sources in galaxies, and have X-ray luminosities in excess of 3 × 10(39) ergs per second. They are thought to be powered by accretion onto a compact object. Possible explanations include accretion onto neutron stars with strong magnetic fields, onto stellar-mass black holes (of up to 20 solar masses) at or in excess of the classical Eddington limit, or onto intermediate-mass black holes (10(3)-10(5) solar masses). The lack of sufficient energy resolution in previous analyses has prevented an unambiguous identification of any emission or absorption lines in the X-ray band, thereby precluding a detailed analysis of the accretion flow. Here we report the presence of X-ray emission lines arising from highly ionized iron, oxygen and neon with a cumulative significance in excess of five standard deviations, together with blueshifted (about 0.2 times light velocity) absorption lines of similar significance, in the high-resolution X-ray spectra of the ultraluminous X-ray sources NGC 1313 X-1 and NGC 5408 X-1. The blueshifted absorption lines must occur in a fast-outflowing gas, whereas the emission lines originate in slow-moving gas around the source. We conclude that the compact object in each source is surrounded by powerful winds with an outflow velocity of about 0.2 times that of light, as predicted by models of accreting supermassive black holes and hyper-accreting stellar-mass black holes.

Harmattan, Saharan heat low, and West African monsoon circulation: modulations on the Saharan dust outflow towards the North Atlantic

NASA Astrophysics Data System (ADS)

Schepanski, Kerstin; Heinold, Bernd; Tegen, Ina

2017-09-01

The outflow of dust from the northern African continent towards the North Atlantic is stimulated by the atmospheric circulation over North Africa, which modulates the spatio-temporal distribution of dust source activation and consequently the entrainment of mineral dust into the boundary layer, as well as the transport of dust out of the source regions. The atmospheric circulation over the North African dust source regions, predominantly the Sahara and the Sahel, is characterized by three major circulation regimes: (1) the harmattan (trade winds), (2) the Saharan heat low (SHL), and (3) the West African monsoon circulation. The strength of the individual regimes controls the Saharan dust outflow by affecting the spatio-temporal distribution of dust emission, transport pathways, and deposition fluxes.This study aims at investigating the atmospheric circulation pattern over North Africa with regard to its role favouring dust emission and dust export towards the tropical North Atlantic. The focus of the study is on summer 2013 (June to August), during which the SALTRACE (Saharan Aerosol Long-range TRansport and Aerosol-Cloud interaction Experiment) field campaign also took place. It involves satellite observations by the Spinning Enhanced Visible and InfraRed Imager (SEVIRI) flying on board the geostationary Meteosat Second Generation (MSG) satellite, which are analysed and used to infer a data set of active dust sources. The spatio-temporal distribution of dust source activation frequencies (DSAFs) allows for linking the diurnal cycle of dust source activations to dominant meteorological controls on dust emission. In summer, Saharan dust source activations clearly differ from dust source activations over the Sahel regarding the time of day when dust emission begins. The Sahara is dominated by morning dust source activations predominantly driven by the breakdown of the nocturnal low-level jet. In contrast, dust source activations in the Sahel are predominantly activated during the second half of the day, when downdrafts associated with deep moist convection are the major atmospheric driver. Complementary to the satellite-based analysis on dust source activations and implications from their diurnal cycle, simulations on atmosphere and dust life cycle were performed using the mesoscale atmosphere-dust model system COSMO-MUSCAT (COSMO: COnsortium for Small-scale MOdelling; MUSCAT: MUltiScale Chemistry Aerosol Transport Model). Fields from this simulation were analysed regarding the variability of the harmattan, the Saharan heat low, and the monsoon circulation as well as their impact on the variability of the Saharan dust outflow towards the North Atlantic. This study illustrates the complexity of the interaction among the three major circulation regimes and their modulation of the North African dust outflow. Enhanced westward dust fluxes frequently appear following a phase characterized by a deep SHL. Ultimately, findings from this study contribute to the quantification of the interannual variability of the atmospheric dust burden.

Fossil and Nonfossil Sources of Organic and Elemental Carbon Aerosols in the Outflow from Northeast China.

PubMed

Zhang, Yan-Lin; Kawamura, Kimitaka; Agrios, Konstantinos; Lee, Meehye; Salazar, Gary; Szidat, Sönke

2016-06-21

Source quantification of carbonaceous aerosols in the Chinese outflow regions still remains uncertain despite their high mass concentrations. Here, we unambiguously quantified fossil and nonfossil contributions to elemental carbon (EC) and organic carbon (OC) of total suspended particles (TSP) from a regional receptor site in the outflow of Northeast China using radiocarbon measurement. OC and EC concentrations were lower in summer, representing mainly marine air, than in other seasons, when air masses mostly traveled over continental regions in Mongolia and northeast China. The annual-mean contribution from fossil-fuel combustion to EC was 76 ± 11% (0.1-1.3 μg m(-3)). The remaining 24 ± 11% (0.03-0.42 μg m(-3)) was attributed to biomass burning, with slightly higher contribution in the cold period (∼31%) compared to the warm period (∼21%) because of enhanced emissions from regional biomass combustion sources in China. OC was generally dominated by nonfossil sources, with an annual average of 66 ± 11% (0.5-2.8 μg m(-3)), approximately half of which was apportioned to primary biomass-burning sources (34 ± 6%). In winter, OC almost equally originated from primary OC (POC) emissions and secondary OC (SOC) formation from fossil fuel and biomass-burning sources. In contrast, summertime OC was dominated by primary biogenic emissions as well as secondary production from biogenic and biomass-burning sources, but fossil-derived SOC was the smallest contributor. Distinction of POC and SOC was performed using primary POC-to-EC emission ratios separated for fossil and nonfossil emissions.

Model intra-comparison of transboundary sulfate loadings over springtime east Asia

NASA Astrophysics Data System (ADS)

Goto, D.; Ohara, T.; Nakajima, T.; Takemura, T.; Kajino, M.; Dai, T.; Matsui, H.; Takami, A.; Hatakeyama, S.; Aoki, K.; Sugimoto, N.; Shimizu, A.

2013-12-01

Over east Asia, a spatial gradient of sulfate aerosols from source to outflow regions has not fully evaluated by simulations. In the present study, we executed a global aerosol-transport model (SPRINTARS) during April 2006 to investigate the spatial gradient of sulfate aerosols using multiple measurements including surface mass concentration, aerosol optical thickness, and vertical profiles of extinction coefficients for spherical particles. We also performed sensitivity experiments to estimate possible uncertainties of sulfate mass loadings caused by macrophysical processes; emission inventory, dynamic core, and spatial resolution. Among the experiments, although a difference in the surface sulfate mass concentrations over east Asia was large, none of the simulations in the present study as well as regional models reproduced the spatial gradient of the surface sulfate from the source over China to the outflow regions in Japan. The sensitivity of different macrophysical factors to the surface sulfate differs from that to sulfate loadings in the column especially in the marine boundary layers (MBL). Therefore, to properly simulate the transboundary air pollution over east Asia is required to use multiple measurements in both the source and outflow regions especially in the MBL during the polluted days.

Flood routing of the Maja outflow across Xanthe Terra

NASA Technical Reports Server (NTRS)

Dehon, R. A.

1991-01-01

The object is to trace a single flood crest through the Maja outflow system and to evaluate the effects of topography on ponding and multiple channel routing. Maja Valles provides a good model because it has a single source and a well defined channel system. The 1500 km long Maja Valles originates in Juventae Chasma. The outflow system stretches 1100 km northward along the Lunae Planum/Xanthe Terra boundary, then eastward across the Xanthe Terra highlands. It descends to Chryse Planitia where it extends northeastward toward the middle of the basin. It is concluded that flood routing through multiple channels and retardation in local impoundments are responsible for breakup of the initial flood crest and the formation of multiple flood crests. Recombined flow near the mouths of these canyons results in an extended flow regime and multiple flood surges. As a result of ponding along the flood course, depositional sites are localized and renewed erosion downstream (from ponded sites) results in sediment source areas not greatly removed from depositional sites.

VHF discharges in storm cells producing microbursts

NASA Technical Reports Server (NTRS)

Laroche, P.; Malherbe, C.; Bondiou, A.; Weber, M.; Engholm, C.; Coel, V.

1991-01-01

An experiment was carried out in which 3-D mapping of VHF sources was compared to a 3-D description of the reflectivity and dynamics of associated cloud cells observed by a radar network. Data from 61 microbursts were analyzed and it was found that, in 93 pct. of the cases, electrical activity precedes outflow development. The results confirm that the peak in intracloud activity precedes the maximum value of the outflow.

Dissecting the Butterfly: Dual Outflows in the Dual AGN NGC 6240

NASA Astrophysics Data System (ADS)

Mueller Sanchez, Francisco; Comerford, Julie; Nevin, Rebecca; Davies, Richard; Treister, Ezequiel; Privon, George

2018-01-01

Current theories of galaxy evolution invoke some kind of feedback (from the stars or the supermassive black hole) to explain the properties of galaxies. However, numerical simulations and observations have not been able to evaluate the real impact of feedback in galaxies. This is largely because most studies have focused on studying stellar feedback or AGN feedback alone, instead of considering the combined effect of both. In fact, this is an unexplored territory for observations due to the difficulty of separating the contribution from the two sources.In this contribution I present the discovery of a dual outflow of different species of gas in the prototypical merging galaxy NGC 6240 using HST imaging, long-slit and integral-eld spectroscopy: an AGN-driven outflow of highly-ionized gas to the northeast and a starburst-driven outflow of ionized hydrogen to the northwest. The AGN outflow extends up to 4 kpc along a position angle of 56 degrees, has a conical shape with an opening angle of 52 degrees and a maximum line-of-sight velocity of 350 km/s. The WFC3 images also reveal a bubble of Halpha emission in the northwest, which has no counterpart in [O III], consistent with a scenario in which the starburst is ionizing and driving outflowing winds which inflate the bubble at an expansion velocity of 380 km/s. Assuming a spherical geometry for the starburst-driven bubble and a conical geometry for the AGN-driven outflow, we estimate mass outflow rates of 26 Msun/yr and 62 Msun/yr, respectively. We conclude that the AGN contribution to the evolution of the merger remnant and the formation of outflowing winds is signicant in the central 5 kpc of NGC 6240.

An X-Ray/SDSS Sample: Observational Characterization of The Outflowing Gas

NASA Astrophysics Data System (ADS)

Perna, Michele; Brusa, M.; Lanzuisi, G.; Mignoli, M.

2016-10-01

Powerful ionised AGN-driven outflows, commonly detected both locally and at high redshift, are invoked to contribute to the co-evolution of SMBH and galaxies through feedback phenomena. Our recent works (Brusa+2015; 2016; Perna+2015a,b) have shown that the XMM-COSMOS targets with evidence of outflows collected so far ( 10 sources) appear to be associated with low X-ray kbol corrections (Lbol /LX ˜ 18), in spite of their spread in obscuration, in the locations on the SFR-Mstar diagram, in their radio emission. A higher statistical significance is required to validate a connection between outflow phenomena and a X-ray loudness. Moreover, in order to validate their binding nature to the galaxy fate, it is crucial to correctly determine the outflow energetics. This requires time consuming integral field spectroscopic (IFS) observations, which are, at present, mostly limited to high luminosity objectsThe study of SDSS data offers a complementary strategy to IFS efforts. I will present physical and demographic characterization of the AGN-galaxy system during the feedback phase obtained studying a sample of 500 X-ray/SDSS AGNs, at z<0.8. Outflow velocity inferred from [OIII]5007 emission line profile has been related to optical (e.g., [OIII] and bolometric luminosities, Eddington ratio, stellar velocity dispersion) and X-ray properties (intrinsic X-ray luminosity, obscuration and X-ray kbol correction), to determine what drives ionised winds. Several diagnostic line ratios have been used to infer the physical properties of the ionised outflowing gas. The knowledge of these properties can reduce the actual uncertainties in the outflow energetics by a factor of ten, pointing to improve our understanding of the AGN outflow phenomenon and its impact on galaxy evolution.

VLA Ammonia Observations of IRAS 16253-2429: A Very Young and Low Mass Protostellar System

NASA Technical Reports Server (NTRS)

Wiseman, Jennifer J.

2011-01-01

IRAS l6253-2429. the source of the Wasp-Waist Nebula seen in Spitzer IRAC images, is an isolated very low luminosity ("VeLLO") Class 0 protostar in the nearby rho Ophiuchi cloud. We present VLA ammonia mapping observations of the dense gas envelope feeding the central core accreting system. We find a flattened envelope perpendicular to the outflow axis, and gas cavities that appear to cradle the outflow lobes as though carved out by the flow and associated (apparently precessing) jet. Based on the NH3 (1,1) and (2,2) emission distribution, we derive the mass, velocity fields and temperature distribution for the envelope. We discuss the combined evidence for this source as possibly one of the youngest and lowest mass sources in formation yet known.

Kinematic GPS Analysis Gives New Insights on the Origin of the Very-Long-Period Seismic Signals at Miyake-Jima Volcano during the Caldera Formation

NASA Astrophysics Data System (ADS)

Munekane, H.; Oikawa, J.; Kobayashi, T.

2014-12-01

Miyake-jima is an active basaltic stratovolcano that is located 200km south of Tokyo, Japan. Its eruption event in 2000 was remarkable in that the large caldera was formed at the summit in approximately one month. During the caldera forming stage, very-long-period (VLP) seismic pulse waves with a duration of about 50-s that were accompanied by the step-like inflation were repeatedly recorded. Based on the broadband seismometer data, the piston model is proposed in which a vertical piston of solid materials in the conduit is intermittently sucked into the magma chamber located 3-5 km beneath the edific. In this study, we used the kinematic displacements from the continuous GPS observation to obtain additonal insights on the source mechanism of the pulse waves. 　We calculated the kinematic displacements of 15 GPS stations on Miyake-jima that were in operation at that time at 30 sec interval. Then we extracted the displacements associated with each event using 20-hour time window centered at the occurrence of the event, and stacked the whole time series to obtain mean displacement time series. The obtained time series contain: 1) step-like displacements associated with the pulse waves, 2) exponential decay following the events with time constant of approximately half-day, and 3) steady linear displacements indicating continuous contraction of the edifice. The type one displacements can be attributed to the simultaneous inflation of an mogi-type spherical pressure source located at the depth of 3.6 km under the edifice, and the opening of the nearby vertical dike whose top is at the depth of 2.3 km. The type two displacements can be interpreted as the pressure adjustment at the type one source by the outflow of the magma driven by the pressure difference between the type one source and surrounding area. The type three displacements can be interpreted as the steady outflow of the magma from the type one source. The above results support the ``piston model'' for the source of the pulse waves. However, it seems that the pressure increases by the collapse of the piston are not adjusted by the steady magma outflow as the ``piston model'' suggests but by the pressure-driven magma outflow. The steady magma outflow instead seems to be responsible for the long-term shrinkage of the edifice observed at that period.

Asymmetric MHD outflows/jets from accreting T Tauri stars

NASA Astrophysics Data System (ADS)

Dyda, S.; Lovelace, R. V. E.; Ustyugova, G. V.; Lii, P. S.; Romanova, M. M.; Koldoba, A. V.

2015-06-01

Observations of jets from young stellar objects reveal the asymmetric outflows from some sources. A large set of 2.5D magnetohydrodynamic simulations was carried out for axisymmetric viscous/diffusive disc accretion to rotating magnetized stars for the purpose of assessing the conditions where the outflows are asymmetric relative to the equatorial plane. We consider initial magnetic fields that are symmetric about the equatorial plane and consist of a radially distributed field threading the disc (disc field) and a stellar dipole field. (1) For pure disc-fields the symmetry or asymmetry of the outflows is affected by the mid-plane plasma β of the disc. For discs with small plasma β, outflows are symmetric to within 10 per cent over time-scales of hundreds of inner disc orbits. For higher β discs, the coupling of the upper and lower coronal plasmas is broken, and quasi-periodic field motion leads to asymmetric episodic outflows. (2) Accreting stars with a stellar dipole field and no disc-field exhibit episodic, two component outflows - a magnetospheric wind and an inner disc wind. Both are characterized by similar velocity profiles but the magnetospheric wind has densities ≳ 10 times that of the disc wind. (3) Adding a disc field parallel to the stellar dipole field enhances the magnetospheric winds but suppresses the disc wind. (4) Adding a disc field which is antiparallel to the stellar dipole field in the disc suppresses the magnetospheric and disc winds. Our simulations reproduce some key features of observations of asymmetric outflows of T Tauri stars.

Modelling the thermal X-ray emission around the Galactic centre from colliding Wolf-Rayet winds

NASA Astrophysics Data System (ADS)

Russell, Christopher M. P.; Wang, Q. Daniel; Cuadra, Jorge

2017-11-01

We compute the thermal X-ray emission from hydrodynamic simulations of the 30 Wolf-Rayet (WR) stars orbiting within a parsec of Sgr A*, with the aim of interpreting the Chandra X-ray observations of this region. The model well reproduces the spectral shape of the observations, indicating that the shocked WR winds are the dominant source of this thermal emission. The model X-ray flux is tied to the strength of the Sgr A* outflow, which clears out hot gas from the vicinity of Sgr A*. A moderate outflow best fits the present-day observations, even though this supermassive black hole (SMBH) outflow ended ~100 yr ago.

Ultra-Fast Outflows in Radio-Loud AGN: New Constraints on Jet-Disk Connection

NASA Astrophysics Data System (ADS)

Sambruna, Rita

There is strong observational and theoretical evidence that outflows/jets are coupled to accretion disks in black hole accreting systems, from Galactic to extragalactic sizes. While in radio-quiet AGN there is ample evidence for the presence of Ultra-Fast Outflows (UFOs) from the presence of blue-shifted absorption features in their 4-10~keV spectra, sub-relativistic winds are expected on theoretical basis in radio-loud AGN but have not been observed until now. Our recent Suzaku observations of 5 bright Broad- Line Radio Galaxies (BLRGs, the radio-loud counterparts of Seyferts) has started to change this picture. We found strong evidence for UFOs in 3 out of 5 BLRGs, with ionization parameters, column densities, and velocities of the absorber similar to Seyferts. Moreover, the outflows in BLRGs are likely to be energetically very significant: from the Suzaku data of the three sources, outflow masses similar to the accretion masses and kinetic energies of the wind similar to the X-ray luminosity and radio power of the jet are inferred. Clearly, UFOs in radio-loud AGN represent a new key ingredient to understand their central engines and in particular, the jet-disk linkage. Our discovery of UFOs in a handful of BLRGs raises the questions of how common disk winds are in radio-loud AGN, what the absorber physical and dynamical characteristics are, and what is the outflow role in broader picture of galaxy-black hole connection for radio sources, i.e., for large-scale feedback models. To address these and other issues, we propose to use archival XMM-Newton and Suzaku spectra to search for Ultra-Fast Outflows in a large number of radio sources. Over a period of two years, we will conduct a systematic, uniform analysis of the archival X-ray data, building on our extensive experience with a similar previous project for Seyferts, and using robust analysis and statistical methodologies. As an important side product, we will also obtain accurate, self- consistent measurements of the broad-band X-ray spectra of radio-loud AGN for comparison to radio-quiet, addressing the origin of the division between the two classes. In addition, the upcoming Astro-H mission will greatly benefit from the outcomes of this project, which will provide templates for realistic simulations to define the scientific requirements of the calorimeter, and a list of targets to design a sample for the core AGN projects of the team.

Discovering a misaligned CO outflow related to the red MSX source G034.5964-01.0292

NASA Astrophysics Data System (ADS)

Paron, S.; Ortega, M. E.; Petriella, A.; Rubio, M.

2014-07-01

Aims: The red MSX source G034.5964-01.0292 (MSXG34), catalogued as a massive young stellar object, was observed in molecular lines with the aim of discovering and studying molecular outflows. Methods: We mapped a region of 3'× 3' centred at MSXG34 using the Atacama Submillimeter Telescope Experiment in the 12CO J = 3-2 and HCO+J = 4-3 lines with an angular and spectral resolution of 22'' and 0.11 km s-1. Additionally, public 13CO J = 1-0 and near-IR UKIDSS data obtained from the Galactic Ring Survey and the WFCAM Sciencie Archive were analysed. Results: We found that the 12CO spectra towards the YSO present a self-absorption dip, as is common in star-forming regions, and spectral wings that indicate outflow activity. The HCO+ was detected only towards the MSXG34 position at vLSR ~ 14.2 km s-1, in coincidence with the 12CO absorption dip and approximately with the velocity of previous ammonia observations. HCO+ and NH3 are known to be enhanced in molecular outflows. When we analysed the spectral wings of the 12CO line, we discovered misaligned red- and blue-shifted molecular outflows associated with MSXG34. The near-IR emission shows a cone-like nebulosity composed of two arc-like features related to the YSO, which might be due to a cavity cleared in the circumstellar material by a precessing jet. This can explain the misalignment in the molecular outflows. From the analysis of the 13CO J = 1-0 data we suggest that the YSO is very likely related to a molecular clump ranging between 10 and 14 km s-1. This suggests that MSXG34, with an associated central velocity of about 14 km s-1, may be located in the background of this clump. Thus, the blue-shifted outflow is probably deflected by the interaction with dense gas along the line of sight. From a spectral energy distribution analysis of MSXG34 we found that its central object probably is an intermediate-mass protostar.

A survey of extended H2 emission from massive YSOs

NASA Astrophysics Data System (ADS)

Navarete, F.; Damineli, A.; Barbosa, C. L.; Blum, R. D.

2015-07-01

We present the results from a survey, designed to investigate the accretion process of massive young stellar objects (MYSOs) through near-infrared narrow-band imaging using the H2 ν=1-0 S(1) transition filter. A sample of 353 MYSO candidates was selected from the Red MSX Source survey using photometric criteria at longer wavelengths (infrared and submillimetre) and chosen with positions throughout the Galactic plane. Our survey was carried out at the Southern Astrophysical Research Telescope Telescope in Chile and Canada-France-Hawaii Telescope in Hawaii covering both hemispheres. The data reveal that extended H2 emission is a good tracer of outflow activity, which is a signpost of accretion process on young massive stars. Almost half of the sample exhibit extended H2 emission and 74 sources (21 per cent) have polar morphology, suggesting collimated outflows. The polar-like structures are more likely to appear on radio-quiet sources, indicating these structures occur during the pre-UCH II phase. We also found an important fraction of sources associated with fluorescent H2 diffuse emission that could be due to a more evolved phase. The images also indicate only ˜23 per cent (80) of the sample is associated with extant (young) stellar clusters. These results support the scenario in which massive stars are formed by accretion discs, since the merging of low-mass stars would not produce outflow structures.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wolf-Chase, Grace; Arvidsson, Kim; Smutko, Michael, E-mail: gwolfchase@adlerplanetarium.org

We present the results of a narrow-band near-infrared imaging survey for Molecular Hydrogen emission-line Objects (MHOs) toward 26 regions containing high-mass protostellar candidates and massive molecular outflows. We have detected a total of 236 MHOs, 156 of which are new detections, in 22 out of the 26 regions. We use H{sub 2} 2.12 μ m/H{sub 2} 2.25 μ m flux ratios, together with morphology, to separate the signatures of fluorescence associated with photo-dissociation regions (PDRs) from shocks associated with outflows in order to identify the MHOs. PDRs have typical low flux ratios of ∼1.5–3, while the vast majority of MHOsmore » display flux ratios typical of C-type shocks (∼6–20). A few MHOs exhibit flux ratios consistent with expected values for J-type shocks (∼3–4), but these are located in regions that may be contaminated with fluorescent emission. Some previously reported MHOs have low flux ratios, and are likely parts of PDRs rather than shocks indicative of outflows. We identify a total of 36 outflows across the 22 target regions where MHOs were detected. In over half these regions, MHO arrangements and fluorescent structures trace features present in CO outflow maps, suggesting that the CO emission traces a combination of dynamical effects, which may include gas entrained in expanding PDRs as well as bipolar outflows. Where possible, we link MHO complexes to distinct outflows and identify candidate driving sources.« less

Do the enigmatic ``Infrared-Faint Radio Sources'' include pulsars?

NASA Astrophysics Data System (ADS)

Hobbs, George; Middelberg, Enno; Norris, Ray; Keith, Michael; Mao, Minnie; Champion, David

2009-04-01

The Australia Telescope Large Area Survey (ATLAS) team have surveyed seven square degrees of sky at 1.4GHz. During processing some unexpected infrared-faint radio sources (IFRS sources) were discovered. The nature of these sources is not understood, but it is possible that some of these sources may be pulsars within our own galaxy. We propose to observe the IFRS sources with steep spectral indices using standard search techniques to determine whether or not they are pulsars. A pulsar detection would 1) remove a subset of the IFRS sources from the ATLAS sample so they would not need to be observed with large optical/IR telescopes to find their hosts and 2) be intrinsically interesting as the pulsar would be a millisecond pulsar and/or have an extreme spatial velocity.

Directly Driven Ion Outflow

NASA Technical Reports Server (NTRS)

Elliott, H. A.; Comfort, R. H.; Craven, P. D.; Moore, T. E.; Russell, C. T.; Rose, M. Franklin (Technical Monitor)

2001-01-01

We examine ionospheric outflows in the high altitude magnetospheric polar cap during the POLAR satellite's apogee on April 19, 1996 using the Thermal Ion Dynamics Experiment (TIDE) instrument. The elevated levels of O(+) observed in this pass may be due to the geophysical conditions during and prior to the apogee pass. In addition to the high abundance of O(+) relative to H(+), several other aspects of this data are noteworthy. We observe relationships between the density, velocity, and temperature which appear to be associated with perpendicular heating and the mirror force, rather than adiabatic expansion. The H(+) outflow is at a fairly constant flux which is consistent with being source limited by charge exchange at lower altitudes. Local centrifugal acceleration in the polar cap is found to be insufficient to account for the main variations we observe in the outflow velocity. The solar wind speed is high during this pass approximately 700 kilometers per second, and there are Alfve'n waves present in the solar wind such that the solar wind speed and IMF Bx are correlated. In this pass both the H(+) and O(+) outflow velocities correlate with both the solar wind speed and IMF fluctuations. Polar cap magnetometer and Hydra electron data show the same long period wave structure as found in the solar wind and polar cap ion outflow. In addition, the polar cap Poynting flux along the magnetic field direction correlates well with the H(+) temperature (R=0.84). We conclude that the solar wind can drive polar cap ion outflow particularly during polar squalls by setting up a parallel drop that is tens of eV which then causes the ion outflow velocity of O(+) and H(+), the electrons, and magnetic perturbations to vary in a similar fashion.

Mass-loss from advective accretion disc around rotating black holes

NASA Astrophysics Data System (ADS)

Aktar, Ramiz; Das, Santabrata; Nandi, Anuj

2015-11-01

We examine the properties of the outflowing matter from an advective accretion disc around a spinning black hole. During accretion, rotating matter experiences centrifugal pressure-supported shock transition that effectively produces a virtual barrier around the black hole in the form of post-shock corona (hereafter PSC). Due to shock compression, PSC becomes hot and dense that eventually deflects a part of the inflowing matter as bipolar outflows because of the presence of extra thermal gradient force. In our approach, we study the outflow properties in terms of the inflow parameters, namely specific energy (E) and specific angular momentum (λ) considering the realistic outflow geometry around the rotating black holes. We find that spin of the black hole (ak) plays an important role in deciding the outflow rate R_{dot{m}} (ratio of mass flux of outflow to inflow); in particular, R_{dot{m}} is directly correlated with ak for the same set of inflow parameters. It is found that a large range of the inflow parameters allows global accretion-ejection solutions, and the effective area of the parameter space (E, λ) with and without outflow decreases with black hole spin (ak). We compute the maximum outflow rate (R^{max}_{dot{m}}) as a function of black hole spin (ak) and observe that R^{max}_{dot{m}} weakly depends on ak that lies in the range ˜10-18 per cent of the inflow rate for the adiabatic index (γ) with 1.5 ≥ γ ≥ 4/3. We present the observational implication of our approach while studying the steady/persistent jet activities based on the accretion states of black holes. We discuss that our formalism seems to have the potential to explain the observed jet kinetic power for several Galactic black hole sources and active galactic nuclei.

Jets from Young Stars in Cygnus-X

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2018-03-01

How do you spot very young, newly formed stars? One giveaway is the presence of jets and outflows that interact with the stars environments. In a new study, scientists have now discovered an unprecedented number of these outflows in a nearby star-forming region of our galaxy.Young Stars Hard at WorkCO map of the Cygnus-X region of the galactic plane, with the grid showing the UWISH2 coverage and the black triangles showing the positions of the detected outflows. [Makin Froebrich 2018]The birth and evolution of young stars is a dynamic, energetic process. As new stars form, material falls inward from the accretion disks surrounding young stellar objects, or YSOs. This material can power collimated streams of gas and dust that flow out along the stars rotation axes, plowing through the surrounding material. Where the outflows collide with the outside environment, shocks form that can be spotted in near-infrared hydrogen emission.Though weve learned a lot about these outflows, there remain a number of open questions. What factors govern their properties, such as their lengths, luminosities, and orientations? What is the origin of the emission features we see within the jets, known as knots? What roles do the driving sources and the environments play in the behavior and appearance of the jets?A selection of previously unknown outflows discovered as a result of this survey. Click for a closer look. [Makin Froebrich 2018]To answer these questions, we need to build a large, unbiased statistical sample of YSOs from across the galactic plane. Now, a large infrared survey known as the UKIRT Widefield Infrared Survey for H2 (UWISH2) is working toward that goal.Jackpot in Cygnus-XIn a recent publication, Sally Makin and Dirk Froebrich (University of Kent, UK), present results from UWISH2s latest release: a survey segment targeting a 42-square-degree region in the galactic plane known as the Cygnus-X star-forming region.The teams search for shock-excited emission in Cygnus-X yielded spectacular results. They found a treasure trove of outflows a remarkable 572 in total, representing a huge increase over the 107 known previously.Makin and Froebrich then measured properties of the outflows themselves such as length, orientation, and flux as well as properties of the sources that appear to drive them.Pinning Down PropertiesThis low-mass bright-rimmed cloud near IRAS 20294+4255 contains a number of stellar outflows. It may warrant further study as a classical example of triggered star formation. [Makin Froebrich 2018]Of the 572 outflows, the authors found that 27% are one-sided jets and 46% are bipolar. The bipolar outflows are typically 1.5 light-years in total length, and they are frequently asymmetric, with the shorter jet lobe averaging only 70% the length of the longer one. The flux from the two sides of bipolar jets is also often asymmetric: typically one side is brighter by about 50%.Exploring the knots of bright emission within the outflows, the authors found that they are typically closely spaced, suggesting that the material generating them is ejected every 9001,400 years. This rapid production faster than what has been found in YSO outflows in other regions rules out some models of how these knots are produced.Based on the fraction of UWISH2 data analyzed so far, the authors estimate that the entire UWISH2 survey will uncover a total of 2,000 jets and outflows from YSOs. This large, unbiased new sample is finally allowing astronomers to build out the statistics of YSO outflows to better understand them.CitationS. V. Makin and D. Froebrich 2018 ApJS 234 8. doi:10.3847/1538-4365/aa8862

Chemical and Physical Picture of IRAS 16293–2422 Source B at a Sub-arcsecond Scale Studied with ALMA

NASA Astrophysics Data System (ADS)

Oya, Yoko; Moriwaki, Kana; Onishi, Shusuke; Sakai, Nami; López–Sepulcre, Ana; Favre, Cécile; Watanabe, Yoshimasa; Ceccarelli, Cecilia; Lefloch, Bertrand; Yamamoto, Satoshi

2018-02-01

We have analyzed the OCS, H2CS, CH3OH, and HCOOCH3 data observed toward the low-mass protostar IRAS 16293–2422 Source B at a sub-arcsecond resolution with ALMA. A clear chemical differentiation is seen in their distributions; OCS and H2CS are extended with a slight rotation signature, while CH3OH and HCOOCH3 are concentrated near the protostar. Such a chemical change in the vicinity of the protostar is similar to the companion (Source A) case. The extended component is interpreted by the infalling-rotating envelope model with a nearly face-on configuration. The radius of the centrifugal barrier of the infalling-rotating envelope is roughly evaluated to be (30–50) au. The observed lines show the inverse P-Cygni profile, indicating the infall motion within a few 10 au from the protostar. The nearly pole-on geometry of the outflow lobes is inferred from the SiO distribution, and thus, the infalling and outflowing motions should coexist along the line of sight to the protostar. This implies that the infalling gas is localized near the protostar and the current launching points of the outflow have an offset from the protostar. A possible mechanism for this configuration is discussed.

Winds of change - a molecular outflow in NGC 1377?. The anatomy of an extreme FIR-excess galaxy

NASA Astrophysics Data System (ADS)

Aalto, S.; Muller, S.; Sakamoto, K.; Gallagher, J. S.; Martín, S.; Costagliola, F.

2012-10-01

Aims: Our goal was to investigate the molecular gas distribution and kinematics in the extreme far-infrared (FIR) excess galaxy NGC 1377 and to address the nature and evolutionary status of the buried source. Methods: We used high- (0''65 × 0''52, (65 × 52 pc)) and low- (4''88 × 2''93) resolution SubMillimeter Array (SMA) observations to image the 12CO and 13CO 2-1 line emission. Results: We find bright, complex 12CO 2-1 line emission in the inner 400 pc of NGC 1377. The 12CO 2-1 line has wings that are tracing a kinematical component that appears to be perpendicular to the component traced by the line core. Together with an intriguing X-shape of the integrated intensity and dispersion maps, this suggests that the molecular emission of NGC 1377 consists of a disk-outflow system. Lower limits to the molecular mass and outflow rate are Mout(H2) > 1 × 107 M⊙ and Ṁ > 8 M⊙ yr-1. The age of the proposed outflow is estimated to be 1.4 Myr, the extent to be 200 pc and the outflow speed to be Vout = 140 km s-1. The total molecular mass in the SMA map is estimated to Mtot(H2) = 1.5 × 108 M⊙ (on a scale of 400 pc) while in the inner r = 29 pc the molecular mass is Mcore(H2) = 1.7 × 107 M⊙ with a corresponding H2 column density of N(H2) = 3.4 × 1023 cm-2 and an average 12CO 2-1 brightness temperature of 19 K. 13CO 2-1 emission is found at a factor 10 fainter than 12CO in the low-resolution map while C18O 2-1 remains undetected. We find weak 1 mm continuum emission of 2.4 mJy with spatial extent less than 400 pc. Conclusions: Observing the molecular properties of the FIR-excess galaxy NGC 1377 allows us to probe the early stages of nuclear activity and the onset of feedback in active galaxies. The age of the outflow supports the notion that the current nuclear activity is young - a few Myr. The outflow may be powered by radiation pressure from a compact, dust enshrouded nucleus, but other driving mechanisms are possible. The buried source may be an active galactic nucleus (AGN) or an extremely young (1 Myr) compact starburst. Limitations on size and mass lead us to favor the AGN scenario, but additional studies are required to settle this question. In either case, the wind with its implied mass outflow rate will quench the nuclear power source within the very short time of 5-25 Myr. It is possible, however, that the gas is unable to escape the galaxy and may eventually fall back onto NGC 1377 again.

The Circumstellar Disk and Asymmetric Outflow of the EX Lup Outburst System

NASA Astrophysics Data System (ADS)

Hales, A. S.; Pérez, S.; Saito, M.; Pinte, C.; Knee, L. B. G.; de Gregorio-Monsalvo, I.; Dent, B.; López, C.; Plunkett, A.; Cortés, P.; Corder, S.; Cieza, L.

2018-06-01

We present Atacama Large Millimeter/submillimeter Array (ALMA) observations at 0.″3 resolution of EX Lup, the prototype of the EXor class of outbursting pre-main-sequence stars. The circumstellar disk of EX Lup is resolved for the first time in 1.3 mm continuum emission and in the J = 2–1 spectral line of three isotopologues of CO. At the spatial resolution and sensitivity achieved, the compact dust continuum disk shows no indications of clumps, fragments, or asymmetries above the 5σ level. Radiative transfer modeling constrains the characteristic radius of the dust disk to 23 au and the total dust mass to 1.0 × 10‑4 M ⊙ (33 M ⊕), similar to other EXor sources. The 13CO and C18O line emissions trace the disk rotation and are used to constrain the disk geometry, kinematics, and a total gas disk mass of 5.1 × 10‑4 M ⊙. The 12CO emission extends out to a radius of 200 au and is asymmetric, with one side deviating from Keplerian rotation. We detect blueshifted, 12CO arc-like emission located 0.″8 to the northwest and spatially disconnected from the disk emission. We interpret this extended structure as the brightened walls of a cavity excavated by an outflow, which are more commonly seen in FUor sources. Such outflows have also been seen in the borderline FU/EXor object V1647 Ori, but not toward EXor objects. Our detection provides evidence that the outflow phenomenon persists into the EXor phase, suggesting that FUor and EXor objects are a continuous population in which outflow activity declines with age, with transitional objects such as EX Lup and V1647 Ori.

Evidence for a Variable Ultrafast Outflow in the Newly Discovered Ultraluminous Pulsar NGC 300 ULX-1

NASA Astrophysics Data System (ADS)

Kosec, P.; Pinto, C.; Walton, D. J.; Fabian, A. C.; Bachetti, M.; Brightman, M.; Fürst, F.; Grefenstette, B. W.

2018-06-01

Ultraluminous pulsars are a definite proof that persistent super-Eddington accretion occurs in nature. They support the scenario according to which most Ultraluminous X-ray Sources (ULXs) are super-Eddington accretors of stellar mass rather than sub-Eddington intermediate mass black holes. An important prediction of theories of supercritical accretion is the existence of powerful outflows of moderately ionized gas at mildly relativistic speeds. In practice, the spectral resolution of X-ray gratings such as RGS onboard XMM-Newton is required to resolve their observational signatures in ULXs. Using RGS, outflows have been discovered in the spectra of 3 ULXs (none of which are currently known to be pulsars). Most recently, the fourth ultraluminous pulsar was discovered in NGC 300. Here we report detection of an ultrafast outflow (UFO) in the X-ray spectrum of the object, with a significance of more than 3σ, during one of the two simultaneous observations of the source by XMM-Newton and NuSTAR in December 2016. The outflow has a projected velocity of 65000 km/s (0.22c) and a high ionisation factor with a log value of 3.9. This is the first direct evidence for a UFO in a neutron star ULX and also the first time that this its evidence in a ULX spectrum is seen in both soft and hard X-ray data simultaneously. We find no evidence of the UFO during the other observation of the object, which could be explained by either clumpy nature of the absorber or a slight change in our viewing angle of the accretion flow.

Measurement of the Expansion Proper Motions of the Ou4 Giant Bipolar Outflow to Determine its Distance and its True Nature

NASA Astrophysics Data System (ADS)

Grosso, Nicolas

2016-10-01

Ou4 is a giant bipolar outflow with a total length of 1.2 degrees on the sky that was discovered in the optical in the direction of the blister HII region Sh2-129. The distance, the nature, and the driving source of Ou4 are, however, not known. Ou4 is relevant for the study of the eruptive phenomena producing collimated outflows from evolved low-mass binary stars and young, massive stellar systems. Our morpho-kinematics study of the Ou4 south bow-shock has allowed us to predict its expansion proper motion that is directly related to its distance. We propose to image the brightest [O III] emission of this bow-shock with the UVIS channel of the WFC3 in Cycle 24 and 26 in order to determine the distance of this largest known stellar bipolar outflow from its expansion proper motions. This measurement is crucial to determine the true nature of Ou4: either a foreground planetary nebula or a giant bipolar outflow launched 90,000 years ago by HR 8119, the young massive triple system ionising Sh2-129.

X-ray Evidence for Ultra-Fast Outflows in Local AGNs

NASA Astrophysics Data System (ADS)

Tombesi, F.; Cappi, M.; Sambruna, R. M.; Reeves, J. N.; Reynolds, C. S.; Braito, V.; Dadina, M.

2012-08-01

X-ray evidence for ultra-fast outflows (UFOs) has been recently reported in a number of local AGNs through the detection of blue-shifted Fe XXV/XXVI absorption lines. We present the results of a comprehensive spectral analysis of a large sample of 42 local Seyferts and 5 Broad-Line Radio Galaxies (BLRGs) observed with XMM-Newton and Suzaku. We detect UFOs in ga 40% of the sources. Their outflow velocities are in the range ˜ 0.03-0.3c, with a mean value of ˜ 0.14c. The ionization is high, in the range logℰ ˜3-6rm erg s-1 cm, and also the associated column densities are large, in the interval ˜ 1022-1024rm cm-2. Overall, these results point to the presence of highly ionized and massive outflowing material in the innermost regions of AGNs. Their variability and location on sub-pc scales favor a direct association with accretion disk winds/outflows. This also suggests that UFOs may potentially play a significant role in the AGN cosmological feedback besides jets, and their study can provide important clues on the connection between accretion disks, winds, and jets.

Evidence for Trivelpiece-Gould modes in a helicon discharge.

PubMed

Blackwell, D D; Madziwa, T G; Arnush, D; Chen, F F

2002-04-08

The high ionization efficiency of helicon discharges has been attributed to Landau damping and mode coupling to Trivelpiece-Gould (TG) modes. Though theory predicts the importance of TG modes, they have rarely been seen. Here they were detected directly by measuring their radiofrequency current with a J-dot probe, thus supporting the contention that TG modes play a role in these enigmatic plasma sources.

Tracing Galactic Outflows to the Source: Spatially Resolved Feedback in M83 with COS

NASA Astrophysics Data System (ADS)

Aloisi, Alessandra

2016-10-01

Star-formation (SF) feedback plays a vital role in shaping galaxy properties, but there are many open questions about how this feedback is created, propagated, and felt by galaxies. SF-driven feedback can be observationally constrained with rest-frame UV absorption-line spectroscopy that accesses a range of powerful gas density and kinematic diagnostics. Studies at both high and low redshift show clear evidence for large-scale outflows in star-forming galaxies that scale with galaxy SF rate. However, by sampling one sightline or the galaxy as a whole, these studies are not tailored to reveal how the large-scale outflows develop from their ultimate sources at the scale of individual SF regions. We propose the first spatially-resolved COS G130M/G160M (1130-1800 A) study of the ISM in the nearby (4.6 Mpc) face-on spiral starburst M83 using individual young star clusters as background sources. This is the first down-the-barrel study where blueshifted absorptions can be identified directly with outflowing gas in a spatially resolved fashion. The kpc-scale flows sampled by the COS pointings will be anchored to the properties of the large-scale (10-100 kpc) flows thanks to the wealth of multi-wavelength observations of M83 from X-ray to radio. A comparison of COS data with mock spectra from constrained simulations of spiral galaxies with FIRE (Feedback In Realistic Environments; a code with unprecedented 1-100 pc spatial resolution and self-consistent treatments of stellar feedback) will provide an important validation of these simulations and will supply the community with a powerful and well-tested tool for galaxy formation predictions applicable to all redshifts.

Super-Eddington Accretion in the Ultraluminous X-Ray Source NGC 1313 X-2: An Ephemeral Feast

NASA Astrophysics Data System (ADS)

Weng, Shan-Shan; Zhang, Shuang-Nan; Zhao, Hai-Hui

2014-01-01

We investigate the X-ray spectrum, variability, and the surrounding ionized bubble of NGC 1313 X-2 to explore the physics of super-Eddington accretion. Beyond the Eddington luminosity, the accretion disk of NGC 1313 X-2 is truncated at a large radius (~50 times the innermost stable circular orbit), and displays the similar evolution track with both luminous Galactic black-hole and neutron star X-ray binaries (XRBs). In super-critical accretion, the speed of radiatively driven outflows from the inner disk is mildly relativistic. Such ultra-fast outflows would be overionized and might produce weak Fe K absorption lines, which may be detected by the coming X-ray mission Astro-H. If NGC 1313 X-2 is a massive stellar XRB, the high luminosity indicates that an ephemeral feast is held in the source. That is, the source must be accreting at a hyper-Eddington mass rate to give the super-Eddington emission over ~104-105 yr. The expansion of the surrounding bubble nebula with a velocity of ~100 km s-1 might indicate that it has existed over ~106 yr and is inflated by the radiatively driven outflows from the transient with a duty cycle of activity of ~ a few percent. Alternatively, if the surrounding bubble nebula is produced by line-driven winds, less energy is required than the radiatively driven outflow scenario, and the radius of the Strömgren radius agrees with the nebula size. Our results are in favor of the line-driven winds scenario, which can avoid the conflict between the short accretion age and the apparently much longer bubble age inferred from the expansion velocity in the nebula.

Proper motions of collimated jets from intermediate-mass protostars in the Carina Nebula

NASA Astrophysics Data System (ADS)

Reiter, Megan; Kiminki, Megan M.; Smith, Nathan; Bally, John

2017-10-01

We present proper motion measurements of 37 jets and HH objects in the Carina Nebula measured in two epochs of H α images obtained ˜10 yr apart with Hubble Space Telescope/Advanced Camera for Surveys (ACS). Transverse velocities in all but one jet are faster than ≳ 25 km s-1, confirming that the jet-like H α features identified in the first epoch images trace outflowing gas. Proper motions constrain the location of the jet-driving source and provide kinematic confirmation of the intermediate-mass protostars that we identify for 20/37 jets. Jet velocities do not correlate with the estimated protostar mass and embedded driving sources do not have slower jets. Instead, transverse velocities (median ˜75 km s-1) are similar to those in jets from low-mass stars. Assuming a constant velocity since launch, we compute jet dynamical ages (median ˜104 yr). If continuous emission from inner jets traces the duration of the most recent accretion bursts, then these episodes are sustained longer (median ˜700 yr) than the typical decay time of an FU Orionis outburst. These jets can carry appreciable momentum that may be injected into the surrounding environment. The resulting outflow force, dP/dt, lies between that measured in low- and high-mass sources, despite the very different observational tracers used. Smooth scaling of the outflow force argues for a common physical process underlying outflows from protostars of all masses. This latest kinematic result adds to a growing body of evidence that intermediate-mass star formation proceeds like a scaled-up version of the formation of low-mass stars.

Time dependent inflow-outflow boundary conditions for 2D acoustic systems

NASA Technical Reports Server (NTRS)

Watson, Willie R.; Myers, Michael K.

1989-01-01

An analysis of the number and form of the required inflow-outflow boundary conditions for the full two-dimensional time-dependent nonlinear acoustic system in subsonic mean flow is performed. The explicit predictor-corrector method of MacCormack (1969) is used. The methodology is tested on both uniform and sheared mean flows with plane and nonplanar sources. Results show that the acoustic system requires three physical boundary conditions on the inflow and one on the outflow boundary. The most natural choice for the inflow boundary conditions is judged to be a specification of the vorticity, the normal acoustic impedance, and a pressure gradient-density gradient relationship normal to the boundary. Specification of the acoustic pressure at the outflow boundary along with these inflow boundary conditions is found to give consistent reliable results. A set of boundary conditions developed earlier, which were intended to be nonreflecting is tested using the current method and is shown to yield unstable results for nonplanar acoustic waves.

Anatomy of the AGN in NGC 5548: Discovery of a fast and massive outflow

NASA Astrophysics Data System (ADS)

Kaastra, J.; Kriss, G.; Cappi, M.; Mehdipour, M.; Petrucci, P.; Steenbrugge, K.; Arav, N.; Behar, E.; Bianchi, S.; Boissay, R.; Branduardi-Raymont, G.; Chamberlain, C.; Costantini, E.; Ely, J.; Ebrero, J.; Di Gesu, L.; Harrison, F.; kaspi, S.; Malzac, J.; De Marco, B.; Matt, G.; Nandra, K.; Paltani, S.; Person, R.; Peterson, B.; Pinto, C.; Ponti, G.; Pozo Nuñez, F.; De Rosa, A.; Seta, H.; Ursini, F.; De Vries, C.; Walton, D.; Whewell, M.

2014-07-01

After a very succesfull multi-satellite campaign on Mrk 509 in 2009, we conducted a similar campaign on the AGN NGC 5548 in 2013. This archetype Seyfert 1 galaxy NGC 5548 has been studied for decades, and high-resolution X-ray and UV observations have previously shown an outflow with standard physical characteristics. However, our recent observing campaign with six space observatories (XMM-Newton, HST, Swift, NuSTAR, Chandra and INTEGRAL) shows the nucleus to be obscured by a stream of new ionized gas never seen before in this source. The gas with hydrogen column densities of 1E26-1E27 per m2 blocks 90% of the soft X-ray emission and causes deep and broad UV absorption troughs. The outflow velocities are up to five times faster than the persistent normal outflow. It is located at a distance of only a few light days from the nucleus close to the broad line region; this might indicate an origin from the accretion disk.

Extreme gaseous outflows in radio-loud narrow-line Seyfert 1 galaxies

NASA Astrophysics Data System (ADS)

Komossa, S.; Xu, D. W.; Wagner, A. Y.

2018-07-01

We present four radio-loud narrow-line Seyfert 1 (NLS1) galaxies with extreme emission-line shifts, indicating radial outflow velocities of the ionized gas of up to 2450 km s-1, above the escape velocity of the host galaxies. The forbidden lines show strong broadening, up to 2270 km s-1. An ionization stratification (higher line shift at higher ionization potential) implies that we see a large-scale outflow rather than single, localized jet-cloud interactions. Similarly, the paucity of zero-velocity [O III] λ5007 emitting gas implies the absence of a second narrow-line region (NLR) component at rest, and therefore a large part of the high-ionization NLR is affected by the outflow. Given the radio loudness of these NLS1 galaxies, the observations are consistent with a pole on view onto their central engines, so that the effects of polar outflows are maximized. In addition, a very efficient driving mechanism is required to reach the high observed velocities. We explore implications from recent hydrodynamic simulations of the interaction between fast winds or jets with the large-scale NLR. Overall, the best agreement with observations (and especially the high outflow speeds of the [Ne V] emitting gas) can be reached if the NLS1 galaxies are relatively young sources with lifetimes not much exceeding 1 Myr. These systems represent sites of strong feedback at NLR scales at work, well below redshift one.

Extreme Gaseous Outflows in Radio-Loud Narrow-Line Seyfert 1 Galaxies

NASA Astrophysics Data System (ADS)

Komossa, S.; Xu, D. W.; Wagner, A. Y.

2018-04-01

We present four radio-loud NLS1 galaxies with extreme emission-line shifts, indicating radial outflow velocities of the ionized gas of up to 2450 km/s, above the escape velocity of the host galaxies. The forbidden lines show strong broadening, up to 2270 km/s. An ionization stratification (higher line shift at higher ionization potential) implies that we see a large-scale outflow rather than single, localized jet-cloud interactions. Similarly, the paucity of zero-velocity [OIII]λ5007 emitting gas implies the absence of a second narrow-line region (NLR) component at rest, and therefore a large part of the high-ionization NLR is affected by the outflow. Given the radio loudness of these NLS1 galaxies, the observations are consistent with a pole on view onto their central engines, so that the effects of polar outflows are maximized. In addition, a very efficient driving mechanism is required, to reach the high observed velocities. We explore implications from recent hydrodynamic simulations of the interaction between fast winds or jets with the large-scale NLR. Overall, the best agreement with observations (and especially the high outflow speeds of the [NeV] emitting gas) can be reached if the NLS1 galaxies are relatively young sources with lifetimes not much exceeding 1 Myr. These systems represent sites of strong feedback at NLR scales at work, well below redshift one.

Catastrophic ice lake collapse in Aram Chaos, Mars

NASA Astrophysics Data System (ADS)

Roda, Manuel; Kleinhans, Maarten G.; Zegers, Tanja E.; Oosthoek, Jelmer H. P.

2014-07-01

Hesperian chaotic terrains have been recognized as the source of outflow channels formed by catastrophic outflows. Four main scenarios have been proposed for the formation of chaotic terrains that involve different amounts of water and single or multiple outflow events. Here, we test these scenarios with morphological and structural analyses of imagery and elevation data for Aram Chaos in conjunction with numerical modeling of the morphological evolution of the catastrophic carving of the outflow valley. The morphological and geological analyses of Aram Chaos suggest large-scale collapse and subsidence (1500 m) of the entire area, which is consistent with a massive expulsion of liquid water from the subsurface in one single event. The combined observations suggest a complex process starting with the outflow of water from two small channels, followed by continuous groundwater sapping and headward erosion and ending with a catastrophic lake rim collapse and carving of the Aram Valley, which is synchronous with the 2.5 Ga stage of the Ares Vallis formation. The water volume and formative time scale required to carve the Aram channels indicate that a single, rapid (maximum tens of days) and catastrophic (flood volume of 9.3 × 104 km3) event carved the outflow channel. We conclude that a sub-ice lake collapse model can best explain the features of the Aram Chaos Valley system as well as the time scale required for its formation.

Radio jets clearing the way through galaxies: the view from Hi and molecular gas

NASA Astrophysics Data System (ADS)

Morganti, Raffaella

2015-03-01

Massive gas outflows are considered a key component in the process of galaxy formation and evolution. Because of this, they are the topic of many studies aimed at learning more about their occurrence, location and physical conditions as well as the mechanism(s) at their origin. This contribution presents recent results on two of the best examples of jet-driven outflows traced by cold and molecular gas. Thanks to high-spatial resolution observations, we have been able to locate the region where the outflow occurs. This appears to be coincident with bright radio features and regions where the interaction between radio plasma jet and ISM is known to occur, thus strongly supporting the idea of jet-driven outflows. We have also imaged the distribution of the outflowing gas. The results clearly show the effect that expanding radio jets and lobes have on the ISM. This appears to be in good agreement with what predicted from numerical simulations. Furthermore, the results show that cold gas is associated with these powerful phenomena and can be formed - likely via efficient cooling - even after a strong interaction and fast shocks. The discovery of similar fast outflows of cold gas in weak radio sources is further increasing the relevance that the effect of the radio plasma can have on the surrounding medium and on the host galaxy.

Better Than Nothing: A Rational Approach for Minimizing the Impact of Outflow Strategy on Cerebrovascular Simulations.

PubMed

Chnafa, C; Brina, O; Pereira, V M; Steinman, D A

2018-02-01

Computational fluid dynamics simulations of neurovascular diseases are impacted by various modeling assumptions and uncertainties, including outlet boundary conditions. Many studies of intracranial aneurysms, for example, assume zero pressure at all outlets, often the default ("do-nothing") strategy, with no physiological basis. Others divide outflow according to the outlet diameters cubed, nominally based on the more physiological Murray's law but still susceptible to subjective choices about the segmented model extent. Here we demonstrate the limitations and impact of these outflow strategies, against a novel "splitting" method introduced here. With our method, the segmented lumen is split into its constituent bifurcations, where flow divisions are estimated locally using a power law. Together these provide the global outflow rate boundary conditions. The impact of outflow strategy on flow rates was tested for 70 cases of MCA aneurysm with 0D simulations. The impact on hemodynamic indices used for rupture status assessment was tested for 10 cases with 3D simulations. Differences in flow rates among the various strategies were up to 70%, with a non-negligible impact on average and oscillatory wall shear stresses in some cases. Murray-law and splitting methods gave flow rates closest to physiological values reported in the literature; however, only the splitting method was insensitive to arbitrary truncation of the model extent. Cerebrovascular simulations can depend strongly on the outflow strategy. The default zero-pressure method should be avoided in favor of Murray-law or splitting methods, the latter being released as an open-source tool to encourage the standardization of outflow strategies. © 2018 by American Journal of Neuroradiology.

Geologic Mapping of Holden Crater and the Uzboi-Ladon-Morava Outflow System

NASA Technical Reports Server (NTRS)

Grant, J. A.; Irwin, R. P., III; Wilson, S. A.

2009-01-01

Geologic mapping in Margaritifer Terra (Fig. 1) yields important new information regarding the inventory, sources, and sinks of water during the Noachian and early Hesperian on Mars [1-7]. Drainage in southwest Margaritifer Terra is dominated by the segmented Uzboi-Ladon-Morava (ULM) meso-scale outflow system that traverses northward along the southwestern flank of the Chryse trough [4-9]. Mapping of lower Uzboi Vallis through Ladon basin highlights the extent and complexity of sedimentary deposits associated with the ULM system [5-13].

Interferometric Mapping of Perseus Outflows with MASSES

NASA Astrophysics Data System (ADS)

Stephens, Ian; Dunham, Michael; Myers, Philip C.; MASSES Team

2017-01-01

The MASSES (Mass Assembly of Stellar Systems and their Evolution with the SMA) survey, a Submillimeter Array (SMA) large-scale program, is mapping molecular lines and continuum emission about the 75 known Class 0/I sources in the Perseus Molecular Cloud. In this talk, I present some of the key results of this project, with a focus on the CO(2-1) maps of the molecular outflows. In particular, I investigate how protostars inherit their rotation axes from large-scale magnetic fields and filamentary structure.

Oxygen Ion Upflow/Outflow Fluxes of Ionospheric Origin in the Stormtime Plasmasphere Boundary Layer

NASA Astrophysics Data System (ADS)

Erickson, P. J.; Zhang, S.; Foster, J. C.; Coster, A. J.

2017-12-01

During geomagnetic storm intervals, Earth's ionosphere is a source of heavy, cold O+ rich plasma to the inner magnetosphere, providing mass flux enhancement with strong dynamic geospace influence. Advancing understanding of the relative strength of ionospheric O+ sources is important for refining modeling of global ionosphere-thermosphere-plasmasphere response, and ultimately for quantitative understanding of the dynamics of energy inputs from solar wind to the magnetosphere. An important but often overlooked source of inner magnetospheric O+ can occur within the plasmasphere boundary layer, well equatorward of higher latitude processes. In particular, at the outer edge of the plasmasphere, O+ dynamics capable of accelerating heavy ions most probably occurs in two steps: (1) ion upflow with thermal velocities above the F2 electron density peak, and (2) ion outflow with suprathermal velocities at higher altitudes. Below approximately 500 km altitude in the near topside ionosphere, ion and electron precipitation in the 10s of eV to 10s of keV range can cause `backsplash' effects, providing sources of upwelling ions. Alternately, strong frictional ion heating from intense horizontal cross-field sub auroral polarization stream (SAPS) flows also provide significant ion temperature enhancements that lead to upwards velocities. Although these vertical flows are challenging to observe due to their short temporal nature and confined spatial extent, direct quantification of the upwelling O+ ion flux is available during several historical storm events using the Millstone Hill incoherent scatter radar, including the recent March 2015 storm interval. DMSP overflights and GPS based large scale TEC maps place these ionospheric radar measurements in correct geophysical context. Results show heavy ion upwelling fluxes lasting for at least 30 minutes to 1 hour (upper bound limited by observational restrictions), at rates exceeding 1E13 ions/m2/sec. We will present a summary of these observations and will quantitatively discuss estimates of the total O+ ion outflow involved, along with an exploration of the relative importance of the two leading mechanisms involved for these upwelling sources. Finally, we will discuss the implications in order to correctly model outflow effects within the inner magnetosphere.

The Resolved Outflow from 3C 48

NASA Astrophysics Data System (ADS)

Shih, Hsin-Yi; Stockton, Alan

2014-10-01

We investigate the properties of the high-velocity outflow driven by the young radio jet of 3C 48, a compact-steep-spectrum source. We use the Space Telescope Imaging Spectrograph on board the Hubble Space Telecope to obtain (1) low-resolution UV and optical spectra and (2) multi-slit medium-resolution spectra of the ionized outflow. With supporting data from ground-based spectrographs, we are able to accurately measure the ratios of diagnostic emission lines such as [O III] λ5007, [O III] λ3727, [N II] λ6548, Hα, Hβ, [Ne V] λ3425, and [Ne III] λ3869. We fit the observed emission-line ratios using a range of ionization models, powered by active galactic nucleus (AGN) radiation and shocks, produced by the MAPPINGS code. We have determined that AGN radiation is likely the dominant ionization source. The outflow's density is estimated to be in the range n = 103-104 cm-3, the mass is ~6 × 106 M ⊙, and the metallicity is likely equal to or higher than solar. Compared with the typical outflows associated with more evolved radio jets, this young outflow is denser, less massive, and more metal rich. Multi-slit observations allow us to construct a two-dimensional velocity map of the outflow that shows a wide range of velocities with distinct velocity components, suggesting a wide-angle clumpy outflow. Based in part on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program GO-11574. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. Some of the observations included were obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministério da Ciência, Tecnologia e Inovação (Brazil) and Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina).

ALMA Cycle 1 Observations of the HH46/47 Molecular Outflow: Structure, Entrainment, and Core Impact

NASA Astrophysics Data System (ADS)

Zhang, Yichen; Arce, Héctor G.; Mardones, Diego; Cabrit, Sylvie; Dunham, Michael M.; Garay, Guido; Noriega-Crespo, Alberto; Offner, Stella S. R.; Raga, Alejandro C.; Corder, Stuartt A.

2016-12-01

We present Atacama Large Millimeter/sub-millimeter Array Cycle 1 observations of the HH 46/47 molecular outflow using combined 12 m array and Atacama Compact Array observations. The improved angular resolution and sensitivity of our multi-line maps reveal structures that help us study the entrainment process in much more detail and allow us to obtain more precise estimates of outflow properties than in previous observations. We use {}13{{CO}} (1-0) and {{{C}}}18{{O}} (1-0) emission to correct for the {}12{{CO}} (1-0) optical depth to accurately estimate the outflow mass, momentum, and kinetic energy. This correction increases the estimates of the mass, momentum, and kinetic energy by factors of about 9, 5, and 2, respectively, with respect to estimates assuming optically thin emission. The new {}13{{CO}} and {{{C}}}18{{O}} data also allow us to trace denser and slower outflow material than that traced by the {}12{{CO}} maps, and they reveal an outflow cavity wall at very low velocities (as low as 0.2 {\\text{km s}}-1 with respect to the core’s central velocity). Adding the slower material traced only by {}13{{CO}} and {{{C}}}18{{O}}, there is another factor of three increase in the mass estimate and 50% increase in the momentum estimate. The estimated outflow properties indicate that the outflow is capable of dispersing the parent core within the typical lifetime of the embedded phase of a low-mass protostar and that it is responsible for a core-to-star efficiency of 1/4 to 1/3. We find that the outflow cavity wall is composed of multiple shells associated with a series of jet bow-shock events. Within about 3000 au of the protostar the {}13{{CO}} and {{{C}}}18{{O}} emission trace a circumstellar envelope with both rotation and infall motions, which we compare with a simple analytic model. The CS (2-1) emission reveals tentative evidence of a slowly moving rotating outflow, which we suggest is entrained not only poloidally but also toroidally by a disk wind that is launched from relatively large radii from the source.

FE K EMISSION AND ABSORPTION FEATURES IN THE XMM-EPIC SPECTRUM OF THE SEYFERT GALAXY IC 4329A

NASA Technical Reports Server (NTRS)

Markowitz, A.; Reeves, J. N.; Braito, V.

2001-01-01

We present a re-analysis of the XMM-Newton long-look of the X-ray bright Seyfert galaxy IC 4329a. The Fe K bandpass is dominated by two peaks, consistent with emission from neutral or near-neutral Fe Ka and KP. A relativistic diskline model whereby both peaks are the result of one doubly-peaked diskline profile is found to be a poor description of the data. Models using two relativistic disklines are found to describe the emission profile well. A low-inclination, moderately-relativistic dual-diskline model is possible if the contribution from narrow components, due to distant material, is small or absent. A high-inclination, moderately relativistic profile for each peak is possible if there are roughly equal contributions from both the broad and narrow components. Upper limits on Fe XXV and Fe XXVI emission and absorption at the systemic velocity of IC 4329a are obtained. We also present the results of RXTE monitoring of this source obtained so far; the combined XMM-Newton and RXTE data sets allow us to explore the time-resolved spectral behavior of this source on time scales ranging from hours to 2 years. We find no strong evidence for variability of the Fe Ka emission line on any time scale probed, likely due to the minimal level of continuum variability. We detect a narrow absorption line, at a energy of 7.68 keV in the rest frame of the source; its significance has been confirmed using Monte Carlo simulations. This feature is most likely due to absorption from Fe XXVI blueshifted to approximately 0.1c relative to the systemic velocity, making IC 4329a the lowest-redshift AGN known with a high-velocity, highly-ionized outflow component. As is often the case with similar outflows seen in high-luminosity quasars, the estimated mass outflow rate is larger than the inflow accretion rate, signaling that the outflow represents a substantial portion of the total energy budget of the AGN. The outflow could arise from a radiatively-driven disk wind, or it may be in the form of a discrete, transient blob of ejected material.

Water in star-forming regions with Herschel (WISH). II. Evolution of 557 GHz 110-101 emission in low-mass protostars

NASA Astrophysics Data System (ADS)

Kristensen, L. E.; van Dishoeck, E. F.; Bergin, E. A.; Visser, R.; Yıldız, U. A.; San Jose-Garcia, I.; Jørgensen, J. K.; Herczeg, G. J.; Johnstone, D.; Wampfler, S. F.; Benz, A. O.; Bruderer, S.; Cabrit, S.; Caselli, P.; Doty, S. D.; Harsono, D.; Herpin, F.; Hogerheijde, M. R.; Karska, A.; van Kempen, T. A.; Liseau, R.; Nisini, B.; Tafalla, M.; van der Tak, F.; Wyrowski, F.

2012-06-01

Context. Water is a key tracer of dynamics and chemistry in low-mass star-forming regions, but spectrally resolved observations have so far been limited in sensitivity and angular resolution, and only data from the brightest low-mass protostars have been published. Aims: The first systematic survey of spectrally resolved water emission in 29 low-mass (L < 40 L⊙) protostellar objects is presented. The sources cover a range of luminosities and evolutionary states. The aim is to characterise the line profiles to distinguish physical components in the beam and examine how water emission changes with protostellar evolution. Methods: H2O was observed in the ground-state 110-101 transition at 557 GHz (Eup/kB ~ 60 K) as single-point observations with the Heterodyne Instrument for the Far-Infrared (HIFI) on Herschel in 29 deeply embedded Class 0 and I low-mass protostars. Complementary far-IR and sub-mm continuum data (including PACS data from our programme) are used to constrain the spectral energy distribution (SED) of each source. H2O intensities are compared to inferred envelope properties, e.g., mass and density, outflow properties and CO 3-2 emission. Results: H2O emission is detected in all objects except one (TMC1A). The line profiles are complex and consist of several kinematic components tracing different physical regions in each system. In particular, the profiles are typically dominated by a broad Gaussian emission feature, indicating that the bulk of the water emission arises in outflows, not in the quiescent envelope. Several sources show multiple shock components appearing in either emission or absorption, thus constraining the internal geometry of the system. Furthermore, the components include inverse P-Cygni profiles in seven sources (six Class 0, one Class I) indicative of infalling envelopes, and regular P-Cygni profiles in four sources (three Class I, one Class 0) indicative of expanding envelopes. Molecular "bullets" moving at ≳50 km s-1 with respect to the source are detected in four Class 0 sources; three of these sources were not known to harbour bullets previously. In the outflow, the H2O/CO abundance ratio as a function of velocity is nearly the same for all line wings, increasing from 10-3 at low velocities (<5 km s-1) to ≳10-1 at high velocities (>10 km s-1). The water abundance in the outer cold envelope is low, ≳10-10. The different H2O profile components show a clear evolutionary trend: in the younger Class 0 sources the emission is dominated by outflow components originating inside an infalling envelope. When large-scale infall diminishes during the Class I phase, the outflow weakens and H2O emission all but disappears. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.Appendices are available in electronic form at http://www.aanda.org

Pulsations, Shocks, and Mass Loss

NASA Technical Reports Server (NTRS)

Bally, John

1998-01-01

This grant provided long-term support for my investigation of the outflows powered by young stars. Several major research results emerged during the course of this research, including: (1) The discovery of giant Herbig-Haro outflows from young stars that can extend for many parsecs from their sources. The first parsec-scale outflow to be recognized led to the realization that Herbig-Haro outflows, even those produced by low mass young stellar objects, can extend orders of magnitude farther from their sources than previously thought. Our preconceptions were to a large extent driven by the narrow fields-of-view then provided by CCD detectors. With the recent advent of large format CCDs and CCD mosaics, we have come to realize that most outflows attain parsec-scale dimensions. Even at the distance of the Orion star forming clouds, such flows can subtend a degree on the sky. Our work has led to the recognition of over two dozen giant. (2) The discovery that outflows are highly clustered. Even regions of relatively isolated star formation such as those in Taurus frequently produce multiple outflows. (3) The discovery of a new family of externally irradiated jets. During the last year of support from this grant, we made the startling discovery that there is a class of jets from young stars that are illuminated by the ionizing radiation field of nearby massive stars. The first four examples were discovered in the vicinity of the a Orionis sub-group of the Orion OB Association which is believed to be at least 2 million years old. Since the jets are photo-ionized, their densities can be reliably estimated. Most HH jets are shock excited, and are therefore notoriously difficult to characterize since their visibility and observed properties depend on the complex and highly non-linear processes associated with shocks. Furthermore, many irradiated jets are one sided rather than bipolar. Thus, irradiated jets may for the first time be used to accurately diagnose jet densities and mass loss rates, and to probe the physics of jet collimation, and may indicate that the jet production phase of certain young stars may last more than a million years. These three discoveries provide us with fundamental new insights into the star formation process, into the physical conditions inside and near star forming clouds, and into new ways to probe the physics and chemistry of such clouds.

The link between rapid enigmatic amphibian decline and the globally emerging chytrid fungus.

PubMed

Lötters, Stefan; Kielgast, Jos; Bielby, Jon; Schmidtlein, Sebastian; Bosch, Jaime; Veith, Michael; Walker, Susan F; Fisher, Matthew C; Rödder, Dennis

2009-09-01

Amphibians are globally declining and approximately one-third of all species are threatened with extinction. Some of the most severe declines have occurred suddenly and for unknown reasons in apparently pristine habitats. It has been hypothesized that these "rapid enigmatic declines" are the result of a panzootic of the disease chytridiomycosis caused by globally emerging amphibian chytrid fungus. In a Species Distribution Model, we identified the potential distribution of this pathogen. Areas and species from which rapid enigmatic decline are known significantly overlap with those of highest environmental suitability to the chytrid fungus. We confirm the plausibility of a link between rapid enigmatic decline in worldwide amphibian species and epizootic chytridiomycosis.

Disentangling the outflow and protostars in HH 900 in the Carina Nebula

NASA Astrophysics Data System (ADS)

Reiter, Megan; Smith, Nathan; Kiminki, Megan M.; Bally, John; Anderson, Jay

2015-04-01

HH 900 is a peculiar protostellar outflow emerging from a small, tadpole-shaped globule in the Carina Nebula. Previous Hα imaging with Hubble Space Telescope (HST)/Advanced Camera for Surveys showed an ionized outflow with a wide opening angle that is distinct from the highly collimated structures typically seen in protostellar jets. We present new narrowband near-IR [Fe II] images taken with the Wide Field Camera 3 on the HST that reveal a remarkably different structure than Hα. In contrast to the unusual broad Hα outflow, the [Fe II] emission traces a symmetric, collimated bipolar jet with the morphology and kinematics that are more typical of protostellar jets. In addition, new Gemini adaptive optics images reveal near-IR H2 emission coincident with the Hα emission, but not the [Fe II]. Spectra of these three components trace three separate and distinct velocity components: (1) H2 from the slow, entrained molecular gas, (2) Hα from the ionized skin of the accelerating outflow sheath, and (3) [Fe II] from the fast, dense, and collimated protostellar jet itself. Together, these data require a driving source inside the dark globule that remains undetected behind a large column density of material. In contrast, Hα and H2 emission trace the broad outflow of material entrained by the jet, which is irradiated outside the globule. As it get dissociated and ionized, it remains visible for only a short time after it is dragged into the H II region.

Formation of outflow channels on Mars: Testing the origin of Reull Vallis in Hesperia Planum by large-scale lava-ice interactions and top-down melting

NASA Astrophysics Data System (ADS)

Cassanelli, James P.; Head, James W.

2018-05-01

The Reull Vallis outflow channel is a segmented system of fluvial valleys which originates from the volcanic plains of the Hesperia Planum region of Mars. Explanation of the formation of the Reull Vallis outflow channel by canonical catastrophic groundwater release models faces difficulties with generating sufficient hydraulic head, requiring unreasonably high aquifer permeability, and from limited recharge sources. Recent work has proposed that large-scale lava-ice interactions could serve as an alternative mechanism for outflow channel formation on the basis of predictions of regional ice sheet formation in areas that also underwent extensive contemporaneous volcanic resurfacing. Here we assess in detail the potential formation of outflow channels by large-scale lava-ice interactions through an applied case study of the Reull Vallis outflow channel system, selected for its close association with the effusive volcanic plains of the Hesperia Planum region. We first review the geomorphology of the Reull Vallis system to outline criteria that must be met by the proposed formation mechanism. We then assess local and regional lava heating and loading conditions and generate model predictions for the formation of Reull Vallis to test against the outlined geomorphic criteria. We find that successive events of large-scale lava-ice interactions that melt ice deposits, which then undergo re-deposition due to climatic mechanisms, best explains the observed geomorphic criteria, offering improvements over previously proposed formation models, particularly in the ability to supply adequate volumes of water.

Outflow off the Beaten Path: Low Energy (< keV) O+ Outflow Directly Into the Inner Magnetosphere as Observed by the Van Allen Probes and the Implications for Mid- and Low-Latitude Magnetosphere-Ionosphere Coupling

NASA Astrophysics Data System (ADS)

Gkioulidou, M.; Mitchell, D. G.; Ukhorskiy, S.; Ohtani, S.; Takahashi, K.

2017-12-01

The low-energy (eV to hundreds of eV) ion population in the inner magnetosphere, the warm plasma cloak, and in particular its heavy ion component, the O+ torus, is crucial to magnetospheric dynamics. Yet, although the effects of high latitude and cusp ionospheric O+ outflow and its subsequent transport and acceleration within the magnetotail and plasma sheet have been extensively studied, the source of low-energy O+ within the inner magnetosphere (already observed by the DE1 spacecraft in the 80s) remains a compelling open question. The HOPE instrument aboard each of the Van Allen Probes, moving in highly elliptical, equatorial orbits with apogee of 5.8 RE, has repeatedly detected low-energy O+ field-aligned enhancements. We present a comprehensive study of one such event, where low energy O+ field-aligned intensity enhancements were observed, both at small and large pitch angles, during a geomagnetic storm. The energy spectrogram exhibited a dispersive signature and a banded structure, features that our simple particle tracing simulation demonstrated are due to O+ ions outflowing from both hemispheres of the night-side ionosphere directly into the magnetosphere within L = 4, and subsequently bouncing from one hemisphere to the other. These outflows are associated with field-aligned Poynting flux enhancements and field-aligned electron beams, as observed at the Van Allen Probes location, revealing energy transport from the magnetosphere to ionosphere as well as simultaneous field-aligned electron heating. We also incorporate ionospheric measurements, such as field-aligned currents, as those are inferred by AMPERE data. The combination of unprecedented simultaneous magnetospheric and ionospheric observations allow us to investigate the processes that lead to an O+ outflow event from the low-latitude, night-side ionosphere directly into the inner magnetosphere. The ubiquity of such events in the Van Allen Probes data might reveal one of the sources for the O+ torus.

Follow-up FOCAS Spectroscopy for [O iii] Blobs at z 0.7

NASA Astrophysics Data System (ADS)

Yuma, Suraphong

2014-01-01

We propose FOCAS spectroscopy for our eight newly selected [O_iii] blobs at z~0.7, showing remarkably extended [O_iii] emission larger than 30 kpc down to 1.2x10^{-18} erg^{-1}cm^{-2} arcsec^{-2} in continuum-subtracted narrowband images. This extended oxygen nebulae beyond stellar component is thought to be hot metal-right gas outflowing from galaxies. However, without spectroscopy to verify gas motion of the system, we cannot certainly conclude that the extended feature of [O_iii] emission is caused by gas outflow. With FOCAS, we expect to observe Fe_ii, Mg_ii absorption lines and [O_ii}], Hbeta, and [O_iii] emission lines, which all fall into optical window at this redshift. We will 1) confirm the outflow of these blobs through Fe_ii and/or Mg_ii absorption lines, 2) constrain energy source of the outflow (AGN or stellar feedback) through line-ratio diagnostic diagram, and 3) for the first time investigate if the extended oxygen emission is just due to the photo-ionized outflowing gas or involving shock heating process through [O_ii]/[O_iii] ratios in extended regions. The last goal can only be accomplished with FOCAS optical spectroscopy, which can observe both [O_ii] and [O_iii] emission lines simultaneously.

X-ray evidence for ultra-fast outflows in Seyfert galaxies

NASA Astrophysics Data System (ADS)

Tombesi, Francesco; Braito, Valentina; Reeves, James; Cappi, Massimo; Dadina, Mauro

2012-07-01

X-ray evidence for massive, highly ionized, ultra-fast outflows (UFOs) has been recently reported in a number of AGNs through the detection of blue-shifted Fe XXV/XXVI absorption lines. We present the results of a comprehensive spectral analysis of a large sample of 42 local Seyferts observed with XMM-Newton. Similar results are also obtained from a Suzaku analysis of 5 radio galaxies. We find that UFOs are common phenomena, being present in >40% of the sources. Their outflow velocity distribution is in the range ˜0.03--0.3c, with mean value of ˜0.14c. The ionization parameter is very high, in the range logξ˜3--6 erg~s^{-1}~cm, and the associated column densities are also large, in the range ˜10^{22}--10^{24} cm^{-2}. Their location is constrained at ˜0.0003--0.03pc (˜10^2--10^4 r_s) from the central black hole, consistent with what is expected for accretion disk winds/outflows. The mass outflow rates are in the interval ˜0.01--1M_{⊙}~yr^{-1}. The associated mechanical power is also high, in the range ˜10^{43}--10^{45} erg/s, which indicates that UFOs are capable to provide a significant contribution to the AGN cosmological feedback.

SURFACE AND LIGHTNING SOURCES OF NITROGEN OXIDES OVER THE UNITED STATES: MAGNITUDES, CHEMICAL EVOLUTION, AND OUTFLOW

EPA Science Inventory

We use observations from two aircraft during the ICARTT campaign over the eastern United States and North Atlantic during summer 2004, interpreted with a global 3-D model of tropospheric chemistry (GEOS-Chem) to test current understanding of regional sources, chemical evolution...

MASS OUTFLOW AND CHROMOSPHERIC ACTIVITY OF RED GIANT STARS IN GLOBULAR CLUSTERS. II. M13 AND M92

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meszaros, Sz.; Dupree, A. K.; Szalai, T.

High-resolution spectra of 123 red giant stars in the globular cluster M13 and 64 red giant stars in M92 were obtained with Hectochelle at the MMT telescope. Emission and line asymmetries in H{alpha} and Ca II K are identified, characterizing motions in the extended atmospheres and seeking differences attributable to metallicity in these clusters and M15. On the red giant branch, emission in H{alpha} generally appears in stars with T {sub eff} {approx}< 4500 K and log L/L {sub sun}{approx}> 2.75. Fainter stars showing emission are asymptotic giant branch (AGB) stars or perhaps binary stars. The line-bisector for H{alpha} revealsmore » the onset of chromospheric expansion in stars more luminous than log (L/L {sub sun}) {approx} 2.5 in all clusters, and this outflow velocity increases with stellar luminosity. However, the coolest giants in the metal-rich M13 show greatly reduced outflow in H{alpha} most probably due to decreased T {sub eff} and changing atmospheric structure. The Ca II K{sub 3} outflow velocities are larger than shown by H{alpha} at the same luminosity and signal accelerating outflows in the chromospheres. Stars clearly on the AGB show faster chromospheric outflows in H{alpha} than RGB objects. While the H{alpha} velocities on the RGB are similar for all metallicities, the AGB stars in the metal-poor M15 and M92 have higher outflow velocities than in the metal-rich M13. Comparison of these chromospheric line profiles in the paired metal-poor clusters, M15 and M92, shows remarkable similarities in the presence of emission and dynamical signatures, and does not reveal a source of the 'second-parameter' effect.« less

High-resolution Near-IR Spectral Mapping with H2 and [Fe II] Lines of Multiple Outflows around LkHα 234

NASA Astrophysics Data System (ADS)

Oh, Heeyoung; Pyo, Tae-Soo; Koo, Bon-Chul; Yuk, In-Soo; Kaplan, Kyle F.; Lee, Yong-Hyun; Sokal, Kimberly R.; Mace, Gregory N.; Park, Chan; Lee, Jae-Joon; Park, Byeong-Gon; Hwang, Narae; Kim, Hwihyun; Jaffe, Daniel T.

2018-05-01

We present a high-resolution, near-IR spectroscopic study of multiple outflows in the LkHα 234 star formation region using the Immersion GRating INfrared Spectrometer (IGRINS). Spectral mapping over the blueshifted emission of HH 167 allowed us to distinguish at least three separate, spatially overlapped outflows in H2 and [Fe II] emission. We show that the H2 emission represents not a single jet but rather complex multiple outflows driven by three known embedded sources: MM1, VLA 2, and VLA 3. There is a redshifted H2 outflow at a low velocity, V LSR <+50 km s‑1, with respect to the systemic velocity of V LSR = ‑11.5 km s‑1, that coincides with the H2O masers seen in earlier radio observations 2″ southwest of VLA 2. We found that the previously detected [Fe II] jet with | {V}LSR}| > 100 km s‑1 driven by VLA 3B is also detected in H2 emission and confirm that this jet has a position angle of about 240°. Spectra of the redshifted knots at 14″–65″ northeast of LkHα 234 are presented for the first time. These spectra also provide clues to the existence of multiple outflows. We detected high-velocity (50–120 km s‑1) H2 gas in the multiple outflows around LkHα 234. Since these gases move at speeds well over the dissociation velocity (>40 km s‑1), the emission must originate from the jet itself rather than H2 gas in the ambient medium. Also, position–velocity and excitation diagrams indicate that emission from knot C in HH 167 comes from two different phenomena, shocks and photodissociation.

Herschel - PACS Survey Of Protoplanetary Disks In Taurus - Auriga Observations Of [O I] And [C Ii], And Far-Infrared Continuum

NASA Technical Reports Server (NTRS)

Howard, Christian; Sandell, Goeran; Vacca, William D.; Duchene, Gaspard; Matthews, Geoffrey; Augereau, Jean-Charles; Barbado, David; Dent, William R. F.; Eiroa, Carlos; Grady, Carol;

A Mini-BAL Outflow at 900 pc from the Central Source: VLT/X-shooter Observations

NASA Astrophysics Data System (ADS)

Xu, Xinfeng; Arav, Nahum; Miller, Timothy; Benn, Chris

2018-05-01

We determine the physical conditions and location of the outflow material seen in the mini-BAL quasar SDSS J1111+1437 (z = 2.138). These results are based on the analysis of a high S/N, medium-resolution VLT/X-shooter spectrum. The main outflow component spans the velocity range ‑1500 to ‑3000 km s‑1 and has detected absorption troughs from both high-ionization species: C IV, N V, O VI, Si IV, P V, and S IV; and low-ionization species: H I, C II, Mg II, Al II, Al III, Si II, and Si III. Measurements of these troughs allow us to derive an accurate photoionization solution for this absorption component: a hydrogen column density, {log}({N}{{H}})={21.47}-0.27+0.21 cm‑2 and ionization parameter, {log}({U}{{H}})=-{1.23}-0.25+0.20. Troughs produced from the ground and excited states of S IV combined with the derived {U}{{H}} value allow us to determine an electron number density of {log}({n}{{e}})={3.62}-0.11+0.09 cm‑3 and to obtain the distance of the ionized gas from the central source: R={880}-260+210 pc.

Water budgets, water quality, and analysis of nutrient loading of the Winter Park chain of lakes, central Florida, 1989-92

USGS Publications Warehouse

Phelps, G.G.; German, E.R.

1995-01-01

The Winter Park chain of lakes (Lakes Maitland, Virginia, Osceola, and Mizell) has a combined area of about 900 acres, an immediate drainage area of about 3,100 acres, and mean depths ranging from 11 to 15 feet. The lakes are an important recreational resource for the surrounding communities, but there is concern about the possible effects of stormwater runoff and seepage of nutrient-enriched ground water on the quality of water in the lakes. The lakes receive water from several sources: rainfall on lake surfaces, inflow from other surface-water bodies, stormflow that enters the lakes through storm drains or by direct runoff from land adjacent to the lakes and ground-water seepage. Water leaves the lakes by evaporation, surface outflow, and ground-water outflow. Of the three, only surface outflow can be measured directly. Rainfall, surface inflow and outflow, and lake-stage data were collected from October 1, 1989, to September 30, 1992. Stormflow, evaporation and ground-water inflow and outflow were estimated for the 3 years of the study. Ground-water outflow was calculated by evaluating the rate of lake-stage decline during dry periods. Estimated ground-water outflow was compared to downward leakage rates estimated by ground-water flow models. Lateral ground-water inflow from surficial sediments was calculated as the residual of the flow budget. Flow budgets were calculated for the 3 years of the study. In water year 1992 (a year with about average rainfall), inflow consisted of rainfall, 48 inches; stormflow, 15 inches; surface inflow, 67 inches; and ground water, 40 inches. The calculated outflows were evaporation, 47 inches; surface outflow, 90 inches; and ground water, 33 inches. Water-quality data also were used to calculate nutrient budgets for the lakes. Bimonthly water samples were collected from the lakes and at surface inflow and outflow sites, and were analyzed for physical characteristics, dissolved oxygen, pH, specific conductance, major ions, the nutrients nitrogen and phosphorus, and chlorophyll (collected at lake sites only). Specific conductance ranged from about 190 to 230 microsiemens per centimeter at 25 degrees Celsius in Lakes Maitland, Virginia and Osceola and from about 226 to 260 microsiemens per centimeter at 25 degrees Celsius in Lake Mizell. The median concentrations of total ammonia-plus-organic nitrogen in all the lakes ranged from 0.79 to 0.99 milligrams per liter. Median total phosphorus concentrations ranged from less than 0.02 to 0.20 milligrams per liter. Stormwater samples were collected for 17 storms at one storm-drain site and 16 storms at another storm-drain site on Lake Osceola. Median total nitrogen concentrations at the sites were 2.23 and 3.06 milligrams per liter and median total phosphorus concentrations were 0.34 and 0.40 milligrams per liter. The water quality in the Winter Park lakes generally is fair to good, based on a trophic-state index used by the Florida Department of Environmental Protection for assessing the tropic state of Florida lakes. This index was determined from median total nitrogen, total phosphorus, and chlorophyll-a concentrations, and median Secchi-disk transparency for all lakes for the period September 1989 to June 1992. Based on a one-time sampling of 20 sites around the lakes, surficial ground-water quality is highly variable. Nutrient concentrations were highly variable and could not be correlated to the proximity of septic tanks. Fertilizer probably is the primary source of nutrients in the surficial ground water. Nutrient budgets were calculated for the lakes for the 3 years of the study. The most variable source of nutrient loading to the lakes is stormwater. Nutrient-loading modeling indicates that reduction of nutrients in stormflow probably would improve lake-water quality. However, even with complete removal of nitrogen and phosphorus from stormwater, the lakes might still be mesotrophic with respect to both nutrients during periods of below ave

Molecular Abundances in the Circumstellar Envelope of Oxygen-Rich Supergiant VY Canis Majoris

NASA Astrophysics Data System (ADS)

Edwards, Jessica L.; Ziurys, Lucy

2014-06-01

A complete set of molecular abundances have been established for the Oxygen-rich circumstellar envelope (CSE) surrounding the supergiant star VY Canis Majoris (VY CMa). These data were obtained from The Arizona Radio Observatory (ARO) 1-mm spectral line survey of this object using the ARO Sub-millimeter Telescope (SMT), as well as complimentary transitions taken with the ARO 12-meter. The non-LTE radiative transfer code ESCAPADE has been used to obtain the molecular abundances and distributions in VY CMa, including modeling of the various asymmetric outflow geometries in this source. For example, SO and SO2 were determined to arise from five distinct outflows, four of which are asymmetric with respect to the central star. Abundances of these two sulfur-bearing molecules range from 3 x 10-8 - 2.5 x 10-7 for the various outflows. Similar results will be presented for molecules like CS, SiS, HCN, and SiO, as well as more exotic species like NS, PO, AlO, and AlOH. The molecular abundances between the various outflows will be compared and implications for supergiant chemistry will be discussed.

MHD Wind Models in X-Ray Binaries and AGN

NASA Astrophysics Data System (ADS)

Behar, Ehud; Fukumura, Keigo; Kazanas, Demosthenes; Shrader, Chris R.; Tombesi, Francesco; Contopoulos, Ioannis

2017-08-01

Self-similar magnetohydrodynamic (MHD) wind models that can explain both the kinematics and the ionization structure of outflows from accretion sources will be presented.The X-ray absorption-line properties of these outflows are diverse, their velocity ranging from 0.001c to 0.1c, and their ionization ranging from neutral to fully ionized.We will show how the velocity structure and density profile of the wind can be tightly constrained, by finding the scaling of the magnetic flux with the distance from the center that best matches observations, and with no other priors.It will be demonstrated that the same basic MHD wind structure that successfully accounts for the X-ray absorber properties of outflows from supermassive black holes, also reproduces the high-resolution X-ray spectrum of the accreting stellar-mass black hole GRO J1655-40 for a series of ions between ~1A and ~12A.These results support both the magnetic nature of these winds, as well as the universal nature of magnetic outflows across all black hole sizes.

Demographics and Case Studies of Galactic Outflows in the Local Universe

NASA Astrophysics Data System (ADS)

Rupke, David

2017-07-01

Galactic outflows driven by both star formation and active black holes are an important driver of galaxy evolution. The local universe is a sensitive laboratory for understanding the scaling relations that characterize these winds and the physics that govern them. I will review what we know from statistical studies about the prevalance and properties of nearby galactic winds and how these properties depend on those of the host galaxy or power source. I will also highlight detailed case studies of key objects that illustrate the multiphase structure of these winds.

Ion energization in Ganymede's magnetosphere: Using multifluid simulations to interpret ion energy spectrograms

NASA Astrophysics Data System (ADS)

Paty, C.; Paterson, W.; Winglee, R.

2008-06-01

We investigate the ion population and energy distribution within Ganymede's magnetosphere by examining Ganymede's ionospheric outflow as a source of heavy (O+) and light (H+) ions and the Jovian magnetospheric plasma as an external source of heavy ions. We develop a method for examining the energy distributions of each ion species in a three-dimensional multifluid simulation in a way directly comparable to the observations of the Plasma Experiment on the Galileo spacecraft. This is used to provide new insight to the existing controversy over the composition of Ganymede's observed ionospheric outflow, and enables further examination of the energetic signatures of the ion population trapped within Ganymede's magnetosphere. The model-predicted ionospheric outflow is consistent with the in situ ion energy spectrograms observed by the Galileo Plasma Experiment at closest approach, and requires that both ionospheric H+ and O+ are present in the population of ions exiting Ganymede's ionosphere over the polar cap. The outward flux of ionospheric ions was calculated to be ~1026 ions/cm2/s, which is in agreement with independently calculated sputtering rates of Ganymede's icy surface. The modeled spectrograms define characteristic energy signatures and populations for various regions of Ganymede's magnetosphere, which illustrate the major sources of ions trapped within the magnetosphere are Ganymede's ionospheric O+ and H+. The fact that very little plasma was observed inside Ganymede's magnetosphere during the G8 flyby is attributed to the region being shadowed from the sun for ~60 h, which may indicate the importance of photoionization for sustaining Ganymede's ionospheric plasma source.

Stellar physics. Observing the onset of outflow collimation in a massive protostar.

PubMed

Carrasco-González, C; Torrelles, J M; Cantó, J; Curiel, S; Surcis, G; Vlemmings, W H T; van Langevelde, H J; Goddi, C; Anglada, G; Kim, S-W; Kim, J-S; Gómez, J F

2015-04-03

The current paradigm of star formation through accretion disks, and magnetohydrodynamically driven gas ejections, predicts the development of collimated outflows, rather than expansion without any preferential direction. We present radio continuum observations of the massive protostar W75N(B)-VLA 2, showing that it is a thermal, collimated ionized wind and that it has evolved in 18 years from a compact source into an elongated one. This is consistent with the evolution of the associated expanding water-vapor maser shell, which changed from a nearly circular morphology, tracing an almost isotropic outflow, to an elliptical one outlining collimated motions. We model this behavior in terms of an episodic, short-lived, originally isotropic ionized wind whose morphology evolves as it moves within a toroidal density stratification. Copyright © 2015, American Association for the Advancement of Science.

Is there any evidence that ionized outflows quench star formation in type 1 quasars at z < 1?

NASA Astrophysics Data System (ADS)

Balmaverde, B.; Marconi, A.; Brusa, M.; Carniani, S.; Cresci, G.; Lusso, E.; Maiolino, R.; Mannucci, F.; Nagao, T.

2016-01-01

Aims: The aim of this paper is to test the basic model of negative active galactic nuclei (AGN) feedback. According to this model, once the central black hole accretes at the Eddington limit and reaches a certain critical mass, AGN driven outflows blow out gas, suppressing star formation in the host galaxy and self-regulating black hole growth. Methods: We consider a sample of 224 quasars selected from the Sloan Digital Sky Survey (SDSS) at z< 1 observed in the infrared band by the Herschel Space Observatory in point source photometry mode. We evaluate the star formation rate in relation to several outflow signatures traced by the [O III] λ4959, 5007 and [O II] λ3726, 3729 emission lines in about half of the sample with high quality spectra. Results: Most of the quasars show asymmetric and broad wings in [O III], which we interpret as outflow signatures. We separate the quasars in two groups, "weakly" and "strongly" outflowing, using three different criteria. When we compare the mean star formation rate in five redshift bins in the two groups, we find that the star formation rate (SFR) are comparable or slightly larger in the strongly outflowing quasars. We estimate the stellar mass from spectral energy distribution (SED) fitting and the quasars are distributed along the star formation main sequence, although with a large scatter. The scatter from this relation is uncorrelated with respect to the kinematic properties of the outflow. Moreover, for quasars dominated in the infrared by starburst or by AGN emission, we do not find any correlation between the star formation rate and the velocity of the outflow, a trend previously reported in the literature for pure starburst galaxies. Conclusions: We conclude that the basic AGN negative feedback scenario seems not to agree with our results. Although we use a large sample of quasars, we did not find any evidence that the star formation rate is suppressed in the presence of AGN driven outflows on large scale. A possibility is that feedback is effective over much longer timescales than those of single episodes of quasar activity.

Cold gas and the disruptive effect of a young radio jet

NASA Astrophysics Data System (ADS)

Morganti, R.; Oosterloo, T.; Maccagni, F. M.; Geréb, K.; Oonk, J. B. R.; Tadhunter, C. N.

2016-02-01

Newly born and young radio sources are in a delicate phase of their life. Their jets are fighting their way through the surrounding gaseous medium, strongly experiencing this interaction while, at the same time, impacting and affecting the interstellar medium (ISM). Quantifying this interplay has far reaching implications: the rate of occurrence and the magnitude of the interaction between radio jets and ISM can have consequences for the evolution of the host galaxy. Despite the hostile conditions, cold gas - neutral atomic hydrogen and molecular - has been often found in these objects and can be also associated to fast outflows. Here we present the results from two studies of H I and molecular gas illustrating what can be learned from these phases of the gas. We first describe a statistical study of the occurrence and kinematics of H I observed in absorption with the Westerbork Synthesis Radio telescope. This allows a comparison between the properties of the gas in extended and in compact/young radio sources. The study shows that the young radio sources not only have an higher detection rate of H I, but also systematically broader and more asymmetric H I profiles, most of them blueshifted. This supports the idea that we are looking at young radio jets making their way through the surrounding ISM, which also appears to be, on average, richer in gas than in evolved radio sources. Signatures of the impact of the jet are seen in the kinematics of the gas, but the resulting outflows may be characteristic of only the initial phase of the radio source evolution. However, even among the young sources, we identify a population that remains undetected in H I even after stacking their profiles. Orientation effects can only partly explain the result. These objects either are genuinely gas-poor or have different conditions of the medium, e.g. higher spin temperature. The upcoming blind H I surveys which are about to start with large-field-of-view radio facilities (i.e. Apertif at the WSRT and ASKAP) will allow us to expand the statistics and reach even higher sensitivity with stacking techniques. We further present the case of the radio source IC 5063 where we have used the molecular gas observed with ALMA to trace in detail the jet impacting the ISM. The kinematics of the cold, molecular gas co-spatial with the radio plasma shows this process in action. The ALMA data reveal a fast outflow of molecular gas extending along the entire radio jet (˜1 kpc), with the highest outflow velocities at the location of the brighter hot-spot. The results can be described by a scenario of a radio plasma jet expanding into a clumpy medium, interacting directly with the clouds and inflating a cocoon that drives a lateral outflow into the ISM. This is consistent with the scenario proposed by numerical simulations for the expansion of a young radio jet, confirming the disruptive effect the radio plasma jet can have. Following this case, more ALMA observations of nearby young radio sources will be able to confirm if this process is common, as expected, in the initial phase of the evolution of the radio source.

Surviving Tight Times or What to Do When the Money Runs Out.

ERIC Educational Resources Information Center

Neugebauer, Roger

1987-01-01

Recommends strategies to help for-profit and non-profit child care centers survive financial crises. These strategies include discovering the source of the problem; monitoring cash flow; trimming the budget; slowing cash outflow; speeding cash inflow; exploring new income sources; enduring the strain effectively; and avoiding crisis repetition.…

Observations of Heavy Ions in the Magnetosphere

NASA Astrophysics Data System (ADS)

Kistler, L. M.

2017-12-01

There are two sources for the hot ions in the magnetosphere: the solar wind and the ionosphere. The solar wind is predominantly protons, with about 4% He++ and less than 1% other high charge state heavy ions. The ionospheric outflow is also predominantly H+, but can contain a significant fraction of heavy ions including O+, N+, He+, O++, and molecular ions (NO+, N2+, O2+). The ionospheric outflow composition varies significantly both with geomagnetic activity and with solar EUV. The variability in the contribution of the two sources, the variability in the ionospheric source itself, and the transport paths of the different species are all important in determining the ion composition at a given location in the magnetosphere. In addition to the source variations, loss processes within the magnetosphere can be mass dependent, changing the composition. In particular, charge exchange is strongly species dependent, and can lead to heavy ion dominance at some energies in the inner magnetosphere. In this talk we will review the current state of our understanding of the composition of the magnetosphere and the processes that determine it.

Alloying of steel and graphite by hydrogen in nuclear reactor

NASA Astrophysics Data System (ADS)

Krasikov, E.

2017-02-01

In traditional power engineering hydrogen may be one of the first primary source of equipment damage. This problem has high actuality for both nuclear and thermonuclear power engineering. Study of radiation-hydrogen embrittlement of the steel raises the question concerning the unknown source of hydrogen in reactors. Later unexpectedly high hydrogen concentrations were detected in irradiated graphite. It is necessary to look for this source of hydrogen especially because hydrogen flakes were detected in reactor vessels of Belgian NPPs. As a possible initial hypothesis about the enigmatical source of hydrogen one can propose protons generation during beta-decay of free neutrons поскольку inasmuch as protons detected by researches at nuclear reactors as witness of beta-decay of free neutrons.

Chemical characteristics of North American surface layer outflow: Insights from Chebogue Point, Nova Scotia

NASA Astrophysics Data System (ADS)

Millet, Dylan B.; Goldstein, Allen H.; Holzinger, Rupert; Williams, Brent J.; Allan, James D.; Jimenez, José L.; Worsnop, Douglas R.; Roberts, James M.; White, Allen B.; Hudman, Rynda C.; Bertschi, Isaac T.; Stohl, Andreas

2006-12-01

We present a factor analysis-based method for differentiating air masses on the basis of source influence and apply the method to a broad suite of trace gas and aerosol measurements collected at Chebogue Point, Nova Scotia, during the summer of 2004 to characterize the chemical composition of atmospheric outflow from eastern North America. CO, ozone, and aerosol mass were elevated by 30%, 56%, and more than 300% at Chebogue Point during U.S. outflow periods. Organic aerosol mass was highest during U.S. pollution events, but made up the largest fraction (70%) of the total aerosol during periods of primary and especially secondary biogenic influence, indicating the importance of both anthropogenic and biogenic organic aerosol. Anthropogenic and oxygenated volatile organic compounds account for the bulk of the gas-phase organic carbon under most conditions; however, biogenic compounds are important in terms of chemical reactivity. Biogenic emissions thus have a significant impact on the chemistry of air masses downwind of the polluted northeastern United States. Using output from a global 3-D model of atmospheric composition (GEOS-Chem), we estimate that CO directly emitted from U.S. pollution sources makes up 28% of the total CO observed at Chebogue Point during U.S. outflow events and 19% at other times, although more work is needed to improve U.S. emission estimates for CO and other pollutants. We conclude that the effects of North American pollution on the chemistry of the western North Atlantic boundary layer are pervasive and not restricted to particular events.

Numerical Simulations of Turbulent Molecular Clouds Regulated by Radiation Feedback Forces. II. Radiation-Gas Interactions and Outflows

NASA Astrophysics Data System (ADS)

Raskutti, Sudhir; Ostriker, Eve C.; Skinner, M. Aaron

2017-12-01

Momentum deposition by radiation pressure from young, massive stars may help to destroy molecular clouds and unbind stellar clusters by driving large-scale outflows. We extend our previous numerical radiation hydrodynamic study of turbulent star-forming clouds to analyze the detailed interaction between non-ionizing UV radiation and the cloud material. Our simulations trace the evolution of gas and star particles through self-gravitating collapse, star formation, and cloud destruction via radiation-driven outflows. These models are idealized in that we include only radiation feedback and adopt an isothermal equation of state. Turbulence creates a structure of dense filaments and large holes through which radiation escapes, such that only ˜50% of the radiation is (cumulatively) absorbed by the end of star formation. The surface density distribution of gas by mass as seen by the central cluster is roughly lognormal with {σ }{ln{{Σ }}}=1.3{--}1.7, similar to the externally projected surface density distribution. This allows low surface density regions to be driven outwards to nearly 10 times their initial escape speed {v}{esc}. Although the velocity distribution of outflows is broadened by the lognormal surface density distribution, the overall efficiency of momentum injection to the gas cloud is reduced because much of the radiation escapes. The mean outflow velocity is approximately twice the escape speed from the initial cloud radius. Our results are also informative for understanding galactic-scale wind driving by radiation, in particular, the relationship between velocity and surface density for individual outflow structures and the resulting velocity and mass distributions arising from turbulent sources.

Kinetic modeling of auroral ion outflows observed by the VISIONS sounding rocket

NASA Astrophysics Data System (ADS)

Albarran, R. M.; Zettergren, M. D.

2017-12-01

The VISIONS (VISualizing Ion Outflow via Neutral atom imaging during a Substorm) sounding rocket was launched on Feb. 7, 2013 at 8:21 UTC from Poker Flat, Alaska, into an auroral substorm with the objective of identifying the drivers and dynamics of the ion outflow below 1000km. Energetic ion data from the VISIONS polar cap boundary crossing show evidence of an ion "pressure cooker" effect whereby ions energized via transverse heating in the topside ionosphere travel upward and are impeded by a parallel potential structure at higher altitudes. VISIONS was also instrumented with an energetic neutral atom (ENA) detector which measured neutral particles ( 50-100 eV energy) presumably produced by charge-exchange with the energized outflowing ions. Hence, inferences about ion outflow may be made via remotely-sensing measurements of ENAs. This investigation focuses on modeling energetic outflowing ion distributions observed by VISIONS using a kinetic model. This kinetic model traces large numbers of individual particles, using a guiding-center approximation, in order to allow calculation of ion distribution functions and moments. For the present study we include mirror and parallel electric field forces, and a source of ion cyclotron resonance (ICR) wave heating, thought to be central to the transverse energization of ions. The model is initiated with a steady-state ion density altitude profile and Maxwellian velocity distribution characterizing the initial phase-space conditions for multiple particle trajectories. This project serves to advance our understanding of the drivers and particle dynamics in the auroral ionosphere and to improve data analysis methods for future sounding rocket and satellite missions.

Kinetic modeling of auroral ion Outflows observed by the VISIONS sounding rocket

NASA Astrophysics Data System (ADS)

Albarran, R. M.; Zettergren, M. D.; Rowland, D. E.; Klenzing, J.; Clemmons, J. H.

2016-12-01

The VISIONS (VISualizing Ion Outflow via Neutral atom imaging during a Substorm) sounding rocket was launched on Feb. 7, 2013 at 8:21 UTC from Poker Flat, Alaska, into an auroral substorm with the objective of identifying the drivers and dynamics of the ion outflow below 1000km. Energetic ion data from the VISIONS polar cap boundary crossing show evidence of an ion "pressure cooker" effect whereby ions energized via transverse heating in the topside ionosphere travel upward and are impeded by a parallel potential structure at higher altitudes. VISIONS was also instrumented with an energetic neutral atom (ENA) detector which measured neutral particles ( 50-100 eV energy) presumably produced by charge-exchange with the energized outflowing ions. Hence, inferences about ion outflow may be made via remotely-sensing measurements of ENAs. This investigation focuses on modeling energetic outflowing ion distributions observed by VISIONS using a kinetic model. This kinetic model traces large numbers of individual particles, using a guiding-center approximation, in order to allow calculation of ion distribution functions and moments. For the present study we include mirror and parallel electric field forces, and a source of ion cyclotron resonance (ICR) wave heating, thought to be central to the transverse energization of ions. The model is initiated with a steady-state ion density altitude profile and Maxwellian velocity distribution characterizing the initial phase-space conditions for multiple particle trajectories. This project serves to advance our understanding of the drivers and particle dynamics in the auroral ionosphere and to improve data analysis methods for future sounding rocket and satellite missions.

VizieR Online Data Catalog: Deconvolved Spitzer images of 89 protostars (Velusamy+, 2014)

NASA Astrophysics Data System (ADS)

Velusamy, T.; Langer, W. D.; Thompson, T.

2016-03-01

The sample of Class 0 protostars, H2 jets, and outflow sour selected for HiRes deconvolution of Spitzer images are listed in Table1. The majority of our target protostellar objects were selected from "The Youngest Protostars" webpage hosted by the University of Kent (http://astro.kent.ac.uk/protostars/old/), which are based on the young Class 0 objects compiled by Froebrich 2005 (cat. J/ApJS/156/169). In addition to these objects, our sample includes some Herbig-Haro (HH) sources and a few well known jet outflow sources. Our sample also includes one high-mass protostar (IRAS20126+4104; cf. Caratti o Garatti et al., 2008A&A...485..137C) to demonstrate the use of HiRes for such sources. Our choice for target selection was primarily based on the availability of Spitzer images in IRAC and MIPS bands in the archives and the feasibility for reprocessing based on the published Spitzer images wherever available. (1 data file).

Lakes as organic matter upgraders - seasonal variation in biochemical compositions of in- and outflowing particles in pre-alpine Lake Lunz, Austria

NASA Astrophysics Data System (ADS)

Khan, Samiullah; Hollaus, Lisa-Maria; Schelker, Jakob; Ejarque, Elisabet; Battin, Tom; Kainz, Martin

2016-04-01

Lakes are typically recharged by inflowing stream water and discharge into outflowing streams. In this multiannual field study on pre-alpine, oligotrophic Lake Lunz, Lower Austria, we hypothesized that, irrespective of seasons, stream water recharging the lake contains predominantly recalcitrant particular organic matter (POM; >1.2 um particle size), whereas outflowing lake water is mostly composed of more labile, algae-derived POM. We collected POM for 3 years (2013-2015) at a monthly basis from the inflowing and outflowing streams of Lake Lunz, analyzed POM content, its carbon and nitrogen, their stable isotopes, and fatty acids as biochemical indicators of POM sources. Preliminary results show that, independent of seasons, inflowing POM is rich in terrestrial markers, as evidenced by long-chain saturated fatty acids (>C22:0), with little contribution of autochthonous stream POM, such as algae-derived long-chain polyunsaturated fatty acids (LC-PUFA). However, POM in outflowing water contained considerably less terrestrial markers, but clearly higher contents of highly nutritious, algae-derived LC-PUFA. These results suggest that oligotrophic Lake Lunz acts as a biochemical upgrader within the fluvial network of this drainage basin and supplies highly nutritional POM to consumers further downstream. Ongoing research is aimed at identifying how much of the terrestrial and autochthonous POM is retained and processed in the lake (biota, sediments, or respired).

Latent outflow activity for western Tharsis, Mars: Significant flood record exposed

USGS Publications Warehouse

Dohm, J.M.; Anderson, R.C.; Baker, V.R.; Ferris, J.C.; Rudd, L.P.; Hare, T.M.; Rice, J. W.; Casavant, R.R.; Strom, R.G.; Zimbelman, J.R.; Scott, D.H.

2001-01-01

Observations permitted by the newly acquired Mars Observer Laser Altimeter data have revealed a system of gigantic valleys northwest of the huge Martian shield volcano, Arsia Mons, in the western hemisphere of Mars (northwestern slope valleys (NSVs)). These features, which generally correspond spatially to gravity lows, are obscured by veneers of materials including volcanic lava flows, air fall deposits, and eolian materials. Geologic investigations of the Tharsis region suggest that the system of gigantic valleys predates the construction of Arsia Mons and its extensive associated lava flows of mainly late Hesperian and Amazonian age and coincides stratigraphically with the early development of the outflow channels that debouch into Chryse Planitia. Similar to the previously identified outflow channels, which issued tremendous volumes of water into topographic lows such as Chryse Planitia, the NSVs potentially represent flooding of immense magnitude and, as such, a source of water for a northern plains ocean.

Radiative GRMHD simulations of accretion and outflow in non-magnetized neutron stars and ultraluminous X-ray sources

NASA Astrophysics Data System (ADS)

Abarca, David; Kluźniak, Wlodek; Sądowski, Aleksander

2018-06-01

We run two GRRMHD simulations of super-Eddington accretion disks around a black hole and a non-magnetized, non-rotating neutron star. The neutron star was modeled using a reflective inner boundary condition. We observe the formation of a transition layer in the inner region of the disk in the neutron star simulation which leads to a larger mass outflow rate and a lower radiative luminosity over the black hole case. Sphereization of the flow leads to an observable luminosity at infinity around the Eddington value when viewed from all directions for the neutron star case, contrasting to the black hole case where collimation of the emission leads to observable luminosities about an order of magnitude higher when observed along the disk axis. We find the outflow to be optically thick to scattering, which would lead to the obscuring of any neutron star pulsations observed in corresponding ULXs.

Extended CO (J = 7-6) emission from Orion molecular cloud 1 - Hot ambient gas, two hot-outflow sources

NASA Astrophysics Data System (ADS)

Schmid-Burgk, J.; Densing, R.; Krugel, E.; Nett, H.; Roser, H. P.; Schafer, F.; Schwaab, G.; van der Wal, P.; Wattenbach, R.

1989-05-01

Observations of a 6 x 8-arcmin region at the core of Orion molecular cloud 1 are reported. Data obtained in the 806-GHz line of CO using the NASA Kuiper Airborne Observatory on September 15 and 17, 1986 are presented graphically and analyzed in detail. The results indicate a region of density 10,000/cu cm or greater and temperature of about 50 K extending several arcmin from the core; the total luminosities due to CO (J = 7-6) and to dust are estimated as 10 and 100,000 solar luminosities, respectively. Particular attention is given to the dust-embedded IR cluster BN-KL (with high-velocity outflow suggesting small optical depths) and a second more prominent feature about 2 arcmin to the south (with outflow of about 1 solar mass of material at 500-1000 K, radiating about 0.25 solar luminosity in CO 7-6).

Two extreme young objects in Barnard 1-b

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hirano, Naomi; Liu, Fang-chun, E-mail: hirano@asiaa.sinica.edu.tw

2014-07-01

Two submillimeter/millimeter sources in the Barnard 1b (B1-b) core, B1-bN and B1-bS, have been studied in dust continuum, H{sup 13}CO{sup +} J = 1-0, CO J = 2-1, {sup 13}CO J = 2-1, and C{sup 18}O J = 2-1. The spectral energy distributions of these sources from the mid-IR to 7 mm are characterized by very cold temperatures of T {sub dust} < 20 K and low bolometric luminosities of 0.15-0.31 L {sub ☉}. The internal luminosities of B1-bN and B1-bS are estimated to be <0.01-0.03 L {sub ☉} and ∼0.1-0.2 L {sub ☉}, respectively. Millimeter interferometric observations have shownmore » that these sources have already formed central compact objects of ∼100 AU sizes. Both B1-bN and B1-bS are driving the CO outflows with low characteristic velocities of ∼2-4 km s{sup –1}. The fractional abundance of H{sup 13}CO{sup +} at the positions of B1-bN and B1-bS is lower than the canonical value by a factor of four to eight. This implies that a significant fraction of CO is depleted onto dust grains in the dense gas surrounding these sources. The observed physical and chemical properties suggest that B1-bN and B1-bS are in an earlier evolutionary stage than most of the known class 0 protostars. In particular, the properties of B1-bN agree with those of the first hydrostatic core predicted by the MHD simulations. The CO outflow was also detected in the mid-IR source located at ∼15'' from B1-bS. Since the dust continuum emission was not detected in this source, the circumstellar material surrounding this source is less than 0.01 M {sub ☉}. It is likely that the envelope of this source was dissipated by the outflow from the protostar that is located to the southwest of B1-b.« less

Shocked molecular hydrogen in the bipolar outflow NGC 2071

NASA Technical Reports Server (NTRS)

Burton, Michael G.; Geballe, T. R.; Brand, P. W. J. L.

1989-01-01

Maps of the emission from the v = 1-0 S(1) line of molecular hydrogen in the bipolar outflow of NGC 2071 are presented. The line emission is shown to peak at six positions distributed irregularly along two lobes which are parallel to, but offset about 20 arcsec from, the lobes of the high-velocity CO-line emission. The energetics and composition of the high-velocity gas support a model in which the driving agent is a bipolar atomic wind which arises from the vicinity of the central IR sources and shocks the surrounding molecular cloud, evacuating a cavity within it.

High-excitation lines of molecular hydrogen: A discriminant between shock models

NASA Technical Reports Server (NTRS)

Burton, M.; Brand, P.; Moorhouse, A.; Geballe, T.

1989-01-01

The results of column densities of molecular hydrogen, calculated from nineteen infrared line intensities, are discussed. They were measured at peak 1 of the outflow of the Orion molecular cloud OMC-1. The 1-0 O(7) and 0-0 S(13) lines of H2, at 3.8 microns, are mapped over the source. Their intensity ratio is found to be independent of position in the outflow. These observations are well fitted by a simple cooling-flow model of the line emitting region, but seem to be at variance with predictions of C-shocks current in the literature.

Spectroscopic Observations of the Outflowing Wind in the Lensed Quasar SDSS J1001+5027

NASA Astrophysics Data System (ADS)

Misawa, Toru; Inada, Naohisa; Oguri, Masamune; Charlton, Jane C.; Eracleous, Michael; Koyamada, Suzuka; Itoh, Daisuke

2018-02-01

We performed spectroscopic observations of the small-separation lensed quasar SDSS J1001+5027, whose images have an angular separation θ =2\\buildrel{\\prime\\prime}\\over{.} 86, and placed constraints on the physical properties of gas clouds in the vicinity of the quasar (i.e., in the outflowing wind launched from the accretion disk). The two cylinders of sight to the two lensed images go through the same region of the outflowing wind and they become fully separated with no overlap at a very large distance from the source (∼330 pc). We discovered a clear difference in the profile of the C IV broad absorption line (BAL) detected in the two lensed images in two observing epochs. Because the kinematic components in the BAL profile do not vary in concert, the observed variations cannot be reproduced by a simple change of ionization state. If the variability is due to gas motion around the background source (i.e., the continuum source), the corresponding rotational velocity is {v}rot} ≥ 18,000 km s‑1, and their distance from the source is r≤slant 0.06 pc assuming Keplerian motion. Among three Mg II and three C IV NAL systems that we detected in the spectra, only the Mg II system at {z}abs} = 0.8716 shows a hint of variability in its Mg I profile on a rest-frame timescale of {{Δ }}{t}rest} ≤slant 191 days and an obvious velocity shear between the sightlines whose physical separation is ∼7 kpc. We interpret this as the result of motion of a cosmologically intervening absorber, perhaps located in a foreground galaxy. Based on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan.

A Plateau in Ares Vallis

NASA Image and Video Library

2015-01-15

This channelized area is near the source region of the huge outflow channel, Ares Vallis. It was at the distal end or long-ways down-river-area where the Pathfinder/Sojourner mission landed on 4 July 1997.

Unification of X-ray Winds in Seyfert Galaxies: From Ultra-fast Outflows to Warm Absorbers

NASA Technical Reports Server (NTRS)

Tombesi, F.; Cappi, M.; Reeves, J. N.; Nemmen, R. S.; Braito, V.; Gaspari, M.; Reynolds, C. S.

2013-01-01

The existence of ionized X-ray absorbing layers of gas along the line of sight to the nuclei of Seyfert galaxies is a well established observational fact. This material is systematically outflowing and shows a large range in parameters. However, its actual nature and dynamics are still not clear. In order to gain insights into these important issues we performed a literature search for papers reporting the parameters of the soft X-ray warm absorbers (WAs) in 35 type 1 Seyferts and compared their properties to those of the ultra-fast outflows (UFOs) detected in the same sample. The fraction of sources with WAs is >60 per cent, consistent with previous studies. The fraction of sources with UFOs is >34 per cent, >67 per cent of which also show WAs. The large dynamic range obtained when considering all the absorbers together, spanning several orders of magnitude in ionization, column, velocity and distance allows us, for the first time, to investigate general relations among them. In particular, we find significant correlations indicating that the closer the absorber is to the central black hole, the higher the ionization, column, outflow velocity and consequently the mechanical power. In all the cases, the absorbers continuously populate the whole parameter space, with the WAs and the UFOs lying always at the two ends of the distribution. These evidence strongly suggest that these absorbers, often considered of different types, could actually represent parts of a single large-scale stratified outflow observed at different locations from the black hole. The UFOs are likely launched from the inner accretion disc and the WAs at larger distances, such as the outer disc and/or torus. We argue that the observed parameters and correlations are, to date, consistent with both radiation pressure through Compton scattering and magnetohydrodynamic processes contributing to the outflow acceleration, the latter playing a major role. Most of the absorbers, especially the UFOs, show a sufficiently high mechanical power (at least approx 0.5 per cent of the bolometric luminosity) to provide a significant contribution to active galactic nuclei (AGN) feedback and thus to the evolution of the host galaxy. In this regard, we find possible evidence for the interaction of the AGN wind with the surrounding environment on large scales.

Carbonate-sulfate volcanism on Venus?

NASA Technical Reports Server (NTRS)

Kargel, Jeffrey S.; Kirk, Randolph L.; Fegley, Bruce, Jr.

1994-01-01

Venusian canali, outflow channels, and associated volcanic deposits resemble fluvial landforms more than they resmeble volcanic features on Earth and Mars. Some canali have meandering habits and features indicative of channel migration that are very similar to meandering river channels and flood plains on Earth, venusian outflow channels closely resemble water-carved outflow channels on Mars and the Channeled Scabland in Washington, collapsed terrains at the sources of some venusian channels resemble chaotic terrains at the sources of martian outflow channels, venusian lava deltas are similar to bird's-foot deltas such as the Mississippi delta, and venusian valley networks indicate sapping. We have developed an alternative possibility that the lava had a water-like rheology and a melting point slightly greater than Venus' surface temperature, thus accounting for the unusual behavior of the lava. Unlike silicate lavas, some carbonatites (including carbonate-sulfate-rich liquids) have these properties; thus they can flow great distances while retaining a high fluidity, significant mechanical erosiveness, and substantial capacity to transport and deposit sediment. Venusian geochemistry and petrology are consistent with extensive eruptions of carbonatite lavas, which could have crustal and/or mantle origins. Venus' atmosphere (especially CO2, HCl, and HF abundances) and rocks may be in local chemical equilibrium, which suggests that the upper crust contains large amounts of calcite, anhydrite, and other salts. Chemical analyses indicate, according to some models, that Venusian rocks may contain 4-19% calcite and anhydrite. Mixtures of crustal salts could melt at temperatures a few tens to a few hundred Kelvins higher than Venus' surface temperature; hence, melting may be induced by modest endogenetic or impact heating. Salts may have many of the same geologic roles on Venus as water and ice have on Mars. A molten salt (carbonatite) 'aquifer' may exist beneath a few hundred meters to several kilometers of solidified salt-rich 'permafrost.' Many geologic features can be explained by carbonatite magmatism: (1) impact melting of crustal salts can explain crater outflows, (2) small, sustained eruptions from molten salt aquifers can explain sapping valleys, (3) large, sustained eruptions may explain canali and their flood plans, and (4) catastrophic outbursts amy have formed outflow channels and chaotic terrain. Landforms created by carbonate-rich lavas would be thermally stable on Venus' surface, though some minerals may weather to other solid substances.

Unification of X-ray winds in Seyfert galaxies: from ultra-fast outflows to warm absorbers

NASA Astrophysics Data System (ADS)

Tombesi, F.; Cappi, M.; Reeves, J. N.; Nemmen, R. S.; Braito, V.; Gaspari, M.; Reynolds, C. S.

2013-04-01

The existence of ionized X-ray absorbing layers of gas along the line of sight to the nuclei of Seyfert galaxies is a well established observational fact. This material is systematically outflowing and shows a large range in parameters. However, its actual nature and dynamics are still not clear. In order to gain insights into these important issues we performed a literature search for papers reporting the parameters of the soft X-ray warm absorbers (WAs) in 35 type 1 Seyferts and compared their properties to those of the ultra-fast outflows (UFOs) detected in the same sample. The fraction of sources with WAs is >60 per cent, consistent with previous studies. The fraction of sources with UFOs is >34 per cent, >67 per cent of which also show WAs. The large dynamic range obtained when considering all the absorbers together, spanning several orders of magnitude in ionization, column, velocity and distance allows us, for the first time, to investigate general relations among them. In particular, we find significant correlations indicating that the closer the absorber is to the central black hole, the higher the ionization, column, outflow velocity and consequently the mechanical power. In all the cases, the absorbers continuously populate the whole parameter space, with the WAs and the UFOs lying always at the two ends of the distribution. These evidence strongly suggest that these absorbers, often considered of different types, could actually represent parts of a single large-scale stratified outflow observed at different locations from the black hole. The UFOs are likely launched from the inner accretion disc and the WAs at larger distances, such as the outer disc and/or torus. We argue that the observed parameters and correlations are, to date, consistent with both radiation pressure through Compton scattering and magnetohydrodynamic processes contributing to the outflow acceleration, the latter playing a major role. Most of the absorbers, especially the UFOs, show a sufficiently high mechanical power (at least ˜0.5 per cent of the bolometric luminosity) to provide a significant contribution to active galactic nuclei (AGN) feedback and thus to the evolution of the host galaxy. In this regard, we find possible evidence for the interaction of the AGN wind with the surrounding environment on large scales.

Probing the Active Galactic Nuclei using optical spectroscopy

NASA Astrophysics Data System (ADS)

Vivek, M.

Variability studies offer one of the best tools for understanding the physical conditions present in regions close to the central engine in an AGN. We probed the various properties of AGN through time variability studies of spectral lines in the optical wavelengths using the 2m telescope in IUCAA Girawali observatory. The absorption line variability studies are mainly concentrated in understanding the nature of outflows in quasars. Quasar outflows have a huge impact on the evolution of central supermassive blackholes, their host galaxies and the surrounding intergalactic medium. Studying the variability in these Broad Absorption Lines (BALs) can help us understand the structure, evolution, and basic physical properties of these outflows. We conducted a repeated Low ionization BAL monitoring program with 27 LoBALs (Low Ionization BALs) at z 0.3-2.1 covering timescales from 3.22 to 7.69 years in the quasar rest frame. We see a variety of phenomena, including some BALs that either appeared or disappeared completely and some BALs which do not vary over the observation period. In one case, the excited fine structure lines have changed dramatically. One source shows signatures of radiative acceleration. Here, we present the results from this program. Emission line studies are concentrated in understanding the peculiar characteristics of a dual-AGN source SDSS J092712.64+294344.0.

Dynamic Fluid-Kinetic (DyFK) Simulations of Storm-Enhanced Density Supply of Cleft Ion Fountain Outflows

NASA Astrophysics Data System (ADS)

Horwitz, J. L.; Zeng, W.; Foster, J. C.; Strangeway, R. J.; Adrian, M. L.; Moore, T. E.

2008-12-01

Elevated ionospheric density regions frequently appear to be convected from the subauroral plasmaspheric region toward noon, in association with convection of plasmaspheric tails in the dayside magnetosphere, typically during large geomagnetic storms. In this presentation, we explore the possibility that these Storm Enhanced Density (SED) regions could provide ionospheric plasma source populations for cleft ion fountain outflows. We use our Dynamic Fluid Kinetic (DyFK) code to simulate the entry of a high-density "plasmasphere-like" flux tube entering the cleft region and subjected to an episode of wave-driven transverse ion heating. The results of including different proportions of SED and soft electron precipitation levels, together with transverse ion heating effects on the resulting outflows, will be presented, including the O+ and H+ ion density and related parameter profiles for the simulated SED involved events. We will also compare these modeling results with SED-outflow observations from GPS TEC, and the FAST and IMAGE spacecraft. Foster, J. C., P. J. Erickson, A. J. Coster, J. Goldstein, and F. J. Rich, Ionospheric signatures of plasmaspheric tails, Geophys. Res. Lett., 29(13), 1623, doi:10.1029/2002GL015067, 2002.

Spin properties of supermassive black holes with powerful outflows

NASA Astrophysics Data System (ADS)

Daly, Ruth. A.

2016-05-01

Relationships between beam power and accretion disc luminosity are studied for a sample of 55 high excitation radio galaxies (HERG), 13 low excitation radio galaxies (LERG), and 29 radio loud quasars (RLQ) with powerful outflows. The ratio of beam power to disc luminosity tends to be high for LERG, low for RLQ, and spans the full range of values for HERG. Writing general expressions for the disc luminosity and beam power and applying the empirically determined relationships allows a function that parametrizes the spins of the holes to be estimated. Interestingly, one of the solutions that is consistent with the data has a functional form that is remarkably similar to that expected in the generalized Blandford-Znajek model with a magnetic field that is similar in form to that expected in magnetically arrested disk (MAD) and advection-dominated accretion flow (ADAF) models. Values of the spin function, obtained independent of specific outflow models, suggest that spin and active galactic nucleus type are not related for these types of sources. The spin function can be used to solve for black hole spin in the context of particular outflow models, and one example is provided.

Radio Jets Clearing the Way Through a Galaxy: Watching Feedback in Action in the Seyfert Galaxy IC 5063

NASA Astrophysics Data System (ADS)

Morganti, R.; Oosterloo, T. A.; Oonk, J. B. R.; Frieswijk, W.; Tadhunter, C. N.

2015-12-01

High-resolution (0.5 arcsec) CO(2-1) observations performed with the Atacama Large Millimetre/submillimetre Array have been used to trace the kinematics of the molecular gas in the Seyfert 2 galaxy{IC 5063}. Although one of the most radio-loud Seyfert galaxy, IC 5063 is a relatively weak radio source (P1.4GHz=3 ×1023 W Hz-1). The data reveal that the kinematics of the gas is very complex. A fast outflow of molecular gas extends along the entire radio jet (˜ 1 kpc), with the highest outflow velocities about 0.5 kpc from the nucleus, at the location of the brighter hot-spot in the W lobe. All the observed characteristics can be described by a scenario of a radio plasma jet expanding into a clumpy medium, interacting directly with the clouds and inflating a cocoon that drives a lateral outflow into the interstellar medium. This suggests that most of the observed cold molecular outflow is due to fast cooling of the gas after the passage of a shock and that it is the end product of the cooling process.

Multiday production of condensing organic aerosol mass in urban and forest outflow

DOE PAGES

Lee-Taylor, J.; Hodzic, A.; Madronich, S.; ...

2014-07-03

Secondary organic aerosol (SOA) production in air masses containing either anthropogenic or biogenic (terpene-dominated) emissions is investigated using the explicit gas-phase chemical mechanism generator GECKO-A. Simulations show several-fold increases in SOA mass continuing for several days in the urban outflow, even as the initial air parcel is diluted into the regional atmosphere. The SOA mass increase in the forest outflow is more modest (∼50%) and of shorter duration (1–2 days). The production in the urban outflow stems from continuing oxidation of gas-phase precursors which persist in equilibrium with the particle phase, and can be attributed to multigenerational reaction products ofmore » both aromatics and alkanes. In particular we find large contributions from substituted maleic anhydrides and multi-substituted peroxide-bicyclic alkenes. The results show that the predicted production is a robust feature of our model even under changing atmospheric conditions, and contradict the notion that SOA undergoes little mass production beyond a short initial formation period. The results imply that anthropogenic aerosol precursors could influence the chemical and radiative characteristics of the atmosphere over an extremely wide region, and that SOA measurements near precursor sources may routinely underestimate this influence.« less

A substellar-mass protostar and its outflow of IRAS 15398–3359 revealed by subarcsecond-resolution observations of H{sub 2}CO and CCH

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oya, Yoko; Sakai, Nami; Watanabe, Yoshimasa

2014-11-10

Subarcsecond (0.''5) images of H{sub 2}CO and CCH line emission have been obtained in the 0.8 mm band toward the low-mass protostar IRAS 15398–3359 in the Lupus 1 cloud as one of the Cycle 0 projects of the Atacama Large Millimeter/Submillimeter Array. We have detected a compact component concentrated in the vicinity of the protostar and a well-collimated outflow cavity extending along the northeast-southwest axis. The inclination angle of the outflow is found to be about 20°, or almost edge-on, based on the kinematic structure of the outflow cavity. This is in contrast to previous suggestions of a more pole-onmore » geometry. The centrally concentrated component is interpreted by use of a model of the infalling rotating envelope with the estimated inclination angle and the mass of the protostar is estimated to be less than 0.09 M {sub ☉}. Higher spatial resolution data are needed to infer the presence of a rotationally supported disk for this source, hinted at by a weak high-velocity H{sub 2}CO emission associated with the protostar.« less

The near-infrared outflow and cavity of the proto-brown dwarf candidate ISO-Oph 200

NASA Astrophysics Data System (ADS)

Whelan, E. T.; Riaz, B.; Rouzé, B.

2018-03-01

In this Letter a near-infrared integral field study of a proto-brown dwarf candidate is presented. A 0.''5 blue-shifted outflow is detected in both H2 and [Fe II] lines at Vsys = (–35 ± 2) km s-1 and Vsys = (–51 ± 5) km s-1 respectively. In addition, slower ( ±10 km s-1) H2 emission is detected out to <5.''4, in the direction of both the blue and red-shifted outflow lobes but along a different position angle to the more compact faster emission. It is argued that the more compact emission is a jet and the extended H2 emission is tracing a cavity. The source extinction is estimated at Av = 18 ± 1 mag and the outflow extinction at Av = 9 ± 0.4 mag. The H2 outflow temperature is calculated to be 1422 ± 255 K and the electron density of the [Fe II] outflow is measured at 10 000 cm-3. Furthermore, the mass outflow rate is estimated at Ṁout [H2] = 3.8 × 10-10 M⊙ yr-1 and Ṁout[Fe II] = 1 × 10-8 M⊙ yr-1. Ṁout[Fe II] takes a Fe depletion of 88% into account. The depletion is investigated using the ratio of the [Fe II] 1.257 μm and [P II] 1.188 μm lines. Using the Paβ and Brγ lines and a range in stellar mass and radius Ṁacc is calculated to be (3–10) × 10-8 M⊙ yr-/1. Comparing these rates puts the jet efficiency in line with predictions of magneto-centrifugal models of jet launching in low mass protostars. This is a further case of a brown dwarf outflow exhibiting analogous properties to protostellar jets. Based on Observations collected with SINFONI at the Very Large Telescope on Cerro Paranal (Chile), operated by the European Southern Observatory (ESO). Program ID: 097.C-0732(A).

A young bipolar outflow from IRAS 15398-3359

NASA Astrophysics Data System (ADS)

Bjerkeli, P.; Jørgensen, J. K.; Brinch, C.

2016-03-01

Context. Changing physical conditions in the vicinity of protostars allow for a rich and interesting chemistry to occur. Heating and cooling of the gas allows molecules to be released from and frozen out on dust grains. These changes in physics, traced by chemistry as well as the kinematical information, allows us to distinguish between different scenarios describing the infall of matter and the launching of molecular outflows and jets. Aims: We aim to determine the spatial distribution of different species that are of different chemical origin. This is to examine the physical processes in play in the observed region. From the kinematical information of the emission lines we aim to determine the nature of the infalling and outflowing gas in the system. We also aim to determine the physical properties of the outflow. Methods: Maps from the Submillimeter Array (SMA) reveal the spatial distribution of the gaseous emission towards IRAS 15398-3359. The line radiative transfer code LIME is used to construct a full 3D model of the system taking all relevant components and scales into account. Results: CO, HCO+, and N2H+ are detected and shown to trace the motions of the outflow. For CO, the circumstellar envelope and the surrounding cloud also have a profound impact on the observed line profiles. N2H+ is detected in the outflow, but is suppressed towards the central region, perhaps because of the competing reaction between CO and H3+ in the densest regions as well as the destruction of N2H+ by CO. N2D+ is detected in a ridge south-west of the protostellar condensation and is not associated with the outflow. The morphology and kinematics of the CO emission suggests that the source is younger than ~1000 years. The mass, momentum, momentum rate, mechanical luminosity, kinetic energy, and mass-loss rate are also all estimated to be low. A full 3D radiative transfer model of the system can explain all the kinematical and morphological features in the system.

Outflow channel sources, reactivation, and chaos formation, Xanthe Terra, Mars

USGS Publications Warehouse

Rodriguez, J.A.P.; Sasaki, S.; Kuzmin, R.O.; Dohm, J.M.; Tanaka, K.L.; Miyamoto, H.; Kurita, K.; Komatsu, G.; Fairen, A.G.; Ferris, J.C.

2005-01-01

The undulating, warped, and densely fractured surfaces of highland regions east of Valles Marineris (located north of the eastern Aureum Chaos, east of the Hydraotes Chaos, and south of the Hydaspis Chaos) resulted from extensional surface warping related to ground subsidence, caused when pressurized water confined in subterranean caverns was released to the surface. Water emanations formed crater lakes and resulted in channeling episodes involved in the excavation of Ares, Tiu, and Simud Valles of the eastern part of the circum-Chryse outflow channel system. Progressive surface subsidence and associated reduction of the subsurface cavernous volume, and/or episodes of magmatic-driven activity, led to increases of the hydrostatic pressure, resulting in reactivation of both catastrophic and non-catastrophic outflow activity. Ancient cratered highland and basin materials that underwent large-scale subsidence grade into densely fractured terrains. Collapse of rock materials in these regions resulted in the formation of chaotic terrains, which occur in and near the headwaters of the eastern circum-Chryse outflow channels. The deepest chaotic terrain in the Hydaspis Chaos region resulted from the collapse of pre-existing outflow channel floors. The release of volatiles and related collapse may have included water emanations not necessarily linked to catastrophic outflow. Basal warming related to dike intrusions, thermokarst activity involving wet sediments and/or dissected ice-enriched country rock, permafrost exposed to the atmosphere by extensional tectonism and channel incision, and/or the injection of water into porous floor material, may have enhanced outflow channel floor instability and subsequent collapse. In addition to the possible genetic linkage to outflow channel development dating back to at least the Late Noachian, clear disruption of impact craters with pristine ejecta blankets and rims, as well as preservation of fine tectonic fabrics, suggest that plateau subsidence and chaos formation may have continued well into the Amazonian Period. The geologic and paleohydrologic histories presented here have important implications, as new mechanisms for outflow channel formation and other fluvial activity are described, and new reactivation mechanisms are proposed for the origin of chaotic terrain as contributors to flooding. Detailed geomorphic analysis indicates that subterranean caverns may have been exposed during chaos formation, and thus chaotic terrains mark prime locations for future geologic, hydrologic, and possible astrobiologic exploration. ?? 2004 Elsevier Inc. All rights reserved.

Incision of the Jezero Crater Outflow Channel by Fluvial Sediment Transport

NASA Astrophysics Data System (ADS)

Holo, S.; Kite, E. S.

2017-12-01

Jezero crater, the top candidate landing site for the Mars 2020 rover, once possessed a lake that over-spilled and eroded a large outflow channel into the Eastern rim. The Western deltaic sediments that would be the primary science target of the rover record a history of lake level, which is modulated by the inflow and outflow channels. While formative discharges for the Western delta exist ( 500 m3/s), little work has been done to see if these flows are the same responsible for outflow channel incision. Other models of the Jezero outflow channel incision assume that a single rapid flood (incision timescales of weeks), with unknown initial hydraulic head and no discharge into the lake (e.g. from the inflow channels or the subsurface), incised an open channel with discharge modulated by flow over a weir. We present an alternate model where, due to an instability at the threshold of sediment motion, the incision of the outflow channel occurs in concert with lake filling. In particular, we assume a simplified lake-channel-valley system geometry and that the channel is hydraulically connected to the filling/draining crater lake. Bed load sediment transport and water discharge through the channel are quantified using the Meyer-Peter and Mueller relation and Manning's law respectively. Mass is conserved for both water and sediment as the lake level rises/falls and the channel incises. This model does not resolve backwater effects or concavity in the alluvial system, but it does capture the non-linear feedbacks between lake draining, erosion rate, channel flow rate, and slope relaxation. We identify controls on incision of the outflow channel and estimate the time scale of outflow channel formation through a simple dynamical model. We find that the observed 300m of channel erosion can be reproduced in decades to centuries of progressive bed load as the delta forming flows fill the lake. This corresponds to time scales on the order of or smaller than the time scale required for the delta forming flows to fill the crater. Comparison with the outflow channel dimensions from other craters on Mars provides the potential to both test our hypothesis of contemporaneous lake filling/channel incision and also constrain the hydrologic sources responsible for filling crater lakes.

Chemical Composition of Asian Continental Outflow over the Western Pacific: Results from Transport and Chemical Evolution over the Pacific (TRACE-P)

NASA Technical Reports Server (NTRS)

Russo, R. S.; Talbot, R. W.; Dibb, J. E.; Scheuer, E.; Seid, G.; Jordan, C. E.; Fuelberg, H. E.; Sachse, G. W.; Avery, M. A.; Vay, S. A.

2003-01-01

We characterize the chemical composition of Asian continental outflow observed during the NASA Transport and Chemical Evolution over the Pacific (TRACE-P) mission during February-April 2001 in the western Pacific using data collected on the NASA DC-8 aircraft. A significant anthropogenic impact was present in the free troposphere and as far east as 150degE longitude reflecting rapid uplift and transport of continental emissions. Five-day backward trajectories were utilized to identify five principal Asian source regions of outflow: central, coastal, north-northwest(NNW), southeast (SE), and west-southwest (WSW). The maximum mixing ratios for several species, such as CO, C2Cl4, CH3Cl, and hydrocarbons, were more than a factor of 2 larger in the boundary layer of the central and coastal regions due to industrial activity in East Asia. CO was well correlated with C2H2, C2H6, C2Cl4, and CH3Cl at low altitudes in these two regions (r(sup 2) approx. 0.77-0.97). The NNW, WSW, and SE regions were impacted by anthropogenic sources above the boundary layer presumably due to the longer transport distances of air masses to the western Pacific. Frontal and convective lifting of continental emissions was most likely responsible for the high altitude outflow in these three regions. Photochemical processing was influential in each source region resulting in enhanced mixing ratios of O3, PAN, HNO3, H2O2, and CH3OOH. The air masses encountered in all five regions were composed of a complex mixture of photcrchemically aged air with more recent emissions mixed into the outflow as indicated by enhanced hydrocarbon ratios (C2H2/CO greater than or equal to 3 and C3H8/C2H6 greater than or equal to 0.2). Combustion, industrial activities, and the burning of biofuels and biomass all contributed to the chemical composition of air masses from each source region as demonstrated by the H6, SO2, and C2Cl4 were compared for the TRACE-P and PEM-West B missions. In the more northern regions, O3, CO, and SO2 were higher at low altitudes during TRACE-P. In general, mixing ratios were fairly similar between the two missions in the southern regions. A comparison between CO/CO2, CO/CH4, C2H6/C3H8, NO(x)/SO2, and NO(y)/(SO2 + nss-SO4) ratios for the five source regions and for the 2000 Asian emissions summary showed vay close agreement indicating that Asian emissions were well represented by the TRACE-P data and tbe emissions inventory.

Zooming into local active galactic nuclei: the power of combining SDSS-IV MaNGA with higher resolution integral field unit observations

NASA Astrophysics Data System (ADS)

Wylezalek, Dominika; Schnorr Müller, Allan; Zakamska, Nadia L.; Storchi-Bergmann, Thaisa; Greene, Jenny E.; Müller-Sánchez, Francisco; Kelly, Michael; Liu, Guilin; Law, David R.; Barrera-Ballesteros, Jorge K.; Riffel, Rogemar A.; Thomas, Daniel

2017-05-01

Ionized gas outflows driven by active galactic nuclei (AGN) are ubiquitous in high-luminosity AGN with outflow speeds apparently correlated with the total bolometric luminosity of the AGN. This empirical relation and theoretical work suggest that in the range Lbol ˜ 1043-45 erg s-1 there must exist a threshold luminosity above which the AGN becomes powerful enough to launch winds that will be able to escape the galaxy potential. In this paper, we present pilot observations of two AGN in this transitional range that were taken with the Gemini North Multi-Object Spectrograph integral field unit (IFU). Both sources have also previously been observed within the Sloan Digital Sky Survey-IV (SDSS) Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey. While the MaNGA IFU maps probe the gas fields on galaxy-wide scales and show that some regions are dominated by AGN ionization, the new Gemini IFU data zoom into the centre with four times better spatial resolution. In the object with the lower Lbol we find evidence of a young or stalled biconical AGN-driven outflow where none was obvious at the MaNGA resolution. In the object with the higher Lbol we trace the large-scale biconical outflow into the nuclear region and connect the outflow from small to large scales. These observations suggest that AGN luminosity and galaxy potential are crucial in shaping wind launching and propagation in low-luminosity AGN. The transition from small and young outflows to galaxy-wide feedback can only be understood by combining large-scale IFU data that trace the galaxy velocity field with higher resolution, small-scale IFU maps.

Suzaku Discovery of Ultra-fast Outflows in Radio-loud AGN

NASA Astrophysics Data System (ADS)

Sambruna, Rita M.; Tombesi, F.; Reeves, J.; Braito, V.; Gofford, J.; Cappi, M.

2010-03-01

We present the results of an analysis of the 3.5--10.5 keV spectra of five bright Broad-Line Radio Galaxies (BLRGs) using proprietary and archival Suzaku observations. In three sources -- 3C 111, 3C 120, and 3C 390.3 -- we find evidence, for the first time in a radio-loud AGN, for absorption features at observed energies 7 keV and 8--9 keV, with high significance according to both the F-test and extensive Monte Carlo simulations (99% or larger). In the remaining two BLRGs, 3C 382 and 3C 445, there is no evidence for such absorption features in the XIS spectra. If interpreted as due to Fe XXV and/or Fe XXVI K-shell resonance lines, the absorption features in 3C 111, 3C 120, and 3C 390.3 imply an origin from an ionized gas outflowing with velocities in the range v 0.04-0.15c, reminiscent of Ultra-Fast Outflows (UFOs) previously observed in radio-quiet Seyfert galaxies. A fit with specific photoionization models gives ionization parameters log ξ 4--5.6 erg s-1 cm and column densities of NH 1022-23 cm-2, similar to the values observed in Seyferts. Based on light travel time arguments, we estimate that the UFOs in the three BLRGs are located within 20--500 gravitational radii from the central black hole, and thus most likely are connected to disk winds/outflows. Our estimates show that the UFOs mass outflow rate is comparable to the accretion rate and their kinetic energy a significant fraction of the AGN bolometric luminosity, making these outflows significant for the global energetic of these systems, in particular for mechanisms of jet formation.

Using telepresence enabled remote-operated vehicles to assess hydrothermal outflow along a collapse scar near the Kick'em Jenny Volcano

NASA Astrophysics Data System (ADS)

Whitley, S. Z.; Mittelstaedt, E. L.

2016-02-01

During expedition NA054 of the E/V Nautilus from 18 September to 9 October 2014 and as part of the TREET (Transforming Remotely Conducted Research through Ethnography, Education, and Rapidly Evolving Technologies) project, a series of photographic surveys along the shoulder of the Kick'em Jenny volcano were performed under direction of a remote research team located at the University of Rhode Island Inner Space Center. The primary goal of these surveys was to map the distribution and extent of active and extinct hydrothermal activity along a large collapse scar surrounding the current edifice of the Kick'em Jenny volcano. Photomosaic surveys cover a area of 3000 m2 and reveal extensive basalt alteration with areas of active diffuse hydrothermal outflow. The spatial extents of orange-colored alteration and white, bacterial mats, taken to indicate active outflow, are quantified using both manual identification and an automated, supervised classification scheme. Both methods find that alteration covers 7-8% and active outflow 1-3% of the survey region. It is unclear if the observed hydrothermal fluids are part of the fluid circulation network of the nearby Kick'em Jenny volcano or if a separate heat source is driving this flow. To test these two endmember cases, we use a 2D, finite-difference, marker-in-cell code to simulate hydrothermal circulation of a single-phase fluid within the oceanic crust. Parameters varied include the permeability structure (e.g., inclusion of a permeability barrier representing the collapse surface), the depth to the heat source beneath Kick'em Jenny, and the bathymetry. We will discuss results from the photomosaic analysis and our initial models.

The molecular gas content of the Pipe Nebula. I. Direct evidence of outflow-generated turbulence in B59?

NASA Astrophysics Data System (ADS)

Duarte-Cabral, A.; Chrysostomou, A.; Peretto, N.; Fuller, G. A.; Matthews, B.; Schieven, G.; Davis, G. R.

2012-07-01

Context. Star forming regions may share many characteristics, but the specific interplay between gravity, magnetic fields, large-scale dynamics, and protostellar feedback will have an impact on the star formation history of each region. The importance of feedback from outflows is a particular subject to debate, as we are yet to understand the details of their impact on clouds and star formation. Aims: The Pipe Nebula is a nearby molecular cloud hosting the B59 region as its only active star-forming clump. This paper focuses on the global dynamics of B59, its temperature structure, and its outflowing gas, with the goal of revealing the local and global impact of the protostellar outflows. Methods: Using HARP at the James Clerk Maxwell Telescope, we have mapped the B59 region in the J = 3 → 2 transition of 12CO to study the kinematics and energetics of the outflows, and the same transitions of 13CO and C18O to study the overall dynamics of the ambient cloud, the physical properties of the gas, and the hierarchical structure of the region. Results: The B59 region has a total of ~30 M⊙ of cold and quiescent material, mostly gravitationally bound, with narrow line widths throughout. Such low levels of turbulence in the non-star-forming regions within B59 are indicative of the intrinsic initial conditions of the cloud. On the other hand, close to the protostars the impact of the outflows is observed as a localised increase of both C18O line widths from ~0.3 km s-1 to ~1 km s-1, and 13CO excitation temperatures by ~2-3 K. The impact of the outflows is also evident in the low column density material which shows signs of being shaped by the outflow bow shocks as they pierce their way out of the cloud. Much of this structure is readily apparent in a dendrogram analysis of the cloud and demonstrates that when decomposing clouds using such techniques a careful interpretation of the results is needed. Conclusions: The low mass of B59 together with its intrinsically quiescent gas and small number of protostars, allows the identification of specific regions where the outflows from the embedded sources interact the dense gas. Our study suggests that outflows are an important mechanism for injecting and sustaining supersonic turbulence at sub-parsec size scales. We find that less than half of the outflow energy is deposited as turbulent energy of the gas, however this turbulent energy is sufficient to slow down the collapse of the region.

Ancient drainage basin of the Tharsis region, Mars: Potential source for outflow channel systems and putative oceans or paleolakes

USGS Publications Warehouse

Dohm, J.M.; Ferris, J.C.; Baker, V.R.; Anderson, R.C.; Hare, T.M.; Strom, R.G.; Barlow, N.G.; Tanaka, K.L.; Klemaszewski, J.E.; Scott, D.H.

2001-01-01

Paleotopographic reconstructions based on a synthesis of published geologic information and high-resolution topography, including topographic profiles, reveal the potential existence of an enormous drainage basin/aquifer system in the eastern part of the Tharsis region during the Noachian Period. Large topographic highs formed the margin of the gigantic drainage basin. Subsequently, lavas, sediments, and volatiles partly infilled the basin, resulting in an enormous and productive regional aquifer. The stacked sequences of water-bearing strata were then deformed locally and, in places, exposed by magmatic-driven uplifts, tectonic deformation, and erosion. This basin model provides a potential source of water necessary to carve the large outflow channel systems of the Tharsis and surrounding regions and to contribute to the formation of putative northern-plains ocean(s) and/or paleolakes. Copyright 2001 by the American Geophysical Union.

Dynamic Agents of Magnetosphere-Ionosphere Coupling

NASA Technical Reports Server (NTRS)

Khazanov, George V.; Rowland, Douglas E.; Moore, Thomas E.; Collier, Michael

2011-01-01

VISIONS sounding rocket mission (VISualizing Ion Outflow via Neutral atom imaging during a Substorm) has been awarded to NASA/GSFC (PI Rowland) in order to provide the first combined remote sensing and in situ measurements of the regions where ion acceleration to above 5 e V is occurring, and of the sources of free energy and acceleration mechanisms that accelerate the ions. The key science question of VISIONS is how, when, and where, are ions accelerated to escape velocities in the auroral zone below 1000 km, following substorm onset? Sources of free energy that power this ion acceleration process include (but not limited) electron precipitation, field-aligned currents, velocity shears, and Alfvenic Poynting flux. The combine effect of all these processes on ionospheric ion outflows will be investigated in a framework of the kinetic model that has been developed by Khazanov et al. in order to study the polar wind transport in the presence of photoelectrons.

Sources and yields of dissolved carbon in northern Wisconsin stream catchments with differing amounts of Peatland

USGS Publications Warehouse

Elder, J.F.; Rybicki, N.B.; Carter, V.; Weintraub, V.

2000-01-01

In five tributary streams (four inflowing and one outflowing) of 1600-ha Trout Lake in northern Wisconsin, USA, we examined factors that can affect the magnitude of stream flow and transport of dissolved organic and inorganic carbon (DOC and DIC) through the streams to the lake. One catchment, the Allequash Creek basin, was investigated in more detail to describe the dynamics of carbon flow and to identify potential carbon sources. Stream flows and carbon loads showed little or no relation to surface-water catchment area. They were more closely related to ground-water watershed area because ground-water discharge, from both local and regional sources, is a major contributor to the hydrologic budgets of these catchments. An important factor in determining carbon influx to the stream is the area of peatland in the catchment. Peatland porewaters contain DOC concentrations up to 40 mg l-1 and are a significant potential carbon source. Ground-water discharge and lateral flow through peat are the suspected mechanisms for transport of that carbon to the streams. Carbon and nitrogen isotopes suggested that the sources of DOC in Allequash Creek above Allequash Lake were wetland vegetation and peat and that the sources below Allequash Lake were filamentous algae and wild rice. Catchments with high proportions of peatland, including the Allequash Creek catchment, tended to have elevated DOC loads in outflowing stream water. Respiration and carbon mineralization in lakes within the system tend to produce low DOC and low DOC/DIC in lake outflows, especially at Trout Lake. In Allequash Lake, however, the shallow peat island and vegetation-filled west end were sources of DOC. Despite the vast carbon reservoir in the peatlands, carbon yields were very low in these catchments. Maximum yields were on the order of 2.5 g m-2 y-1 DOC and 5.5 g m-2 y-1 DIC. The small yields were attributable to low stream flows due to lack of significant overland runoff and very limited stream channel coverage of the total catchment area.

An Outflow-shaped Magnetic Field Toward the Class 0 Protostellar Source Serpens SMM1

NASA Astrophysics Data System (ADS)

Hull, Charles; Girart, Josep M.; Tychoniec, Lukasz; Rao, Ramprasad; Cortés, Paulo; Pokhrel, Riwaj; Zhang, Qizhou; Houde, Martin; Dunham, Michael; Kristensen, Lars; Lai, Shih-Ping; Li, Zhi-Yun; Plambeck, Richard

2018-01-01

The results from the polarization system at the Atacama Large Millimeter/submillimeter Array (ALMA) have begun both to expand and to confound our understanding of the role of the magnetic field in low-mass star formation. Here we show the highest resolution and highest sensitivity polarization images made to date toward the very young, intermediate-mass Class 0 protostellar source Serpens SMM1, the brightest source in the Serpens Main star-forming region. These ALMA observations achieve ~140 AU resolution, allowing us to probe dust polarization—and thus magnetic field orientation—in the innermost regions surrounding the protostar. By complementing these observations with polarization observations from the Submillimeter Array (SMA) and archival data from the Combined Array for Research in Millimeter-wave Astronomy (CARMA) and the James Clerk Maxwell Telescopes (JCMT), we can compare the magnetic field orientations at different spatial scales. We find major changes in the magnetic field orientation between large (~0.1 pc) scales—where the magnetic field is oriented E–W, perpendicular to the major axis of the dusty filament where SMM1 is embedded—and the intermediate and small scales probed by CARMA (~1000 au resolution), the SMA (~350 au resolution), and ALMA. The ALMA maps reveal that the redshifted lobe of the bipolar outflow is clearly shaping the magnetic field in SMM1 on the southeast side of the source. High-spatial-resolution continuum and spectral-line observations also reveal a tight (~130 au) protobinary system in SMM1-b, the eastern component of which is launching an extremely high-velocity, one-sided jet visible in both CO(2-1) and SiO(5-4); however, that jet does not appear to be shaping the magnetic field. These observations show that with the sensitivity and resolution of ALMA, we can now begin to understand the role that feedback (e.g., from protostellar outflows) plays in shaping the magnetic field in very young, star-forming sources like SMM1.

A Catalogue of Massive Young Stellar Objects

NASA Astrophysics Data System (ADS)

Chan, S. J.; Henning, Th.; Schreyer, K.

1994-12-01

We report on an ongoing project to compile a catalogue of massive young stellar objects (YSOs). Massive young stellar objects are compact and luminous infrared sources. The stellar core is still surrounded by optically thick dust shells (cf. Henning 1990, Fundamentals of Cosmic Physics, 14, 321). This catalogue, which contains about 250 objects, will provide comprehensive information such as infrared and radio flux densities, association with maser sources, and outflow phenomena. The objects were selected from the IRAS Point Source Catalogue based on the following criteria: (1) IRAS flux density qualities >= 2 in the 4 IRAS bands (12 microns, 25 microns, 60 microns and 100 microns). (2) Fnu(12microns) <= Fnu(25microns) <= Fnu(60microns) <= F_ν(100microns) Fnu(100microns) >= 1000 Jy (3) IRAS colors (including uncertainty 0.15) should be within the following color box: -0.15 >= R(12/25) >= 1.15, -0.15 >= R(25/60) >= 0.75, -0.35 >= R(60/100) >= 0.35, where R(i/j)=jF_nu (i)/iF_nu (j) (Henning et al. 1990, A&A, 227, 542) (4) IRAS idtype (type of objects)!= 1; objects are not associated with galaxies or late-type stars; ∣b∣ <= 10{(deg}) Our main goal is to collect the observational data of these sources as complete as possible. The flux densities from near-infrared to radio range are assembled (J, H, K bands, IRAS bands, 350 microns, 800 microns and 1.3 mm bands, 2 cm and 6 cm bands). The information on dust features (such as ice, silicate, PAH) comes from the IRAS Low Resolution Spectrometer Atlas and literature (cf. Volk & Cohen, 1989, AJ, 98, 931). The maser sources (H_2O, type I OH, CH_3OH) and NH_3, HCO(+) , and CS molecular line data towards these objects, which have been observed, are also reported. The CO outflow velocity will be given if the object is found to be associated with an outflow.

Correction: Phylogenetic placement of the enigmatic parasite, Polypodium hydriforme, within the Phylum Cnidaria.

PubMed

Evans, Nathaniel M; Lindner, Alberto; Raikova, Ekaterina V; Collins, Allen G; Cartwright, Paulyn

2009-07-15

Correction to Evans, N.M., Lindner, A., Raikova, E.V., Collins, A.G. and Cartwright, P. Phylogenetic placement of the enigmatic parasite, Polypodium hydriforme, within the phylum Cnidaria. BMC Evol Biol, 2008, 8:139.

Highly Collimated Jets and Wide-angle Outflows in HH 46/47: New Evidence from Spitzer Infrared Images

NASA Technical Reports Server (NTRS)

Velusamy, T.; Langer, William D.; Marsh, Kenneth. A.

2007-01-01

We present new details of the structure and morphology of the jets and outflows in HH 46/47 as seen in Spitzer infrared images from IRAC and MIPS, reprocessed using the 'HiRes' deconvolution technique. HiRes improves the visualization of spatial morphology by enhancing resolution (to subarcsecond levels in IRAC bands) and removing the contaminating side lobes from bright sources. In addition to sharper views of previously reported bow shocks, we have detected (1) the sharply delineated cavity walls of the wide-angle biconical outflow, seen in scattered light on both sides of the protostar, (2) several very narrow jet features at distances approximately 400 AU to approximately 0.1 pc from the star, and (3) compact emissions at MIPS 24 m with the jet heads, tracing the hottest atomic/ionic gas in the bow shocks. Together the IRAC and MIPS images provide a more complete picture of the bow shocks, tracing both the molecular and atomic/ionic gases, respectively. The narrow width and alignment of all jet-related features indicate a high degree of jet collimation and low divergence (width of approximately 400 AU increasing by only a factor of 2.3 over 0.2 pc). The morphology of this jet, bow shocks, wide-angle outflows, and the fact that the jet is nonprecessing and episodic, constrain the mechanisms for producing the jet's entrained molecular gas, and origins of the fast jet, and slower wide-angle outflow.

Multi-wavelength campaign on NGC 7469. II. Column densities and variability in the X-ray spectrum

NASA Astrophysics Data System (ADS)

Peretz, U.; Behar, E.; Kriss, G. A.; Kaastra, J.; Arav, N.; Bianchi, S.; Branduardi-Raymont, G.; Cappi, M.; Costantini, E.; De Marco, B.; Di Gesu, L.; Ebrero, J.; Kaspi, S.; Mehdipour, M.; Middei, R.; Paltani, S.; Petrucci, P. O.; Ponti, G.; Ursini, F.

2018-01-01

We have investigated the ionic column density variability of the ionized outflows associated with NGC 7469, to estimate their location and power. This could allow a better understanding of galactic feedback of AGNs to their host galaxies. Analysis of seven XMM-Newton grating observations from 2015 is reported. We used an individual-ion spectral fitting approach, and compared different epochs to accurately determine variability on timescales of years, months, and days. We find no significant column density variability in a ten-year period implying that the outflow is far from the ionizing source. The implied lower bound on the ionization equilibrium time, ten years, constrains the lower limit on the distance to be at least 12 pc, and up to 31 pc, much less but consistent with the 1 kpc wide starburst ring. The ionization distribution of column density is reconstructed from measured column densities, nicely matching results of two 2004 observations, with one large high ionization parameter (ξ) component at 2 < log ξ< 3.5, and one at 0.5 < log ξ< 1 in cgs units. The strong dependence of the expression for kinetic power, ∝ 1 /ξ, hampers tight constraints on the feedback mechanism of outflows with a large range in ionization parameter, which is often observed and indicates a non-conical outflow. The kinetic power of the outflow is estimated here to be within 0.4 and 60% of the Eddington luminosity, depending on the ion used to estimate ξ.

X-ray evidence for ultra-fast outflows in AGNs

NASA Astrophysics Data System (ADS)

Tombesi, Francesco; Sambruna, Rita; Braito, Valentina; Reeves, James; Reynolds, Christopher; Cappi, Massimo

2012-07-01

X-ray evidence for massive, highly ionized, ultra-fast outflows (UFOs) has been recently reported in a number of AGNs through the detection of blue-shifted Fe XXV/XXVI absorption lines. We present the results of a comprehensive spectral analysis of a large sample of 42 local Seyferts and 5 radio galaxies observed with XMM-Newton and Suzaku. We assessed the global detection significance of the absorption lines and performed a detailed photo-ionization modeling. We find that UFOs are common phenomena, being present in >40% of the sources. Their outflow velocity distribution is in the range ˜0.03--0.3c, with mean value of ˜0.14c. The ionization parameter is very high, in the range logξ˜3--6 erg~s^{-1}~cm, and the associated column densities are also large, in the range ˜10^{22}--10^{24} cm^{-2}. Their location is constrained at ˜0.0003--0.03pc (˜10^2--10^4 r_s) from the central black hole, consistent with what is expected for accretion disk winds/outflows. The mass outflow rates are in the interval ˜0.01--1M_{⊙}~yr^{-1} and the associated mechanical power is high, in the range ˜10^{43}--10^{45} erg/s. Therefore, UFOs are capable to provide a significant contribution to the AGN cosmological feedback and their study can provide important clues on the connection between accretion disks, winds and jets.

VISIONS: Remote Observations of a Spatially-Structured Filamentary Source of Energetic Neutral Atoms near the Polar Cap Boundary During an Auroral Substorm

NASA Technical Reports Server (NTRS)

Collier, Michael R.; Chornay, D.; Clemmons, J.; Keller, J. W.; Klenzing, J.; Kujawski, J.; McLain, J.; Pfaff, R.; Rowland, D.; Zettergren, M.

2015-01-01

We report initial results from the VISualizing Ion Outflow via Neutral atom imaging during a Substorm (VISIONS) rocket that flew through and near several regions of enhanced auroral activity and also sensed regions of ion outflow both remotely and directly. The observed neutral atom fluxes were largest at the lower energies and generally higher in the auroral zone than in the polar cap. In this paper, we focus on data from the latter half of the VISIONS trajectory when the rocket traversed the polar cap region. During this period, many of the energetic neutral atom spectra show a peak at 100 electronvolts. Spectra with peaks around 100 electronvolts are also observed in the Electrostatic Ion Analyzer (EIA) data consistent with these ions comprising the source population for the energetic neutral atoms. The EIA observations of this low energy population extend only over a few tens of kilometers. Furthermore, the directionality of the arriving energetic neutral atoms is consistent with either this spatially localized source of energetic ions extending from as low as about 300 kilometers up to above 600 kilometers or a larger source of energetic ions to the southwest.

A Survey of Extended H_{2} Emission Towards a Sample of Massive YSOs

NASA Astrophysics Data System (ADS)

Navarete, F.; Damineli, A.; Barbosa, C. L.; Blum, R. D.

2014-10-01

Very few massive stars in early formation stages were clearly identified in the Milky Way and moreover, the processes of formation of such objects lacks of observational evidences. Two theories predict the formation of massive star: i) by merging of low mass stars or ii) by an accretion disk. One of the most prominent evidences for the accretion scenario is the presence of bipolar outflows associated to the central sources. Those structures were found on both intermediate and low-mass YSOs, but there are no evidences for associations with MYSOs. Based on that, a survey was designed to investigate the earliest stages of massive star formation through the molecular hydrogen transition at 2.12μm. A sample of ˜ 300 MYSOs candidates was selected from the Red MSX Source program and the sources were observed with the IR cameras Spartan (SOAR, Chile) and WIRCam (CFHT, Hawaii). Extended H_{2} emission was found toward 55% of the sample and 30% of the positive detections (50 sources) have bipolar morphology, suggesting collimated outflows. These results support the accretion scenario, since the merging of low mass stars would not produce jet-like structures.

Outflow and Accretion Physics in Active Galactic Nuclei

NASA Astrophysics Data System (ADS)

McGraw, Sean Michael

2016-09-01

This dissertation focuses on placing observational constraints on outflows and accretion disks in active galactic nuclei (AGN) for the purpose of better understanding the physics of super-massive black holes (SMBHs) and their evolution with the host galaxy over cosmic time. Quasar outflows and their importance in SMBH-host galaxy co-evolution can be further understood by analyzing broad absorption lines (BALs) in rest-frame UV spectra that trace a range of wind conditions. We quantify the properties of the flows by conducting BAL variability studies using multiple-epoch spectra acquired primarily from MDM Observatory and from the Sloan Digital Sky Survey. Iron low-ionization BALs (FeLoBALs) are a rare type of outflow that may represent a transient phase in galaxy evolution, and we analyze the variations in 12 FeLoBAL quasars with redshifts between 0.7 ≤ z ≤ 1.9 and rest frame timescales between ˜10 d to 7.6 yr. We investigate BAL variability in 71 quasar outflows that exhibit P V absorption, a tracer of high column density gas (i.e. NH ≥ 1022 cm -2), in order to quantify the energies and momenta of the flows. We also characterize the variability patterns of 26 quasars with mini-BALs, an interesting class of absorbers that may represent a distinct phase in the evolution of outflows. Low-luminosity AGN (LLAGN) are important objects to study since their prominence in the local Universe suggest a possible evolution from the quasar era, and their low radiative outputs likely indicate a distinct mode of accretion onto the SMBH. We probe the accretion conditions in the LLAGN NGC 4203 by estimating the SMBH mass, which is obtained by modeling the 2-dimensional velocity field of the nebular gas using spectra from the Hubble Space Telescope. We detect significant BAL and mini-BAL variability in a subset of quasars from each of our samples, with measured rest-frame variability time-scales from days to years and over multiple years on average. Variable wavelength intervals are associated with high-ionization species such as C IV and N V, low-ionization lines including Mg II and Al III, and ground and excited states from Fe II multiplets. The detected BAL and mini-BAL variations in a subset of sources provide evidence supporting scenarios involving either transverse motions of gas or ionization changes within the absorbers. We conclude that some outflows in our samples likely exist on the order of 0.01-1 pc from the SMBH, and the possibility remains that we are tracing outflowing gas on larger scales within limits ranging from ≤10 pc to ≤1 kpc from the central source. We estimate outflow kinetic luminosities between ˜10 6 and 1 times the bolometric luminosity of the quasar, indicating that the BAL outflows we probe likely possess a range of energies and only some absorber energies are likely sufficient for AGN feedback processes. We estimate the SMBH mass in the LLAGN in NGC 4203 to be ˜1.1x10 7 solar masses within a factor of ˜2. This mass estimate in conjunction with theoretical predictions is consistent with the existence of a two-component accretion flow in the nucleus of NGC 4203, consisting of a hot, advection-dominated torus at small radii connected with a thin, radiatively efficient disk at larger scales. These results provide a significant increase in the information available for quasar outflow properties and the conditions in low-luminosity accretion disks, and will inform future observational and theoretical studies that attempt to construct a more complete picture of AGN and their effects on the surrounding environments.

Crista Supraventricularis Purkinje Network and Its Relation to Intraseptal Purkinje Network.

PubMed

De Almeida, Marcos C; Araujo, Mayssa; Duque, Mathias; Vilhena, Virginia

2017-10-01

Using transparent specimens with a dual color injection, microscopy, and computer tomography, this report shows that the right and left ventricular subendocardial Purkinje networks are connected by an extensive septal network in the bovine heart. The septal network is present along the entire septum except at a free zone below ventricular valves. Being the only communication of the basal right septum with the right free wall, the supraventricular crest is an enigmatic but not, by any means, hidden muscular structure. It is one of the last structures to be activated in human heart. It is shown here that the supraventricular crest Purkinje network connects the anterosuperior right ventricular basal free wall Purkinje network to anterior right ventricular basal septal Purkinje network. It is suggested that the stimulus initiated at middle left ventricular endocardium will activate the supraventricular crest. The intraseptal connection found between the basal left ventricular subendocardial septal Purkinje network and the right ventricular basal septal Purkinje network is, probably, the pathway for the stimulus. An anatomic basis is provided to explain why the inflow tract contracts earlier than the outflow tract in the right ventricle systole. Anat Rec, 2017. © 2017 Wiley Periodicals, Inc. Anat Rec, 300:1793-1801, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Downscattering due to Wind Outflows in Compact X-ray Sources: Theory and Interpretation

NASA Technical Reports Server (NTRS)

Titarchuk, Lev; Shrader, Chris

2004-01-01

A number of recent lines of evidence point towards the presence of hot, outflowing plasma from the central regions of compact Galactic and extragalactic X-ray sources. Additionally, it has long been noted that many of these sources exhibit an "excess" continuum component, above approx. 10 keV, usually attributed to Compton Reflection from a static medium. Motivated by these facts, as well as by recent observational constraints on the Compton reflection models - specifically apparently discrepant variability timescales for line and continuum components in some cases - we consider possible of effects of out-flowing plasma on the high-energy continuum spectra of accretion powered compact objects. We present a general formulation for photon downscattering diffusion which includes recoil and Comptonization effects due to divergence of the flow. We then develop an analytical theory for the spectral formation in such systems that allows us to derive formulae for the emergent spectrum. Finally we perform the analytical model fitting on several Galactic X-ray binaries. Objects which have been modeled with high-covering-fraction Compton reflectors, such as GS1353-64 are included in our analysis. In addition, Cyg X-3, is which is widely believed to be characterized by dense circumstellar winds with temperature of order 10(exp 6) K, provides an interesting test case. Data from INTEGRAL and RXTE covering the approx. 3 - 300 keV range are used in our analysis. We further consider the possibility that the widely noted distortion of the power-law continuum above 10 keV may in some cases be explained by these spectral softening effects.

Episodes of fluvial and volcanic activity in Mangala Valles, Mars.

PubMed

Keske, Amber L; Hamilton, Christopher W; McEwen, Alfred S; Daubar, Ingrid J

2015-01-01

A new mapping-based study of the 900-km-long Mangala Valles outflow system was motivated by the availability of new high-resolution images and continued debates about the roles of water and lava in outflow channels on Mars. This study uses photogeologic analysis, geomorphic surface mapping, cratering statistics, and relative stratigraphy. Results show that Mangala Valles underwent at least two episodes of fluvial activity and at least three episodes of volcanic activity during the Late Amazonian. The occurrence of scoured bedrock at the base of the mapped stratigraphy, in addition to evidence provided by crater retention ages, suggests that fluvial activity preceded the deposition of two of the volcanic units. Crater counts performed at 30 locations throughout the area have allowed us to construct the following timeline: (1) formation of Noachian Highlands and possible initial flooding event(s) before ~1 Ga, (2) emplacement of Tharsis lava flows in the valley from ~700 to 1000 Ma, (3) a megaflooding event at ~700-800 Ma sourced from Mangala Fossa, (4) valley fill by a sequence of lava flows sourced from Mangala Fossa ~400-500 Ma, (5) another megaflooding event from ~400 Ma, (6) a final phase of volcanism sourced from Mangala Fossa ~300-350 Ma, and (7) emplacement of eolian sedimentary deposits in the northern portion of the valley ~300 Ma. These results are consistent with alternating episodes of aqueous flooding and volcanism in the valles. This pattern of geologic activity is similar to that of other outflow systems, such as Kasei Valles, suggesting that there is a recurring, and perhaps coupled, nature of these processes on Mars.

The [O III] Profiles of Infrared-selected Active Galactic Nuclei: More Powerful Outflows in the Obscured Population

NASA Astrophysics Data System (ADS)

DiPompeo, M. A.; Hickox, R. C.; Carroll, C. M.; Runnoe, J. C.; Mullaney, J. R.; Fischer, T. C.

2018-03-01

We explore the kinematics of ionized gas via the [O III] λ5007 emission lines in active galactic nuclei (AGNs) selected on the basis of their mid-infrared (IR) emission, and split into obscured and unobscured populations based on their optical‑IR colors. After correcting for differences in redshift distributions, we provide composite spectra of spectroscopically and photometrically defined obscured/Type 2 and unobscured/Type 1 AGNs from 3500 to 7000 Å. The IR-selected obscured sources contain a mixture of narrow-lined Type 2 AGNs and intermediate sources that have broad Hα emission and significantly narrower Hβ. Using both [O III] luminosities and AGN luminosities derived from optical‑IR spectral energy distribution fitting, we find evidence for enhanced large-scale obscuration in the obscured sources. In matched bins of luminosity we find that the obscured population typically has broader, more blueshifted [O III] emission than in the unobscured sample, suggestive of more powerful AGN-driven outflows. This trend is not seen in spectroscopically classified samples, and is unlikely to be entirely explained by orientation effects. In addition, outflow velocities increase from small to moderate AGN E(B ‑ V) values, before flattening out (as traced by FWHM) and even decreasing (as traced by blueshift). While difficult to fully interpret in a single physical model, due to both the averaging over populations and the spatially averaged spectra, these results agree with previous findings that simple geometric unification models are insufficient for the IR-selected AGN population, and may fit into an evolutionary model for obscured and unobscured AGNs.

Correction: Phylogenetic placement of the enigmatic parasite, Polypodium hydriforme, within the Phylum Cnidaria

PubMed Central

2009-01-01

Correction to Evans, N.M., Lindner, A., Raikova, E.V., Collins, A.G. and Cartwright, P. Phylogenetic placement of the enigmatic parasite, Polypodium hydriforme, within the phylum Cnidaria. BMC Evol Biol, 2008, 8:139. PMID:19604374

Atmospheric outflow of PM2.5 saccharides from megacity Shanghai to East China Sea: Impact of biological and biomass burning sources

NASA Astrophysics Data System (ADS)

Li, Xiang; Chen, Minxuan; Le, Hoa Phuoc; Wang, Fengwen; Guo, Zhigang; Iinuma, Yoshiteru; Chen, Jianmin; Herrmann, Hartmut

2016-10-01

In an effort to more fully understand atmospheric outflow of PM2.5-associated saccharide species, we investigated primary saccharides (fructose, glucose, sucrose, and trehalose), saccharide alcohols (arabitol and mannitol), and anhydrosaccharides (levoglucosan and mannosan) in atmospheric aerosols at both a megacity site, Shanghai, and a sea background site, Huaniao Island. The results showed that the saccharide species presented pronounced temporal and spatial variability in the outflow from the megacity to the East China Sea, and varied widely with a total concentration range of 8.6-2400 ng m-3 (283 ng m-3 mean) in Shanghai and 0-1050 ng m-3 (51 ng m-3 mean) in Huaniao Island. Both saccharide species (e.g., levoglucosan and sucrose) showed higher concentrations and a noticeable seasonal gradient during the study period ― there was a high level of levoglucosan in the cold season (161 ng m-3 in winter and 229 ng m-3 in autumn) due to elevated biomass burning activities, and a high level of sucrose in the warm seasons (146 ng m-3 in summer and 145 ng m-3 in spring) due to elevated levels of intense biological aerosols including fungal spores and pollen. The calculated levoglucosan/mannosan (L/M) ratio, which may represent the signature of aerosol particles at the two sites, ranged from 5.2 to 10.9 during the cold season. Back-trajectory analysis results indicated that the saccharides originated from regional sources in East and North China before being transported to the sampling site. Emissions due to biomass burning were estimated to correspond to 46% (mass) of the saccharides quantified in the haze particle samples, whereas biogenic emissions corresponded to 18%, indicating that biomass burning was a considerable aerosol source to the regional atmosphere throughout the year. The results presented here support the theory that levoglucosan could be utilized as a molecular marker for East Asian biomass burning outflow, and sucrose as a molecular marker for airborne pollen grains. The results of this study may help future researchers clarify the aerosol sources, as well as their atmospheric transport pathways over East Asia to the western Pacific Ocean.

SUBARU near-infrared multi-color images of Class II Young Stellar Object, RNO91

NASA Astrophysics Data System (ADS)

Mayama, Satoshi; Tamura, Motohide; Hayashi, Masahiko

RNO91 is class II source currently in a transition phase between a protostar and a main-sequence star. It is known as a source of complex molecular outflows. Previous studies suggested that RNO91 was associated with a reflection nebula, a CO outflow, shock-excited H[2] emission, and disk type structure. But geometry of RNO91, especially its inner region, is not well confirmed yet. High resolution imaging is needed to understand the nature of RNO91 and its interaction with outflow. Furthermore, RNO91 is an important candidate for studying YSOs in a transition phase. Thus, we conducted near-infrared imaging observations of RNO91 with the infrared camera CIAO mounted on the Subaru 8.2m Telescope. We present JHK band and optical images which resolve a complex asymmetrical circumstellar structure. We examined the color of RNO91 nebula and compare the geometry of the system suggested by our data with that already proposed on the basis of other studies. Our main results are as follows; 1. At J and optical, several bluer clumps are detected and they are aligned nearly perpendicular to the outflow axis. 2. The NIR images show significant halo emission detected within 2'' around the peak position while less halo emission is seen in the optical image. The nebula appears to become more circular and more diffuse with increasing wavelengths. The power-law dependence of radial surface brightness profile is shallower than that of normal stars, indicating that RNO91 is still optically thick objects. We suggest that the halo emission is the NIR light scattered by an optically thick disk or envelope surrounding the RNO91. 3. In the shorter wavelength images, the nebula appears to become more extended (2".3 long) to the southwest. This extended emission might trace a bottom of outflow emanating to southwest direction. 4. Color composite image of RNO91 reveals that the emission extending to the north and to the east through RNO91 is interpreted as a part of the cavity wall seen relatively edge-on. The northern ridge is 11" long and eastern ridge is 7" long.

THE SPITZER SURVEY OF INTERSTELLAR CLOUDS IN THE GOULD BELT. III. A MULTI-WAVELENGTH VIEW OF CORONA AUSTRALIS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peterson, Dawn E.; Bourke, Tyler L.; Forbrich, Jan

2011-06-01

We present Spitzer Space Telescope IRAC and MIPS observations of a 0.85 deg{sup 2} field including the Corona Australis (CrA) star-forming region. At a distance of 130 pc, CrA is one of the closest regions known to be actively forming stars, particularly within its embedded association, the Coronet. Using the Spitzer data, we identify 51 young stellar objects (YSOs) in CrA which include sources in the well-studied Coronet cluster as well as sources distributed throughout the molecular cloud. Twelve of the YSOs discussed are new candidates, one of which is located in the Coronet. Known YSOs retrieved from the literaturemore » are also added to the list, and a total of 116 candidate YSOs in CrA are compiled. Based on these YSO candidates, the star formation rate is computed to be 12 M{sub sun} Myr{sup -1}, similar to that of the Lupus clouds. A clustering analysis was also performed, finding that the main cluster core, consisting of 68 members, is elongated (having an aspect ratio of 2.36), with a circular radius of 0.59 pc and mean surface density of 150 pc{sup -2}. In addition, we analyze outflows and jets in CrA by means of new CO and H{sub 2} data. We present 1.3 mm interferometric continuum observations made with the Submillimeter Array (SMA) covering R CrA, IRS 5, IRS 7, and IRAS 18595-3712 (IRAS 32). We also present multi-epoch H{sub 2} maps and detect jets and outflows, study their proper motions, and identify exciting sources. The Spitzer and ISAAC/VLT observations of IRAS 32 show a bipolar precessing jet, which drives a CO(2-1) outflow detected in the SMA observations. There is also clear evidence for a parsec-scale precessing outflow, which is east-west oriented and originates in the SMA 2 region and likely driven by SMA 2 or IRS 7A.« less

Accretion and Outflows in X-ray Binaries: What's Really Going on During X-ray Quiescence

NASA Astrophysics Data System (ADS)

MacDonald, Rachel K. D.; Bailyn, Charles D.; Buxton, Michelle

2015-01-01

X-ray binaries, consisting of a star and a stellar-mass black hole, are wonderful laboratories for studying accretion and outflows. They evolve on timescales quite accessible to us, unlike their supermassive cousins, and allow the possibility of gaining a deeper understanding of these two common astrophysical processes. Different wavelength regimes reveal different aspects of the systems: radio emission is largely generated by outflows and jets, X-ray emission by inner accretion flows, and optical/infrared (OIR) emission by the outer disk and companion star. The search for relationships between these different wavelengths is thus an area of active research, aiming to reveal deeper connections between accretion and outflows.Initial evidence for a strong, tight correlation between radio and X-ray emission has weakened as further observations and newly-discovered sources have been obtained. This has led to discussions of multiple tracks or clusters, or the possibility that no overall relation exists for the currently-known population of X-ray binaries. Our ability to distinguish among these options is hampered by a relative lack of observations at lower luminosities, and especially of truly X-ray quiescent (non-outbursting) systems. Although X-ray binaries spend the bulk of their existence in quiescence, few quiescent sources have been observed and multiple observations of individual sources are largely nonexistent. Here we discuss new observations of the lowest-luminosity quiescent X-ray binary, A0620-00, and the place this object occupies in investigations of the radio/X-ray plane. For the first time, we also incorporate simultaneous OIR data with the radio and X-ray data.In December 2013 we took simultaneous observations of A0620-00 in the X-ray (Chandra), the radio (EVLA), and the OIR (SMARTS 1.3m). These X-ray and radio data allowed us to investigate similarities among quiescent X-ray binaries, and changes over time for this individual object, in the radio/X-ray plane. In addition, our OIR observations allowed us to examine the radio and X-ray information in relation to the different OIR states of behavior (passive and active) known to exist during X-ray quiescence.

SPECTROSCOPY ALONG MULTIPLE, LENSED SIGHT LINES THROUGH OUTFLOWING WINDS IN THE QUASAR SDSS J1029+2623

DOE Office of Scientific and Technical Information (OSTI.GOV)

Misawa, Toru; Inada, Naohisa; Ohsuga, Ken

2013-02-01

We study the origin of absorption features on the blue side of the C IV broad emission line of the large-separation lensed quasar SDSS J1029+2623 at z{sub em} {approx} 2.197. The quasar images, produced by a foreground cluster of galaxies, have a maximum separation angle of {theta} {approx} 22.''5. The large angular separation suggests that the sight lines to the quasar central source can go through different regions of outflowing winds from the accretion disk of the quasar, providing a unique opportunity to study the structure of outflows from the accretion disk, a key ingredient for the evolution of quasarsmore » as well as for galaxy formation and evolution. Based on medium- and high-resolution spectroscopy of the two brightest images conducted at the Subaru telescope, we find that each image has different intrinsic levels of absorptions, which can be attributed either to variability of absorption features over the time delay between the lensed images, {Delta}t {approx} 744 days, or to the fine structure of quasar outflows probed by the multiple sight lines toward the quasar. While both these scenarios are consistent with the current data, we argue that they can be distinguished with additional spectroscopic monitoring observations.« less

Photospheric Emission from Stratified Jets

NASA Astrophysics Data System (ADS)

Ito, Hirotaka; Nagataki, Shigehiro; Ono, Masaomi; Lee, Shiu-Hang; Mao, Jirong; Yamada, Shoichi; Pe'er, Asaf; Mizuta, Akira; Harikae, Seiji

2013-11-01

We explore photospheric emissions from stratified two-component jets, wherein a highly relativistic spine outflow is surrounded by a wider and less relativistic sheath outflow. Thermal photons are injected in regions of high optical depth and propagated until the photons escape at the photosphere. Because of the presence of shear in velocity (Lorentz factor) at the boundary of the spine and sheath region, a fraction of the injected photons are accelerated using a Fermi-like acceleration mechanism such that a high-energy power-law tail is formed in the resultant spectrum. We show, in particular, that if a velocity shear with a considerable variance in the bulk Lorentz factor is present, the high-energy part of observed gamma-ray bursts (GRBs) photon spectrum can be explained by this photon acceleration mechanism. We also show that the accelerated photons might also account for the origin of the extra-hard power-law component above the bump of the thermal-like peak seen in some peculiar bursts (e.g., GRB 090510, 090902B, 090926A). We demonstrate that time-integrated spectra can also reproduce the low-energy spectrum of GRBs consistently using a multi-temperature effect when time evolution of the outflow is considered. Last, we show that the empirical E p-L p relation can be explained by differences in the outflow properties of individual sources.

Depressed emission between magnetic arcades near a sunspot

NASA Astrophysics Data System (ADS)

Ryabov, B. I.; Shibasaki, K.

The locations of the depressed emission in microwaves, EUV and soft X-rays are compared with each other and with the location of the plasma outflow in the active region (AR) 8535 on the Sun. We found that two open-field regions overlap the regions of depressed emission near the AR's sunspot. These two open-field regions are simulated with the potential-field source-surface (PFSS) model under radial distances of RSS = 1.8 R⊙ and RSS = 2.5 R⊙. Each open-field region is located between the arcades of the loops of the same magnetic polarity. The former open-field region covers the region of the plasma outflow, which is thus useful for the tests on connection to the heliosphere. The utmost microwave depression of the intensity in the ordinary mode (the Very Large Array 15 GHz observations) also overlaps the region of the plasma outflow and thus indicates this outflow. The lasting for eight days depression in soft X-rays and the SOHO EIT 2.84× 10-8 m images are attributed to the evacuation of as hot coronal plasma as T≥ 2× 106 K from the extended in height (``open") magnetic structures. We conclude that the AR 8535 presents the sunspot atmosphere affected by the large-scale magnetic fields.

Multiday production of condensing organic aerosol mass in urban and forest outflow

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee-Taylor, J.; Hodzic, A.; Madronich, S.

2015-01-16

Secondary organic aerosol (SOA) production in air masses containing either anthropogenic or biogenic (terpene-dominated) emissions is investigated using the explicit gas-phase chemical mechanism generator GECKO-A. Simulations show several-fold increases in SOA mass continuing for multiple days in the urban outflow, even as the initial air parcel is diluted into the regional atmosphere. The SOA mass increase in the forest outflow is more modest (~50%) and of shorter duration (1–2 days). The multiday production in the urban outflow stems from continuing oxidation of gas-phase precursors which persist in equilibrium with the particle phase, and can be attributed to multigenerational reaction productsmore » of both aromatics and alkanes, especially those with relatively low carbon numbers (C4–15). In particular we find large contributions from substituted maleic anhydrides and multi-substituted peroxide-bicyclic alkenes. The results show that the predicted production is a robust feature of our model even under changing atmospheric conditions and different vapor pressure schemes, and contradict the notion that SOA undergoes little mass production beyond a short initial formation period. The results imply that anthropogenic aerosol precursors could influence the chemical and radiative characteristics of the atmosphere over an extremely wide region, and that SOA measurements near precursor sources may routinely underestimate this influence.« less

Multiday production of condensing organic aerosol mass in urban and forest outflow

DOE PAGES

Lee-Taylor, J.; Hodzic, A.; Madronich, S.; ...

2015-01-16

Secondary organic aerosol (SOA) production in air masses containing either anthropogenic or biogenic (terpene-dominated) emissions is investigated using the explicit gas-phase chemical mechanism generator GECKO-A. Simulations show several-fold increases in SOA mass continuing for multiple days in the urban outflow, even as the initial air parcel is diluted into the regional atmosphere. The SOA mass increase in the forest outflow is more modest (~50%) and of shorter duration (1–2 days). The multiday production in the urban outflow stems from continuing oxidation of gas-phase precursors which persist in equilibrium with the particle phase, and can be attributed to multigenerational reaction productsmore » of both aromatics and alkanes, especially those with relatively low carbon numbers (C4–15). In particular we find large contributions from substituted maleic anhydrides and multi-substituted peroxide-bicyclic alkenes. The results show that the predicted production is a robust feature of our model even under changing atmospheric conditions and different vapor pressure schemes, and contradict the notion that SOA undergoes little mass production beyond a short initial formation period. Here, the results imply that anthropogenic aerosol precursors could influence the chemical and radiative characteristics of the atmosphere over an extremely wide region, and that SOA measurements near precursor sources may routinely underestimate this influence.« less

Chandra and Swift Observations of Unidentified Fermi-LAT Objects

NASA Astrophysics Data System (ADS)

Donato, Davide; Cheung, T.; Gehrels, N.

2010-03-01

In the last year we targeted some of the unidentified Fermi-LAT objects (UFOs) at high Galactic latitude with Chandra and Swift in order to determine the basic properties (positions, fluxes, hardness ratios) of all X-ray sources within the Fermi-LAT localization circles. These satellites enable us to detect the X-ray conterparts with a flux limit that is at least an order of magnitude lower than achieved in extant RASS data and to further follow-up at other wavelengths, with the ultimate goal to reveal the nature of these enigmatic gamma-ray sources. Here we present the results obtained with 5 Chandra pointings of high Galactic latitude UFOs in the Fermi-LAT 3-months bright source list. The association of detected X-ray sources within the improved 11-months Fermi-LAT localization circles with available optical and radio observations is discussed.

Optical and X-ray luminosities of expanding nebulae around ultraluminous X-ray sources

NASA Astrophysics Data System (ADS)

Siwek, Magdalena; Sądowski, Aleksander; Narayan, Ramesh; Roberts, Timothy P.; Soria, Roberto

2017-09-01

We have performed a set of simulations of expanding, spherically symmetric nebulae inflated by winds from accreting black holes in ultraluminous X-ray sources (ULXs). We implemented a realistic cooling function to account for free-free and bound-free cooling. For all model parameters we considered, the forward shock in the interstellar medium becomes radiative at a radius ˜100 pc. The emission is primarily in optical and UV, and the radiative luminosity is about 50 per cent of the total kinetic luminosity of the wind. In contrast, the reverse shock in the wind is adiabatic so long as the terminal outflow velocity of the wind vw ≳ 0.003c. The shocked wind in these models radiates in X-rays, but with a luminosity of only ˜1035 erg s-1. For wind velocities vw ≲ 0.001c, the shocked wind becomes radiative, but it is no longer hot enough to produce X-rays. Instead it emits in optical and UV, and the radiative luminosity is comparable to 100 per cent of the wind kinetic luminosity. We suggest that measuring the optical luminosities and putting limits on the X-ray and radio emission from shock-ionized ULX bubbles may help in estimating the mass outflow rate of the central accretion disc and the velocity of the outflow.

The hydrology of a drained topographical depression within an agricutlural field in north-central Iowa

USGS Publications Warehouse

Roth, Jason L.; Capel, Paul D.

2012-01-01

North-central Iowa is an agriculturally intensive area comprising the southeastern portion of the Prairie Pothole Region, a landscape containing a high density of enclosed topographical depressions. Artificial drainage practices have been implemented throughout the area to facilitate agricultural production. Vertical surface drains are utilized to drain the topographical depressions that accumulate water. This study focuses on the hydrology of a drained topographical depression located in a 39.5 ha agricultural field. To assess the hydrology of the drained depression, a water balance was constructed for 11 ponding events during the 2008 growing season. Continuous pond and groundwater level data were obtained with pressure transducers. Flows into the vertical surface drain were calculated based on pond depth. Precipitation inflows and evaporative outflows of the ponds were calculated using climatic data. Groundwater levels were used to assess groundwater/pond interactions. Results of the water balances show distinct differences between the inflows to and outflows from the depression based on antecedent conditions. In wet conditions, groundwater inflow sustained the ponds. The ponds receded only after the groundwater level declined to below the land surface. In drier conditions, groundwater was not a source of water to the depression. During these drier conditions, infiltration comprised 30% of the outflows from the depression during declining pond stages. Over the entire study period, the surface drain, delivering water to the stream, was the largest outflow from the pond, accounting for 97% of the outflow, while evapotranspiration was just 2%. Precipitation onto the pond surface proved to be a minor component, accounting for 4% of the total inflows.

Identification of possible recent water/lava source fissures in the Cerberus Plains: stratigraphic and crater count age constraints

NASA Astrophysics Data System (ADS)

Thomas, Rebecca J.

2013-04-01

The Cerberus plains are one of the youngest surfaces on Mars. They are thought to have been formed by lava and/or water flows, but there is considerable debate regarding the source of this material. Much of the material forming the western plains, including the Athabasca Valles outflow channels, appears to have flowed from the region of the Cerberus Fossae graben system [1,2,3] and limited areas forming the eastern plains may have been erupted by low shield volcanoes [4,5]. However, flow of material from west to east is obstructed by a ridge centred on 157°E, 7°N and, prior to this study, vents which might be the source of fluid of a low enough viscosity to form the majority of the flat eastern plains had not been identified. We studied new HiRISE (25cm/px, High Resolution Science Imaging Experiment) images of the ridge between the east and west plains and observed possible source vents for this material: the ridge is cut by a series of pits and fissures which lie at the heads of flows and channels extending towards the surrounding plains. In order to establish the stratigraphic relationships between the vents and plains, this study produced large scale geomorphological maps based on the HiRISE images. The mapping showed that both incised channels and leveed flows extend onto the plain to the south of the ridge and that these were the final phase of plains-forming activity in that region. Conversely, to the north, ridge-sourced deposits only form the plains surface close to the ridge - beyond that, they are overlain by large-scale regional flows that appear to have originated from the direction of Athabasca Valles. In the southeast, a large-scale flow which does not emanate from this ridge forms the plains surface, but there is evidence that the youngest outflow activity from the ridge was contemporaneous with emplacement of this unit. We also performed crater counts to age-date the surfaces and these indicate that plains-forming and ridge-sourced units are of a similar Late Amazonian age (<100Ma), with the latest activity tentatively dating to 10Ma. Thus, this study implies that very recent outflows from these vents contributed to the formation of the Cerberus Plains. It also constrains the timing of other large-scale plains-forming flows in the region and suggests that outflows from this ridge were part of a broader process of Cerberus plains formation from multiple sources [6]. References: [1] Plescia, J. B. (1990) Icarus, 88 (2), 465-490. [2] Burr et al. (2002) Geophysical Research Letters, 29, 1013. [3] Berman & Hartmann (2002) Icarus 159, 1-7. [4] Plescia et al. (2003) Icarus, 164, 79-95. [5] Vaucher et al. (2009) Icarus, 204, 418-442. [6] Thomas, R. (2012) JGR Planets (submitted).

Enigmatic Sedimentary Deposits Within Partially Exhumed Impact Craters in the Aeolis Dorsa Region, Mars: Evidence for Past Crater Lakes

NASA Astrophysics Data System (ADS)

Peel, S. E.; Burr, D. M.

2018-06-01

We mapped enigmatic sedimentary deposits within five partially exhumed impact craters within the Aeolis Dorsa Region of Mars. Ten units have been identified and are found to be consistent with deposition within and adjacent to lacustrine systems.

Episodes of fluvial and volcanic activity in Mangala Valles, Mars

PubMed Central

Keske, Amber L.; Hamilton, Christopher W.; McEwen, Alfred S.; Daubar, Ingrid J.

2017-01-01

A new mapping-based study of the 900-km-long Mangala Valles outflow system was motivated by the availability of new high-resolution images and continued debates about the roles of water and lava in outflow channels on Mars. This study uses photogeologic analysis, geomorphic surface mapping, cratering statistics, and relative stratigraphy. Results show that Mangala Valles underwent at least two episodes of fluvial activity and at least three episodes of volcanic activity during the Late Amazonian. The occurrence of scoured bedrock at the base of the mapped stratigraphy, in addition to evidence provided by crater retention ages, suggests that fluvial activity preceded the deposition of two of the volcanic units. Crater counts performed at 30 locations throughout the area have allowed us to construct the following timeline: (1) formation of Noachian Highlands and possible initial flooding event(s) before ~1 Ga, (2) emplacement of Tharsis lava flows in the valley from ~700 to 1000 Ma, (3) a megaflooding event at ~700–800 Ma sourced from Mangala Fossa, (4) valley fill by a sequence of lava flows sourced from Mangala Fossa ~400–500 Ma, (5) another megaflooding event from ~400 Ma, (6) a final phase of volcanism sourced from Mangala Fossa ~300–350 Ma, and (7) emplacement of eolian sedimentary deposits in the northern portion of the valley ~300 Ma. These results are consistent with alternating episodes of aqueous flooding and volcanism in the valles. This pattern of geologic activity is similar to that of other outflow systems, such as Kasei Valles, suggesting that there is a recurring, and perhaps coupled, nature of these processes on Mars. PMID:29176911

The ALMA early science view of FUor/EXor objects - V. Continuum disc masses and sizes

NASA Astrophysics Data System (ADS)

Cieza, Lucas A.; Ruíz-Rodríguez, Dary; Perez, Sebastian; Casassus, Simon; Williams, Jonathan P.; Zurlo, Alice; Principe, David A.; Hales, Antonio; Prieto, Jose L.; Tobin, John J.; Zhu, Zhaohuan; Marino, Sebastian

2018-03-01

Low-mass stars build a significant fraction of their total mass during short outbursts of enhanced accretion known as FUor and EXor outbursts. FUor objects are characterized by a sudden brightening of ˜5 mag at visible wavelengths within 1 yr and remain bright for decades. EXor objects have lower amplitude outbursts on shorter time-scales. Here we discuss a 1.3 mm Atacama Large Millimeter/submillimeter Array (ALMA) mini-survey of eight outbursting sources (three FUors, four EXors, and the borderline object V1647 Ori) in the Orion Molecular Cloud. While previous papers in this series discuss the remarkable molecular outflows observed in the three FUor objects and V1647 Ori, here we focus on the continuum data and the differences and similarities between the FUor and EXor populations. We find that FUor discs are significantly more massive (˜80-600 MJup) than the EXor objects (˜0.5-40 MJup). We also report that the EXor sources lack the prominent outflows seen in the FUor population. Even though our sample is small, the large differences in disc masses and outflow activity suggest that the two types of objects represent different evolutionary stages. The FUor sources seem to be rather compact (Rc < 20-40 au) and to have a smaller characteristic radius for a given disc mass when compared to T Tauri stars. V1118 Ori, the only known close binary system in our sample, is shown to host a disc around each one of the stellar components. The disc around HBC 494 is asymmetric, hinting at a structure in the outer disc or the presence of a second disc.

A movie of accretion/ejection of material in a high-mass YSO in Orion BN/KL at radii comparable to the Solar System

NASA Astrophysics Data System (ADS)

Goddi, C.; Greenhill, L.; Humphreys, E.; Matthews, L.; Chandler, C.

2010-11-01

Around high-mass Young Stellar Objects (YSOs), outflows are expected to be launched and collimated by accretion disks inside radii of 100 AU. Strong observational constraints on disk-mediated accretion in this context have been scarce, largely owing to difficulties in probing the circumstellar gas at scales 10-100 AU around high-mass YSOs, which are on average distant (>1 Kpc), form in clusters, and ignite quickly whilst still enshrouded in dusty envelopes. Radio Source I in Orion BN/KL is the nearest example of a high-mass YSO, and only one of three YSOs known to power SiO masers. Using VLA and VLBA observations of different SiO maser transitions, the KaLYPSO project (http://www.cfa.harvard.edu/kalypso/) aims to overcome past observational limitations by mapping the structure, 3-D velocity field, and dynamical evolution of the circumstellar gas within 1000 AU from Source I. Based on 19 epochs of VLBA observations of v=1,2 SiO masers over ~2 years, we produced a movie of bulk gas flow tracing the compact disk and the base of the protostellar wind at radii < 100 AU from Source I. In addition, we have used the VLA to map 7mm SiO v=0 emission and track proper motions over 10 years. We identify a narrowly collimated outflow with a mean motion of 18 km/s at radii 100-1000 AU, along a NE-SW axis perpendicular to that of the disk traced by the v=1,2 masers. The VLBA and VLA data exclude alternate models that place outflow from Source I along a NW-SE axis. The analysis of the complete (VLBA and VLA) dataset provides the most detailed evidence to date that high-mass star formation occurs via disk-mediated accretion.

The nature of AFGL 2591 and its associated molecular outflow: Infrared and millimeter-wave observations

NASA Technical Reports Server (NTRS)

Lada, C. J.; Thronson, H. A., Jr.; Smith, H. A.; Schwartz, P. R.; Glaccum, W.

1984-01-01

The results of infrared photometry from 2 to 160 microns of AFGL and CO(12) observations of its associated molecular cloud and high velocity molecular outflow are presented and discussed. The observed solar luminosity is 6.7 x 10(4) at a distance of 2 kpc. The spectrum of AFGL 2591 is interpreted in the context of a model in which a single embedded object is the dominant source of the infrared luminosity. This object is determined to be surrounded by a compact, optically thick dust shell with a temperature in excess of several hundred degrees kelvin. The extinction to this source is estimated to be between 26 and 50 visual magnitudes. The absolute position of the infrared sources at 10 microns was determined to an accuracy of + or in. This indicates for the first time that the IR source and H2O source are not coincident. The CO(12) observations show the high-velocity molecular flow near AFGL 2591 to be extended, bipolar and roughly centered on the infrared emission. The observations suggest that the red-shifted flow component extends beyond the boundary of the ambient cloud within which AFGL 2591 is embedded. The CO(12) observations also show that AFGL 2591 is embedded in a molecular cloud with an LSR velocity of -5 km/s.

Discovery of Suprathermal Fe+ in and near Earth's Magnetosphere

NASA Astrophysics Data System (ADS)

Christon, S. P.; Hamilton, D. C.; Plane, J. M. C.; Mitchell, D. G.; Grebowsky, J. M.; Spjeldvik, W. N.; Nylund, S. R.

2017-12-01

Suprathermal (87-212 keV/e) singly charged iron, Fe+, has been observed in and near Earth's equatorial magnetosphere using long-term ( 21 years) Geotail/STICS ion composition data. Fe+ is rare compared to dominant suprathermal solar wind and ionospheric origin heavy ions. Earth's suprathermal Fe+ appears to be positively associated with both geomagnetic and solar activity. Three candidate lower-energy sources are examined for relevance: ionospheric outflow of Fe+ escaped from ion layers altitude, charge exchange of nominal solar wind Fe+≥7, and/or solar wind transported inner source pickup Fe+ (likely formed by solar wind Fe+≥7 interaction with near sun interplanetary dust particles, IDPs). Semi-permanent ionospheric Fe+ layers form near 100 km altitude from the tons of IDPs entering Earth's atmosphere daily. Fe+ scattered from these layers is observed up to 1000 km altitude, likely escaping in strong ionospheric outflows. Using 26% of STICS's magnetosphere-dominated data at low-to-moderate geomagnetic activity levels, we demonstrate that solar wind Fe charge exchange secondaries are not an obvious Fe+ source then. Earth flyby and cruise data from Cassini/CHEMS, a nearly identical instrument, show that inner source pickup Fe+ is likely not important at suprathermal energies. Therefore, lacking any other candidate sources, it appears that ionospheric Fe+ constitutes at least an important portion of Earth's suprathermal Fe+, comparable to observations at Saturn where ionospheric origin suprathermal Fe+ has also been observed.

Longterm lightcurves of X-ray binaries

NASA Astrophysics Data System (ADS)

Clarkson, William

The X-ray Binaries (XRB) consist of a compact object and a stellar companion, which undergoes large-scale mass-loss to the compact object by virtue of the tight ( P orb usually hours-days) orbit, producing an accretion disk surrounding the compact object. The liberation of gravitational potential energy powers exotic high-energy phenomena, indeed the resulting accretion/ outflow process is among the most efficient energy-conversion machines in the universe. The Burst And Transient Source Experiment (BATSE) and RXTE All Sky Monitor (ASM) have provided remarkable X-ray lightcurves above 1.3keV for the entire sky, at near-continuous coverage, for intervals of 9 and 7 years respectively (with ~3 years' overlap). With an order of magnitude increase in sensitivity compared to previous survey instruments, these instruments have provided new insight into the high-energy behaviour of XRBs on timescales of tens to thousands of binary orbits. This thesis describes detailed examination of the long-term X-ray lightcurves of the neutron star XRB X2127+119, SMC X-1, Her X- 1, LMC X-4, Cyg X-2 and the as yet unclassified Circinus X-1, and for Cir X-1, complementary observations in the IR band. Chapters 1 & 2 introduce X-ray Binaries in general and longterm periodicities in particular. Chapter 3 introduces the longterm datasets around which this work is based, and the chosen methods of analysis of these datasets. Chapter 4 examines the burst history of the XRB X2127+119, suggesting three possible interpretations of the apparently contradictory X-ray emission from this system, including a possible confusion of two spatially distinct sources (which was later vindicated by high-resolution imaging). Chapters 5 and 6 describe the characterisation of accretion disk warping, providing observational verification of the prevailing theoretical framework for such disk-warps. Chapters 7 & 8 examine the enigmatic XRB Circinus X-1 with high-resolution IR spectroscopy (chapter 7) and the RXTE/ASM (chapter 8), establishing an improved orbital ephemeris and suggesting the system may be in a state of rapid post- supernova evolution. In chapter 8 we follow this up with a direct search for the X-ray supernova remnant expected from such a system, concluding that with present observations the diffuse emission from Cir X-1 is indistinguishable from scattering by dust-grains in the interstellar medium.

X-ray Properties of the Central kpc of AGN and Starbursts: The Latest News from Chandra

NASA Technical Reports Server (NTRS)

Weaver, Kimberly A.; White, Nicholas E. (Technical Monitor)

2001-01-01

The X-ray properties of 15 nearby (v less than 3,000 km/s) galaxies that possess AGN (active galactic nuclei) and/or starbursts are discussed. Two-thirds have nuclear extended emission on scales from approx. 0.5 to approx. 1.5 kpc that is either clearly associated with a nuclear outflow or morphologically resembles an outflow. Galaxies that are AGN-dominated tend to have linear structures while starburst-dominated galaxies tend to have plume-like structures. Significant X-ray absorption is present in the starburst regions, indicating that a circumnuclear starburst is sufficient to block an AGN at optical wavelengths. Galaxies with starburst activity possess more X-ray point sources within their central kpc than non-starbursts. Many of these sources are more luminous than typical X-ray binaries. The Chandra results are discussed in terms of the starburst-AGN connection, a revised unified model for AGN, and possible evolutionary scenarios.

Turbulence induced radial transport of toroidal momentum in boundary plasma of EAST tokamak

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, N.; Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031; Yan, N., E-mail: yanning@ipp.ac.cn

Turbulence induced toroidal momentum transport in boundary plasma is investigated in H-mode discharge using Langmuir-Mach probes on EAST. The Reynolds stress is found to drive an inward toroidal momentum transport, while the outflow of particles convects the toroidal momentum outwards in the edge plasma. The Reynolds stress driven momentum transport dominates over the passive momentum transport carried by particle flux, which potentially provides a momentum source for the edge plasma. The outflow of particles delivers a momentum flux into the scrape-off layer (SOL) region, contributing as a momentum source for the SOL flows. At the L-H transitions, the outward momentummore » transport suddenly decreases due to the suppression of edge turbulence and associated particle transport. The SOL flows start to decelerate as plasma entering into H-mode. The contributions from turbulent Reynolds stress and particle transport for the toroidal momentum transport are identified. These results shed lights on the understanding of edge plasma accelerating at L-H transitions.« less

Impact of intense rains and flooding on mercury riverine input to the coastal zone.

PubMed

Saniewska, Dominika; Bełdowska, Magdalena; Bełdowski, Jacek; Saniewski, Michał; Gębka, Karolina; Szubska, Marta; Wochna, Agnieszka

2018-02-01

The aim of the present research was to determine the impact of intense rains and flooding on mercury riverine input to the coastal zone. This study focused on four small rivers (Reda, Zagórska Struga, Płutnica, Gizdepka), typical of the Southern Baltic region, with no significant mercury sources. Samples were collected for 16months during average flow conditions and during selected meteorological events: floods, downpours, thaws and droughts. Results showed decreased retention of mercury during intense rainfalls, thus demonstrating mercury elution from the catchment. Floods and melting snow also have a tremendous impact on the outflow of mercury from the catchment. Development of urban infrastructure and farmlands increases the outflow of mercury from the catchment too, making such areas a significant source of mercury in the river. On the other hand, areas with natural character, predominated by forests, stimulate retention of mercury that reaches them through dry and wet atmospheric deposition. Copyright © 2017 Elsevier Ltd. All rights reserved.

Deuterated formaldehyde in the low-mass protostar HH212

NASA Astrophysics Data System (ADS)

Sahu, Dipen; Minh, Y. C.; Lee, Chin-Fei; Liu, Sheng-Yuan; Das, Ankan; Chakrabarti, S. K.; Sivaraman, Bhala

2018-04-01

HH212, a nearby (400 pc) object in Orion, is a class 0 protostellar system with a Keplerian disc and collimated bipolar SiO jets. Deuterated water, HDO, and a deuterated complex molecule, methanol (CH2DOH), have been reported in the source. Here, we report the HDCO (deuterated formaldehyde) line observation from Atacama Large Millimeter Array data to probe the inner region of HH212. We compare HDCO line with other molecular lines to understand the possible chemistry and physics of the source. The distribution of HDCO emission suggests that it may be associated with the base of the outflow. The emission also shows a rotation but it is not associated with the Keplerian rotation of disc or the rotating infalling envelope, rather it is associated with the outflow as previously seen in C34S. From the possible deuterium fractionation, we speculate that the gas phase formation of deuterated formaldehyde is active in the central hot region of the low-mass protostar system, HH212.

A Lagrangian view of ozone production tendency in North American outflow in summers 2009 and 2010

NASA Astrophysics Data System (ADS)

Zhang, Bo; Owen, R. Chris; Perlinger, Judith; Kumar, Aditya; Wu, Shiliang; Martin, Maria Val; Kramer, Louisa; Helmig, Detlev

2013-04-01

The Pico Mountain Observatory, located at 2,225 ma.s.l. in the Azores Islands, was established in 2001 to observe long-range transport from North America to the central North Atlantic. In previous research conducted at the Observatory, ozone enhancements (> 55 ppbv) were observed in North American outflows containing anthropogenic and biomass burning emissions, and efficient ozone production in these outflows was postulated. One of the major objectives of BORTAS is to better understand chemical composition and evolution during transport of biomass burning outflows. A key to the study of pollution plumes at a ground-based station is identification of emission type and source region(s). Transport pathways of individual plumes are also thought to be critical to plume aging. In this study, by analyzing observations of atmospheric tracer gases at Pico and FLEXPART simulation results, we were able to identify transport events induced by anthropogenic or biomass burning emissions during summers 2009 and 2010. In order to assess ozone production tendency during these long-range transport events, the convolved or "folded" retroplume technique developed by Owen and Honrath (2009) was applied to combine upwind FLEXPART transport pathways with GEOS-Chem chemical fields, providing a semi-lagrangian view of physical properties and production/loss of ozone in polluted North American outflows. Two anthropogenic events from North America were selected for detailed analysis because anthropogenic emissions were considered to be more predictable and consistent over time. Ozone enhancement was observed in both plumes, but due to differing transport mechanisms, ozone production tendency was found to be different between the two. In the first case, ozone production was found during the last two days of transport, when the pollution plume subsided from the free troposphere to the altitude of Pico station in the high pressure system centered over the Azores region at the time. Increase of temperature during the subsidence prompted thermal decomposition of peroxyacetyl nitrate, and consequently, a net ozone production layer (~2 ppbv/day) was formed at 2 km a.s.l. over the Azores area. In the second case, net ozone production was absent during transport over the North Atlantic, however the plume was transported at low altitude and carried elevated concentrations of ozone to Pico. Modeled non-methane hydrocarbon (NMHC) aging in plumes suggested sufficient performance of the folded GEOS-Chem and FLEXPART technique to diagnose the extent of mixing vs. chemical reaction in determining NMHC ratios. In biomass burning outflows, ozone production tendency may be more complicated due to heterogeneous chemical reactions. Biomass burning outflows will be the subject of future folded retroplume analysis. Reference Owen, R. C., and Honrath, R. E. (2009). Technical note: a new method for the Lagrangian tracking of pollution plumes from source to receptor using gridded model output. Atmos. Chem. Phys., 9(7), 2577-2595.

Extremely Low Mass: The Circumstellar Envelope of a Potential Proto-Brown Dwarf

NASA Technical Reports Server (NTRS)

Wiseman, Jennifer

2011-01-01

What is the environment for planet formation around extremely low mass stars? Is the environment around brown dwarfs and extremely low mass stars conducive and sufficiently massive for planet production? The determining conditions may be set very early in the process of the host object's formation. IRAS 16253-2429, the source of the Wasp-Waist Nebula seen in Spitzer IRAC images, is an isolated, very low luminosity ("VeLLO") Class 0 protostar in the nearby rho Ophiuchi cloud. We present VLA ammonia mapping observations of the dense gas envelope feeding the central core accreting system. We find a flattened envelope perpendicular to the outflow axis, and gas cavities that appear to cradle the outflow lobes as though carved out by the flow and associated (apparently precessing) jet, indicating environmental disruption. Based on the NH3 (1,1) and (2,2) emission distribution, we derive the mass, velocity fields and temperature distribution for the envelope. We discuss the combined evidence for this source to be one of the youngest and lowest mass sources in formation yet known, and discuss the ramifications for planet formation potential in this extremely low mass system.

Regional Air Pollutions in Three Different Regions of Asia From a Transcontinental Transport Perspective

NASA Astrophysics Data System (ADS)

Pochanart, P.; Kanaya, Y.; Komazaki, Y.; Liu, Y.; Akimoto, H.

2007-12-01

Asia is known as one of the regions with the fastest rate of growing in industrialization and urbanization. As a result, the rapid increases of large-scale air pollution in Asia emerge as a serious concern at both domestic and international levels. Apart from the problems of air quality degradation, emission control, environmental risk, and health effect in a domestic level, evidences from scientific studies indicate that by the long-range transport, Asian air pollution is becoming a global problem. Observations and model studies confirm that air pollution from Asia could be transported to North America or farther. In this work, we investigate the Asian air pollutions, in particular ozone and some other atmospheric components such as carbon monoxide and black carbon, from the ground- based observations in the three different regions, namely 1) background region of Siberia and central Asia, 2) highly anthropogenic region in eastern China, and 3) the rim region of the Asia-Pacific. In a transcontinental transport perspective, these regions are regarded as the inflow region, source region, and outflow region of Asia, respectively. From the results, it is found that the influences from large-scale emission in East Asia are observed clearly in the source region, and to the significant extent in the outflow region. For the inflow region of Asia, our data in Siberia and Kyrgyzstan indicate that air masses in this region are mostly intact from large-scale anthropogenic emission, and remain much of the global background atmospheric pollution characteristic. When the air masses are transported to source region, the air pollutants level increased sharply and frequent episodes of extremely high pollutions have been observed. Our results show good correlation between the residence time of air masses over the source region in eastern China and the observed levels of air pollutants verifying the strong enhancements by anthropogenic emissions from industrialization and urbanization. In the outflow region, air pollutants characteristics depend largely on the air mass climatology. In most cases, increases of air pollutants level are observed with the transport events directly from the source region.

A Three Parsec-Scale Jet-Driven Outflow from Sgr A

NASA Technical Reports Server (NTRS)

Yusef-Zadeh, F.; Arendt, R.; Bushouse, H.; Cotton, W.; Haggard, D.; Pound, M. W.; Roberts, D. A.; Royster, M.; Wardle, M.

2012-01-01

The compact radio source Sgr A* is coincident with a 4x 10(exp 6) solar Mass black hole at the dynamical center of the Galaxy and is surrounded by dense orbiting ionized and molecular gas. We present high resolution radio continuum images of the central 3' and report a faint continuous linear structure centered on Sgr A*. This feature is rotated by 28 deg in PA with respect to the Galactic plane. A number of weak blobs of radio emission with X-ray counterparts are detected along the axis of the linear structure. In addition, the continuous linear feature appears to be terminated symmetrically by two linearly polarized structures at 8.4 GHz, approx 75" from Sgr A*. The linear structure is best characterized by a mildly relativistic jet-driven outflow from Sgr A*, and an outflow rate 10(exp 6) solar M / yr. The near and far-sides of the jet are interacting with orbiting ionized and molecular gas over the last 1-3 hundred years and are responsible for the origin of a 2" hole, the "minicavity", where disturbed kinematics, enhanced FeII/III line emission, and diffuse X-ray gas have been detected. The estimated kinetic luminosity of the outflow is approx 1.2 X 10(exp 41) erg/s which can produce the Galactic center X-ray flash that has recently been identified

Ultrafast outflows disappear in high-radiation fields

NASA Astrophysics Data System (ADS)

Pinto, C.; Alston, W.; Parker, M. L.; Fabian, A. C.; Gallo, L. C.; Buisson, D. J. K.; Walton, D. J.; Kara, E.; Jiang, J.; Lohfink, A.; Reynolds, C. S.

2018-05-01

Ultrafast outflows (UFOs) are the most extreme winds launched by active galactic nuclei (AGN) due to their mildly relativistic speeds (˜0.1-0.3c) and are thought to significantly contribute to galactic evolution via AGN feedback. Their nature and launching mechanism are however not well understood. Recently, we have discovered the presence of a variable UFO in the narrow-line Seyfert 1 IRAS 13224-3809. The UFO varies in response to the brightness of the source. In this work we perform flux-resolved X-ray spectroscopy to study the variability of the UFO and found that the ionization parameter is correlated with the luminosity. In the brightest states the gas is almost completely ionized by the powerful radiation field and the UFO is hardly detected. This agrees with our recent results obtained with principal component analysis. We might have found the tip of the iceberg: the high ionization of the outflowing gas may explain why it is commonly difficult to detect UFOs in AGN and possibly suggest that we may underestimate their actual feedback. We have also found a tentative correlation between the outflow velocity and the luminosity, which is expected from theoretical predictions of radiation-pressure-driven winds. This trend is rather marginal due to the Fe XXV-XXVI degeneracy. Further work is needed to break such degeneracy through time-resolved spectroscopy.

Inverse Compton X-ray signature of AGN feedback

NASA Astrophysics Data System (ADS)

Bourne, Martin A.; Nayakshin, Sergei

2013-12-01

Bright AGN frequently show ultrafast outflows (UFOs) with outflow velocities vout ˜ 0.1c. These outflows may be the source of AGN feedback on their host galaxies sought by galaxy formation modellers. The exact effect of the outflows on the ambient galaxy gas strongly depends on whether the shocked UFOs cool rapidly or not. This in turn depends on whether the shocked electrons share the same temperature as ions (one-temperature regime, 1T) or decouple (2T), as has been recently suggested. Here we calculate the inverse Compton spectrum emitted by such shocks, finding a broad feature potentially detectable either in mid-to-high energy X-rays (1T case) or only in the soft X-rays (2T). We argue that current observations of AGN do not seem to show evidence for the 1T component. The limits on the 2T emission are far weaker, and in fact it is possible that the observed soft X-ray excess of AGN is partially or fully due to the 2T shock emission. This suggests that UFOs are in the energy-driven regime outside the central few pc, and must pump considerable amounts of not only momentum but also energy into the ambient gas. We encourage X-ray observers to look for the inverse Compton components calculated here in order to constrain AGN feedback models further.

The formation of the doubly stable stratification in the Mediterranean Outflow

NASA Astrophysics Data System (ADS)

Bormans, M.; Turner, J. S.

1990-11-01

The Mediterranean Outflow as it exits from the Strait of Gibraltar can be seen as a gravity current flowing down the slope and mixing with Atlantic Water until it reaches its own density level. Typical salinity and temperature profiles through the core region of a Meddy show that the bottom of the core is colder and saltier than the top, leading to a stably stratified core with respect to double-diffusive processes. The bottom of the core is also more enriched with Mediterranean Water than the top, and this behaviour can be explained by a reduced mixing of the source water with the environment close to the rigid bottom. Although the mechanism involved is different from the actual case, we have successfully produced these doubly stable gradient in some laboratory experiments which incorporate the "filling-box" mechanism. Salt and sugar were used as laboratory analogues of temperature and salt, respectively. The laboratory experiments consisted of supplying a dense input fluid at the surface of a linearly salt stratified environment. We suggest that req, the ratio of the initial volume flux at the source to the volume flux at the equilibrium level, is an important parameter, and that in our experiments this must be in general smaller than 0.1 in order to produce a doubly stable region of salt and sugar. The most relevant experiments had a mixed sugar/salt input which is the analogue of the Mediterranean Outflow as it mixes with Atlantic Water outside the Strait of Gibraltar.

Glider observations of the Dotson Ice Shelf outflow and its connection to the Amundsen Sea Polynya

NASA Astrophysics Data System (ADS)

Miles, T. N.; Schofield, O.; Lee, S. H.; Yager, P. L.; Ha, H. K.

2016-02-01

The Amundsen Sea is one of the most productive polynyas in the Antarctic per unit area and is undergoing rapid changes including a reduction in sea ice duration, thinning ice sheets, retreat of glaciers and the potential collapse of the Thwaites Glacier in Pine Island Bay. A growing body of research has indicated that these changes are altering the water mass properties and associated biogeochemistry within the polynya. Unfortunately difficulties in accessing the remote location have greatly limited the amount of in situ data that has been collected. In this study data from a Teledyne-Web Slocum glider was used to supplement ship-based sampling along the Dotson Ice Shelf (DIS). This autonomous underwater vehicle revealed a detailed view of a meltwater laden outflow from below the western flank of the DIS. Circumpolar Deep Water intruding onto the shelf drives glacial melt and the supply of macronutrients that, along with ample light, supports the large phytoplankton blooms in the Amundsen Sea Polynya. Less well understood is the source of micronutrients, such as iron, necessary to support this bloom to the central polynya where chlorophyll concentrations are highest. This outflow region showed decreasing optical backscatter with proximity to the bed indicating that particulate matter was sourced from the overlying glacier rather than resuspended sediment. This result suggests that particulate iron, and potentially phytoplankton primary productivity, is intrinsically linked to the magnitude and duration of sub-glacial melt from Circumpolar Deep Water intrusions onto the shelf.

Glider observations of the Dotson Ice Shelf outflow

NASA Astrophysics Data System (ADS)

Miles, Travis; Lee, Sang Hoon; Wåhlin, Anna; Ha, Ho Kyung; Kim, Tae Wan; Assmann, Karen M.; Schofield, Oscar

2016-01-01

The Amundsen Sea is one of the most productive polynyas in the Antarctic per unit area and is undergoing rapid changes including a reduction in sea ice duration, thinning ice sheets, retreat of glaciers and the potential collapse of the Thwaites Glacier in Pine Island Bay. A growing body of research has indicated that these changes are altering the water mass properties and associated biogeochemistry within the polynya. Unfortunately difficulties in accessing the remote location have greatly limited the amount of in situ data that has been collected. In this study data from a Teledyne-Webb Slocum glider was used to supplement ship-based sampling along the Dotson Ice Shelf (DIS). This autonomous underwater vehicle revealed a detailed view of a meltwater laden outflow from below the western flank of the DIS. Circumpolar Deep Water intruding onto the shelf drives glacial melt and the supply of macronutrients that, along with ample light, supports the large phytoplankton blooms in the Amundsen Sea Polynya. Less well understood is the source of micronutrients, such as iron, necessary to support this bloom to the central polynya where chlorophyll concentrations are highest. This outflow region showed decreasing optical backscatter with proximity to the bed indicating that particulate matter was sourced from the overlying glacier rather than resuspended sediment. This result suggests that particulate iron, and potentially phytoplankton primary productivity, is intrinsically linked to the magnitude and duration of sub-glacial melt from Circumpolar Deep Water intrusions onto the shelf.

A CONNECTION BETWEEN PLASMA CONDITIONS NEAR BLACK HOLE EVENT HORIZONS AND OUTFLOW PROPERTIES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Koljonen, K. I. I.; Russell, D. M.; Bernardini, F.

Accreting black holes are responsible for producing the fastest, most powerful outflows of matter in the universe. The formation process of powerful jets close to black holes is poorly understood, and the conditions leading to jet formation are currently hotly debated. In this paper, we report an unambiguous empirical correlation between the properties of the plasma close to the black hole and the particle acceleration properties within jets launched from the central regions of accreting stellar-mass and supermassive black holes. In these sources the emission of the plasma near the black hole is characterized by a power law at X-raymore » energies during times when the jets are produced. We find that the photon index of this power law, which gives information on the underlying particle distribution, correlates with the characteristic break frequency in the jet spectrum, which is dependent on magnetohydrodynamical processes in the outflow. The observed range in break frequencies varies by five orders of magnitude in sources that span nine orders of magnitude in black hole mass, revealing a similarity of jet properties over a large range of black hole masses powering these jets. This correlation demonstrates that the internal properties of the jet rely most critically on the conditions of the plasma close to the black hole, rather than other parameters such as the black hole mass or spin, and will provide a benchmark that should be reproduced by the jet formation models.« less

Three-Dimensional General-Relativistic Magnetohydrodynamic Simulations of Remnant Accretion Disks from Neutron Star Mergers: Outflows and r -Process Nucleosynthesis

NASA Astrophysics Data System (ADS)

Siegel, Daniel M.; Metzger, Brian D.

2017-12-01

The merger of binary neutron stars, or of a neutron star and a stellar-mass black hole, can result in the formation of a massive rotating torus around a spinning black hole. In addition to providing collimating media for γ -ray burst jets, unbound outflows from these disks are an important source of mass ejection and rapid neutron capture (r -process) nucleosynthesis. We present the first three-dimensional general-relativistic magnetohydrodynamic (GRMHD) simulations of neutrino-cooled accretion disks in neutron star mergers, including a realistic equation of state valid at low densities and temperatures, self-consistent evolution of the electron fraction, and neutrino cooling through an approximate leakage scheme. After initial magnetic field amplification by magnetic winding, we witness the vigorous onset of turbulence driven by the magnetorotational instability (MRI). The disk quickly reaches a balance between heating from MRI-driven turbulence and neutrino cooling, which regulates the midplane electron fraction to a low equilibrium value Ye≈0.1 . Over the 380-ms duration of the simulation, we find that a fraction ≈20 % of the initial torus mass is unbound in powerful outflows with asymptotic velocities v ≈0.1 c and electron fractions Ye≈0.1 - 0.25 . Postprocessing the outflows through a nuclear reaction network shows the production of a robust second- and third-peak r process. Though broadly consistent with the results of previous axisymmetric hydrodynamical simulations, extrapolation of our results to late times suggests that the total ejecta mass from GRMHD disks is significantly higher. Our results provide strong evidence that postmerger disk outflows are an important site for the r process.

Three-Dimensional General-Relativistic Magnetohydrodynamic Simulations of Remnant Accretion Disks from Neutron Star Mergers: Outflows and r-Process Nucleosynthesis.

PubMed

Siegel, Daniel M; Metzger, Brian D

2017-12-08

The merger of binary neutron stars, or of a neutron star and a stellar-mass black hole, can result in the formation of a massive rotating torus around a spinning black hole. In addition to providing collimating media for γ-ray burst jets, unbound outflows from these disks are an important source of mass ejection and rapid neutron capture (r-process) nucleosynthesis. We present the first three-dimensional general-relativistic magnetohydrodynamic (GRMHD) simulations of neutrino-cooled accretion disks in neutron star mergers, including a realistic equation of state valid at low densities and temperatures, self-consistent evolution of the electron fraction, and neutrino cooling through an approximate leakage scheme. After initial magnetic field amplification by magnetic winding, we witness the vigorous onset of turbulence driven by the magnetorotational instability (MRI). The disk quickly reaches a balance between heating from MRI-driven turbulence and neutrino cooling, which regulates the midplane electron fraction to a low equilibrium value Y_{e}≈0.1. Over the 380-ms duration of the simulation, we find that a fraction ≈20% of the initial torus mass is unbound in powerful outflows with asymptotic velocities v≈0.1c and electron fractions Y_{e}≈0.1-0.25. Postprocessing the outflows through a nuclear reaction network shows the production of a robust second- and third-peak r process. Though broadly consistent with the results of previous axisymmetric hydrodynamical simulations, extrapolation of our results to late times suggests that the total ejecta mass from GRMHD disks is significantly higher. Our results provide strong evidence that postmerger disk outflows are an important site for the r process.

Measurements of outflow velocities in on-disk plumes from EIS/Hinode observations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fu, Hui; Xia, Lidong; Li, Bo

2014-10-20

The contribution of plumes to the solar wind has been subject to hot debate in the past decades. The EUV Imaging Spectrometer (EIS) on board Hinode provides a unique means to deduce outflow velocities at coronal heights via direct Doppler shift measurements of coronal emission lines. Such direct Doppler shift measurements were not possible with previous spectrometers. We measure the outflow velocity at coronal heights in several on-disk long-duration plumes, which are located in coronal holes (CHs) and show significant blueshifts throughout the entire observational period. In one case, a plume is measured four hours apart. The deduced outflow velocitiesmore » are consistent, suggesting that the flows are quasi-steady. Furthermore, we provide an outflow velocity profile along the plumes, finding that the velocity corrected for the line-of-sight effect can reach 10 km s{sup –1} at 1.02 R {sub ☉}, 15 km s{sup –1} at 1.03 R {sub ☉}, and 25 km s{sup –1} at 1.05 R {sub ☉}. This clear signature of steady acceleration, combined with the fact that there is no significant blueshift at the base of plumes, provides an important constraint on plume models. At the height of 1.03 R {sub ☉}, EIS also deduced a density of 1.3 × 10{sup 8} cm{sup –3}, resulting in a proton flux of about 4.2 × 10{sup 9} cm{sup –2} s{sup –1} scaled to 1 AU, which is an order of magnitude higher than the proton input to a typical solar wind if a radial expansion is assumed. This suggests that CH plumes may be an important source of the solar wind.« less

Three-dimensional structure of clumpy outflow from supercritical accretion flow onto black holes

NASA Astrophysics Data System (ADS)

Kobayashi, Hiroshi; Ohsuga, Ken; Takahashi, Hiroyuki R.; Kawashima, Tomohisa; Asahina, Yuta; Takeuchi, Shun; Mineshige, Shin

2018-03-01

We perform global three-dimensional (3D) radiation-hydrodynamic (RHD) simulations of outflow from supercritical accretion flow around a 10 M⊙ black hole. We only solve the outflow part, starting from the axisymmetric 2D simulation data in a nearly steady state but with small perturbations in a sinusoidal form being added in the azimuthal direction. The mass accretion rate onto the black hole is ˜102LE/c2 in the underlying 2D simulation data, and the outflow rate is ˜10 LE/c2 (with LE and c being the Eddington luminosity and speed of light, respectively). We first confirm the emergence of clumpy outflow, which was discovered by the 2D RHD simulations, above the photosphere located at a few hundreds of Schwarzschild radii (rS) from the central black hole. As prominent 3D features we find that the clumps have the shape of a torn sheet, rather than a cut string, and that they are rotating around the central black hole with a sub-Keplerian velocity at a distance of ˜103 rS from the center. The typical clump size is ˜30 rS or less in the radial direction, and is more elongated in the angular directions, ˜ hundreds of rS at most. The sheet separation ranges from 50 to 150 rS. We expect stochastic time variations when clumps pass across the line of the sight of a distant observer. Variation timescales are estimated to be several seconds for a black hole with mass of ten to several tens of M⊙, in rough agreement with the observations of some ultra-luminous X-ray sources.

Refining previous estimates of groundwater outflows from the Medina/Diversion Lake system, San Antonio area, Texas

USGS Publications Warehouse

Slattery, Richard N.; Asquith, William H.; Gordon, John D.

2017-02-15

IntroductionIn 2016, the U.S. Geological Survey (USGS), in cooperation with the San Antonio Water System, began a study to refine previously derived estimates of groundwater outflows from Medina and Diversion Lakes in south-central Texas near San Antonio. When full, Medina and Diversion Lakes (hereinafter referred to as the Medina/Diversion Lake system) (fig. 1) impound approximately 255,000 acre-feet and 2,555 acre-feet of water, respectively.Most recharge to the Edwards aquifer occurs as seepage from streams as they cross the outcrop (recharge zone) of the aquifer (Slattery and Miller, 2017). Groundwater outflows from the Medina/Diversion Lake system have also long been recognized as a potentially important additional source of recharge. Puente (1978) published methods for estimating monthly and annual estimates of the potential recharge to the Edwards aquifer from the Medina/Diversion Lake system. During October 1995–September 1996, the USGS conducted a study to better define short-term rates of recharge and to reduce the error and uncertainty associated with estimates of monthly recharge from the Medina/Diversion Lake system (Lambert and others, 2000). As a followup to that study, Slattery and Miller (2017) published estimates of groundwater outflows from detailed water budgets for the Medina/Diversion Lake system during 1955–1964, 1995–1996, and 2001–2002. The water budgets were compiled for selected periods during which time the water-budget components were inferred to be relatively stable and the influence of precipitation, stormwater runoff, and changes in storage were presumably minimal. Linear regression analysis techniques were used by Slattery and Miller (2017) to assess the relation between the stage in Medina Lake and groundwater outflows from the Medina/Diversion Lake system.

The Class 0 Protostar BHR71: Herschel Observations and Dust Continuum Models

NASA Astrophysics Data System (ADS)

Yang, Yao-Lun; Evans, Neal J., II; Green, Joel D.; Dunham, Michael M.; Jørgensen, Jes K.

2017-02-01

We use Herschel spectrophotometry of BHR71, an embedded Class 0 protostar, to provide new constraints on its physical properties. We detect 645 (non-unique) spectral lines among all spatial pixels. At least 61 different spectral lines originate from the central region. A CO rotational diagram analysis shows four excitation temperature components, 43, 197, 397, and 1057 K. Low-J CO lines trace the outflow while the high-J CO lines are centered on the infrared source. The low-excitation emission lines of {{{H}}}2{{O}} trace the large-scale outflow, while the high-excitation emission lines trace a small-scale distribution around the equatorial plane. We model the envelope structure using the dust radiative transfer code, hyperion, incorporating rotational collapse, an outer static envelope, outflow cavity, and disk. The evolution of a rotating collapsing envelope can be constrained by the far-infrared/millimeter spectral energy distribution along with the azimuthally averaged radial intensity profile, and the structure of the outflow cavity plays a critical role at shorter wavelengths. Emission at 20-40 μm requires a cavity with a constant-density inner region and a power-law density outer region. The best-fit model has an envelope mass of 19 {M}⊙ inside a radius of 0.315 pc and a central luminosity of 18.8 {L}⊙ . The time since collapse began is 24,630-44,000 years, most likely around 36,000 years. The corresponding mass infall rate in the envelope (1.2 × 10-5 {M}⊙ {{yr}}-1) is comparable to the stellar mass accretion rate, while the mass-loss rate estimated from the CO outflow is 20% of the stellar mass accretion rate. We find no evidence for episodic accretion.

Discovery of Ultra-fast Outflows in a Sample of Broad-line Radio Galaxies Observed with Suzaku

NASA Astrophysics Data System (ADS)

Tombesi, F.; Sambruna, R. M.; Reeves, J. N.; Braito, V.; Ballo, L.; Gofford, J.; Cappi, M.; Mushotzky, R. F.

2010-08-01

We present the results of a uniform and systematic search for blueshifted Fe K absorption lines in the X-ray spectra of five bright broad-line radio galaxies observed with Suzaku. We detect, for the first time in radio-loud active galactic nuclei (AGNs) at X-rays, several absorption lines at energies greater than 7 keV in three out of five sources, namely, 3C 111, 3C 120, and 3C 390.3. The lines are detected with high significance according to both the F-test and extensive Monte Carlo simulations. Their likely interpretation as blueshifted Fe XXV and Fe XXVI K-shell resonance lines implies an origin from highly ionized gas outflowing with mildly relativistic velocities, in the range v ~= 0.04-0.15c. A fit with specific photoionization models gives ionization parameters in the range log ξ ~= 4-5.6 erg s-1 cm and column densities of N H ~= 1022-1023 cm-2. These characteristics are very similar to those of the ultra-fast outflows (UFOs) previously observed in radio-quiet AGNs. Their estimated location within ~0.01-0.3 pc of the central super-massive black hole suggests a likely origin related with accretion disk winds/outflows. Depending on the absorber covering fraction, the mass outflow rate of these UFOs can be comparable to the accretion rate and their kinetic power can correspond to a significant fraction of the bolometric luminosity and is comparable to their typical jet power. Therefore, these UFOs can play a significant role in the expected feedback from the AGN to the surrounding environment and can give us further clues on the relation between the accretion disk and the formation of winds/jets in both radio-quiet and radio-loud AGNs.

Evidence for Ultra-fast Outflows in Radio-quiet Active Galactic Nuclei. II. Detailed Photoionization Modeling of Fe K-shell Absorption Lines

NASA Astrophysics Data System (ADS)

Tombesi, F.; Cappi, M.; Reeves, J. N.; Palumbo, G. G. C.; Braito, V.; Dadina, M.

2011-11-01

X-ray absorption line spectroscopy has recently shown evidence for previously unknown Ultra-fast Outflows (UFOs) in radio-quiet active galactic nuclei (AGNs). These have been detected essentially through blueshifted Fe XXV/XXVI K-shell transitions. In the previous paper of this series we defined UFOs as those highly ionized absorbers with an outflow velocity higher than 10,000 km s-1 and assessed the statistical significance of the associated blueshifted absorption lines in a large sample of 42 local radio-quiet AGNs observed with XMM-Newton. The present paper is an extension of that work. First, we report a detailed curve of growth analysis of the main Fe XXV/XXVI transitions in photoionized plasmas. Then, we estimate an average spectral energy distribution for the sample sources and directly model the Fe K absorbers in the XMM-Newton spectra with the detailed Xstar photoionization code. We confirm that the frequency of sources in the radio-quiet sample showing UFOs is >35% and that the majority of the Fe K absorbers are indeed associated with UFOs. The outflow velocity distribution spans from ~10,000 km s-1 (~0.03c) up to ~100,000 km s-1 (~0.3c), with a peak and mean value of ~42,000 km s-1 (~0.14c). The ionization parameter is very high and in the range log ξ ~ 3-6 erg s-1 cm, with a mean value of log ξ ~ 4.2 erg s-1 cm. The associated column densities are also large, in the range N H ~ 1022-1024 cm-2, with a mean value of N H ~ 1023 cm-2. We discuss and estimate how selection effects, such as those related to the limited instrumental sensitivity at energies above 7 keV, may hamper the detection of even higher velocities and higher ionization absorbers. We argue that, overall, these results point to the presence of extremely ionized and possibly almost Compton-thick outflowing material in the innermost regions of AGNs. This also suggests that UFOs may potentially play a significant role in the expected cosmological feedback from AGNs and their study can provide important clues on the connection between accretion disks, winds, and jets.

North-south asymmetries in cold ion outflow and lobe density

NASA Astrophysics Data System (ADS)

Haaland, Stein; Laundal, Karl; Maes, Lukas; Baddeley, Lisa; Lybekk, Bjørn

2016-04-01

A significant fraction of the plasma in the terrestrial magnetosphere is supplied by the high-latitude ionosphere. The filling process starts with ionization of atoms and gas molecules in the thermosphere, and is often accompanied by upflow due to thermal and electromagnetic forces. Some of this material can reach escape velocities and be further accelerated and eventually evacuated into space. Ions are governed by electromagnetic forces and their transport path from the ionosphere to the magnetosphere go through the magnetotail lobes. The transport is largely dictated by magnetospheric convection. External influences, such as daily and seasonal variations in the Earth's tilt angle, but also non-dipolar terms in the Earth's internal magnetic field introduce north-south asymmetries in the magnetic field and thus north-south asymmetries in the ion outflow and lobe filling. In this presentation, we show observational results of this asymmetry. The results are based on more than a full solar cycle of cold ion measurements from the Cluster constellation of spacecraft, and allows us to quantify the outflow, identify sources of asymmetry and estimate transport paths.

Constraining physical parameters of ultra-fast outflows in PDS 456 with Monte Carlo simulations

NASA Astrophysics Data System (ADS)

Hagino, K.; Odaka, H.; Done, C.; Gandhi, P.; Takahashi, T.

2014-07-01

Deep absorption lines with extremely high velocity of ˜0.3c observed in PDS 456 spectra strongly indicate the existence of ultra-fast outflows (UFOs). However, the launching and acceleration mechanisms of UFOs are still uncertain. One possible way to solve this is to constrain physical parameters as a function of distance from the source. In order to study the spatial dependence of parameters, it is essential to adopt 3-dimensional Monte Carlo simulations that treat radiation transfer in arbitrary geometry. We have developed a new simulation code of X-ray radiation reprocessed in AGN outflow. Our code implements radiative transfer in 3-dimensional biconical disk wind geometry, based on Monte Carlo simulation framework called MONACO (Watanabe et al. 2006, Odaka et al. 2011). Our simulations reproduce FeXXV and FeXXVI absorption features seen in the spectra. Also, broad Fe emission lines, which reflects the geometry and viewing angle, is successfully reproduced. By comparing the simulated spectra with Suzaku data, we obtained constraints on physical parameters. We discuss launching and acceleration mechanisms of UFOs in PDS 456 based on our analysis.

THE RADIO JET ASSOCIATED WITH THE MULTIPLE V380 ORI SYSTEM

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rodríguez, Luis F.; Yam, J. Omar; Carrasco-González, Carlos

The giant Herbig–Haro object 222 extends over ∼6′ in the plane of the sky, with a bow shock morphology. The identification of its exciting source has remained uncertain over the years. A non-thermal radio source located at the core of the shock structure was proposed to be the exciting source. However, Very Large Array studies showed that the radio source has a clear morphology of radio galaxy and a lack of flux variations or proper motions, favoring an extragalactic origin. Recently, an optical–IR study proposed that this giant HH object is driven by the multiple stellar system V380 Ori, locatedmore » about 23′ to the SE of HH 222. The exciting sources of HH systems are usually detected as weak free–free emitters at centimeter wavelengths. Here, we report the detection of an elongated radio source associated with the Herbig Be star or with its close infrared companion in the multiple V380 Ori system. This radio source has the characteristics of a thermal radio jet and is aligned with the direction of the giant outflow defined by HH 222 and its suggested counterpart to the SE, HH 1041. We propose that this radio jet traces the origin of the large scale HH outflow. Assuming that the jet arises from the Herbig Be star, the radio luminosity is a few times smaller than the value expected from the radio–bolometric correlation for radio jets, confirming that this is a more evolved object than those used to establish the correlation.« less

RADIO OBSERVATIONS OF THE STAR FORMATION ACTIVITIES IN THE NGC 2024 FIR 4 REGION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Choi, Minho; Kang, Miju; Lee, Jeong-Eun, E-mail: minho@kasi.re.kr

Star formation activities in the NGC 2024 FIR 4 region were studied by imaging centimeter continuum sources and water maser sources using several archival data sets from the Very Large Array. The continuum source VLA 9 is elongated in the northwest–southeast direction, consistent with the FIR 4 bipolar outflow axis, and has a flat spectrum in the 6.2–3.6 cm interval. The three water maser spots associated with FIR 4 are also distributed along the outflow axis. One of the spots is located close to VLA 9, and another one is close to an X-ray source. Examinations of the positions ofmore » compact objects in this region suggest that the FIR 4 cloud core contains a single low-mass protostar. VLA 9 is the best indicator of the protostellar position. VLA 9 may be a radio thermal jet driven by this protostar, and it is unlikely that FIR 4 contains a high-mass young stellar object (YSO). A methanol 6.7 GHz maser source is located close to VLA 9, at a distance of about 100 AU. The FIR 4 protostar must be responsible for the methanol maser action, which suggests that methanol class II masers are not necessarily excited by high-mass YSOs. Also discussed are properties of other centimeter continuum sources in the field of view and the water masers associated with FIR 6n. Some of the continuum sources are radio thermal jets, and some are magnetically active young stars.« less

Under the radar: mitigating enigmatic ecological impacts.

PubMed

Raiter, Keren G; Possingham, Hugh P; Prober, Suzanne M; Hobbs, Richard J

2014-11-01

Identifying the deleterious ecological effects of developments, such as roads, mining, and urban expansion, is essential for informing development decisions and identifying appropriate mitigation actions. However, there are many types of ecological impacts that slip 'under the radar' of conventional impact evaluations and undermine the potential for successful impact mitigation (including offsets). These 'enigmatic' impacts include those that are small but act cumulatively; those outside of the area directly considered in the evaluation; those not detectable with the methods, paradigms, or spatiotemporal scales used to detect them; those facilitated, but not directly caused, by development; and synergistic impact interactions. Here, we propose a framework for conceptualising enigmatic impacts and discuss ways to address them. Copyright © 2014 Elsevier Ltd. All rights reserved.

Evidence of volcanic and glacial activity in Chryse and Acidalia Planitiae, Mars

USGS Publications Warehouse

Martinez-Alonso, Sara; Mellon, Michael T.; Banks, Maria E.; Keszthelyi, Laszlo P.; McEwen, Alfred S.

2011-01-01

Chryse and Acidalia Planitiae show numerous examples of enigmatic landforms previously interpreted to have been influenced by a water/ice-rich geologic history. These landforms include giant polygons bounded by kilometer-scale arcuate troughs, bright pitted mounds, and mesa-like features. To investigate the significance of the last we have analyzed in detail the region between 60°N, 290°E and 10°N, 360°E utilizing HiRISE (High Resolution Imaging Science Experiment) images as well as regional-scale data for context. The mesas may be analogous to terrestrial tuyas (emergent sub-ice volcanoes), although definitive proof has not been identified. We also report on a blocky unit and associated landforms (drumlins, eskers, inverted valleys, kettle holes) consistent with ice-emplaced volcanic or volcano-sedimentary flows. The spatial association between tuya-like mesas, ice-emplaced flows, and further possible evidence of volcanism (deflated flow fronts, volcanic vents, columnar jointing, rootless cones), and an extensive fluid-rich substratum (giant polygons, bright mounds, rampart craters), allows for the possibility of glaciovolcanic activity in the region.Landforms indicative of glacial activity on Chryse/Acidalia suggest a paleoclimatic environment remarkably different from today's. Climate changes on Mars (driven by orbital/obliquity changes) or giant outflow channel activity could have resulted in ice-sheet-related landforms far from the current polar caps.

Outflow from the outer Lagrangian point - Observations and models of 4U 2127 + 12 in M15

NASA Technical Reports Server (NTRS)

Bailyn, Charles D.; Garcia, Michael R.; Grindlay, Jonathan

1989-01-01

MMT observations of AC 211, the optical counterpart of the high-luminosity X-ray source in globular cluster M15, are presented. The observation of Naylor et al. (1988) that the He I absorption is blueshifted by more than 100 km/s with respect to the mean velocity of the cluster is confirmed. It is shown that if the absorption occurs in a stream of gas outflowing from the L2 point of a binary system, as might be expected for a common envelope binary, both the blueshift and the unexpectedly low velocity variations of the He I lines can be understood. The model predicts that the He I velocity curve is not sinusoidal.

From Cores to Envelopes to Disks: A Multi-scale View of Magnetized Star Formation

NASA Astrophysics Data System (ADS)

Hull, Charles L. H.

2014-12-01

Observations of polarization in star forming regions have been made across many wavelengths, many size scales, and many stages of stellar evolution. One of the overarching goals of these observations has been to determine the importance of magnetic fields -- which are the cause of the polarization -- in the star formation process. We begin by describing the commissioning and the calibration of the 1.3 mm dual-polarization receiver system we built for CARMA (the Combined Array for Research in Millimeter-wave Astronomy), a radio telescope in the eastern Sierra region of California. One of the primary science drivers behind the polarization system is to observe polarized thermal emission from dust grains in the dense clumps of dust and gas where the youngest, Class 0 protostars are forming. We go on to describe the CARMA TADPOL survey -- the largest high-resolution (~1000 AU scale) survey to date of dust polarization in low-mass protostellar cores -- and discuss our main findings: (1) Magnetic fields (B-fields) on scales of ~1000 AU are not tightly aligned with protostellar outflows. Rather, the data are consistent both with scenarios where outflows and magnetic fields are preferentially misaligned (perpendicular) and where they are randomly aligned. (2) Sources with high CARMA polarization fractions have consistent B-field orientations on large scales (~20'', measured using single-dish submillimeter telescopes) and small scales (~2.5'', measured by CARMA). We interpret this to mean that in at least some cases B-fields play a role in regulating the infall of material all the way down to the ~1000 AU scales of protostellar envelopes. Finally, (3) While on the whole outflows appear to be randomly aligned with B-fields, in sources with low polarization fractions there is a hint that outflows are preferentially perpendicular to small-scale B-fields, which suggests that in these sources the fields have been wrapped up by envelope rotation. This work shows that the ~1000 AU protostellar envelope may be a turning point: at larger scales B-fields may still retain the memory of the global B-field drawn in from the ambient medium; but at smaller scales the B-fields may be affected by the dynamics of both envelope and disk rotation. This sets the stage for ALMA (the Atacama Large Millimeter/submillimeter Array), which will soon reveal the morphology of B-fields in circumstellar disks themselves.

No Mystery! Water Carved the Outflow Channels on Mars

NASA Astrophysics Data System (ADS)

Coleman, N.

2002-12-01

The enormous outflow channels of Chryse Planitia provide the best evidence that large amounts of water were once released onto the martian surface. The role of water has recently been challenged by the White Mars hypothesis, which claims that the channels were cut by CO2 gas-supported debris flows that also resurfaced the northern plains. Hoffman [Icarus, 2000] refers to a volumetric "misfit" between outburst channels and the chaos source zones. He explains that chaos collapse "...involves regolith alone which generates its own fluids from liquid CO2 and CO2-bearing ices within its own volume." Hoffman [LPSC 32, #1257] argues that release of liquid CO2 produced Aromatum Chaos, and a hypothetical energetic "jet" of gas and debris carved Ravi Vallis. He notes that water would have had to be locally recharged in many episodes to provide enough discharge to form the chaos and channel. However, these assertions appear incorrect because the fluid source was a distant surface impoundment, not local recharge. Carr [Water on Mars, 1996] describes a 400-km-long zone of subsidence that extends northward from Ganges Chasma to the source of Shalbatana Vallis. MOLA data reveal that this subsidence also extends eastward to Aromatum Chaos, the source of Ravi Vallis. The field relations show that a liquid-filled impoundment in Ganges Chasma drained northward via subterranean flowpaths to maintain surface flows in Shalbatana and Ravi Valles. The fact that the flows began at a surface impoundment virtually eliminates liquid CO2 as the flowing agent. Liquid CO2 would not be stable at the surface unless the atmospheric pressure exceeded 5 atm. A recent study by Stewart and Nimmo [JGR, in press] suggests that CO2 in liquid, solid, or clathrate form could not be preserved within the crust over geologic time. Liquid water is much closer to its stability field even on present-day Mars. Large outflow channels, such as Kasei and Tiu-Simud Valles, likely formed through the release of floodwaters dammed by ice and debris, analogous to the scabland flooding of eastern Washington. The water sources were probably ice-covered impoundments in ancestral Valles Marineris canyons. Subice volcanism was a possible source of heat to create liquid water. The former existence of transient water bodies near the surface can help to calibrate models of a volcanic-hydrologic climax during the Hesperian.

Statistical survey of pitch angle distributions in core (0-50 eV) ions from Dynamics Explorer 1: Outflow in the auroral zone, polar cap, and cusp

NASA Technical Reports Server (NTRS)

Giles, B. L.; Chappell, C. R.; Moore, T. E.; Comfort, R. H.; Waite, J. H., Jr.

1994-01-01

Core (0-50 eV) ion pitch angle measurements from the retarding ion mass spectrometer on Dynamics Explorer 1 are examined with respect to magnetic disturbance, invariant latitude, magnetic local time, and altitude for ions H(+), He(+), O(+), M/Z = 2 (D(+) or He(++)), and O(++). Included are outflow events in the auroral zone, polar cap, and cusp, separated into altitude regions below and above 3 R(sub E). In addition to the customary division into beam, conic, and upwelling distributions, the high-latitude observations fall into three categories corresponding to ion bulk speeds that are (1) less than, (2) comparable to, or (3) faster than that of the spacecraft. This separation, along with the altitude partition, serves to identify conditions under which ionospheric source ions are gravita- tionally bound and when they are more energetic and able to escape to the outer magnetosphere. Features of the cleft ion fountain inferred from single event studies are clearly identifiable in the statistical results. In addition, it is found that the dayside pre-noon cleft is a dayside afternoon cleft, or auroral zone, becomes an additional source for increased activity. The auroral oval as a whole appears to be a steady source of escape velocity H(+), a steady source of escape velocity He(+) ions for the dusk sector, and a source of escape velocity heavy ions for dusk local times primarily during increased activity. The polar cap above the auroral zone is a consistent source of low-energy ions, although only the lighter mass particles appear to have sufficient velocity, on average, to escape to higher altitudes. The observations support two concepts for outflow: (1) The cleft ion fountain consists of ionospheric plasma of 1-20 eV energy streaming upward into the magnetosphere where high-latitude convection electric fields cause poleward dispersion. (2) The auroral ion fountain involves field-aligned beams which flow out along auroral latitude field lines; and, in addition, for late afternoon local times, they experience additional acceleration such that the ion energy distribution tends to exceed the detection range of the instrument (greater than 50-60 eV).

SCUBA and HIRES Results for Protostellar Cores in the MON OB1 Dark Cloud

NASA Astrophysics Data System (ADS)

Wolf-Chase, G.; Moriarty-Schieven, G.; Fich, M.; Barsony, M.

1999-05-01

We have used HIRES-processing of IRAS data and point-source modelling techniques (Hurt & Barsony 1996; O'Linger 1997; Barsony et al. 1998), together with submillimeter continuum imaging using the Submillimeter Common-User Bolometer Array (SCUBA) on the 15-meter James Clerk Maxwell Telescope (JCMT), to search CS cores in the Mon OB1 dark cloud (Wolf-Chase, Walker, & Lada 1995; Wolf-Chase & Walker 1995) for deeply embedded sources. These observations, as well as follow-up millimeter photometry at the National Radio Astronomy Observatory (NRAO) 12-meter telescope on Kitt Peak, have lead to the identification of two Class 0 protostellar candidates, which were previously unresolved from two brighter IRAS point sources (IRAS 06382+0939 & IRAS 06381+1039) in this cloud. Until now, only one Class 0 object had been confirmed in Mon OB1; the driving source of the highly-collimated outflow NGC 2264 G (Ward-Thompson, Eiroa, & Casali 1995; Margulis et al. 1990; Lada & Fich 1996), which lies well outside the extended CS cores. One of the new Class 0 candidates may be an intermediate-mass source associated with an H_2O maser, and the other object is a low-mass source which may be associated with a near-infrared jet, and possibly with a molecular outflow. We report accurate positions for the new Class 0 candidates, based on the SCUBA images, and present new SEDs for these sources, as well as for the brighter IRAS point sources. A portion of this work was performed while GWC held a President's Fellowship from the University of California. MB and GWC gratefully acknowledge financial support from MB's NSF CAREER Grant, AST97-9753229.

FOUR DUAL AGN CANDIDATES OBSERVED WITH THE VLBA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gabányi, K. É.; Frey, S.; An, T.

According to hierarchical structure formation models, merging galaxies are expected to be seen in different stages of coalescence. However, there are currently no straightforward observational methods to either select or to confirm a large number of dual active galactic nucleus (AGN) candidates. Most attempts involve obtaining a better understanding of double-peaked narrow emission line sources, in order to distinguish the objects for which the emission lines originate from narrow-line kinematics or jet-driven outflows, from those which might harbor dual AGNs. We observed four such candidate sources with the Very Long Baseline Array (VLBA), at 1.5 GHz with a ∼10 masmore » angular resolution, for which the spectral profiles of AGN optical emission suggested the existence of dual AGNs. In SDSS J210449.13–000919.1 and SDSS J23044.82–093345.3 the radio structures are aligned with the optical emission features, thus the double-peaked emission lines might be the results of jet-driven outflows. In the third detected source SDSS J115523.74+150756.9, the radio structure is less extended and is oriented nearly perpendicular to the position angle derived from optical spectroscopy. The fourth source remained undetected with the VLBA, but it was imaged with the Very Large Array at arcsec resolution a few months before our observations, suggesting the existence of an extended radio structure. We did not detect two radio-emitting cores in any of the four sources, a convincing signature of duality.« less

Stellar-mass black holes and ultraluminous x-ray sources.

PubMed

Fender, Rob; Belloni, Tomaso

2012-08-03

We review the likely population, observational properties, and broad implications of stellar-mass black holes and ultraluminous x-ray sources. We focus on the clear empirical rules connecting accretion and outflow that have been established for stellar-mass black holes in binary systems in the past decade and a half. These patterns of behavior are probably the keys that will allow us to understand black hole feedback on the largest scales over cosmological time scales.

The enigmatic fire regime of coast redwood forests and why it matters

Treesearch

J. Morgan Varner; Erik S. Jules

2017-01-01

Of perhaps all forests in North America, the fire regime of coast redwoods (Sequoia sempervirens (D. Don) Endl.) is most enigmatic. Widely considered a temperate rainforest, a large number of fire history studies depict a forest dominated by frequent surface fire regimes. Coast redwood also has a long list of traits that allow it to persist and...

Magnetorotational instability in decretion disks of critically rotating stars and the outer structure of Be and Be/X-ray disks

NASA Astrophysics Data System (ADS)

Krtička, J.; Kurfürst, P.; Krtičková, I.

2015-01-01

Context. Evolutionary models of fast-rotating stars show that the stellar rotational velocity may approach the critical speed. Critically rotating stars cannot spin up more, therefore they lose their excess angular momentum through an equatorial outflowing disk. The radial extension of such disks is unknown, partly because we lack information about the radial variations of the viscosity. Aims: We study the magnetorotational instability, which is considered to be the origin of anomalous viscosity in outflowing disks. Methods: We used analytic calculations to study the stability of outflowing disks submerged in the magnetic field. Results: The magnetorotational instability develops close to the star if the plasma parameter is large enough. At large radii the instability disappears in the region where the disk orbital velocity is roughly equal to the sound speed. Conclusions: The magnetorotational instability is a plausible source of anomalous viscosity in outflowing disks. This is also true in the region where the disk radial velocity approaches the sound speed. The disk sonic radius can therefore be roughly considered as an effective outer disk radius, although disk material may escape from the star to the insterstellar medium. The radial profile of the angular momentum-loss rate already flattens there, consequently, the disk mass-loss rate can be calculated with the sonic radius as the effective disk outer radius. We discuss a possible observation determination of the outer disk radius by using Be and Be/X-ray binaries.

Neutrino-heated winds from rotating protomagnetars

NASA Astrophysics Data System (ADS)

Vlasov, Andrey D.; Metzger, Brian D.; Thompson, Todd A.

2014-11-01

We calculate the steady-state properties of neutrino-driven winds from strongly magnetized, rotating protoneutron stars (PNSs; `protomagnetars') under the assumption that the outflow geometry is set by the force-free magnetic field of an aligned dipole. Our goal is to assess protomagnetars as sites of r-process nucleosynthesis and gamma-ray burst engines using a more realistic outflow geometry than assumed in previous works. One-dimensional solutions calculated along flux tubes corresponding to different polar field lines are stitched together to determine the global properties of the flow at a given neutrino luminosity and rotation period. Protomagnetars with rotation periods of P ˜ 2-5 ms are shown to produce outflows more favourable for the production of third-peak r-process nuclei due to their much shorter expansion times through the seed nucleus formation region, yet only moderately lower entropies, as compared to normal spherical PNS winds. Protomagnetars with moderately rapid birth periods P ˜ 3-5 ms may thus represent a promising galactic r-process site which is compatible with a variety of other observations, including the recent discovery of possible magnetar-powered supernovae in metal-poor galaxies. We also confirm previous results that the outflows from protomagnetars with P ˜ 1-2 ms can achieve maximum Lorentz factors Γmax ˜ 100-1000 in the range necessary to power gamma-ray bursts (GRBs). The implications of GRB jets with a heavy nuclei-dominated composition as sources of ultrahigh energy cosmic rays are also addressed.

KINEMATICS OF THE OUTFLOW FROM THE YOUNG STAR DG TAU B: ROTATION IN THE VICINITIES OF AN OPTICAL JET

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zapata, Luis A.; Lizano, Susana; Rodríguez, Luis F.

2015-01-10

We present {sup 12}CO(2-1) line and 1300 μm continuum observations made with the Submillimeter Array of the young star DG Tau B. We find, in the continuum observations, emission arising from the circumstellar disk surrounding DG Tau B. The {sup 12}CO(2-1) line observations, on the other hand, revealed emission associated with the disk and the asymmetric outflow related with this source. Velocity asymmetries about the flow axis are found over the entire length of the flow. The amplitude of the velocity differences is of the order of 1-2 km s{sup –1} over distances of about 300-400 AU. We interpret themmore » as a result of outflow rotation. The sense of the outflow and disk rotation is the same. Infalling gas from a rotating molecular core cannot explain the observed velocity gradient within the flow. Magneto-centrifugal disk winds or photoevaporated disk winds can produce the observed rotational speeds if they are ejected from a Keplerian disk at radii of several tens of AU. Nevertheless, these slow winds ejected from large radii are not very massive, and cannot account for the observed linear momentum and angular momentum rates of the molecular flow. Thus, the observed flow is probably entrained material from the parent cloud. DG Tau B is a good laboratory to model in detail the entrainment process and see if it can account for the observed angular momentum.« less

MULTIPLE OUTFLOWS IN THE GIANT ERUPTION OF A MASSIVE STAR

DOE Office of Scientific and Technical Information (OSTI.GOV)

Humphreys, Roberta M.; Gordon, Michael S.; Jones, Terry J.

The supernova impostor PSN J09132750+7627410 in NGC 2748 reached a maximum luminosity of ≈−14 mag. It was quickly realized that it was not a true supernova, but another example of a nonterminal giant eruption. PSN J09132750+7627410 is distinguished by multiple P Cygni absorption minima in the Balmer emission lines that correspond to outflow velocities of −400, −1100, and −1600 km s{sup −1}. Multiple outflows have been observed in only a few other objects. In this paper we describe the evolution of the spectrum and the P Cygni profiles for 3 months past maximum, the post-maximum formation of a cool, densemore » wind, and the identification of a possible progenitor. One of the possible progenitors is an infrared source. Its pre-eruption spectral energy distribution suggests a bolometric luminosity of −8.3 mag and a dust temperature of 780 K. If it is the progenitor, it is above the AGB limit, unlike the intermediate-luminosity red transients. The three P Cygni profiles could be due to ejecta from the current eruption, the wind of the progenitor, or previous mass-loss events. We suggest that they were all formed as part of the same high-mass-loss event and are due to material ejected at different velocities or energies. We also suggest that multiple outflows during giant eruptions may be more common than reported.« less

Efficient cold outflows driven by cosmic rays in high-redshift galaxies and their global effects on the IGM

NASA Astrophysics Data System (ADS)

Samui, Saumyadip; Subramanian, Kandaswamy; Srianand, Raghunathan

2018-05-01

We present semi-analytical models of galactic outflows in high-redshift galaxies driven by both hot thermal gas and non-thermal cosmic rays. Thermal pressure alone may not sustain a large-scale outflow in low-mass galaxies (i.e. M ˜ 108 M⊙), in the presence of supernovae feedback with large mass loading. We show that inclusion of cosmic ray pressure allows outflow solutions even in these galaxies. In massive galaxies for the same energy efficiency, cosmic ray-driven winds can propagate to larger distances compared to pure thermally driven winds. On an average gas in the cosmic ray-driven winds has a lower temperature which could aid detecting it through absorption lines in the spectra of background sources. Using our constrained semi-analytical models of galaxy formation (that explains the observed ultraviolet luminosity functions of galaxies), we study the influence of cosmic ray-driven winds on the properties of the intergalactic medium (IGM) at different redshifts. In particular, we study the volume filling factor, average metallicity, cosmic ray and magnetic field energy densities for models invoking atomic cooled and molecular cooled haloes. We show that the cosmic rays in the IGM could have enough energy that can be transferred to the thermal gas in presence of magnetic fields to influence the thermal history of the IGM. The significant volume filling and resulting strength of IGM magnetic fields can also account for recent γ-ray observations of blazars.

Active galactic nuclei

PubMed Central

Fabian, Andrew C.

1999-01-01

Active galactic nuclei are the most powerful, long-lived objects in the Universe. Recent data confirm the theoretical idea that the power source is accretion into a massive black hole. The common occurrence of obscuration and outflows probably means that the contribution of active galactic nuclei to the power density of the Universe has been generally underestimated. PMID:10220363

MULTI-COMPONENT ANALYSIS OF POSITION-VELOCITY CUBES OF THE HH 34 JET

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rodriguez-Gonzalez, A.; Esquivel, A.; Raga, A. C.

We present an analysis of H{alpha} spectra of the HH 34 jet with two-dimensional spectral resolution. We carry out multi-Gaussian fits to the spatially resolved line profiles and derive maps of the intensity, radial velocity, and velocity width of each of the components. We find that close to the outflow source we have three components: a high (negative) radial velocity component with a well-collimated, jet-like morphology; an intermediate velocity component with a broader morphology; and a positive radial velocity component with a non-collimated morphology and large linewidth. We suggest that this positive velocity component is associated with jet emission scatteredmore » in stationary dust present in the circumstellar environment. Farther away from the outflow source, we find only two components (a high, negative radial velocity component, which has a narrower spatial distribution than an intermediate velocity component). The fitting procedure was carried out with the new AGA-V1 code, which is available online and is described in detail in this paper.« less

Ionized Outflows in 3-D Insights from Herbig-Haro Objects and Applications to Nearby AGN

NASA Technical Reports Server (NTRS)

Cecil, Gerald

1999-01-01

HST shows that the gas distributions of these objects are complex and clump at the limit of resolution. HST spectra have lumpy emission-line profiles, indicating unresolved sub-structure. The advantages of 3D over slits on gas so distributed are: robust flux estimates of various dynamical systems projected along lines of sight, sensitivity to fainter spectral lines that are physical diagnostics (reddening-gas density, T, excitation mechanisms, abundances), and improved prospects for recovery of unobserved dimensions of phase-space. These advantages al- low more confident modeling for more profound inquiry into underlying dynamics. The main complication is the effort required to link multi- frequency datasets that optimally track the energy flow through various phases of the ISM. This tedium has limited the number of objects that have been thoroughly analyzed to the a priori most spectacular systems. For HHO'S, proper-motions constrain the ambient B-field, shock velocity, gas abundances, mass-loss rates, source duty-cycle, and tie-ins with molecular flows. If the shock speed, hence ionization fraction, is indeed small then the ionized gas is a significant part of the flow energetics. For AGN'S, nuclear beaming is a source of ionization ambiguity. Establishing the energetics of the outflow is critical to determining how the accretion disk loses its energy. CXO will provide new constraints (especially spectral) on AGN outflows, and STIS UV-spectroscopy is also constraining cloud properties (although limited by extinction). HHO's show some of the things that we will find around AGN'S. I illustrate these points with results from ground-based and HST programs being pursued with collaborators.

Relativistic baryonic jets from an ultraluminous supersoft X-ray source.

PubMed

Liu, Ji-Feng; Bai, Yu; Wang, Song; Justham, Stephen; Lu, You-Jun; Gu, Wei-Min; Liu, Qing-Zhong; Di Stefano, Rosanne; Guo, Jin-Cheng; Cabrera-Lavers, Antonio; Álvarez, Pedro; Cao, Yi; Kulkarni, Shri

2015-12-03

The formation of relativistic jets by an accreting compact object is one of the fundamental mysteries of astrophysics. Although the theory is poorly understood, observations of relativistic jets from systems known as microquasars (compact binary stars) have led to a well established phenomenology. Relativistic jets are not expected to be produced by sources with soft or supersoft X-ray spectra, although two such systems are known to produce relatively low-velocity bipolar outflows. Here we report the optical spectra of an ultraluminous supersoft X-ray source (ULS) in the nearby galaxy M81 (M81 ULS-1; refs 9, 10). Unexpectedly, the spectra show blueshifted, broad Hα emission lines, characteristic of baryonic jets with relativistic speeds. These time-variable emission lines have projected velocities of about 17 per cent of the speed of light, and seem to be similar to those from the prototype microquasar SS 433 (refs 11, 12). Such relativistic jets are not expected to be launched from white dwarfs, and an origin from a black hole or a neutron star is hard to reconcile with the persistence of M81 ULS-1's soft X-rays. Thus the unexpected presence of relativistic jets in a ULS challenges canonical theories of jet formation, but might be explained by a long-speculated, supercritically accreting black hole with optically thick outflows.

The active nucleus of the ULIRG IRAS F00183-7111 viewed by NuSTAR

NASA Astrophysics Data System (ADS)

Iwasawa, K.; Spoon, H. W. W.; Comastri, A.; Gilli, R.; Lanzuisi, G.; Piconcelli, E.; Vignali, C.; Brusa, M.; Puccetti, S.

2017-10-01

We present an X-ray study of the ultra-luminous infrared galaxy IRAS F00183-7111 (z = 0.327), using data obtained from NuSTAR, Chandra X-ray Observatory, Suzaku and XMM-Newton. The Chandra imaging shows that a point-like X-ray source is located at the nucleus of the galaxy at energies above 2 keV. However, the point source resolves into diffuse emission at lower energies, extending to the east, where the extranuclear [Oiii]λ5007 emission, presumably induced by a galactic-scale outflow, is present. The nuclear source is detected by NuSTAR up to the rest-frame 30 keV. The strong, high-ionization Fe K line, first seen by XMM-Newton, and subsequently by Suzaku and Chandra, is not detected in the NuSTAR data. The line flux appears to have been declining continuously between 2003 and 2016, while the continuum emission remained stable to within 30%. Further observations are needed to confirm this. The X-ray continuum below 10 keV is characterised by a hard spectrum caused by cold absorption of NH 1 × 1023 cm-2, compatible to that of the silicate absorption at 9.7 μm, and a broad absorption feature around 8 keV which we attribute to a high-ionization Fe K absorption edge. The latter is best described by a blueshifted, high-ionization (log ξ 3) absorber with a column density of NH 1 × 1024 cm-2, similar to the X-ray high-velocity outflows observed in a number of active nuclei. No extra hard component, which would arise from a strongly absorbed (I.e. Compton-thick) source, is seen in the NuSTAR data. While a pure reflection scenario (with a totally hidden central source) is viable, direct emission from the central source of L2-10 keV ≃ 2 × 1044 erg s-1, behind layers of cold and hot absorbing gas may be an alternative explanation. In this case, the relative X-ray quietness (Lx/Lbol,AGN ≤ 6 × 10-3), the high-ionization Fe line, strong outflows inferred from various observations, and other similarities to the well-studied ULIRG/QSO Mrk 231 point that the central source in this ULIRG might be accreting close to the Eddington limit. This research has also made use of data obtained from ESO telescopes at the La Silla Paranal Observatory. The ESO VLT data are under programme IDs 386.B-0346, 088.B-0405, and 090.B-0098.

Chandra X-Ray Observations of the Two Brightest Unidentified High Galactic Latitude Fermi-LAT Gamma-Ray Sources

NASA Technical Reports Server (NTRS)

Cheung, C. C.; Donato, D.; Gehrels, N.; Sokolovsky, K. V.; Giroletti, M.

2012-01-01

We present Chandra ACIS-I X-ray observations of 0FGL J1311.9-3419 and 0FGL J1653.4-0200, the two brightest high Galactic latitude (absolute value (beta) >10 deg) gamma-ray sources from the three-month Fermi Large Area Telescope (LAT) bright source list that are still unidentified. Both were also detected previously by EGRET, and despite dedicated multi-wavelength follow-up, they are still not associated with established classes of gamma-ray emitters like pulsars or radio-loud active galactic nuclei. X-ray sources found in the ACIS-I fields of view are cataloged, and their basic properties are determined. These are discussed as candidate counterparts to 0FGL J1311.9-3419 and 0FGL J1653.4-0200, with particular emphasis on the brightest of the 9 and 13 Chandra sources detected within the respective Fermi-LAT 95% confidence regions. Further follow-up studies, including optical photometric and spectroscopic observations, are necessary to identify these X-ray candidate counterparts in order to ultimately reveal the nature of these enigmatic gamma-ray objects.

What's Going on Around BN

NASA Technical Reports Server (NTRS)

Erickson, Edwin; Colgan, S. W. J.; Schultz, A. S. B.; Simpson, J. P.; Burton, M. G.; Kaufman, M. J.; Young, E. T.; Stolovy, S.

2005-01-01

The Becklin-Neugebauer object, discovered in observations made by Eric Becklin as a graduate student, is the brightest mid-infrared source outside the solar system, and a beacon in the nearest region of massive star formation. Using NICMOS on HST, we have obtained near infrared photometric, spectroscopic, and polarimetric images of the region immediately around BN. These images, with resolutions < -0.2", reveal remarkable morphologies, shock details, new young stellar objects, faint stars with variable intensities, and outflow features. We will summarize these results and inferences regarding the shock properties, illuminating sources of the nebulosity, and IRc sources near BN.

HIGHLY VARIABLE EXTINCTION AND ACCRETION IN THE JET-DRIVING CLASS I-TYPE YOUNG STAR PTF 10nvg (V2492 Cyg, IRAS 20496+4354)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hillenbrand, Lynne A.; Carpenter, John M.; Muirhead, Philip S.

2013-03-15

We report extensive new photometry and spectroscopy of the highly variable young stellar object PTF 10nvg (also known as IRAS 20496+4354 and V2492 Cyg), including optical and near-infrared time-series data as well as mid-infrared and millimeter data. Following the previously reported 2010 rise to R{sub PTF} {approx}<13.{sup m}5 and subsequent fade, during 2011 and 2012 the source underwent additional episodes of brightening, followed by several magnitude dimming events including prolonged faint states at R{sub PTF} {approx}> 20{sup m}. The observed high-amplitude variations are largely consistent with extinction changes ({Delta}A{sub V} up to 30 mag) having a {approx}220 day quasi-periodic signal.more » However, photometry measured when the source was near maximum brightness in mid-2010 as well as in late-2012 does not phase well to this period. Spectral evolution includes not only changes in the spectral slope but also correlated variation in the prominence of TiO/VO/CO bands and atomic line emission, as well as anti-correlated variation in forbidden line emission which, along with H{sub 2}, dominates optical and infrared spectra at faint epochs. Notably, night-to-night variations in several forbidden doublet strengths and ratios are observed. High-dispersion spectra were obtained in a variety of photometric states and reveal time-variable line profiles. Neutral and singly ionized atomic species are likely formed in an accretion flow and/or impact while the origin of zero-velocity atomic Li I {lambda}6707 in emission is unknown. Forbidden lines, including several rare species, exhibit blueshifted emission profiles and likely arise from an outflow/jet. Several of these lines are also seen spatially offset from the continuum source position, presumably in a shocked region of an extended jet. Blueshifted absorption components of the Na I D doublet, K I {lambda}{lambda}7665, 7669 doublet, and the O I 7774 triplet, as well as blueshifted absorption components seen against the broad H{alpha} and Ca II triplet emission lines, similarly are formed in the outflow. CARMA maps resolve on larger scales a spatially extended outflow in millimeter-wavelength CO. We attribute the recently observed photometric and spectroscopic behavior to rotating circumstellar disk material located at separation a Almost-Equal-To 0.7(M{sub *}/M{sub Sun }){sup 1/3} AU from the continuum source, causing the semi-periodic dimming. Occultation of the central star as well as the bright inner disk and the accretion/outflow zones renders shocked gas in the inner part of the jet amenable to observation at the faint epochs. We discuss PTF 10nvg as a source exhibiting both accretion-driven (perhaps analogous to V1647 Ori) and extinction-driven (perhaps analogous to UX Ori or GM Cep) high-amplitude variability phenomena.« less

Self-organization of hydrothermal outflow and recharge in young oceanic crust: Constraints from open-top porous convection analog experiments

NASA Astrophysics Data System (ADS)

Mittelstaedt, E. L.; Olive, J. A. L.; Barreyre, T.

2016-12-01

Hydrothermal circulation at the axis of mid-ocean ridges has a profound effect on chemical and biological processes in the deep ocean, and influences the thermo-mechanical state of young oceanic lithosphere. Yet, the geometry of fluid pathways beneath the seafloor and its relation to spatial gradients in crustal permeability remain enigmatic. Here we present new laboratory models of hydrothermal circulation aimed at constraining the self-organization of porous convection cells in homogeneous as well as highly heterogeneous crust analogs. Oceanic crust analogs of known permeability are constructed using uniform glass spheres and 3-D printed plastics with a network of mutually perpendicular tubes. These materials are saturated with corn syrup-water mixtures and heated at their base by a resistive silicone strip heater to initiate thermal convection. A layer of pure fluid (i.e., an analog ocean) overlies the porous medium and allows an "open-top" boundary condition. Areas of fluid discharge from the crust into the ocean are identified by illuminating microscopic glass particles carried by the fluid, using laser sheets. Using particle image velocimetry, we estimate fluid discharge rates as well as the location and extent of fluid recharge. Thermo-couples distributed throughout the crust provide insights into the geometry of convection cells at depth, and enable estimates of convective heat flux, which can be compared to the heat supplied at the base of the system. Preliminary results indicate that in homogeneous crust, convection is largely confined to the narrow slot overlying the heat source. Regularly spaced discharge zones appear focused while recharge areas appear diffuse, and qualitatively resemble the along-axis distribution of hydrothermal fields at oceanic spreading centers. By varying the permeability of the crustal analogs, the viscosity of the convecting fluid, and the imposed basal temperature, our experiments span Rayleigh numbers between 10 and 10,000. This allows us to precisely map the conditions of convection initiation, and test scaling relations between the Nusselt and Rayleigh numbers. Finally, we investigate how these scalings and convection geometry change when a slot of high-permeability material (i.e., an analog fault) is introduced in the middle of the porous domain.

Studying the outflow-core interaction with ALMA Cycle 1 observations of the HH 46/47 molecular outflow

NASA Astrophysics Data System (ADS)

Zhang, Yichen; Arce, Hector G.; Mardones, Diego; Dunham, Michael; Garay, Guido; Noriega-Crespo, Alberto; Corder, Stuartt; Offner, Stella; Cabrit, Sylvie

2016-01-01

We present ALMA Cycle 1 observations of the HH 46/47 molecular outflow which is driven by a low-mass Class 0/I protostar. Previous ALMA Cycle 0 12CO observation showed outflow cavities produced by the entrainment of ambient gas by the protostellar jet and wide-angle wind. Here we present analysis of observation of 12CO, 13CO, C18O and other species using combined 12m array and ACA observations. The improved angular resolution and sensitivity allow us to detect details of the outflow structure. Specially, we see that the outflow cavity wall is composed of two or more layers of outflowing gas, which separately connect to different shocked regions along the outflow axis inside the cavity, suggesting the outflow cavity wall is composed of multiple shells entrained by a series of jet bow-shock events. The new 13CO and C18O data also allow us to trace relatively denser and slower outflow material than that traced by the 12CO. These species are only detected within about 1 to 2 km/s from the cloud velocity, tracing the outflow to lower velocities than what is possible using only the 12CO emission. Interestingly, the cavity wall of the red lobe appears at very low outflow velocities (as low as ~0.2 km/s). In addition, 13CO and C18O allow us to correct for the CO optical depth, allowing us to obtain more accurate estimates of the outflow mass, momentum and kinetic energy. Applying the optical depth correction significantly increases the previous mass estimate by a factor of 14. The outflow kinetic energy distribution shows that even though the red lobe is mainly entrained by jet bow-shocks, most of the outflow energy is being deposited into the cloud at the base of the outflow cavity rather than around the heads of the bow shocks. The estimated total mass, momentum, and energy of the outflow indicate that the outflow has the ability to disperse the parent core. We found possible evidence for a slowly moving rotating outflow in CS. Our 13CO and C18O observations also trace a circumstellar envelope with both rotation and infall motions.

Fast Outflow of Molecular Gas in the Seyfert Galaxy IC 5063

NASA Astrophysics Data System (ADS)

Morganti, Raffaella; Oosterloo, T.; Oonk, R.; Tadhunter, C.

2017-11-01

AGN-driven gas outflows may play an important role in the evolution of galaxies, as they impact on the growth on the central supermassive black hole as well on the star formation of the host galaxy. Much of the detailed physics of these gas outflows, and their actual impact on the host galaxy, is still not well understood. We present a detailed analysis, using ALMA observations, of the radio-jet driven outflow of molecular gas in the nearby radio-loud Seyfert galaxy IC 5063 which allows to derive important physical parameters of the gas and the outflow which, in turn, provide crucial input to numerical models. In recent years, a surprising result in the field of AGN-driven outflows has been that the cold phases of the gas (atomic and molecular) in some galaxies are the massive components of these outflows, despite the huge amounts of energy involved in driving these outflows. However, why most of the outflowing gas should be molecular/atomic, and in general, what are the physical conditions of the gas in the outflows and what really drives them, are still open questions. We present the results obtained from ALMA observations of multiple CO transitions and other molecules of what appears to be a textbook case of a jet-driven multi- phase outflow in the central regions of the Seyfert galaxy IC 5063. The data on multiple transitions allow us to derive the physical conditions in the different regions of the outflowing molecular gas. The signature of the impact of the radio jet is clearly seen in the spatial distribution of the excitation temperature and pressure of the outflowing gas, with the highest excitation and pressure found for the gas with the highest outflow velocities. We obtain a detailed three- dimensional picture of the outflow, and its kinematics, and find that outflowing molecular gas is present across the entire region co-spatial with the radio plasma, providing unambiguous evidence that the radio jets/cocoon are responsible for the outflow. The detailed information about the physical condition of the gas in a fast outflow will serve as template for the signatures of the impact of a radio plasma jet on a gas-rich ISM and its associated star formation, and guide the studies of outflows in other galaxies, including higher redshift objects.

Uncertainty Quantification applied to flow simulations in thoracic aortic aneurysms

NASA Astrophysics Data System (ADS)

Boccadifuoco, Alessandro; Mariotti, Alessandro; Celi, Simona; Martini, Nicola; Salvetti, Maria Vittoria

2015-11-01

The thoracic aortic aneurysm is a progressive dilatation of the thoracic aorta causing a weakness in the aortic wall, which may eventually cause life-threatening events. Clinical decisions on treatment strategies are currently based on empiric criteria, like the aortic diameter value or its growth rate. Numerical simulations can give the quantification of important indexes which are impossible to be obtained through in-vivo measurements and can provide supplementary information. Hemodynamic simulations are carried out by using the open-source tool SimVascular and considering patient-specific geometries. One of the main issues in these simulations is the choice of suitable boundary conditions, modeling the organs and vessels not included in the computational domain. The current practice is to use outflow conditions based on resistance and capacitance, whose values are tuned to obtain a physiological behavior of the patient pressure. However it is not known a priori how this choice affects the results of the simulation. The impact of the uncertainties in these outflow parameters is investigated here by using the generalized Polynomial Chaos approach. This analysis also permits to calibrate the outflow-boundary parameters when patient-specific in-vivo data are available.

Outflow structure of the quiet sun corona probed by spacecraft radio scintillations in strong scattering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Imamura, Takeshi; Ando, Hiroki; Toda, Tomoaki

Radio scintillation observations have been unable to probe flow speeds in the low corona where the scattering of radio waves is exceedingly strong. Here we estimate outflow speeds continuously from the vicinity of the Sun to the outer corona (heliocentric distances of 1.5-20.5 solar radii) by applying the strong scattering theory to radio scintillations for the first time, using the Akatsuki spacecraft as the radio source. Small, nonzero outflow speeds were observed over a wide latitudinal range in the quiet-Sun low corona, suggesting that the supply of plasma from closed loops to the solar wind occurs over an extended area.more » The existence of power-law density fluctuations down to the scale of 100 m was suggested, which is indicative of well-developed turbulence which can play a key role in heating the corona. At higher altitudes, a rapid acceleration typical of radial open fields is observed, and the temperatures derived from the speed profile show a distinct maximum in the outer corona. This study opened up a possibility of observing detailed flow structures near the Sun from a vast amount of existing interplanetary scintillation data.« less

Sublimating comets as the source of nucleation seeds for grain condensation in the gas outflow from AGB stars

NASA Technical Reports Server (NTRS)

Whitmire, D. P.; Matese, John J.; Reynolds, R. T.

1989-01-01

A growing amount of observational and theoretical evidence suggests that most main sequence stars are surrounded by disks of cometary material. The dust production by comets in such disks is investigated when the central stars evolve up the red giant and asymptotic giant branch (AGB). Once released, the dust is ablated and accelerated by the gas outflow and the fragments become the seeds necessary for condensation of the gas. The origin of the requisite seeds has presented a well known problem for classical nucleation theory. This model is consistent with the dust production observed in M giants and supergiants (which have increasing luminosities) and the fact that earlier supergiants and most WR stars (whose luminosities are unchanging) do not have significant dust clouds even though they have significant stellar winds. Another consequence of the model is that the spatial distribution of the dust does not, in general, coincide with that of the gas outflow, in contrast to the conventional condensation model. A further prediction is that the condensation radius is greater that that predicted by conventional theory which is in agreement with IR interferometry measurements of alpha-Ori.

Bipolar Molecular Outflows within 1pc of Sgr A*:Evidence for Low-mass Star Formation Activity

NASA Astrophysics Data System (ADS)

Yusef-Zadeh, Farhad; Wardle, Mark; Kunneriath, Devaky; Royster, Marc; Wootten, Al; Roberts, Douglas

2018-01-01

The 4 million solar mass black hole, Sgr A*, is expected to suppress star formation because the measured density of the cloud is insufficient for self-gravity to overcome tidal disruption by the black hole's gravitational field. Nevertheless, objects resembling dust-enshrouded young stars and photo-evaporative flows from their disks have been identified within 2pc of Sgr A*. Clear identification of the nature of these objects has been hampered by the Galactic center's distance, 30 magnitudes of foreground extinction, and stellar crowding. Here, we report the discovery of 11 bipolar molecular outflows using ALMA within a projected distance of one pc from Sgr A*. These unambiguous signatures of young protostars manifest as approaching and receding lobes of dense gas swept up by the jets created during the formation and early evolution of low-mass stars. The mean dynamical age of the outflow sources and the rate of star formation are estimated to be ~6500 years and ~5x10^{-4} solar mass per year, respectively. These measurements suggest that star formation could take place in the immediate vicinity of supermassive black holes in the nuclei of external galaxies.

Mars, the funny history of canals.1-the enigmatic planet. the plurality of worlds; Mars, la folle histoire des canaux. 1-l'énigmatique planète. la pluralité des mondes

NASA Astrophysics Data System (ADS)

Raffaitin, Gérard; Durand, Pierre

2016-03-01

Since the 17th century, the study of the planet Mars interested astronomers. The changes observed on Mars were enigmatic. Several philosophers thought that this planet does have inhabitants. Giovanni Schiaparelli observed canals and their changes. Was it the sign of a life on this planet?

Springtime variations of organic and inorganic constituents in submicron aerosols (PM1.0) from Cape Hedo, Okinawa

NASA Astrophysics Data System (ADS)

Kunwar, Bhagawati; Torii, K.; Zhu, Chunmao; Fu, Pingqing; Kawamura, Kimitaka

2016-04-01

During the spring season with enhanced Asian outflow, we collected submicron aerosol (PM1.0) samples at Cape Hedo, Okinawa Island in the western North Pacific Rim. We analyzed the filter samples for diacids, oxoacids, pyruvic acid, α-dicarbonyls and fatty acids to better understand the sources and atmospheric processes in the outflow regions of Asian pollutants. Molecular distributions of diacids show a predominance of oxalic acid (C2) followed by malonic (C3) and succinic (C4) acids. Total diacids strongly correlated with secondary source tracers such as SO42- (r = 0.87), NH4+ (0.90) and methanesulfonate (MSA-) (0.84), suggesting that diacids are secondarily formed from their precursor compounds. We also found good correlations among C2, organic carbon (OC) and elemental carbon (EC) in the Okinawa aerosols, suggesting that diacids are mainly derived from anthropogenic sources. However, a weak correlation of diacids with levoglucosan, a biomass burning tracer, suggests that biomass buring is not the main source of diacids, rather diacids are secondarily formed by photochemical oxidation of organic precursors derived from fossil fuel combustion. We found a strong correlation (r = 0.98) between inorganic nitrogen (NO3-N + NH4-N) and total nitrogen (TN), to which organic nitrogen (ON) contributed 23%. Fatty acids were characterized by even carbon number predominance, suggesting that they are derived from biogenic sources. The higher abundances of short chain fatty acids (C20) further suggest that fatty acids are largely derived from marine phytoplankton during spring bloom.

Carbonate-Sulfate Volcanism on Venus?

USGS Publications Warehouse

Kargel, J.S.; Kirk, R.L.; Fegley, B.; Treiman, A.H.

1994-01-01

Venusian canali, outflow channels, and associated volcanic deposits resemble fluvial landforms more than they resemble volcanic features on Earth and Mars. Some canali have meandering habits and features indicative of channel migration that are very similar to meandering river channels and flood plains on Earth, venusian outflow channels closely resemble water-carved outflow channels on Mars and the Channeled Scabland in Washington, collapsed terrains at the sources of some venusian channels resemble chaotic terrains at the sources of martian outflow channels, venusian lava deltas are similar to bird's-foot deltas such as the Mississippi delta, and venusian valley networks indicate sapping. The depositional fluvial-type features (deltas, braided bars, and channeled plains) are generally among the smoothest terrains at the Magellan radar wavelength (12.6 cm) on Venus. These features suggest the involvement of an unusual lava, unexpected processes, and/or extraordinary eruption conditions. Possibly the lava was an ordinary silicate lava such as basalt or a less common type of silicate lava, and conditions unique to Venus or to those particular eruptions may have caused an unusual volcanological behavior. We have developed the alternative possibility that the lava had a water-like rheology and a melting point slightly greater than Venus' surface temperature, thus accounting for the unusual behavior of the lava. Unlike silicate lavas, some carbonatites (including carbonate-sulfate-rich liquids) have these properties; thus they can flow great distances while retaining a high fluidity, significant mechanical erosiveness, and substantial capacity to transport and deposit sediment. Venusian geochemistry and petrology are consistent with extensive eruptions of carbonatite lavas, which could have crustal and/or mantle origins. Venus' atmosphere (especially CO2, HCl, and HF abundances) and rocks may be in local chemical equilibrium, which suggests that the upper crust contains large amounts of calcite, anhydrite, and other salts. Chemical analyses indicate, according to some models, that Venusian rocks may contain 4-19% calcite and anhydrite. Mixtures of crustal salts could melt at temperatures a few tens to a few hundred Kelvins higher than Venus' surface temperature; hence, melting may be induced by modest endogenetic or impact heating. Salts may have many of the same geologic roles on Venus as water and ice have on Mars. A molten salt (carbonatite) "aquifer" may exist beneath a few hundred meters to several kilometers of solidified salt-rich "permafrost." Many geologic features can be explained by carbonatite magmatism: (1) impact melting of crustal salts can explain crater outflows, (2) small, sustained eruptions from molten salt aquifers can explain sapping valleys, (3) large, sustained eruptions may explain canali and their flood plans, and (4) catastrophic outbursts may have formed outflow channels and chaotic terrain. Landforms created by carbonate-rich lavas would be thermally stable on Venus' surface, though some minerals may weather to other solid substances. ?? 1994 Academic Press. All rights reserved.

Identifying the TeV gamma-ray source MGRO J2228+61, FINALLY!

NASA Astrophysics Data System (ADS)

Aliu, Ester

2012-09-01

New VERITAS observations of MGRO J2228+61 allow us to associate its TeV emission with the enigmatic radio supernova remnant SNR G106.3+2.7. This remnant is part of a large complex that includes the Boomerang pulsar and nebula. The reduced field suggests that the TeV emission is not powered by the Boomerang, but instead associated with a much larger remnant. A recent SUZAKU X-ray observation of the smaller gamma-ray error box reveals two possible pulsar candidates. We propose short ACIS exposures to identify these sources to determine if one or both can be responsible for the gamma-ray emission. This will allow us to address the long standing problem on the nature of both MGRO J2228+61 and SNR G106.3+2.7.

The Dependence of Galactic Outflows on the Properties and Orientation of zCOSMOS Galaxies at z ~ 1

NASA Astrophysics Data System (ADS)

Bordoloi, R.; Lilly, S. J.; Hardmeier, E.; Contini, T.; Kneib, J.-P.; Le Fevre, O.; Mainieri, V.; Renzini, A.; Scodeggio, M.; Zamorani, G.; Bardelli, S.; Bolzonella, M.; Bongiorno, A.; Caputi, K.; Carollo, C. M.; Cucciati, O.; de la Torre, S.; de Ravel, L.; Garilli, B.; Iovino, A.; Kampczyk, P.; Kovač, K.; Knobel, C.; Lamareille, F.; Le Borgne, J.-F.; Le Brun, V.; Maier, C.; Mignoli, M.; Oesch, P.; Pello, R.; Peng, Y.; Perez Montero, E.; Presotto, V.; Silverman, J.; Tanaka, M.; Tasca, L.; Tresse, L.; Vergani, D.; Zucca, E.; Cappi, A.; Cimatti, A.; Coppa, G.; Franzetti, P.; Koekemoer, A.; Moresco, M.; Nair, P.; Pozzetti, L.

2014-10-01

We present an analysis of cool outflowing gas around galaxies, traced by Mg II absorption lines in the coadded spectra of a sample of 486 zCOSMOS galaxies at 1 <= z <= 1.5. These galaxies span a range of stellar masses (9.45 <= log10[M */M ⊙] <= 10.7) and star formation rates (0.14 <= log10[SFR/M ⊙ yr-1] <= 2.35). We identify the cool outflowing component in the Mg II absorption and find that the equivalent width of the outflowing component increases with stellar mass. The outflow equivalent width also increases steadily with the increasing star formation rate of the galaxies. At similar stellar masses, the blue galaxies exhibit a significantly higher outflow equivalent width as compared to red galaxies. The outflow equivalent width shows strong correlation with the star formation surface density (ΣSFR) of the sample. For the disk galaxies, the outflow equivalent width is higher for the face-on systems as compared to the edge-on ones, indicating that for the disk galaxies, the outflowing gas is primarily bipolar in geometry. Galaxies typically exhibit outflow velocities ranging from -150 km s-1 ~-200 km s-1 and, on average, the face-on galaxies exhibit higher outflow velocity as compared to the edge-on ones. Galaxies with irregular morphologies exhibit outflow equivalent width as well as outflow velocities comparable to face on disk galaxies. These galaxies exhibit mass outflow rates >5-7 M ⊙ yr-1 and a mass loading factor ({ η = \\dot{M}out /SFR}) comparable to the star formation rates of the galaxies. Based on observations undertaken at the European Southern Observatory (ESO) Very Large Telescope (VLT) under Large Program 175.A-0839.

Use of stable isotope ratios for evaluating sulfur sources and losses at the Hubbard Brook Experimental Forest

Treesearch

M.J. Mitchell; B. Mayer; S.W. Bailey; J.W. Hornbeck; C. Alewell; C.T. Driscoll; G.E. Likens

2001-01-01

Anthropogenic S emissions have been declining in eastern North America since the early 1970s. Declines in atmospheric S deposition have resulted in decreases in concentrations and fluxes of SO42-) in precipitation and drainage waters. Recent S mass balance studies have shown that the outflow of SO4...

Chandra imaging of the kpc extended outflow in 1H 0419-577

NASA Astrophysics Data System (ADS)

Di Gesu, L.; Costantini, E.; Piconcelli, E.; Kaastra, J. S.; Mehdipour, M.; Paltani, S.

2017-12-01

The Seyfert 1 galaxy 1H 0419-577 hosts a kpc extended outflow that is evident in the [O III] image and that is also detected as a warm absorber in the UV/X-ray spectrum. Here, we analyze a 30 ks Chandra-ACIS X-ray image, with the aim of resolving the diffuse extranuclear X-ray emission and of investigating its relationship with the galactic outflow. Thanks to its sub-arcsecond spatial resolution, Chandra resolves the circumnuclear X-ray emission, which extends up to a projected distance of at least 16 kpc from the center. The morphology of the diffuse X-ray emission is spherically symmetrical. We could not recover a morphological resemblance between the soft X-ray emission and the ionization bicone that is traced by the [O III] outflow. Our spectral analysis indicates that one of the possible explanations for the extended emission is thermal emission from a low-density (nH 10-3 cm-3) hot plasma (Te 0.22 keV). If this is the case, we may be witnessing the cooling of a shock-heated wind bubble. In this scenario, the [O III] emission line and the X-ray/UV absorption lines may trace cooler clumps that are entrained in the hot outflow. Alternatively, the extended emission could be to due to a blend of emission lines from a photoionized gas component having a hydrogen column density of NH 2.1 × 1022 cm-2 and an ionization parameter of log ξ 1.3. Because the source is viewed almost edge-on we argue that the photoionized gas nebula must be distributed mostly along the polar directions, outside our line of sight. In this geometry, the X-ray/UV warm absorber must trace a different gas component, physically disconnected from the emitting gas, and located closer to the equatorial plane.

Evidence for Ultra-Fast Outflows in Radio-Quiet AGNs. 2; Detailed Photoionization Modeling of Fe K-Shell Absorption Lines

NASA Technical Reports Server (NTRS)

Tombesi, Francesco; Clapp, M.; Reeves, J. N.; Palumbo, G. G. C.; Braito, V.; Dadina, M.

2011-01-01

X-ray absorption line spectroscopy has recently shown evidence for previously unknown Ultra-fast Outflows (UFOs) in radio-quiet AGNs. In the previous paper of this series we defined UFOs as those absorbers with an outflow velocity higher than 10,000km/s and assessed the statistical significance of the associated blue shifted FeK absorption lines in a large sample of 42 local radio-quiet AGNs observed with XMM-Newton. In the present paper we report a detailed curve of growth analysis and directly model the FeK absorbers with the Xstar photo-ionization code. We confirm that the frequency of sources in the radio-quiet sample showing UFOs is >35%. The outflow velocity distribution spans from \\sim10,000km/s (\\sim0.03c) up to \\siml00,000kmis (\\sim0.3c), with a peak and mean value of\\sim42,000km/s (\\sim0.14c). The ionization parameter is very high and in the range log\\xi 3-6 erg s/cm, with a mean value of log\\xi 4.2 erg s/cm. The associated column densities are also large, in the range N_H\\siml0(exp 22)-10(exp 24)/sq cm, with a mean value of N_H\\siml0(exp23)/sq cm. We discuss and estimate how selection effects, such as those related to the limited instrumental sensitivity at energies above 7keV, may hamper the detection of even higher velocities and higher ionization absorbers. We argue that, overall, these results point to the presence of extremely ionized and possibly almost Compton thick outflowing material in the innermost regions of AGNs. This also suggests that UFOs may potentially play a significant role in the expected cosmological feedback from AGNs and their study can provide important clues on the connection between accretion disks, winds and jets.

Mapping UV properties throughout the Cosmic Horseshoe: lessons from VLT-MUSE

NASA Astrophysics Data System (ADS)

James, Bethan L.; Auger, Matt; Pettini, Max; Stark, Daniel P.; Belokurov, V.; Carniani, Stefano

2018-05-01

We present the first spatially resolved rest-frame ultraviolet (UV) study of the gravitationally lensed galaxy, the `Cosmic Horseshoe' (J1148+1930) at z = 2.38. Our gravitational lens model shows that the system is made up of four star-forming regions, each ˜4-8 kpc2 in size, from which we extract four spatially exclusive regional spectra. We study the interstellar and wind absorption lines, along with C III] doublet emission lines, in each region to investigate any variation in emission/absorption line properties. The mapped C III] emission shows distinct kinematical structure, with velocity offsets of ˜±50 km s-1 between regions suggestive of a merging system, and a variation in equivalent width that indicates a change in ionization parameter and/or metallicity between the regions. Absorption line velocities reveal a range of outflow strengths, with gas outflowing in the range -200 ≲ v (km s-1) ≲ -50 relative to the systemic velocity of that region. Interestingly, the strongest gas outflow appears to emanate from the most diffuse star-forming region. The star formation rates remain relatively constant (˜8-16 M⊙ yr-1), mostly due to large uncertainties in reddening estimates. As such, the outflows appear to be `global' rather than `locally' sourced. We measure electron densities with a range of log (Ne) = 3.92-4.36 cm-3, and point out that such high densities may be common when measured using the C III] doublet due to its large critical density. Overall, our observations demonstrate that while it is possible to trace variations in large-scale gas kinematics, detecting inhomogeneities in physical gas properties and their effects on the outflowing gas may be more difficult. This study provides important lessons for the spatially resolved rest-frame UV studies expected with future observatories, such as James Webb Space Telescope.

A Massive Bipolar Outflow and a Dusty Torus with Large Grains in the Preplanetary Nebula IRAS 22036+5306

NASA Technical Reports Server (NTRS)

Sahai, Raghvendra; Young, K.; Patel, N. A.; Sanchez Contreras, C.; Morris, M.

2006-01-01

We report high angular resolution (approx.1") CO J=3-2 interferometric mapping using the Submillimeter Array (SMA) of IRAS 22036+5306 (I22036), a bipolar preplanetary nebula (PPN) with knotty jets discovered in our HST snapshot survey of young PPNs. In addition, we have obtained supporting lower resolution (approx.10") CO and 13CO J=1-0 observations with the Owens Valley Radio Observatory (OVRO) interferometer, as well as optical long-slit echelle spectra at the Palomar Observatory. The CO J=3-2 observations show the presence of a very fast (approx.220 km/s), highly collimated, massive (0.03 Solar Mass) bipolar outflow with a very large scalar momentum (about 10(exp 39) g cm/s), and the characteristic spatiokinematic structure of bow shocks at the tips of this outflow. The H(alpha) line shows an absorption feature blueshifted from the systemic velocity by approx.100 km/s, which most likely arises in neutral interface material between the fast outflow and the dense walls of the bipolar lobes at low latitudes. The fast outflow in I22036, as in most PPNs, cannot be driven by radiation pressure. We find an unresolved source of submillimeter (and millimeter-wave) continuum emission in I22036, implying a very substantial mass (0.02-0.04 Solar Mass) of large (radius > or approx.1 mm), cold (< or approx.50 K) dust grains associated with I22036's toroidal waist. We also find that the C-13/C-12 ratio in I22036 is very high (0.16), close to the maximum value achieved in equilibrium CNO nucleosynthesis (0.33). The combination of the high circumstellar mass (i.e., in the extended dust shell and the torus) and the high C-13/C-12 ratio in I22036 provides strong support for this object having evolved from a massive (> or approx.4 Solar Mass) progenitor in which hot-bottom-burning has occurred.

AGN feedback on molecular gas reservoirs in quasars at z 2.4

NASA Astrophysics Data System (ADS)

Carniani, S.; Marconi, A.; Maiolino, R.; Feruglio, C.; Brusa, M.; Cresci, G.; Cano-Díaz, M.; Cicone, C.; Balmaverde, B.; Fiore, F.; Ferrara, A.; Gallerani, S.; La Franca, F.; Mainieri, V.; Mannucci, F.; Netzer, H.; Piconcelli, E.; Sani, E.; Schneider, R.; Shemmer, O.; Testi, L.

2017-09-01

We present new ALMA observations aimed at mapping molecular gas reservoirs through the CO(3-2) transition in three quasars at z ≃ 2.4, LBQS 0109+0213, 2QZ J002830.4-281706, and [HB89] 0329-385. Previous [Oiii]λ5007 observations of these quasars showed evidence for ionised outflows quenching star formation in their host galaxies. Systemic CO(3-2) emission has been detected only in one quasar, LBQS 0109+0213, where the CO(3-2) emission is spatially anti-correlated with the ionised outflow, suggesting that most of the molecular gas may have been dispersed or heated in the region swept by the outflow. In all three sources, including the one detected in CO, our constraints on the molecular gas mass indicate a significantly reduced reservoir compared to main-sequence galaxies at the same redshift, supporting a negative feedback scenario. In the quasar 2QZ J002830.4-281706, we tentatively detect an emission line blob blue-shifted by v - 2000 km s-1 with respect to the galaxy systemic velocity and spatially offset by 0.2'' (1.7 kpc) with respect to the ALMA continuum peak. Interestingly, such emission feature is coincident in both velocity and space with the ionised outflow as seen in [Oiii]λ5007. This tentative detection must be confirmed with deeper observations but, if real, it could represent the molecular counterpart of the ionised gas outflow driven by the Active Galactic Nucleus (AGN). Finally, in all ALMA maps we detect the presence of serendipitous line emitters within a projected distance 160 kpc from the quasars. By identifying these features with the CO(3-2) transition, we find that the serendipitous line emitters would be located within | Δv | < 500 km s-1 from the quasars, hence suggesting an overdensity of galaxies in two out of three quasars.

Discovery of Suprathermal Ionospheric Origin Fe+ in and Near Earth's Magnetosphere

NASA Astrophysics Data System (ADS)

Christon, S. P.; Hamilton, D. C.; Plane, J. M. C.; Mitchell, D. G.; Grebowsky, J. M.; Spjeldvik, W. N.; Nylund, S. R.

2017-11-01

Suprathermal (87-212 keV/e) singly charged iron, Fe+, has been discovered in and near Earth's 9-30 RE equatorial magnetosphere using 21 years of Geotail STICS (suprathermal ion composition spectrometer) data. Its detection is enhanced during higher geomagnetic and solar activity levels. Fe+, rare compared to dominant suprathermal solar wind and ionospheric origin heavy ions, might derive from one or all three candidate lower-energy sources: (a) ionospheric outflow of Fe+ escaped from ion layers near 100 km altitude, (b) charge exchange of nominal solar wind iron, Fe+≥7, in Earth's exosphere, or (c) inner source pickup Fe+ carried by the solar wind, likely formed by solar wind Fe interaction with near-Sun interplanetary dust particles. Earth's semipermanent ionospheric Fe+ layers derive from tons of interplanetary dust particles entering Earth's atmosphere daily, and Fe+ scattered from these layers is observed up to 1000 km altitude, likely escaping in strong ionospheric outflows. Using 26% of STICS's magnetosphere-dominated data when possible Fe+2 ions are not masked by other ions, we demonstrate that solar wind Fe charge exchange secondaries are not an obvious Fe+ source. Contemporaneous Earth flyby and cruise data from charge-energy-mass spectrometer on the Cassini spacecraft, a functionally identical instrument, show that inner source pickup Fe+ is likely not important at suprathermal energies. Consequently, we suggest that ionospheric Fe+ constitutes at least a significant portion of Earth's suprathermal Fe+, comparable to the situation at Saturn where suprathermal Fe+ is also likely of ionospheric origin.

Redistribution of Lunar Polar Water to Mid-latitudes and its Role in Forming an OH veneer - Revisited

NASA Technical Reports Server (NTRS)

Farrell, W. M.; Killen, R. M.; Hurley, D. M.; Hodges, R. R.; Halekas, J. S.; Delory, G. T.

2012-01-01

We suggest that energization processes like ion sputtering and impact vaporization can eject/release polar water molecules residing within lunar cold trapped regions with sufficient velocity to allow their redistribution to mid-latitudes. We consider the possibility that these polar-ejected molecules can be an additional (but not dominant) contribution to the water/OH veneer observed as a 3 micron absorption feature at mid-latitudes by Chandrayaan-I, Cassini, and EPOXI. Taking the conservative case that polar water is ejected only from the floor of polar craters with an 0.1 % icy regolith then overall source rates are near 10(exp 18) H20s/s. This outflow amounts to approx 10(exp -7) kg/s of water to be ejected from each pole and is a water source rate that is 10(exp .5 lower than the overall exospheric source rate for all species. Hence, the out-flowing polar water is a perturbation in the overall exosphere composition & dynamics. This polar water 'fountain' model may not fully account for the relatively high concentrations in the mid-latitude water veneer observed in the IR (approx 10-1000 ppm). However, it may account for some part of the veneer. We note that the polar water fountain source rates scale linearly with ice concentration, and larger mass fractions of polar crater water should provide correspondingly larger fractions of water emission out of the poles which then 'spills' on to mid-latitude surfaces.

Environmental Services from Agricultural Stormwater Detention Systems in Florida

NASA Astrophysics Data System (ADS)

Shukla, A.; Shukla, S.; Knowles, J. M.

2011-12-01

Agricultural Stormwater Detention Areas (ADAs) commonly exist for the purpose of downstream flood protection in high water table regions of Florida. In addition to flood protection, they are also considered an important Best Management Practice due to their presumed effectiveness in reducing nitrogen (N) and phosphorus (P) loads to the Kissimmee-Lake Okeechobee-Everglades (KLE) ecosystem. The KLE ecosystem has been adversely impacted due to excessive P loads. Despite their presumed water quality effectiveness, limited data exist on actual N and P treatment efficiencies. A study was conducted at two ADAs (ADA 1 and ADA 2) located in two row crop farms to quantify the total N and P treatment efficiencies. Water, N, and P inflow and outflows at both ADAs were monitored for a year. Results from ADA 1 suggested that P treatment efficiency was below zero indicating that the ADA was a source of P rather than a sink. On the other hand, N treatment efficiency was found to be 20%. Mean inflow and outflow N concentrations for ADA 1 were 1.6 and 1.4 mg/l respectively, indicating a 9% reduction. Mean inflow and outflow P concentrations were 0.04 and 0.06 mg/l respectively, showing an increase of 67%. Although ADA 1 was effective in retaining N it was not for P. In contrast to ADA 1, the P treatment efficiency of ADA 2 was positive (20%). Nitrogen treatment efficiency of ADA 2 was 22%. Mean inflow and outflow N concentrations for ADA 2 were 4.0 and 2.0 mg/l respectively, indicating 50% reduction. A reduction of 32% was observed for P concentrations with mean inflow and outflow P concentrations of 0.5 and 0.3 mg/l respectively. No P retention at ADA 1 was mainly due to low P adsorption capacity of the soil. Analysis of surface (0-10 cm) and subsurface (10-20 cm) soil P retention characteristics suggested that ADA 1 had no remaining P storage capacity which resulted in it being a source of P. At ADA 2, a large fraction of the area still had P storage capacity which resulted in positive treatment efficiency. Several modifications were identified for the two ADAs to increase N and P treatment efficiencies. These modifications include increasing the travel time, available water storage, changing inflow locations, modifying outlet control structure and biomass harvesting. Biomass harvesting has the potential to make these systems play an important role in providing environmental services. The harvested biomass can not only remove N and P from the system but also acts as a source of bioenergy feedstock. Biomass N and P storage at ADA 2 suggested that harvesting of easily accessible biomass could account for removal of 157 kg from the ADA which accounts for 76% of the annual P retention. Biomass harvesting can become a potential source of additional income for producers for providing the environmental services of not only additional nutrient treatment but also bioenergy. The comparison between these two ADAs suggested that the P treatment by these systems can vary considerably depending on hydraulic, hydrologic, soil, and vegetation characteristics. Future research needs for making these systems provide additional environmental services such as increased P treatment, bioenergy, and carbon sequestration were identified.

The origin of ultrafast outflows in AGN: Monte Carlo simulations of the wind in PDS 456

NASA Astrophysics Data System (ADS)

Hagino, Kouichi; Odaka, Hirokazu; Done, Chris; Gandhi, Poshak; Watanabe, Shin; Sako, Masao; Takahashi, Tadayuki

2015-01-01

Ultrafast outflows (UFOs) are seen in many AGN, giving a possible mode for AGN feedback on to the host galaxy. However, the mechanism(s) for the launch and acceleration of these outflows are currently unknown, with UV line driving apparently strongly disfavoured as the material along the line of sight is so highly ionized that it has no UV transitions. We revisit this issue using the Suzaku X-ray data from PDS 456, an AGN with the most powerful UFO seen in the local Universe. We explore conditions in the wind by developing a new 3D Monte Carlo code for radiation transport. The code only handles highly ionized ions, but the data show the ionization state of the wind is high enough that this is appropriate, and this restriction makes it fast enough to explore parameter space. We reproduce the results of earlier work, confirming that the mass-loss rate in the wind is around 30 per cent of the inferred inflow rate through the outer disc. We show for the first time that UV line driving is likely to be a major contribution to the wind acceleration. The mass-loss rate in the wind matches that predicted from a purely line driven system, and this UV absorption can take place out of the line of sight. Continuum driving should also play a role as the source is close to Eddington. This predicts that the most extreme outflows will be produced from the highest mass accretion rate flows on to high-mass black holes, as observed.

Solar Jets as Sources of Outflows, Heating and Waves

NASA Astrophysics Data System (ADS)

Nishizuka, N.

2013-05-01

Recent space solar observations of the Sun, such as Hinode and SDO, have revealed that magnetic reconnection is ubiquitous in the solar atmosphere, ranging from small scale reconnection (observed as nanoflares) to large scale one (observed as long duration flares or giant arcades). Especially recent Hinode observations has found various types of tiny chromospheric jets, such as chromospheric anemone jets, penumbral microjets and light bridge jets from sunspot umbra. It was also found that the corona is full of tiny X-ray jets. Often they are seen as helical spinning jets with Alfvenic waves in the corona. Sometimes they are seen as chromospheric jets with slow-mode magnetoacoustic waves and sometimes as unresolved jet-like events at the footpoint of recurrent outflows and waves at the edge of the active region. There is increasing evidence of magnetic reconnection in these tiny jets and its association with waves. The origin of outflows and waves is one of the issues concerning coronal heating and solar wind acceleration. To answer this question, we had a challenge to reproduce solar jets with laboratory plasma experiment and directly measured outflows and waves. As a result, we could find a propagating wave excited by magnetic reconnection, whose energy flux is 10% of the released magnetic energy. That is enough for solar wind acceleration and locally enough for coronal heating, consistent with numerical MHD simulations of solar jets. Here we would discuss recent observations with Hinode, theories and experimental results related to jets and waves by magnetic reconnection, and discuss possible implication to reconnection physics, coronal heating and solar wind acceleration.

Revisiting the Inner Magnetospheric Oxygen Torus with DE 1 RIMS

NASA Technical Reports Server (NTRS)

Gallagher, D. L.; Goldstein, J.; Craven, P. D.; Comfort, R. H.

2016-01-01

Nearly 35 years ago direct observations of cold plasmaspheric ions found enhanced O(+), O(++), and even N(+) densities in the outer plasmasphere, in particular during storm recovery conditions. Enhancements were seen inside or just outside of the plasmapause at all magnetic local times. Whereas nominal O(+) concentrations were found to be 1% or less inside the plasmasphere, enhanced O(+) in the vicinity of the plasmapause was found to reach densities comparable to H(+). Enhanced ion outflow (including oxygen) from high latitudes has also become part of our picture of storm-time phenomena. More recently it has become apparent that high latitude outflow is a source of inner magnetospheric warm ions that convect into morning and afternoon local times, to form what we now call the warm plasma cloak. Low to middle latitude ionospheric outflow and high latitude outflow are thought to result from very different processes and can be expected to contribute differently as a function of conditions and locations to the dynamic processes of energy and particle transport in the inner magnetosphere. Given the apparent proximity of their delivery to the vicinity of the plasmapause during plasmaspheric refilling conditions it becomes worthwhile to question the origin of the oxygen torus and its role in this region. While the observations do not yet exist to settle this question, there are measurements that contribute to the discussion in the new emerging context of cold plasma in the inner magnetosphere. In this paper we present and discuss DE 1 RIMS derived ion densities and temperatures that contribute to answering these outstanding questions about the origin and dynamics of the oxygen torus.

Evaluation of nitrous acid sources and sinks in urban outflow

NASA Astrophysics Data System (ADS)

Gall, Elliott T.; Griffin, Robert J.; Steiner, Allison L.; Dibb, Jack; Scheuer, Eric; Gong, Longwen; Rutter, Andrew P.; Cevik, Basak K.; Kim, Saewung; Lefer, Barry; Flynn, James

2016-02-01

Intensive air quality measurements made from June 22-25, 2011 in the outflow of the Dallas-Fort Worth (DFW) metropolitan area are used to evaluate nitrous acid (HONO) sources and sinks. A two-layer box model was developed to assess the ability of established and recently identified HONO sources and sinks to reproduce observations of HONO mixing ratios. A baseline model scenario includes sources and sinks established in the literature and is compared to scenarios including three recently identified sources: volatile organic compound-mediated conversion of nitric acid to HONO (S1), biotic emission from the ground (S2), and re-emission from a surface nitrite reservoir (S3). For all mechanisms, ranges of parametric values span lower- and upper-limit values. Model outcomes for 'likely' estimates of sources and sinks generally show under-prediction of HONO observations, implying the need to evaluate additional sources and variability in estimates of parameterizations, particularly during daylight hours. Monte Carlo simulation is applied to model scenarios constructed with sources S1-S3 added independently and in combination, generally showing improved model outcomes. Adding sources S2 and S3 (scenario S2/S3) appears to best replicate observed HONO, as determined by the model coefficient of determination and residual sum of squared errors (r2 = 0.55 ± 0.03, SSE = 4.6 × 106 ± 7.6 × 105 ppt2). In scenario S2/S3, source S2 is shown to account for 25% and 6.7% of the nighttime and daytime budget, respectively, while source S3 accounts for 19% and 11% of the nighttime and daytime budget, respectively. However, despite improved model fit, there remains significant underestimation of daytime HONO; on average, a 0.15 ppt/s unknown daytime HONO source, or 67% of the total daytime source, is needed to bring scenario S2/S3 into agreement with observation. Estimates of 'best fit' parameterizations across lower to upper-limit values results in a moderate reduction of the unknown daytime source, from 0.15 to 0.10 ppt/s.

Ionised outflows in z ~ 2.4 quasar host galaxies

NASA Astrophysics Data System (ADS)

Carniani, S.; Marconi, A.; Maiolino, R.; Balmaverde, B.; Brusa, M.; Cano-Díaz, M.; Cicone, C.; Comastri, A.; Cresci, G.; Fiore, F.; Feruglio, C.; La Franca, F.; Mainieri, V.; Mannucci, F.; Nagao, T.; Netzer, H.; Piconcelli, E.; Risaliti, G.; Schneider, R.; Shemmer, O.

2015-08-01

Aims: Outflows driven by active galactic nuclei (AGN) are invoked by galaxy evolutionary models to quench star formation and to explain the origin of the relations observed locally between super-massive black holes and their host galaxies. We here aim to detect extended ionised outflows in luminous quasars, where we expect the highest activity both in star formation and in black-hole accretion. Currently, there are only a few studies based on spatially resolved observations of outflows at high redshift, z > 2. Methods: We analysed a sample of six luminous (L > 1047 erg/s) quasars at z ~ 2.4, observed in H-band using the near-IR integral field spectrometer SINFONI at the VLT. We performed a kinematic analysis of the [Oiii] emission line at λ = 5007 Å. Results: We detect fast, spatially extended outflows in five out of six targets. [Oiii]λ5007 has a complex gas kinematic, with blue-shifted velocities of a few hundreds of km s-1 and line widths up to 1500 km s-1. Using the spectroastrometric method, we infer a size of the ionised outflows of up to ~2 kpc. The properties of the ionised outflows, mass outflow rate, momentum rate, and kinetic power, are correlated with the AGN luminosity. The increase in outflow rate with increasing AGN luminosity is consistent with the idea that a luminous AGN pushes away the surrounding gas through fast outflows that are driven by radiation pressure, which depends on the emitted luminosity. Conclusions: We derive mass outflow rates of about 6-700 M⊙ yr-1 for our sample, which are lower than those observed in molecular outflows. The physical properties of ionised outflows show dependences on AGN luminosity that are similar to those of molecular outflows, but indicate that the mass of ionised gas is lower than that of molecular outflows. Alternatively, this discrepancy between ionised and molecular outflows could be explained with different acceleration mechanisms. Based on Observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile, P.ID: 086.B-0579(A).

GRACE Gravity Data Target Possible Mega-impact in North Central Wilkes Land, Antarctica

NASA Technical Reports Server (NTRS)

vonFrese, Ralph R. B.; Wells, Stuart B.; Potts. Laramie V.; Gaya-Pique, Luis R.; Golynsky, Alexander V.; Hernandez, Orlando; Kim, Jeong Woo; Kim, Hyung Rae; Hwang, Jong Sun; Taylor, Patrick T.

2005-01-01

A prominent positive GRACE satellite-measured free-air gravity anomaly over regionally depressed subglacial topography may identify a mascon centered on (70 deg S, 120 deg E) between the Gamburtsev and Transantarctic Mountains of East Antarctica. Being more than twice the size of the Chicxulub crater, the inferred Wilkes Land impact crater is a strong candidate for a Gondwana source of the greatest extinction of life at the end of the Permian. Its ring structure intersects the coastline and thus may have strongly influenced the Cenozoic rifting of East Antarctica from Australia that resulted in the enigmatic lack of crustal thinning on the conjugate Australian block.

1 Hz FLARING IN SAX J1808.4-3658: FLOW INSTABILITIES NEAR THE PROPELLER STAGE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Patruno, Alessandro; Watts, Anna; Klein Wolt, Marc

2009-12-20

We present a simultaneous periodic and aperiodic timing study of the accreting millisecond X-ray pulsar SAX J1808.4-3658. We analyze five outbursts of the source and for the first time provide a full and systematic investigation of the enigmatic phenomenon of the 1 Hz flares observed during the final stages of some of the outbursts. We show that links between pulsations and 1 Hz flares might exist, and suggest that they are related with hydrodynamic disk instabilities that are triggered close to the disk-magnetosphere boundary layer when the system is entering the propeller regime.

The Hermetic Frontispiece: Contextualising John Dee's Hieroglyphic Monad.

PubMed

Forshaw, Peter J

2017-05-01

This essay examines the elaborate title pages of some of alchemist, astrologer, and bibliophile John Dee's publications with a focus on the two best known works that feature his famous Hieroglyphic Monad, the Propaedeumata Aphoristica (1558) and Monas Hieroglyphica (1564). The aim is to cast light on its context, identify sources for some textual influences in the works, unpack the visual symbolism in the two "monadic" title pages in relation to the two complementary sciences of "superior" and "inferior" astronomy, speculate on some of the more enigmatic details, and conclude with a brief discussion of a possible astrological significance to the dates of composition of the Monas Hieroglyphica.

Massive outflow properties suggest AGN fade slowly

NASA Astrophysics Data System (ADS)

Zubovas, Kastytis

2018-01-01

Massive large-scale active galactic nucleus (AGN) outflows are an important element of galaxy evolution, being a way through which the AGN can affect most of the host galaxy. However, outflows evolve on time-scales much longer than typical AGN episode durations, therefore most AGN outflows are not observed simultaneously with the AGN episode that inflated them. It is therefore remarkable that rather tight correlations between outflow properties and AGN luminosity exist. In this paper, I show that such correlations can be preserved during the fading phase of the AGN episode, provided that the AGN luminosity evolves as a power law with exponent αd ∼ 1 at late times. I also show that subsequent AGN episodes that illuminate an ongoing outflow are unlikely to produce outflow momentum or energy rates rising above the observed correlations. However, there may be many difficult-to-detect outflows with momentum and energy rates lower than expected from the current AGN luminosity. Detailed observations of AGN outflow properties might help constrain the activity histories of typical and/or individual AGN.

Reducing pathogens in combined sewer overflows using ozonation or UV irradiation.

PubMed

Tondera, Katharina; Klaer, Kassandra; Gebhardt, Jens; Wingender, Jost; Koch, Christoph; Horstkott, Marina; Strathmann, Martin; Jurzik, Lars; Hamza, Ibrahim Ahmed; Pinnekamp, Johannes

2015-11-01

Fecal contamination of water resources is a major public health concern in densely populated areas since these water bodies are used for drinking water production or recreational purposes. A main source of this contamination originates from combined sewer overflows (CSOs) in regions with combined sewer systems. Thus, the treatment of CSO discharges is urgent. In this study, we explored whether ozonation or UV irradiation can efficiently reduce pathogenic bacteria, viruses, and protozoan parasites in CSOs. Experiments were carried out in parallel settings at the outflow of a stormwater settling tank in the Ruhr area, Germany. The results showed that both techniques reduce most hygienically relevant bacteria, parasites and viruses. Under the conditions tested, ozonation yielded lower outflow values for the majority of the tested parameters. Copyright © 2015 Elsevier GmbH. All rights reserved.

Simulating Supernovae Driven Outflows in Dwarf Galaxies

NASA Astrophysics Data System (ADS)

Rodriguez, Jaimee-Ian

2018-01-01

Galactic outflows, or winds, prove to be a necessary input for galactic simulations to produce results comparable to observation, for it solves issues caused by what previous literature dubbed the “angular momentum catastrophe.” While it is known that the nature of outflows depends on the nature of the Interstellar Medium (ISM), the mechanisms behind outflows are still not completely understood. We investigate the driving force behind galactic outflows and the factors that influence their behavior, hypothesizing that supernovae within the galaxy drive these winds. We study isolated, high-resolution, smooth particle hydrodynamic simulations, focusing specifically on dwarf galaxies due to their shallow potential wells, which allow for more significant outflows. We find that outflows follow star formation (and associated supernovae) suggesting the causal relationship between the two. Furthermore, simulations with higher diffusivity differ little in star formation rate, but show significantly lower outflow rates, suggesting that environmental factors that have little effect on regulating star formation can greatly influence outflows, and so efficient outflows can be driven by a constant rate of supernovae, depending on ISM behavior. We are currently analyzing disk morphology and ambient density in order to comprehend the effect of supernovae on the immediate interstellar gas. By attaining greater understanding of the origin of galactic outflows, we will be able to not only improve the accuracy of simulations, we will also be able to gain greater insight into galactic formation and evolution, as outflows and resultant inflows may be vital to the regulation of galaxies throughout their lifetimes.

The Broadband Spectral Variability of Holmberg IX X-1

NASA Astrophysics Data System (ADS)

Walton, D. J.; Fürst, F.; Harrison, F. A.; Middleton, M. J.; Fabian, A. C.; Bachetti, M.; Barret, D.; Miller, J. M.; Ptak, A.; Rana, V.; Stern, D.; Tao, L.

2017-04-01

We present results from four new broadband X-ray observations of the extreme ultraluminous X-ray source Holmberg IX X-1 ({L}{{X}}> {10}40 erg s-1), performed by Suzaku and NuSTAR in coordination. Combined with the archival data, we now have broadband observations of this remarkable source from six separate epochs. Two of these new observations probe lower fluxes than seen previously, allowing us to extend our knowledge of the broadband spectral variability exhibited. The spectra are well fit by two thermal blackbody components that dominate the emission below 10 keV, as well as a steep ({{Γ }}˜ 3.5) power-law tail that dominates above ˜15 keV. Remarkably, while the 0.3-10.0 keV flux varies by a factor of ˜3 between all these epochs, the 15-40 keV flux varies by only ˜20%. Although the spectral variability is strongest in the ˜1-10 keV band, both of the thermal components are required to vary when all epochs are considered. We also revisit the search for iron absorption features by leveraging the high-energy NuSTAR data to improve our sensitivity to extreme velocity outflows in light of the ultra-fast outflow recently detected in NGC 1313 X-1. Iron absorption from a similar outflow along our line of sight can be ruled out in this case. We discuss these results in the context of super-Eddington accretion models that invoke a funnel-like geometry for the inner flow, and propose a scenario in which we have an almost face-on view of a funnel that expands to larger radii with increasing flux, resulting in an increasing degree of geometrical collimation for the emission from intermediate-temperature regions.

Pulsar emission amplified and resolved by plasma lensing in an eclipsing binary.

PubMed

Main, Robert; Yang, I-Sheng; Chan, Victor; Li, Dongzi; Lin, Fang Xi; Mahajan, Nikhil; Pen, Ue-Li; Vanderlinde, Keith; van Kerkwijk, Marten H

2018-05-01

Radio pulsars scintillate because their emission travels through the ionized interstellar medium along multiple paths, which interfere with each other. It has long been realized that, independent of their nature, the regions responsible for the scintillation could be used as 'interstellar lenses' to localize pulsar emission regions 1,2 . Most such lenses, however, resolve emission components only marginally, limiting results to statistical inferences and detections of small positional shifts 3-5 . As lenses situated close to their source offer better resolution, it should be easier to resolve emission regions of pulsars located in high-density environments such as supernova remnants 6 or binaries in which the pulsar's companion has an ionized outflow. Here we report observations of extreme plasma lensing in the 'black widow' pulsar, B1957+20, near the phase in its 9.2-hour orbit at which its emission is eclipsed by its companion's outflow 7-9 . During the lensing events, the observed radio flux is enhanced by factors of up to 70-80 at specific frequencies. The strongest events clearly resolve the emission regions: they affect the narrow main pulse and parts of the wider interpulse differently. We show that the events arise naturally from density fluctuations in the outer regions of the outflow, and we infer a resolution of our lenses that is comparable to the pulsar's radius, about 10 kilometres. Furthermore, the distinct frequency structures imparted by the lensing are reminiscent of what is observed for the repeating fast radio burst FRB 121102, providing observational support for the idea that this source is observed through, and thus at times strongly magnified by, plasma lenses 10 .

Swift observations of V404 Cyg during the 2015 outburst: X-ray outflows from super-Eddington accretion

NASA Astrophysics Data System (ADS)

Motta, S. E.; Kajava, J. J. E.; Sánchez-Fernández, C.; Beardmore, A. P.; Sanna, A.; Page, K. L.; Fender, R.; Altamirano, D.; Charles, P.; Giustini, M.; Knigge, C.; Kuulkers, E.; Oates, S.; Osborne, J. P.

2017-10-01

The black hole (BH) binary V404 Cyg entered the outburst phase in 2015 June after 26 yr of X-ray quiescence, and with its behaviour broke the outburst evolution pattern typical of most BH binaries. We observed the entire outburst with the Swift satellite and performed time-resolved spectroscopy of its most active phase, obtaining over a thousand spectra with exposures from tens to hundreds of seconds. All the spectra can be fitted with an absorbed power-law model, which most of the time required the presence of a partial covering. A blueshifted iron-Kα line appears in 10 per cent of the spectra together with the signature of high column densities, and about 20 per cent of the spectra seem to show signatures of reflection. None of the spectra showed the unambiguous presence of soft disc-blackbody emission, while the observed bolometric flux exceeded the Eddington value in 3 per cent of the spectra. Our results can be explained assuming that the inner part of the accretion flow is inflated into a slim disc that both hides the innermost (and brightest) regions of the flow, and produces a cold, clumpy, high-density outflow that introduces the high absorption and fast spectral variability observed. We argue that the BH in V404 Cyg might have been accreting erratically or even continuously at Eddington/super-Eddington rates - thus sustaining a surrounding slim disc - while being partly or completely obscured by the inflated disc and its outflow. Hence, the largest flares produced by the source might not be accretion-driven events, but instead the effects of the unveiling of the extremely bright source hidden within the system.

Light breeze in the local Universe

NASA Astrophysics Data System (ADS)

Concas, A.; Popesso, P.; Brusa, M.; Mainieri, V.; Erfanianfar, G.; Morselli, L.

2017-10-01

We analyze a complete spectroscopic sample of galaxies ( 600 000) drawn from Sloan Digital Sky Survey (SDSS, DR7) to look for evidence of galactic winds in the local Universe. We focus on the shape of the [OIII]λ5007 emission line as a tracer of ionizing gas outflows. We stack our spectra in a fine grid of star formation rate (SFR) and stellar mass to analyze the dependence of winds on the position of galaxies in the SFR versus mass diagram. We do not find any significant evidence of broad and shifted [OIII]λ5007 emission line which we interpret as no evidence of outflowing ionized gas in the global population. We have also classified these galaxies as star-forming or AGN-dominated according to their position in the standard BPT diagram. We show how the average [OIII]λ5007 profile changes as a function of the nature of the dominant ionizing source. We find that in the star-forming dominated source the oxygen line is symmetric and governed by the gravitational potential well. The AGN or composite AGN/star-formation activity objects, in contrast, display a prominent and asymmetric profile that can be well described by a broad Gaussian component that is blue-shifted from a narrow symmetric core. In particular, we find that the blue wings of the average [OIII]λ5007 profiles are increasingly prominent in the LINERs and Seyfert galaxies. We conclude that, through the identification of strong bulk motion as traced by the warm ionized gas, in the low-redshift Universe, "pure" star-formation activity does not seem capable of driving ionized-gas outflows, while, the presence of optically selected AGN seems to play a primary role. We discuss the implications of these results for the role of the quenching mechanism in the present-day Universe.

Pulsar emission amplified and resolved by plasma lensing in an eclipsing binary

NASA Astrophysics Data System (ADS)

Main, Robert; Yang, I.-Sheng; Chan, Victor; Li, Dongzi; Lin, Fang Xi; Mahajan, Nikhil; Pen, Ue-Li; Vanderlinde, Keith; van Kerkwijk, Marten H.

2018-05-01

Radio pulsars scintillate because their emission travels through the ionized interstellar medium along multiple paths, which interfere with each other. It has long been realized that, independent of their nature, the regions responsible for the scintillation could be used as `interstellar lenses' to localize pulsar emission regions1,2. Most such lenses, however, resolve emission components only marginally, limiting results to statistical inferences and detections of small positional shifts3-5. As lenses situated close to their source offer better resolution, it should be easier to resolve emission regions of pulsars located in high-density environments such as supernova remnants6 or binaries in which the pulsar's companion has an ionized outflow. Here we report observations of extreme plasma lensing in the `black widow' pulsar, B1957+20, near the phase in its 9.2-hour orbit at which its emission is eclipsed by its companion's outflow7-9. During the lensing events, the observed radio flux is enhanced by factors of up to 70-80 at specific frequencies. The strongest events clearly resolve the emission regions: they affect the narrow main pulse and parts of the wider interpulse differently. We show that the events arise naturally from density fluctuations in the outer regions of the outflow, and we infer a resolution of our lenses that is comparable to the pulsar's radius, about 10 kilometres. Furthermore, the distinct frequency structures imparted by the lensing are reminiscent of what is observed for the repeating fast radio burst FRB 121102, providing observational support for the idea that this source is observed through, and thus at times strongly magnified by, plasma lenses10.

The Broadband Spectral Variability of Holmberg IX X-1

NASA Technical Reports Server (NTRS)

Walton, D.J.; Furst, F.; Harrison, F.A.; Middleton, M.J.; Fabian, A. C.; Bachetti, M.; Barret, D.; Miller, J. M.; Ptak, A.; Rana, V.;

Effect of incremental levels of sunflower-seed oil in the diet on ruminal lipid metabolism in lactating cows.

PubMed

Shingfield, K J; Ahvenjärvi, S; Toivonen, V; Vanhatalo, A; Huhtanen, P; Griinari, J M

2008-05-01

Based on the potential benefits of cis-9, trans-11-conjugated linoleic acid (CLA) for human health there is interest in developing sustainable nutritional strategies for enhancing the concentration of this fatty acid in ruminant-derived foods. Most evidence to date suggests that endogenous synthesis is the major source of cis-9, trans-11 in milk fat and ruminal outflow is limited and largely independent of dietary 18 : 2n-6 supply. Four lactating cows fitted with a rumen cannula were used in a 4 x 4 Latin square with 14 d experimental periods to examine the effects of sunflower-seed oil (SFO) as a source of 18 : 2n-6 on ruminal lipid metabolism. Cows were offered grass silage-based diets supplemented with 0, 250, 500 or 750 g SFO/d. Supplements of SFO had no effect on DM intake, milk fat or protein secretion, but increased linearly (P < 0.01) milk yield and milk lactose output and shifted (P < 0.001) rumen fermentation towards propionate at the expense of acetate. SFO supplements increased linearly (P < 0.05) the flow of 18 : 0, 18 : 1, 18 : 2n-6 and total CLA at the omasum and enhanced ruminal cis-9-18 : 1, 18 : 2n-6 and 18 : 3n-3 metabolism. Flows of all-trans- (Delta4-16) and cis- (Delta9-16) 18 : 1 isomers were elevated, while increases in ruminal CLA outflow were confined to trans-8, trans-10 and geometric 9,11 and 10,12 isomers. It is concluded that supplementing grass silage-based diets with plant oils rich in 18 : 2n-6 enhances ruminal outflow of trans-11-18 : 1 and cis-9, trans-11-CLA in lactating cows.

Quantifying the AGN-driven outflows in ULIRGs (QUADROS) II: evidence for compact outflow regions from HST [OIII] imaging observations

NASA Astrophysics Data System (ADS)

Tadhunter, C.; Zaurín, J. Rodríguez; Rose, M.; Spence, R. A. W.; Batcheldor, D.; Berg, M. A.; Ramos Almeida, C.; Spoon, H. W. W.; Sparks, W.; Chiaberge, M.

2018-05-01

The true importance of the warm, AGN-driven outflows for the evolution of galaxies remains uncertain. Measurements of the radial extents of the outflows are key for quantifying their masses and kinetic powers, and also establishing whether the AGN outflows are galaxy-wide. Therefore, as part of a larger project to investigate the significance of warm, AGN-driven outflows in the most rapidly evolving galaxies in the local universe, here we present deep Hubble Space Telescope (HST) narrow-band [OIII]λ5007 observations of a complete sample of 8 nearby ULIRGs with optical AGN nuclei. Combined with the complementary information provided by our ground-based spectroscopy, the HST images show that the warm gas outflows are relatively compact for most of the objects in the sample: in three objects the outflow regions are barely resolved at the resolution of HST (0.065 < R[OIII] < 0.12 kpc); in a further four cases the outflows are spatially resolved but with flux weighted mean radii in the range 0.65 < R[OIII] < 1.2 kpc; and in only one object (Mrk273) is there clear evidence for a more extended outflow, with a maximum extent of R[OIII] ˜ 5 kpc. Overall, our observations show little evidence for the galaxy-wide outflows predicted by some models of AGN feedback.

The Swift Burst Alert Telescope Detected Seyfert 1 Galaxies: X-Ray Broadband Properties and Warm Absorbers

NASA Technical Reports Server (NTRS)

Winter, Lisa M.; Veilleux, Sylvain; McKernan, Barry; Kallman, T.

2012-01-01

We present results from an analysis of the broadband, 0.3-195 keV, X-ray spectra of 48 Seyfert 1-1.5 sources detected in the very hard X-rays with the Swift Burst Alert Telescope (BAT). This sample is selected in an all-sky survey conducted in the 14-195 keV band. Therefore, our sources are largely unbiased toward both obscuration and host galaxy properties. Our detailed and uniform model fits to Suzaku/BAT and XMM-Newton/BAT spectra include the neutral absorption, direct power-law, reflected emission, soft excess, warm absorption, and narrow Fe I K[alpha] emission properties for the entire sample. We significantly detect O VII and O VIII edges in 52% of our sample. The strength of these detections is strongly correlated with the neutral column density measured in the spectrum. Among the strongest detections, X-ray grating and UV observations, where available, indicate outflowing material. The ionized column densities of sources with O VII and O VIII detections are clustered in a narrow range with Nwarm [approx] 1021 cm-2, while sources without strong detections have column densities of ionized gas an order of magnitude lower. Therefore, we note that sources without strong detections likely have warm ionized outflows present but at low column densities that are not easily probed with current X-ray observations. Sources with strong complex absorption have a strong soft excess, which may or may not be due to difficulties in modeling the complex spectra of these sources. Still, the detection of a flat [Gamma] [approx] 1 and a strong soft excess may allow us to infer the presence of strong absorption in low signal-to-noise active galactic nucleus spectra. Additionally, we include a useful correction from the Swift BAT luminosity to bolometric luminosity, based on a comparison of our spectral fitting results with published spectral energy distribution fits from 33 of our sources.

ALMA Images of the Orion Hot Core at 349 GHz

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wright, M. C. H.; Plambeck, R. L., E-mail: wright@astro.berkeley.edu

We present ALMA images of the dust and molecular line emission in the Orion Hot Core at 349 GHz. At 0.″2 angular resolution the images reveal multiple clumps in an arc ∼1″ east of Orion Source I, the protostar at the center of the Kleinmann–Low Nebula, and another chain of peaks from IRc7 toward the southwest. The molecular line images show narrow filamentary structures at velocities >10 km s{sup −1} away from the heavily resolved ambient cloud velocity ∼5 km s{sup −1}. Many of these filaments trace the SiO outflow from Source I, and lie along the edges of themore » dust emission. Molecular line emission at excitation temperatures 300–2000 K, and velocities >10 km s{sup −1} from the ambient cloud, suggest that the Hot Core may be heated in shocks by the outflow from Source I or from the Becklin–Neugebauer (BN)/SrcI explosion. The spectral line observations also reveal a remarkable molecular ring, ∼2″ south of SrcI, with a diameter ∼600 au. The ring is seen in high-excitation transitions of HC{sub 3}N, HCN v 2 = 1, and SO{sub 2}. An impact of ejecta from the BN/SrcI explosion with a dense dust clump could result in the observed ring of shocked material.« less

Impact of urban WWTP and CSO fluxes on river peak flow extremes under current and future climate conditions.

PubMed

Keupers, Ingrid; Willems, Patrick

2013-01-01

The impact of urban water fluxes on the river system outflow of the Grote Nete catchment (Belgium) was studied. First the impact of the Waste Water Treatment Plant (WWTP) and the Combined Sewer Overflow (CSO) outflows on the river system for the current climatic conditions was determined by simulating the urban fluxes as point sources in a detailed, hydrodynamic river model. Comparison was made of the simulation results on peak flow extremes with and without the urban point sources. In a second step, the impact of climate change scenarios on the urban fluxes and the consequent impacts on the river flow extremes were studied. It is shown that the change in the 10-year return period hourly peak flow discharge due to climate change (-14% to +45%) was in the same order of magnitude as the change due to the urban fluxes (+5%) in current climate conditions. Different climate change scenarios do not change the impact of the urban fluxes much except for the climate scenario that involves a strong increase in rainfall extremes in summer. This scenario leads to a strong increase of the impact of the urban fluxes on the river system.

TESTING WIND AS AN EXPLANATION FOR THE SPIN PROBLEM IN THE CONTINUUM-FITTING METHOD

DOE Office of Scientific and Technical Information (OSTI.GOV)

You, Bei; Czerny, Bożena; Sobolewska, Małgosia

2016-04-20

The continuum-fitting method is one of the two most advanced methods of determining the black hole spin in accreting X-ray binary systems. There are, however, still some unresolved issues with the underlying disk models. One of these issues manifests as an apparent decrease in spin for increasing source luminosity. Here, we perform a few simple tests to establish whether outflows from the disk close to the inner radius can address this problem. We employ four different parametric models to describe the wind and compare these to the apparent decrease in spin with luminosity measured in the sources LMC X-3 andmore » GRS 1915+105. Wind models in which parameters do not explicitly depend on the accretion rate cannot reproduce the spin measurements. Models with mass accretion rate dependent outflows, however, have spectra that emulate the observed ones. The assumption of a wind thus effectively removes the artifact of spin decrease. This solution is not unique; the same conclusion can be obtained using a truncated inner disk model. To distinguish among the valid models, we will need high-resolution X-ray data and a realistic description of the Comptonization in the wind.« less

Correlated fast X-ray and optical variability in the black-hole candidate XTE J1118+480.

PubMed

Kanbach, G; Straubmeier, C; Spruit, H C; Belloni, T

2001-11-08

Black holes become visible when they accrete gas, a common source of which is a close stellar companion. The standard theory for this process (invoking a 'thin accretion disk') does not explain some spectacular phenomena associated with these systems, such as their X-ray variability and relativistic outflows, indicating some lack of understanding of the actual physical conditions. Simultaneous observations at multiple wavelengths can provide strong constraints on these conditions. Here we report simultaneous high-time-resolution X-ray and optical observations of the transient source XTE J1118+480, which show a strong but puzzling correlation between the emissions. The optical emission rises suddenly following an increase in the X-ray output, but with a dip 2-5 seconds in advance of the X-rays. This result is not easy to understand within the simplest model of the optical emission, where the light comes from reprocessed X-rays. It is probably more consistent with an earlier suggestion that the optical light is cyclosynchrotron emission that originates in a region about 20,000 km from the black hole. We propose that the time dependence is evidence for a relatively slow (<0.1c), magnetically controlled outflow.

On the Fraction of Quasars with Outflows

NASA Astrophysics Data System (ADS)

Ganguly, Rajib; Brotherton, Michael S.

2008-01-01

Outflows from active galactic nuclei (AGNs) seem to be common and are thought to be important from a variety of perspectives: as an agent of chemical enhancement of the interstellar and intergalactic media, as an agent of angular momentum removal from the accreting central engine, and as an agent limiting star formation in starbursting systems by blowing out gas and dust from the host galaxy. To understand these processes, we must determine what fraction of AGNs feature outflows and understand what forms they take. We examine recent surveys of quasar absorption lines, reviewing the best means to determine if systems are intrinsic and result from outflowing material, and the limitations of approaches taken to date. The surveys reveal that, while the fraction of specific forms of outflows depends on AGN properties, the overall fraction displaying outflows is fairly constant, approximately 60%, over many orders of magnitude in luminosity. We emphasize some issues concerning classification of outflows driven by data type rather than necessarily the physical nature of outflows and illustrate how understanding outflows probably requires a more comprehensive approach than has usually been taken in the past.

Ground-Water Budgets for the Wood River Valley Aquifer System, South-Central Idaho, 1995-2004

USGS Publications Warehouse

Bartolino, James R.

2009-01-01

The Wood River Valley contains most of the population of Blaine County and the cities of Sun Valley, Ketchum, Haley, and Bellevue. This mountain valley is underlain by the alluvial Wood River Valley aquifer system which consists of a single unconfined aquifer that underlies the entire valley, an underlying confined aquifer that is present only in the southernmost valley, and the confining unit that separates them. The entire population of the area depends on ground water for domestic supply, either from domestic or municipal-supply wells, and rapid population growth since the 1970s has caused concern about the long-term sustainability of the ground-water resource. To help address these concerns this report describes a ground-water budget developed for the Wood River Valley aquifer system for three selected time periods: average conditions for the 10-year period 1995-2004, and the single years of 1995 and 2001. The 10-year period 1995-2004 represents a range of conditions in the recent past for which measured data exist. Water years 1995 and 2001 represent the wettest and driest years, respectively, within the 10-year period based on precipitation at the Ketchum Ranger Station. Recharge or inflow to the Wood River Valley aquifer system occurs through seven main sources (from largest to smallest): infiltration from tributary canyons, streamflow loss from the Big Wood River, areal recharge from precipitation and applied irrigation water, seepage from canals and recharge pits, leakage from municipal pipes, percolation from septic systems, and subsurface inflow beneath the Big Wood River in the northern end of the valley. Total estimated mean annual inflow or recharge to the aquifer system for 1995-2004 is 270,000 acre-ft/yr (370 ft3/s). Total recharge for the wet year 1995 and the dry year 2001 is estimated to be 270,000 acre-ft/yr (370 ft3/s) and 220,000 acre-ft/yr (300 ft3/s), respectively. Discharge or outflow from the Wood River Valley aquifer system occurs through five main sources (from largest to smallest): Silver Creek streamflow gain, ground-water pumpage, Big Wood River streamflow gain, direct evapotranspiration from riparian vegetation, and subsurface outflow (treated separately). Total estimated mean 1995-2004 annual outflow or discharge from the aquifer system is 250,000 acre-ft/yr (350 ft3/s). Estimated total discharge is 240,000 acre-ft/yr (330 ft3/s) for both the wet year 1995 and the dry year 2001. The budget residual is the difference between estimated ground-water inflow and outflow and encompasses subsurface outflow, ground-water storage change, and budget error. For 1995-2004, mean annual inflow exceeded outflow by 20,000 acre-ft/yr (28 ft3/s); for the wet year 1995, mean annual inflow exceeded outflow by 30,000 acre-ft/yr (41 ft3/s); for the dry year 2001, mean annual outflow exceeded inflow by 20,000 acre-ft/yr (28 ft3/s). These values represent 8, 13, and 8 percent, respectively, of total outflows for the same periods. It is difficult to differentiate the relative contributions of the three residual components, although the estimated fluctuations between the wet and dry year budgets likely are primarily caused by changes in ground-water storage. The individual components in the wet and dry year ground-water budgets responded in a consistent manner to changes in precipitation and temperature. Although the ground-water budgets for the three periods indicated that ground-water storage is replenished in wet years, statistical analyses by Skinner and others (2007) suggest that such replenishment is not complete and over the long term more water is removed from storage than is replaced. In other words, despite restoration of water to ground-water storage in wet years, changes have occurred in either recharge and (or) discharge to cause ground-water storage to decline over time. Such changes may include, but are not limited to: lining or abandoning canals and ditches, conversion of surface-water irriga

Two separate outflows in the dual supermassive black hole system NGC 6240

NASA Astrophysics Data System (ADS)

Müller-Sánchez, F.; Nevin, R.; Comerford, J. M.; Davies, R. I.; Privon, G. C.; Treister, E.

2018-04-01

Theoretical models and numerical simulations have established a framework of galaxy evolution in which galaxies merge and create dual supermassive black holes (with separations of one to ten kiloparsecs), which eventually sink into the centre of the merger remnant, emit gravitational waves and coalesce. The merger also triggers star formation and supermassive black hole growth, and gas outflows regulate the stellar content1-3. Although this theoretical picture is supported by recent observations of starburst-driven and supermassive black hole-driven outflows4-6, it remains unclear how these outflows interact with the interstellar medium. Furthermore, the relative contributions of star formation and black hole activity to galactic feedback remain unknown7-9. Here we report observations of dual outflows in the central region of the prototypical merger NGC 6240. We find a black-hole-driven outflow of [O iii] to the northeast and a starburst-driven outflow of Hα to the northwest. The orientations and positions of the outflows allow us to isolate them spatially and study their properties independently. We estimate mass outflow rates of 10 and 75 solar masses per year for the Hα bubble and the [O iii] cone, respectively. Their combined mass outflow is comparable to the star formation rate10, suggesting that negative feedback on star formation is occurring.

Two separate outflows in the dual supermassive black hole system NGC 6240.

PubMed

Müller-Sánchez, F; Nevin, R; Comerford, J M; Davies, R I; Privon, G C; Treister, E

2018-04-01

Theoretical models and numerical simulations have established a framework of galaxy evolution in which galaxies merge and create dual supermassive black holes (with separations of one to ten kiloparsecs), which eventually sink into the centre of the merger remnant, emit gravitational waves and coalesce. The merger also triggers star formation and supermassive black hole growth, and gas outflows regulate the stellar content 1-3 . Although this theoretical picture is supported by recent observations of starburst-driven and supermassive black hole-driven outflows 4-6 , it remains unclear how these outflows interact with the interstellar medium. Furthermore, the relative contributions of star formation and black hole activity to galactic feedback remain unknown 7-9 . Here we report observations of dual outflows in the central region of the prototypical merger NGC 6240. We find a black-hole-driven outflow of [O III] to the northeast and a starburst-driven outflow of Hα to the northwest. The orientations and positions of the outflows allow us to isolate them spatially and study their properties independently. We estimate mass outflow rates of 10 and 75 solar masses per year for the Hα bubble and the [O III] cone, respectively. Their combined mass outflow is comparable to the star formation rate 10 , suggesting that negative feedback on star formation is occurring.

High spectral resolution spectroscopy of the SiO fundamental lines in red giants and red supergiants with VLT/VISIR

NASA Astrophysics Data System (ADS)

Ohnaka, K.

2014-01-01

Context. The mass-loss mechanism in red giants and red supergiants is not yet understood well. The SiO fundamental lines near 8 μm are potentially useful for probing the outer atmosphere, which is essential for clarifying the mass-loss mechanism. However, these lines have been little explored until now. Aims: We present high spectral resolution spectroscopic observations of the SiO fundamental lines near 8.1 μm in 16 bright red giants and red supergiants. Our sample consists of seven normal (i.e., non-Mira) K-M giants (from K1.5 to M6.5), three Mira stars, three optically bright red supergiants, two dusty red supergiants, and the enigmatic object GCIRS3 near the Galactic center. Methods: Our program stars were observed between 8.088 μm and 8.112 μm with a spectral resolution of 30 000 using VLT/VISIR. Results: We detected SiO fundamental lines in all of our program stars except for GCIRS3. The SiO lines in normal K and M giants as well as optically bright (i.e., not dusty) red supergiants do not show P-Cyg profiles or blueshifts, which means the absence of systematic outflows in the SiO line forming region. We detected P-Cyg profiles in the SiO lines in the dusty red supergiants VY CMa and VX Sgr, with the latter object being a new detection. These SiO lines originate in the outflowing gas with the thermal dust continuum emission seen as the background. The outflow velocities of the SiO line forming region in VY CMa and VX Sgr are estimated to be 27 km s-1 and 17 km s-1, respectively. We derived basic stellar parameters (effective temperature, surface gravity, luminosity, and mass) for the normal K-M giants and optically bright red supergiants in our sample and compared the observed VISIR spectra with synthetic spectra predicted from MARCS photospheric models. Most of the SiO lines observed in the program stars warmer than ~3400 K are reasonably reproduced by the MARCS models, which allowed us to estimate the silicon abundance as well as the 28Si/29Si and 28Si/30Si ratios. However, we detected possible absorption excess in some SiO lines. Moreover, the SiO lines in the cooler red giants and red supergiant cannot be explained by the MARCS models at all, even if the dust emission is taken into account. This disagreement may be a signature of the dense, extended molecular outer atmosphere. Based on VISIR observations made with the Very Large Telescope of the European Southern Observatory. Program ID: 087.D-0522(A).Reduced spectra are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/561/A47

Study of the Outflow and Disk surrounding a Post-Outburst FU-Orionis Star

NASA Astrophysics Data System (ADS)

Mellon, Samuel N.; Perez, L. M.

2014-01-01

PP 13 is a fan-shaped cometary nebula located in the constellation of Perseus and embedded in the L1473 dark cloud. At optical wavelengths this region is obscured by the surrounding dark cloud, while at infrared and longer wavelengths two northern objects (PP13Na & PP13Nb) and one southern object (PP13S) are revealed. In the past, the young stellar object inside PP13S, called PP13S*, experienced an FU-Orionis type outburst due to a massive accretion episode and is currently returning to its quiescent state. Studying the FU-Orionis phase is crucial to our understanding of how low mass stars form; it is theorized that all low-mass stars go through this outburst phase while they are forming. I used CARMA 3mm interferometric observations of the PP13 region to study the continuum and molecular line emissions from PP13. With these observations, I determined the source of the previously detected outflow and learned new information about the double star system PP13Na and PP13Nb. Although I was not able to detect the accretion disk in the gas emissions, I plan to use computer modeling to help provide constraints on the properties of PP13S* and its outflow.

Mechanism of the 2015 volcanic tsunami earthquake near Torishima, Japan

PubMed Central

Satake, Kenji

2018-01-01

Tsunami earthquakes are a group of enigmatic earthquakes generating disproportionally large tsunamis relative to seismic magnitude. These events occur most typically near deep-sea trenches. Tsunami earthquakes occurring approximately every 10 years near Torishima on the Izu-Bonin arc are another example. Seismic and tsunami waves from the 2015 event [Mw (moment magnitude) = 5.7] were recorded by an offshore seafloor array of 10 pressure gauges, ~100 km away from the epicenter. We made an array analysis of dispersive tsunamis to locate the tsunami source within the submarine Smith Caldera. The tsunami simulation from a large caldera-floor uplift of ~1.5 m with a small peripheral depression yielded waveforms remarkably similar to the observations. The estimated central uplift, 1.5 m, is ~20 times larger than that inferred from the seismologically determined non–double-couple source. Thus, the tsunami observation is not compatible with the published seismic source model taken at face value. However, given the indeterminacy of Mzx, Mzy, and M{tensile} of a shallow moment tensor source, it may be possible to find a source mechanism with efficient tsunami but inefficient seismic radiation that can satisfactorily explain both the tsunami and seismic observations, but this question remains unresolved. PMID:29740604

Mechanism of the 2015 volcanic tsunami earthquake near Torishima, Japan.

PubMed

Fukao, Yoshio; Sandanbata, Osamu; Sugioka, Hiroko; Ito, Aki; Shiobara, Hajime; Watada, Shingo; Satake, Kenji

2018-04-01

Tsunami earthquakes are a group of enigmatic earthquakes generating disproportionally large tsunamis relative to seismic magnitude. These events occur most typically near deep-sea trenches. Tsunami earthquakes occurring approximately every 10 years near Torishima on the Izu-Bonin arc are another example. Seismic and tsunami waves from the 2015 event [ M w (moment magnitude) = 5.7] were recorded by an offshore seafloor array of 10 pressure gauges, ~100 km away from the epicenter. We made an array analysis of dispersive tsunamis to locate the tsunami source within the submarine Smith Caldera. The tsunami simulation from a large caldera-floor uplift of ~1.5 m with a small peripheral depression yielded waveforms remarkably similar to the observations. The estimated central uplift, 1.5 m, is ~20 times larger than that inferred from the seismologically determined non-double-couple source. Thus, the tsunami observation is not compatible with the published seismic source model taken at face value. However, given the indeterminacy of M zx , M zy , and M {tensile} of a shallow moment tensor source, it may be possible to find a source mechanism with efficient tsunami but inefficient seismic radiation that can satisfactorily explain both the tsunami and seismic observations, but this question remains unresolved.

Star Formation Under the Outflow: The Discovery of a Non-thermal Jet from OMC-2 FIR 3 and Its Relationship to the Deeply Embedded FIR 4 Protostar

DOE Office of Scientific and Technical Information (OSTI.GOV)

Osorio, Mayra; Díaz-Rodríguez, Ana K.; Anglada, Guillem

We carried out multiwavelength (0.7–5 cm), multi-epoch (1994–2015) Very Large Array (VLA) observations toward the region enclosing the bright far-IR sources FIR 3 (HOPS 370) and FIR 4 (HOPS 108) in OMC-2. We report the detection of 10 radio sources, 7 of them identified as young stellar objects. We image a well-collimated radio jet with a thermal free–free core (VLA 11) associated with the Class I intermediate-mass protostar HOPS 370. The jet features several knots (VLA 12N, 12C, 12S) of non-thermal radio emission (likely synchrotron from shock-accelerated relativistic electrons) at distances of ∼7500–12,500 au from the protostar, in a regionmore » where other shock tracers have been previously identified. These knots are moving away from the HOPS 370 protostar at ∼100 km s{sup −1}. The Class 0 protostar HOPS 108, which itself is detected as an independent, kinematically decoupled radio source, falls in the path of these non-thermal radio knots. These results favor the previously proposed scenario in which the formation of HOPS 108 is triggered by the impact of the HOPS 370 outflow with a dense clump. However, HOPS 108 has a large proper motion velocity of ∼30 km s{sup −1}, similar to that of other runaway stars in Orion, whose origin would be puzzling within this scenario. Alternatively, an apparent proper motion could result because of changes in the position of the centroid of the source due to blending with nearby extended emission, variations in the source shape, and/or opacity effects.« less

SOURCES AND SINKS OF NEUTRALS AND PLASMA IN THE SATURNIAN MAGNETOSPHERE (Invited)

NASA Astrophysics Data System (ADS)

Richardson, J. D.

2009-12-01

This talk will review current knowledge on the source and sinks of plasm and energy in Saturn's magnetosphere. Enceladus dominates the water group source, with most of the material escaping from the plume near the southern pole. The relatively low corotation energy in this region results in less energy being available to heat electrons. The electrons are too cold to ionize the neutrals and the inner magnetosphere is dominated by neutrals. In addition, Saturn's atmosphere is a large source of neutral H, the rings contribute O2, and Titan is a source whose magnitude is controversial. In the inner magnetosphere most particles and energy are removed as fast neutrals; transport is more important further out and may be dominated by fingers of inflow and outflow as at Jupiter.

Advances in understanding ventromedial prefrontal function: the accountant joins the executive.

PubMed

Fellows, Lesley K

2007-03-27

Studies of the brain basis of decision-making and economic behavior are providing a new perspective on the organization and functions of human prefrontal cortex. This line of inquiry has focused particularly on the ventral and medial portions of prefrontal cortex, arguably the most enigmatic regions of the "enigmatic frontal lobes." This review highlights recent advances in the cognitive neuroscience of decision making and neuroeconomics and discusses how these findings can inform clinical thinking about frontal lobe dysfunction.

Molecular hydrogen fluorescence and accretion in far-ultraviolet spectra of classical T Tauri stars

NASA Astrophysics Data System (ADS)

Herczeg, Gregory J.

2005-11-01

Far-ultraviolet spectra of classical T Tauri stars reveal accretion, outflows, and H 2 fluorescence. The E140M echelle spectrograph on HST /STIS and the FUSE satellite offer high spectral resolution and broad wavelength coverage, and enables our unique and detailed analysis of the H 2 lines. A strong and broad Lya emission line excites warm H 2 into many levels of the B and C electronic states, from which we can detect as many as 200 H 2 emission lines. These H2 lines are narrow and often asymmetric, with excess blueshifted emission that can extend to 100 km s -1 from some sources. The fluorescent H 2 emission probes diverse environments around CTTSs. High spectral and spatial resolution are essential for identifying the location and studying the kinematics of the gas, which constrain the origin of the H 2 emission. Several other spectral characteristics, including absorption of H2 emission by the wind and H 2 absorption lines, also provide valuable diagnostics of the origin of this emission. The H 2 emission is most likely produced at the surface of a circumstellar disk in some sources, but is produced by outflows from other sources. DF Tau appears to show H 2 emission from both a disk and an outflow. The excitation of H 2 can be determined from relative line strengths by measuring self-absorption in lines with low-energy lower levels, or by reconstructing the Lya profile incident upon the warm H 2 using the total flux from a single upper level and the opacity in the pumping transition. Based on those diagnostics and the rich H 2 spectrum of TW Hya, the H 2 at the warm disk surface has a column density of log N (H 2 ) = [Special characters omitted.] , a temperature T = [Special characters omitted.] K, and a filling factor of H 2 , as seen by the source of Lya emission, of 0.25 +/- 0.08 (all 2s error bars). The total FUV luminosity from CTTSs ranges from 2 x 10 -3 to 3 x 10 -2 [Special characters omitted.] , much of which is in the Lya line. With the exception of the nearby CTTS TW Hya, this Lya emission is mostly or completely hidden from us by H I absorption in the interstellar medium and stellar winds. Since the H 2 emission traces the Lya emission strength at each pumping wavelength, we can reconstruct the Lya emission across the profile. At least 80% of the total FUV emission from TW Hya, DF Tau, and V836 Tau occurs in Lya. A much smaller Lya flux is produced by RU Lupi, T Tau, and DG Tau, although this estimate is affected by several uncertainties, including whether we are estimating the Lya emission produced by the accreting gas or by outflows.

Key Issues in the Production of Ionospheric Outflows

NASA Astrophysics Data System (ADS)

Lotko, W.

2017-12-01

Global models demonstrate that outflows of ionospheric ions can have profound effects on the dynamics of the solar wind-magnetosphere-ionosphere-thermosphere system, particularly during geomagnetic storms. Yet the processes that determine where and when outflows occur are poorly understood, in large part because a full complement of critical multivariable measurements of outflows and their causal drivers has yet to be assembled. Development of accurate regional and global predictive models of outflows has been hampered by this lack of empirical knowledge, but models are also challenged by the additional requirement of having to reduce the complex microphysics of ion energization into lumped relations that specify outflow characteristics through causal regulators. Opportunities to improve understanding of this problem are vast. This overview will focus on a limited set of priority questions that address how ions overcome gravity to leave the ionosphere; the timing, rate, spatial distribution and energetics of their exodus; how their flight impacts the ionosphere-thermosphere environment that spawns outflows; and the influence of magnetospheric feedback on outflow production.

Numerical Study on Outflows in Seyfert Galaxies I: Narrow Line Region Outflows in NGC 4151

NASA Astrophysics Data System (ADS)

Mou, Guobin; Wang, Tinggui; Yang, Chenwei

2017-07-01

The origin of narrow line region (NLR) outflows remains unknown. In this paper, we explore the scenario in which these outflows are circumnuclear clouds driven by energetic accretion disk winds. We choose the well-studied nearby Seyfert galaxy NGC 4151 as an example. By performing 3D hydrodynamical simulations, we are able to reproduce the radial distributions of velocity, mass outflow rate, and kinetic luminosity of NLR outflows in the inner 100 pc deduced from spatial resolved spectroscopic observations. The demanded kinetic luminosity of disk winds is about two orders of magnitude higher than that inferred from the NLR outflows, but is close to the ultrafast outflows (UFO) detected in the X-ray spectrum and a few times lower than the bolometric luminosity of the Seyfert. Our simulations imply that the scenario is viable for NGC 4151. The existence of the underlying disk winds can be confirmed by their impacts on higher density ISM, e.g., shock excitation signs, and the pressure in NLR.

The JCMT Gould Belt Survey: Understanding the influence of outflows on Gould Belt clouds

NASA Astrophysics Data System (ADS)

Drabek-Maunder, E.; Hatchell, J.; Buckle, J. V.; Di Francesco, J.; Richer, J.

2016-03-01

Using James Clerk Maxwell Telescope (JCMT) Gould Belt Survey data from CO J = 3 → 2 isotopologues, we present a meta-analysis of the outflows and energetics of star-forming regions in several Gould Belt clouds. The majority of the regions are strongly gravitationally bound. There is evidence that molecular outflows transport large quantities of momentum and energy. Outflow energies are at least 20 per cent of the total turbulent kinetic energies in all of the regions studied and greater than the turbulent energy in half of the regions. However, we find no evidence that outflows increase levels of turbulence, and there is no correlation between the outflow and turbulent energies. Even though outflows in some regions contribute significantly to maintaining turbulence levels against dissipation, this relies on outflows efficiently coupling to bulk motions. Other mechanisms (e.g. supernovae) must be the main drivers of turbulence in most if not all of these regions.

A Spatially Continuous Model of Carbohydrate Digestion and Transport Processes in the Colon

PubMed Central

Moorthy, Arun S.; Brooks, Stephen P. J.; Kalmokoff, Martin; Eberl, Hermann J.

2015-01-01

A spatially continuous mathematical model of transport processes, anaerobic digestion and microbial complexity as would be expected in the human colon is presented. The model is a system of first-order partial differential equations with context determined number of dependent variables, and stiff, non-linear source terms. Numerical simulation of the model is used to elucidate information about the colon-microbiota complex. It is found that the composition of materials on outflow of the model does not well-describe the composition of material in other model locations, and inferences using outflow data varies according to model reactor representation. Additionally, increased microbial complexity allows the total microbial community to withstand major system perturbations in diet and community structure. However, distribution of strains and functional groups within the microbial community can be modified depending on perturbation length and microbial kinetic parameters. Preliminary model extensions and potential investigative opportunities using the computational model are discussed. PMID:26680208

Storm Enhanced Density (SED) plumes as possible suppliers of dayside cleft ion fountain

NASA Astrophysics Data System (ADS)

Horwitz, James

Foster et al. [2002] have observed elevated ionospheric density regions being convected from the subauroral plasmaspheric region toward noon, in association with convection of plasmaspheric tails in the dayside magnetosphere. These so-called Storm Enhanced Density (SED) regions could serve as ionospheric plasma source populations for cleft ion fountain outflows. Here we examine this scenario and employ our fluid-kinetic ionospheric plasma transport code to simulate the entry of a high-density "plasmasphere-like" flux tube entering the cleft region and subjected to an episode of wave-driven transverse ion heating. We find that such pronounced intervals of SED at F-region and topside altitudes passing through regions of CIF processes indeed appear capable of supporting episodes of strong CIF outflows. Foster, J. C., P. J. Erickson, A. J. Coster, J. Goldstein, and F. J. Rich, Ionospheric signatures of plasmaspheric tails, Geophys. Res. Lett., 29(13), 1623, doi:10.1029/2002GL015067, 2002.

Initiation of Martian Outflow Channels: Related to the Dissociation of Gas Hydrate?

NASA Technical Reports Server (NTRS)

Max, Michael D.; Clifford, Stephen M.

2001-01-01

We propose that the disruption of subpermafrost aquifers on Mars by the thermal- or pressure-induced dissociation of methane hydrate may have been a frequent trigger for initiating outflow channel activity. This possibility is raised by recent work that suggests that significant amounts of methane and gas hydrate may have been produced within and beneath the planet's cryosphere. On Earth, the build-up of overpressured water and gas by the decomposition of hydrate deposits has been implicated in the formation of large blowout features on the ocean floor. These features display a remarkable resemblance (in both morphology and scale) to the chaotic terrain found at the source of many Martian channels. The destabilization of hydrate can generate pressures sufficient to disrupt aquifers confined by up to 5 kilometers of frozen ground, while smaller discharges may result from the water produced by the decomposition of near-surface hydrate alone.

Propagation and Dissipation of MHD Waves in Coronal Holes

NASA Astrophysics Data System (ADS)

Dwivedi, B. N.

2006-11-01

bholadwivedi@gmail.com In view of the landmark result on the solar wind outflow, starting between 5 Mm and 20 Mm above the photosphere in magnetic funnels, we investigate the propagation and dissipation of MHD waves in coronal holes. We underline the importance of Alfvén wave dissipation in the magnetic funnels through the viscous and resistive plasma. Our results show that Alfvén waves are one of the primary energy sources in the innermost part of coronal holes where the solar wind outflow starts. We also consider compressive viscosity and thermal conductivity to study the propagation and dissipation of long period slow longitudinal MHD waves in polar coronal holes. We discuss their likely role in the line profile narrowing, and in the energy budget for coronal holes and the solar wind. We compare the contribution of longitudinal MHD waves with high frequency Alfvén waves.

A Comparison of Techniques for Determining Mass Outflow Rates in the Type 2 Quasar Markarian 34

NASA Astrophysics Data System (ADS)

Revalski, Mitchell; Crenshaw, D. Michael; Fischer, Travis C.; Kraemer, Steven B.; Schmitt, Henrique R.; Dashtamirova, Dzhuliya; Pope, Crystal L.

2018-06-01

We present spatially resolved measurements of the mass outflow rates and energetics for the Narrow Line Region (NLR) outflows in the type 2 quasar Markarian 34. Using data from the Hubble Space Telescope and Apache point observatory, together with Cloudy photoionization models, we calculate the radial mass distribution of ionized gas and map its kinematics. We compare the results of this technique to global outflow rates that characterize NLR outflows with a single outflow rate and energetic measurement. We find that NLR mass estimates based on emission line luminosities produce more consistent results than techniques employing filling factors.

Sources, solubility, and acid processing of aerosol iron and phosphorous over the South China Sea: East Asian dust and pollution outflows vs. Southeast Asian biomass burning

NASA Astrophysics Data System (ADS)

Hsu, S.-C.; Gong, G.-C.; Shiah, F.-K.; Hung, C.-C.; Kao, S.-J.; Zhang, R.; Chen, W.-N.; Chen, C.-C.; Chou, C. C.-K.; Lin, Y.-C.; Lin, F.-J.; Lin, S.-H.

2014-08-01

Iron and phosphorous are essential to marine microorganisms in vast regions in oceans worldwide. Atmospheric inputs are important allochthonous sources of Fe and P. The variability in airborne Fe deposition is hypothesized to serve an important function in previous glacial-interglacial cycles, contributing to the variability in atmospheric CO2 and ultimately the climate. Understanding the mechanisms underlying the mobilization of airborne Fe and P from insoluble to soluble forms is critical to evaluate the biogeochemical effects of these elements. In this study, we present a robust power-law correlation between fractional Fe solubility and non-sea-salt-sulfate / Total-Fe (nss-sulfate / FeT) molar ratio independent of distinct sources of airborne Fe of natural and/or anthropogenic origins over the South China Sea. This area receives Asian dust and pollution outflows and Southeast Asian biomass burning. This correlation is also valid for nitrate and total acids, demonstrating the significance of acid processing in enhancing Fe mobilization. Such correlations are also found for P, yet source dependent. These relationships serve as straightforward parameters that can be directly incorporated into available atmosphere-ocean coupling models that facilitate the assessment of Fe and P fertilization effects. Although biomass burning activity may supply Fe to the bioavailable Fe pool, pyrogenic soils are possibly the main contributors, not the burned plants. This finding warrants a multidisciplinary investigation that integrates atmospheric observations with the resulting biogeochemistry in the South China Sea, which is influenced by atmospheric forcings and nutrient dynamics with monsoons.

Sand Sources Near Athabasca Valles

NASA Image and Video Library

2014-10-29

This image captured by NASA Mars Reconnaissance Orbiter shows a small channel cutting into young volcanic lavas in a region where massive catastrophic flooding took place in the relatively recent past. The Athabasca Valles region includes a vast lava flow, thought to be the youngest on Mars, with even younger outflow channels that were carved by running water. The source of the water is believed to be the Cerberus Fossae valleys to the north, which may have penetrated to an over-pressurized aquifer in the subsurface. Nowadays, erosion by gravity, wind, and frost gradually wears down the rims of the outflow channels. In this scene, we see dark materials along the channel rim that were probably exposed by this erosion. The dark materials are less red than the surrounding surface and so they appear blue in this enhanced color picture. Viewed close up, the dark materials show ripples that suggest they are made up of mobile sand. It is possible that this sand originated elsewhere and simply collected where we see it today, but the fact that sand is not found elsewhere in the scene suggest to us that it is eroding out of the volcanic layers at the retreating rim of the channel. Sand sources are important because mobile sand grains have only a limited lifetime, wearing down and chipping apart each time they impact the surface. Erosion of the volcanic materials in this region may provide sands to replace those that are destroyed. Few such sand sources have so far been identified on Mars. http://photojournal.jpl.nasa.gov/catalog/PIA18889

Testing Models of the Black-Hole X-ray Source in the NGC4472 Globular Cluster RZ2109 with COS UV Spectroscopy

NASA Astrophysics Data System (ADS)

Zepf, Stephen

2014-10-01

We propose to obtain COS ultraviolet spectroscopy of the black-hole X-ray source in the NGC 4472 globular cluster RZ2109. This object was the first unambiguous black hole X-ray source in a globular cluster. It is clearly identified as a black hole through its high X-ray luminosity and short-term variability. The optical spectrum of RZ2109 shows strong and extraordinarily broad [OIII]4959, 5007 emission, and our recent STIS spectrum demonstrates that this comes from an outflow extended across most of the globular cluster. The optical spectrum also remarkably shows no emission lines other than [OIII] to sensitive limits, indicating that the material is very hydrogen-poor. One way to account for these observations is if RZ2109 hosts a CO white dwarf accreting onto a stellar mass black hole. In this case, CIV 1549 emission is expected and no nitrogren lines will be seen. However, if nitrogen lines such as NIV 1486 and NV 1239, 1243 are observed, then a different source for the accreting material such as a nova shell or a horizontal branch star would be required, and a re-evaluation of all aspects of our understanding of the dynamics and accretion in RZ2109 would be needed. Determining which of these is the case is a major step for understanding how accreting black holes form and grow in dense stellar systems, whether they make intermediate mass black holes, and what accretion and feedback processes lead to strong outflows rich in elements such as oxygen.

Title: Water Quality Monitoring to Restore and Enhance Lake Herrick

NASA Astrophysics Data System (ADS)

Kannan, A.; Saintil, T.; Radcliffe, D. E.; Rasmussen, T. C.

2017-12-01

Lake Allyn M. Herrick is about 1.5 km2 and covers portions of the University of Georgia's East campus, the Oconee forest, residential and commercial land use. Lake Herrick, a 15-acre water body established in 1982 at the University of Georgia's campus was closed in 2002 for recreation due to fecal contamination, color change, and heavy sedimentation. Subsequent monitoring confirmed cyanobacterium blooms on the surface of lake and nutrient concentration especially phosphorus was one of the primary reasons. However, no studies have been done on lake inflows and outflows after 2005 in terms of nutrients and fecal Indicator bacteria. Two inflow tributaries and the outlet stream were monitored for discharge, E. coli, total coliform, forms of nitrogen and phosphorus and other water quality parameters during base flow and storm conditions. External environmental factors like precipitation, land-use/location, discharge, and internal factors within the water like temperature, DO, pH, conductivity, and turbidity influencing fecal indicator bacteria and nutrients will be discussed with data collected from the inflows/outflow between February 2016 to October 2017. Following this, microbial source tracking methods were also used to detect the bacterial source in the samples specific to a ruminant or human host. The source tracking data will be presented during the timeframe of January 2017 to September 2017, to draw a conclusion on the potential source of fecal contamination. The future aim of the project will include modeling flow and bacteria at the watershed scale in order to make management decisions to restore the lake for recreational uses where green infrastructure could play a key role.

Binary energy source of the HH 250 outflow and its circumstellar environment

NASA Astrophysics Data System (ADS)

Comerón, Fernando; Reipurth, Bo; Yen, Hsi-Wei; Connelley, Michael S.

2018-04-01

Aims: Herbig-Haro flows are signposts of recent major accretion and outflow episodes. We aim to determine the nature and properties of the little-known outflow source HH 250-IRS, which is embedded in the Aquila clouds. Methods: We have obtained adaptive optics-assisted L-band images with the NACO instrument on the Very Large Telescope (VLT), together with N- and Q-band imaging with VISIR also on the VLT. Using the SINFONI instrument on the VLT we carried out H- and K-band integral field spectroscopy of HH 250-IRS, complemented with spectra obtained with the SpeX instrument at the InfraRed Telescope Facility (IRTF) in the JHKL bands. Finally, the SubMillimeter Array (SMA) interferometer was used to study the circumstellar environment of HH 250-IRS at 225 and 351 GHz with CO (2-1) and CO (3-2) maps and 0.9 mm and 1.3 mm continuum images. Results: The HH 250-IRS source is resolved into a binary with 0.''53 separation, corresponding to 120 AU at the adopted distance of 225 pc. The individual components show heavily veiled spectra with weak CO absorption indicative of late-type stars. Both are Class I sources, but their spectral energy distributions between 1.5 μm and 19 μm differ markedly and suggest the existence of a large cavity around one of the components. The millimeter interferometric observations indicate that the gas mainly traces a circumbinary envelope or disk, while the dust emission is dominated by one of the circumstellar envelopes. Conclusions: HH 250-IRS is a new addition to the handful of multiple systems where the individual stellar components, the circumstellar disks and a circumbinary disk can be studied in detail, and a rare case among those systems in which a Herbig-Haro flow is present. Based on observations obtained with the VLT (Cerro Paranal, Chile) in programs 089.C-0196(A), 095.C-0488(A), and 095.C-0488(B), as well as with IRTF (Mauna Kea, Hawaii), SMA (Mauna Kea, Hawaii), and the Nordic Optical Telescope (La Palma, Canary Islands, Spain).Staff Astronomer at the Infrared Telescope Facility, which is operated by the University of Hawaii under contract NNH14CK55B with the National Aeronautics and Space Administration.

Ancient Streamlined Islands of the Palos Outflow Channel

NASA Image and Video Library

2016-08-24

This image shows the northern terminus of an outflow channel located in the volcanic terrains of Amenthes Planum. The channel sources from the Palos impact crater to the south, where water flowed into the crater from Tinto Vallis and eventually formed a paleo lake. As rising lake levels breached through the crater's rim and inundated the plains to the north, the resulting high velocity, large discharge floods plucked out and eroded the volcanic plains scouring out the "Palos Outflow Channel" and the streamlined mesa-islands on its floor. These streamlined forms are the eroded remnants of plains material sculpted by catastrophic floods and are not sediment deposits emplaced by lower magnitude stream flows. Both the fluvial channel floor and the volcanic island surfaces are densely cratered by impacts suggesting that both the surfaces and the flood events are ancient. The morphology (shape) of the channel system and its islands have been preserved through the eons, but water has long been absent from this drainage system. Since then, winds have transported light-toned sediments across this terrain forming extensive dune fields within the channel system, on the floors of impact craters, and in other protected locations in the Palos Outflow Channel region. A closer look shows chevron, or fish-bone shaped, light-toned dunes located near the top of the image where numerous smaller channels have cut through the landscape. These dunes likely started out as Transverse Aeolian Ridges (TAR) that form perpendicular to the prevailing wind direction where the wind-blown sediment supply is scarce. This intriguing morphology likely reflects changes in the prevailing wind environment over time. http://photojournal.jpl.nasa.gov/catalog/PIA21023

Comparing Sources of Storm-Time Ring Current O+

NASA Astrophysics Data System (ADS)

Kistler, L. M.

2015-12-01

The first observations of the storm-time ring current composition using AMPTE/CCE data showed that the O+ contribution to the ring current increases significantly during storms. The ring current is predominantly formed from inward transport of the near-earth plasma sheet. Thus the increase of O+ in the ring current implies that the ionospheric contribution to the plasma sheet has increased. The ionospheric plasma that reaches the plasma sheet can come from both the cusp and the nightside aurora. The cusp outflow moves through the lobe and enters the plasma sheet through reconnection at the near-earth neutral line. The nightside auroral outflow has direct access to nightside plasma sheet. Using data from Cluster and the Van Allen Probes spacecraft, we compare the development of storms in cases where there is a clear input of nightside auroral outflow, and in cases where there is a significant cusp input. We find that the cusp input, which enters the tail at ~15-20 Re becomes isotropized when it crosses the neutral sheet, and becomes part of the hot (>1 keV) plasma sheet population as it convects inward. The auroral outflow, which enters the plasma sheet closer to the earth, where the radius of curvature of the field line is larger, does not isotropize or become significantly energized, but remains a predominantly field aligned low energy population in the inner magnetosphere. It is the hot plasma sheet population that gets accelerated to high enough energies in the inner magnetosphere to contribute strongly to the ring current pressure. Thus it appears that O+ that enters the plasma sheet further down the tail has a greater impact on the storm-time ring current than ions that enter closer to the earth.

The Nature of the UV/X-ray Absorber In PG 2302+029

NASA Technical Reports Server (NTRS)

Sabra, Bassem M.; Hamann, Fred; Jannuzi, Buell T.; George, Ian M.; Shields, Joseph C.

2003-01-01

We present Chandra X-ray observations of the radio-quiet QSO PG 2302+029. This quasar has a rare system of ultra-high velocity (-56,000 km s(exp -1) UV absorption lines that form in an outflow from the active nucleus. The Chandra data indicate that soft X-ray absorption is also present. We perform a joint UV and X-ray analysis, using photoionization calculations, to determine the nature of the absorbing gas. The UV and X-ray datasets were not obtained simultaneously. Nonetheless, our analysis suggests that the X-ray absorption occurs at high velocities in the same general region as the UV absorber. There are not enough constraints to rule out multi-zone models. In fact, the distinct broad and narrow UV line profiles clearly indicate that multiple zones are present. Our preferred estimates of the ionization and total column density in the X-ray absorber (logU = 1.6, N(sub eta) = 10(exp 22.4) cm (exp -2) over predict the O VI lambda lambda1032,1038 absorption unless the X-ray absorber is also outflowing at approximately 56,000 km s(exp-l), but they over predict the Ne VIII lambda lambda 770,780 absorption at all velocities. If we assume that the X-ray absorbing gas is outflowing at the same velocity of the UV-absorbing wind and that the wind is radiatively accelerated, then the outflow must be launched at a radius of less than or equal to 10(exp 15) cm from the central continuum source. The smallness of this radius casts doubts on the assumption of radiative acceleration.

Quasars with P v broad absorption in BOSS data release 9

NASA Astrophysics Data System (ADS)

Capellupo, D. M.; Hamann, F.; Herbst, H.; Brandt, W. N.; Ge, J.; Pâris, I.; Petitjean, P.; Schneider, D. P.; Streblyanska, A.; York, D.

2017-07-01

Broad absorption lines (BALs) found in a significant fraction of quasar spectra identify high-velocity outflows that might be present in all quasars and could be a major factor in feedback to galaxy evolution. Understanding the nature of these flows requires further constraints on their physical properties, including their column densities, for which well-studied BALs, such as C IV λλ1548,1551, typically provide only a lower limit because of saturation effects. Low-abundance lines, such as P v λλ1118,1128, indicate large column densities, implying that outflows more powerful than measurements of C IV alone would indicate. We search through a sample of 2694 BAL quasars from the Sloan Digital Sky Survey III/Baryon Oscillation Spectroscopic Survey data release 9 quasar catalogue for such absorption, and we identify 81 'definite' and 86 'probable' detections of P v broad absorption, yielding a firm lower limit of 3.0-6.2 per cent for the incidence of such absorption among BAL quasars. The P v-detected quasars tend to have stronger C IV and Si IV absorption, as well as a higher incidence of LoBAL absorption, than the overall BAL quasar population. Many of the P v-detected quasars have C IV troughs that do not reach zero intensity (at velocities where P v is detected), confirming that the outflow gas only partially covers the UV continuum source. P v appears significantly in a composite spectrum of non-P v-detected BAL quasars, indicating that P v absorption (and large column densities) is much more common than indicated by our search results. Our sample of P v detections significantly increases the number of known P v detections, providing opportunities for follow-up studies to better understand BAL outflow energetics.

Unconventional Aqueous Humor Outflow: A Review

PubMed Central

Johnson, Mark; McLaren, Jay W.; Overby, Darryl R.

2016-01-01

Aqueous humor flows out of the eye primarily through the conventional outflow pathway that includes the trabecular meshwork and Schlemm's canal. However, a fraction of aqueous humor passes through an alternative or ‘unconventional’ route that includes the ciliary muscle, supraciliary and suprachoroidal spaces. From there, unconventional outflow may drain through two pathways: a uveoscleral pathway where aqueous drains across the sclera to be resorbed by orbital vessels, and a uveovortex pathway where aqueous humor enters the choroid to drain through the vortex veins. We review the anatomy, physiology and pharmacology of these pathways. We also discuss methods to determine unconventional outflow rate, including direct techniques that use radioactive or fluorescent tracers recovered from tissues in the unconventional pathway and indirect methods that estimate unconventional outflow based on total outflow over a range of pressures. Indirect methods are subject to a number of assumptions and generally give poor agreement with tracer measurements. We review the variety of animal models that have been used to study conventional and unconventional outflow. The mouse appears to be a promising model because it captures several aspects of conventional and unconventional outflow dynamics common to humans, although questions remain regarding the magnitude of unconventional outflow in mice. Finally, we review future directions. There is a clear need to develop improved methods for measuring unconventional outflow in both animals and humans. PMID:26850315

The energetics of AGN radiation pressure-driven outflows

NASA Astrophysics Data System (ADS)

Ishibashi, W.; Fabian, A. C.; Maiolino, R.

2018-05-01

The increasing observational evidence of galactic outflows is considered as a sign of active galactic nucleus (AGN) feedback in action. However, the physical mechanism responsible for driving the observed outflows remains unclear, and whether it is due to momentum, energy, or radiation is still a matter of debate. The observed outflow energetics, in particular the large measured values of the momentum ratio (\\dot{p}/(L/c) ˜ 10) and energy ratio (\\dot{E}_k/L ˜ 0.05), seems to favour the energy-driving mechanism; and most observational works have focused their comparison with wind energy-driven models. Here, we show that AGN radiation pressure on dust can adequately reproduce the observed outflow energetics (mass outflow rate, momentum flux, and kinetic power), as well as the scalings with luminosity, provided that the effects of radiation trapping are properly taken into account. In particular, we predict a sublinear scaling for the mass outflow rate (\\dot{M} ∝ L^{1/2}) and a superlinear scaling for the kinetic power (\\dot{E}_k ∝ L^{3/2}), in agreement with the observational scaling relations reported in the most recent compilation of AGN outflow data. We conclude that AGN radiative feedback can account for the global outflow energetics, at least equally well as the wind energy-driving mechanism, and therefore both physical models should be considered in the interpretation of future AGN outflow observations.

The bipolar jet of the symbiotic star R Aquarii: A study of its morphology using the high-resolution HST WFC3/UVIS camera

NASA Astrophysics Data System (ADS)

Melnikov, Stanislav; Stute, Matthias; Eislöffel, Jochen

2018-04-01

Context. R Aqr is a symbiotic binary system consisting of a Mira variable with a pulsation period of 387 days and a hot companion which is presumably a white dwarf with an accretion disk. This binary system is the source of a prominent bipolar gaseous outflow. Aims: We use high spatial resolution and sensitive images from the Hubble Space Telescope (HST) to identify and investigate the different structural components that form the complex morphology of the R Aqr jet. Methods: We present new high-resolution HST WFC3/UVIS narrow-band images of the R Aqr jet obtained in 2013/14 using the [OIII]λ5007, [OI]λ6300, [NII]λ6583, and Hα emission lines. These images also allow us to produce detailed maps of the jet flow in several line ratios such as [OIII]λ5007/[OI]λ6300 and [NII]λ6583/[OI]λ6300 which are sensitive to the outflow temperature and its hydrogen ionisation fraction. The new emission maps together with archival HST data are used to derive and analyse the proper motion of prominent emitting features which can be traced over 20 years with the HST observations. Results: The images reveal the fine gas structure of the jet out to distances of a few tens of arcseconds from the central region, as well as in the innermost region, within a few arcseconds around the stellar source. They reveal for the first time the straight, highly collimated jet component which can be traced to up to 900 AU in the NE direction. Images in [OIII]λ5007, [OI]λ6300, and [NII]λ6583 clearly show a helical pattern in the jet beams which may derive from the small-scale precession of the jet. The highly collimated jet is accompanied by a wide opening angle outflow which is filled by low excitation gas. The position angles of the jet structures as well as their opening angles are calculated. Our measurements of the proper motions of some prominent emission knots confirm the scenario of gas acceleration during the propagation of the outflow. Finally, we produce several detailed line ratio maps which present a mosaic combined from the large field and the PSF-subtracted inner region. Conclusions: The high signal-to-noise HST WFC3/UVIS images provide powerful tools for the study of the jet morphology and also bring detailed information about the physical jet gas conditions. The simultaneous observations of [OIII], [OI], [NII], and [SII] would allow us to measure basic parameters of the ionised gas in the R Aqr outflow such as electron density, electron temperature and hydrogen ionisation fraction, and compare them with other stellar jets.

Broad Absorption Line Quasars with Polar Outflows

NASA Astrophysics Data System (ADS)

Wang, Junxian

2005-10-01

It is widely accepted that the broad absorption line (BAL) outflow exists in most (if not all) quasars with a small covering factor. Various evidences show that equatorial outflows are responsible for the BALs in most BAL QSOs. By searching for radio variable quasars in SDSS, we built the first sample of 6 BAL QSOs with polar BAL outflows. It is very likely that polar outflows are associated with relativistic jets, and their origins should be different from the equatorial outflows in the majority of BAL QSOs. We propose an XMM snapshot survey to a) check whether strong X-ray absorption, one of the most prominent characteristics of most BAL QSOs, also exist in the polar outflows b) check whether face-on BAL QSOs are otherwise X-ray normal c) provide a baseline for future extensive X-ray studies.

A resolved outflow of matter from a brown dwarf.

PubMed

Whelan, Emma T; Ray, Thomas P; Bacciotti, Francesca; Natta, Antonella; Testi, Leonardo; Randich, Sofia

2005-06-02

The birth of stars involves not only accretion but also, counter-intuitively, the expulsion of matter in the form of highly supersonic outflows. Although this phenomenon has been seen in young stars, a fundamental question is whether it also occurs among newborn brown dwarfs: these are the so-called 'failed stars', with masses between stars and planets, that never manage to reach temperatures high enough for normal hydrogen fusion to occur. Recently, evidence for accretion in young brown dwarfs has mounted, and their spectra show lines that are suggestive of outflows. Here we report spectro-astrometric data that spatially resolve an outflow from a brown dwarf. The outflow's characteristics appear similar to, but on a smaller scale than, outflows from normal young stars. This result suggests that the outflow mechanism is universal, and perhaps relevant even to the formation of planets.

Dimerization deficiency of enigmatic retinitis pigmentosa-linked rhodopsin mutants

PubMed Central

Ploier, Birgit; Caro, Lydia N.; Morizumi, Takefumi; Pandey, Kalpana; Pearring, Jillian N.; Goren, Michael A.; Finnemann, Silvia C.; Graumann, Johannes; Arshavsky, Vadim Y.; Dittman, Jeremy S.; Ernst, Oliver P.; Menon, Anant K.

2016-01-01

Retinitis pigmentosa (RP) is a blinding disease often associated with mutations in rhodopsin, a light-sensing G protein-coupled receptor and phospholipid scramblase. Most RP-associated mutations affect rhodopsin's activity or transport to disc membranes. Intriguingly, some mutations produce apparently normal rhodopsins that nevertheless cause disease. Here we show that three such enigmatic mutations—F45L, V209M and F220C—yield fully functional visual pigments that bind the 11-cis retinal chromophore, activate the G protein transducin, traffic to the light-sensitive photoreceptor compartment and scramble phospholipids. However, tests of scramblase activity show that unlike wild-type rhodopsin that functionally reconstitutes into liposomes as dimers or multimers, F45L, V209M and F220C rhodopsins behave as monomers. This result was confirmed in pull-down experiments. Our data suggest that the photoreceptor pathology associated with expression of these enigmatic RP-associated pigments arises from their unexpected inability to dimerize via transmembrane helices 1 and 5. PMID:27694816

Dimerization deficiency of enigmatic retinitis pigmentosa-linked rhodopsin mutants

NASA Astrophysics Data System (ADS)

Ploier, Birgit; Caro, Lydia N.; Morizumi, Takefumi; Pandey, Kalpana; Pearring, Jillian N.; Goren, Michael A.; Finnemann, Silvia C.; Graumann, Johannes; Arshavsky, Vadim Y.; Dittman, Jeremy S.; Ernst, Oliver P.; Menon, Anant K.

2016-10-01

Retinitis pigmentosa (RP) is a blinding disease often associated with mutations in rhodopsin, a light-sensing G protein-coupled receptor and phospholipid scramblase. Most RP-associated mutations affect rhodopsin's activity or transport to disc membranes. Intriguingly, some mutations produce apparently normal rhodopsins that nevertheless cause disease. Here we show that three such enigmatic mutations--F45L, V209M and F220C--yield fully functional visual pigments that bind the 11-cis retinal chromophore, activate the G protein transducin, traffic to the light-sensitive photoreceptor compartment and scramble phospholipids. However, tests of scramblase activity show that unlike wild-type rhodopsin that functionally reconstitutes into liposomes as dimers or multimers, F45L, V209M and F220C rhodopsins behave as monomers. This result was confirmed in pull-down experiments. Our data suggest that the photoreceptor pathology associated with expression of these enigmatic RP-associated pigments arises from their unexpected inability to dimerize via transmembrane helices 1 and 5.

Chemical Characteristics of Continental Outflow from Asia to the Troposphere over the Western Pacific Ocean during September - October 1991: Results from PEM-West A

NASA Technical Reports Server (NTRS)

Talbot, R. W.; Dibb, J. E.; Klemm, K. I.; Bradshaw, J. D.; Sandholm, S. T.; Blake, D. R.; Sachse, G. W.; Collins, J.; Heikes, B. G.; Gregory, G. L.;

Analysis of Tropical Cyclone Initialization in COAMPS-TC for Hurricane Patricia (2015) Utilizing TCI Experiment Datasets

DTIC Science & Technology

2017-06-01

aboard the NASA WB-57 aircraft flying over outflow region of Tropical Storm Patricia. Source: Doyle et al. (2017...flight track of the NASA WB-57 through the center of Hurricane Patricia at approximately 1800 UTC 23 October ......28 Figure 20. HDSS-observed wind...29 Figure 21. NASA WB-57 flight path (yellow line) overlaid on GOES enhanced infrared

Hydrology of the Nevin Wetland near Madison, Wisconsin

USGS Publications Warehouse

Novitzki, R.P.

1978-01-01

Inflows and outflows are quantified, and nutrient and sediment sources are identified, with the result that the effect of proposed land-use changes in the basin can be evaluated. Land-use practices that affect the wetland include drainage, urbanization, and water-supply development. Additional ground-water supplies can be obtained in the basin, but springflow and upward leakage of ground water through the organic soils will decrease.

The Effects of FUV Radiation on C-Shocks: Implications for Water and Other O-bearing Species

NASA Astrophysics Data System (ADS)

Kaufman, Michael; Melick, Gary; Tolls, Volker

2015-08-01

Protostellar outflows have long been known to drive endothermic reactions that produce high abundances of oxygen-bearing species. Models of shocks in well-shielded gas made the strong prediction that essentially all of the pre-shock oxygen gets driven into water, so that the post-shock water abundances are order 10-4. Herschel observations, however, including those from the key program “Water in Star Forming Regions with Herschel (WISH)” show that for most sources, the shocked gas water abundances of are far lower, 10-7 - 10-5.This pattern of lower-than-predicted water abundance has led us to consider that our C-shock model (Kaufman & Neufeld 1996) is incomplete. In particular, we did not previously take into account that many outflow sources have higher than average far-ultraviolet radiation fields within their outflow cavities. Strong FUV radiation has important effects on the structure of C-shocks: the ionization fraction is larger than in well-shielded gas, decreasing the coupling length between neutrals and ions, and leading to higher temperatures and a lower breakdown speeds; the pre-shock gas composition, including the presence of ice mantles and the dominant charge carriers, is strongly affected; and abundant species such as water are diminished by photodissociation in the cooled down stream gas.In addition to the normal parameters of density, shock velocity, and magnetic field strength, we now include the external FUV field strength and the extinction between the FUV source and the shock. We use the results of a detailed PDR model to compute pre-shock chemical conditions, including the ionization fraction, the increase of which decreases the maximum velocities of C- shocks. FUV also keeps oxygen in the gas phase, making more available for H2O formarion ; however, photodissociation beyond the temperature peak keeps the average H2O abundance down. We present comparisons of our model results with the inferred water abundances and with observations of H2O, CO, O and OH lines from the Herschel archive.

3D modelling of the climatic impact of outflow channel formation events on early Mars

NASA Astrophysics Data System (ADS)

Turbet, Martin; Forget, Francois; Head, James W.; Wordsworth, Robin

2017-05-01

Mars was characterized by cataclysmic groundwater-sourced surface flooding that formed large outflow channels and that may have altered the climate for extensive periods during the Hesperian era. In particular, it has been speculated that such events could have induced significant rainfall and caused the formation of late-stage valley networks. We present the results of 3-D Global Climate Model simulations reproducing the short and long term climatic impact of a wide range of outflow channel formation events under cold ancient Mars conditions. We find that the most intense of these events (volumes of water up to 107 km3 and released at temperatures up to 320 K) cannot trigger long-term greenhouse global warming, regardless of how favorable are the external conditions (e.g. obliquity and seasons). Furthermore, the intensity of the response of the events is significantly affected by the atmospheric pressure, a parameter not well constrained for the Hesperian era. Thin atmospheres (P < 80 mbar) can be heated efficiently because of their low volumetric heat capacity, triggering the formation of a convective plume that is very efficient in transporting water vapor and ice at the global scale. Thick atmospheres (P > 0.5 bar) have difficulty in producing precipitation far from the water flow area, and are more efficient in generating snowmelt. In any case, outflow channel formation events at any atmospheric pressure are unable to produce rainfall or significant snowmelt at latitudes below 40°N. As an example, for an outflow channel event (under a 0.2 bar atmospheric pressure and 45° obliquity) releasing 106 km3 of water heated at 300 K and at a discharge rate of 109 m3 s-1 , the flow of water reaches the lowest point of the northern lowlands (around ∼70°N, 30°W) after ∼3 days and forms a 200 m deep lake of 4.2 × 106 km2 after ∼20 days; the lake becomes entirely covered by an ice layer after ∼500 days. Over the short term, such an event leaves 6.5 × 103 km3 of ice deposits by precipitation (0.65% of the initial outflow volume) and can be responsible for the melting of ∼80 km3 (0.008% of the initial outflow volume; 1% of the deposited precipitation). Furthermore, these quantities decrease drastically (faster than linearly) for lower volumes of released water. Over the long term, we find that the presence of the ice-covered lake has a climatic impact similar to a simple body of water ice located in the Northern Plains. For an obliquity of ∼45° and atmospheric pressures > 80 mbar, we find that the lake ice is transported progressively southward through the mechanisms of sublimation and adiabatic cooling. At the same time, and as long as the initial water reservoir is not entirely sublimated (a lifetime of 105 martian years for the outflow channel event described above), ice deposits remain in the West Echus Chasma Plateau region where hints of hydrological activity contemporaneous with outflow channel formation events have been observed. However, because the high albedo of ice drives Mars to even colder temperatures, snowmelt produced by seasonal solar forcing is difficult to attain.

Under the mirror of the sleeping water: Poussin's Narcissus.

PubMed

Tutter, Adele

2014-12-01

Examined in conjunction with a close reading of Ovid's Metamorphoses, Nicolas Poussin's four paintings on the preoccupying theme of Narcissus and Echo reflect a developing aesthetic interpretation of its textual source. Poussin's reflective vision supports a radical reappraisal of the enigmatic myth at the heart of psychoanalytic theory and practice, in which Narcissus is construed as a far more object-related figure that seeks the formative, affirmative mirroring of the other. This in turn encourages a more versatile conceptualization of narcissistic disturbance, in which an etiologically heterogenous constellation of issues stems from a variety of disturbances in the myriad dynamic and developmental aspects of mirroring and attunement: the narcissisms. Copyright © 2014 Institute of Psychoanalysis.

Compact binary merger and kilonova: outflows from remnant disc

NASA Astrophysics Data System (ADS)

Yi, Tuan; Gu, Wei-Min; Liu, Tong; Kumar, Rajiv; Mu, Hui-Jun; Song, Cui-Ying

2018-05-01

Outflows launched from a remnant disc of compact binary merger may have essential contribution to the kilonova emission. Numerical calculations are conducted in this work to study the structure of accretion flows and outflows. By the incorporation of limited-energy advection in the hyper-accretion discs, outflows occur naturally from accretion flows due to imbalance between the viscous heating and the sum of the advective and radiative cooling. Following this spirit, we revisit the properties of the merger outflow ejecta. Our results show that around 10-3 ˜ 10-1 M⊙ of the disc mass can be launched as powerful outflows. The amount of unbound mass varies with the disc mass and the viscosity. The outflow-contributed peak luminosity is around 1040 ˜ 1041 erg s-1. Such a scenario can account for the observed kilonovae associated with short gamma-ray bursts, including the recent event AT2017gfo (GW170817).

Generation of shockwave and vortex structures at the outflow of a boiling water jet

NASA Astrophysics Data System (ADS)

Alekseev, M. V.; Lezhnin, S. I.; Pribaturin, N. A.; Sorokin, A. L.

2014-12-01

Results of numerical simulation for shock waves and generation of vortex structures during unsteady outflow of boiling liquid jet are presented. The features of evolution of shock waves and vortex structures formation during unsteady outflow of boiling water are compared with corresponding structures during unsteady gas outflow.

Numerical Study on Outflows in Seyfert Galaxies I: Narrow Line Region Outflows in NGC 4151

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mou, Guobin; Wang, Tinggui; Yang, Chenwei, E-mail: gbmou@ustc.edu.cn

The origin of narrow line region (NLR) outflows remains unknown. In this paper, we explore the scenario in which these outflows are circumnuclear clouds driven by energetic accretion disk winds. We choose the well-studied nearby Seyfert galaxy NGC 4151 as an example. By performing 3D hydrodynamical simulations, we are able to reproduce the radial distributions of velocity, mass outflow rate, and kinetic luminosity of NLR outflows in the inner 100 pc deduced from spatial resolved spectroscopic observations. The demanded kinetic luminosity of disk winds is about two orders of magnitude higher than that inferred from the NLR outflows, but ismore » close to the ultrafast outflows (UFO) detected in the X-ray spectrum and a few times lower than the bolometric luminosity of the Seyfert. Our simulations imply that the scenario is viable for NGC 4151. The existence of the underlying disk winds can be confirmed by their impacts on higher density ISM, e.g., shock excitation signs, and the pressure in NLR.« less

Bright crater outflows: Possible emplacement mechanisms

NASA Technical Reports Server (NTRS)

Chadwick, D. John; Schaber, Gerald G.; Strom, Robert G.; Duval, Darla M.

1992-01-01

Lobate features with a strong backscatter are associated with 43 percent of the impact craters cataloged in Magellan's cycle 1. Their apparent thinness and great lengths are consistent with a low-viscosity material. The longest outflow yet identified is about 600 km in length and flows from the 90-km-diameter crater Addams. There is strong evidence that the outflows are largely composed of impact melt, although the mechanisms of their emplacement are not clearly understood. High temperatures and pressures of target rocks on Venus allow for more melt to be produced than on other terrestrial planets because lower shock pressures are required for melting. The percentage of impact craters with outflows increases with increasing crater diameter. The mean diameter of craters without outflows is 14.4 km, compared with 27.8 km for craters with outflows. No craters smaller than 3 km, 43 percent of craters in the 10- to 30-km-diameter range, and 90 percent in the 80- to 100-km-diameter range have associated bright outflows. More melt is produced in the more energetic impact events that produce larger craters. However, three of the four largest craters have no outflows. We present four possible mechanisms for the emplacement of bright outflows. We believe this 'shotgun' approach is justified because all four mechanisms may indeed have operated to some degree.

THE MOLECULAR WIND IN THE NEAREST SEYFERT GALAXY CIRCINUS REVEALED BY ALMA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zschaechner, Laura K.; Walter, Fabian; Farina, Emanuele P.

2016-12-01

We present ALMA observations of the inner 1′ (1.2 kpc) of the Circinus galaxy, the nearest Seyfert. We target CO (1–0) in the region associated with a well-known multiphase outflow driven by the central active galactic nucleus (AGN). While the geometry of Circinus and its outflow make disentangling the latter difficult, we see indications of outflowing molecular gas at velocities consistent with the ionized outflow. We constrain the mass of the outflowing molecular gas to be 1.5 × 10{sup 5}−5.1 × 10{sup 6} M {sub ⊙}, yielding a molecular outflow rate of 0.35–12.3 M {sub ⊙} yr{sup −1}. The values within this range aremore » comparable to the star formation (SF) rate in Circinus, indicating that the outflow indeed regulates SF to some degree. The molecular outflow in Circinus is considerably lower in mass and energetics than previously studied AGN-driven outflows, especially given its high ratio of AGN luminosity to bolometric luminosity. The molecular outflow in Circinus is, however, consistent with some trends put forth by Cicone et al., including a linear relation between kinetic power and AGN luminosity, as well as its momentum rate versus bolometric luminosity (although the latter places Circinus among the starburst galaxies in that sample). We detect additional molecular species including CN and C{sup 17}O.« less

First image of the L1157 molecular jet by the CALYPSO IRAM-PdBI survey

NASA Astrophysics Data System (ADS)

Podio, L.; Codella, C.; Gueth, F.; Cabrit, S.; Maury, A.; Tabone, B.; Lefèvre, C.; Anderl, S.; André, P.; Belloche, A.; Bontemps, S.; Hennebelle, P.; Lefloch, B.; Maret, S.; Testi, L.

2016-09-01

Context. Fast jets are thought to be a crucial ingredient of star formation because they might extract angular momentum from the disk and thus allow mass accretion onto the star. However, it is unclear whether jets are ubiquitous, and likewise, their contribution to mass and angular momentum extraction during protostar formation remains an open question. Aims: Our aim is to investigate the ejection process in the low-mass Class 0 protostar L1157. This source is associated with a spectacular bipolar outflow, and the recent detection of high-velocity SiO suggests the occurrence of a jet. Methods: Observations of CO 2 -1 and SiO 5 - 4 at ~0.8 arcsec resolution were obtained with the IRAM Plateau de Bure Interferometer (PdBI) as part of the CALYPSO large program. The jet and outflow structure were fit with a precession model. We derived the column density of CO and SiO, as well as the jet mass-loss rate and mechanical luminosity. Results: High-velocity CO and SiO emission resolve for the first time the first 200 au of the outflow-driving molecular jet. The jet is strongly asymmetric, with the blue lobe ~0.65 times slower than the red lobe. This suggests that the large-scale asymmetry of the outflow is directly linked to the jet velocity and that the asymmetry in the launching mechanism has been at work for the past 1800 yr. Velocity asymmetries are common in T Tauri stars, which suggests that the jet formation mechanism from Class 0 to Class II stages might be similar. Our model simultaneously fits the properties of the inner jet and of the clumpy 0.2 pc scale outflow by assuming that the jet precesses counter-clockwise on a cone inclined by 73° to the line of sight with an opening angle of 8° on a period of ~1640 yr. The estimated jet mass flux and mechanical luminosity are Ṁjet ~ 7.7 × 10-7M⊙ yr-1 and Ljet ~ 0.9L⊙, indicating that the jet could extract at least 25% of the gravitational energy released by the forming star.

Growth of left ventricular outflow tract and predictors of future re-intervention after repair for ventricular septal defect and aortic arch obstruction.

PubMed

Jijeh, Abdulraouf; Ismail, Muna; Alhabshan, Fahad

2017-09-01

Ventricular septal defect and aortic arch obstruction are usually associated with a narrow left ventricular outflow tract. The aim of the present study was to analyse the growth and predictors of future obstruction of the left ventricular outflow tract after surgical repair. We carried out a retrospective review of patients who underwent repair for ventricular septal defect and aortic arch obstruction - coarctation or interrupted aortic arch - between July, 2002 and June, 2013. Echocardiographic data were reviewed, and the need for re-intervention was evaluated. A total of 89 patients were included in this study. A significant left ventricular outflow tract growth was noticed after surgical repair. Preoperatively, the mean left ventricular outflow tract Z-score was -1.46±1 (range -5.5 to 1.1) and increased to a mean value of -0.7±1.3 (range -2.7 to 3.2) at last follow-up (p=0.0001), demonstrating relevant growth of the left ventricular outflow tract after repair for ventricular septal defect and aortic arch obstruction. After primary repair, 11 patients (12.3%) required re-intervention with surgical repair for left ventricular outflow tract obstruction after a mean period of 36±21 months. There were no significant differences in age, weight, and indexed aortic valve and left ventricular outflow tract measurements between those who developed obstruction and those who did not. Significant left ventricular outflow tract growth is expected after repair of ventricular septal defect and aortic arch obstruction. Small aortic valve and left ventricular outflow tract at diagnosis are not risk factors to predict the need for surgical re-intervention for left ventricular outflow tract obstruction in future.

Chandra Observation of Luminous and Ultraluminous X-ray Binaries in M101

NASA Technical Reports Server (NTRS)

Mukai, K.; Pence, W. D.; Snowden, S. L.; Kuntz, K. D.; White, Nicholas E. (Technical Monitor)

2002-01-01

X-ray binaries in the Milky Way are among the brightest objects on the X-ray sky. With the increasing sensitivity of recent missions, it is now possible to study X-ray binaries in nearby galaxies. We present data on six ultraluminous binaries in the nearby spiral galaxy, M101, obtained with Chandra ACIS-S. Of these, five appear to be similar to ultraluminous sources in other galaxies, while the brightest source, P098, shows some unique characteristics. We present our interpretation of the data in terms of an optically thick outflow, and discuss implications.

Analytical modeling of Cosmic Winds and Jets

NASA Astrophysics Data System (ADS)

Vlahakis, Nektarios

1998-11-01

A widespread phenomenon in astrophysics is the outflow of plasma from the environment of stellar or galactic objects. This plasma outflows range from nonuniform winds to highly collimated jets which are common to many stages of stellar evolution. For example, collimated outflows are found around young stars (e.g., as in HH 30), older mass losing stars (as in eta-Carinae), symbiotic stars (e.g. in R Aqr), planetary nebulae nuclei (as in the hourglass nebula), black hole X-ray transients (as in GRS 1915+105 and GRO J1655-40), low- and high-mass X-ray binaries and recently also in cataclysmic variables (e.g. T Pyxidis). Similarly, they are also found emerging from the nuclei of many radio galaxies and quasars. Nevertheless, despite their abundance the questions of the formation, acceleration and propagation of nonuniform winds and jets have not been fully resolved. One of the main difficulties in dealing with the theoretical problem posed by cosmical outflows is that their dynamics needs to be described - even to lowest order - by the highly intractable set of the MHD equations. As is well known, this is a nonlinear system of partial differential equations with several critical points, and only very few classes of solutions are available for axisymmetric systems obtained by assuming a separation of variables in several key functions. This hypothesis allows an analysis in a 2-D geometry of the full MHD equations which reduce then to a system of ordinary differential equations. By a systematic method we construct general classes of exact and self-consistent axisymmetric MHD solutions. The unifying scheme contains three large groups of exact MHD outflow models, (I) meridionally self-similar ones with spherical critical surfaces, (II) radially self-similar models with conical critical surfaces and (III) generalized self-similar models with arbitrary shape critical surfaces. This classification includes known polytropic models, such as the classical Parker description of a stellar wind and the Blandford and Payne (1982) model of a disk-wind; it also contains nonpolytropic models, such as those of winds/jets in Sauty and Tsinganos (1994), Lima et al (1996) and Trussoni et al (1997). Besides the unification of all known cases under a common scheme, several new classes emerge and some are briefly analyzed; they could be explored for a further understanding of the physical properties of MHD outflows from various magnetized astrophysical rotators. We also propose a new class of exact and self-consistent MHD solutions which describe steady and axisymmetric hydromagnetic outflows from the magnetized atmosphere of a rotating gravitating central object with possibly an orbiting accretion disk. The plasma is driven by a thermal pressure gradient, as well as by magnetic rotator and radiative forces. At the Alfvenic and fast critical points the appropriate criticality conditions are applied. The outflows start almost radially but after the Alfven transition and before the fast critical surface is encountered the magnetic pinching force bends the poloidal streamlines into a cylindrical jet-type shape. The terminal speed, Alfven number, cross-sectional area of the jet, as well as its final pressure and density obtain uniform values at large distances from the source. The goal of the study is to give an analytical discussion of the two-dimensional interplay of the thermal pressure gradient, gravitational, Lorentz and inertial forces in accelerating and collimating an MHD flow. A parametric study of the model is given, as well as a brief sketch of its applicability to a self-consistent modeling of collimated outflows from various astrophysical objects. For example, the obtained characteristics of the collimated outflow in agreement with those in jets associated with YSO's. General theoretical arguments and various analytic self-similar solutions have recently shown that magnetized and rotating astrophysical outflows may become asymptotically cylindrical, in agreement with observations of cosmical jets. A notable common feature in all such self-consistent, self-similar MHD solutions is that before final cylindrical collimation is achieved, the jet passes from a stage of oscillations in its radius, Mach number and other physical parameters. It is shown that under rather general assumptions this oscillatory behaviour of collimated outflows is not restricted to the few specific models examined so far, but instead it seems to be a rather general physical property of an MHD outflow which starts noncylindrically before it reaches collimation. It is concluded thence that astrophysical jets are topologically stable to small amplitude, time-independent perturbations in their asymptotically cylindrical shape. Also, similarly to the familiar fluid instabilities these oscillations may give rise to brightness enhancements along jets.

Star Formation near Berkeley 59: Embedded Protostars

NASA Astrophysics Data System (ADS)

Rosvick, J. M.; Majaess, D.

2013-12-01

A group of suspected protostars in a dark cloud northwest of the young (~2 Myr) cluster Berkeley 59 and two sources in a pillar south of the cluster have been studied in order to determine their evolutionary stages and ascertain whether their formation was triggered by Berkeley 59. Narrowband near-infrared observations from the Observatoire du Mont Mégantic, 12CO (J = 3-2) and SCUBA-2 (450 and 850 μm) observations from the JCMT, 2MASS, and WISE images, and data extracted from the IPHAS survey catalog were used. Of 12 sources studied, two are Class I objects, while three others are flat/Class II, one of which is a T Tauri candidate. A weak CO outflow and two potential starless cores are present in the cloud, while the pillar possesses substructure at different velocities, with no outflows present. The CO spectra of both regions show peaks in the range v LSR = -15 to -17 km s-1, which agrees with the velocity adopted for Berkeley 59 (-15.7 km s-1), while spectral energy distribution models yield an average interstellar extinction AV and distance of 15 ± 2 mag and 830 ± 120 pc, respectively, for the cloud, and 6.9 mag and 912 pc for the pillar, indicating that the regions are in the same vicinity as Berkeley 59. The formation of the pillar source appears to have been triggered by Berkeley 59. It is unclear whether Berkeley 59 triggered the association's formation.

CONTROLLING INFLUENCE OF MAGNETIC FIELD ON SOLAR WIND OUTFLOW: AN INVESTIGATION USING CURRENT SHEET SOURCE SURFACE MODEL

DOE Office of Scientific and Technical Information (OSTI.GOV)

Poduval, B., E-mail: bpoduval@spacescience.org

2016-08-10

This Letter presents the results of an investigation into the controlling influence of large-scale magnetic field of the Sun in determining the solar wind outflow using two magnetostatic coronal models: current sheet source surface (CSSS) and potential field source surface. For this, we made use of the Wang and Sheeley inverse correlation between magnetic flux expansion rate (FTE) and observed solar wind speed (SWS) at 1 au. During the period of study, extended over solar cycle 23 and beginning of solar cycle 24, we found that the coefficients of the fitted quadratic equation representing the FTE–SWS inverse relation exhibited significantmore » temporal variation, implying the changing pattern of the influence of FTE on SWS over time. A particularly noteworthy feature is an anomaly in the behavior of the fitted coefficients during the extended minimum, 2008–2010 (CRs 2073–2092), which is considered due to the particularly complex nature of the solar magnetic field during this period. However, this variation was significant only for the CSSS model, though not a systematic dependence on the phase of the solar cycle. Further, we noticed that the CSSS model demonstrated better solar wind prediction during the period of study, which we attribute to the treatment of volume and sheet currents throughout the corona and the more accurate tracing of footpoint locations resulting from the geometry of the model.« less

Enceladus's Plumes: A Rocket Analogy

NASA Astrophysics Data System (ADS)

McNutt, R. L.; Perry, M. E.; Waite, J. H.; Fletcher, G.; Cravens, T. E.

2009-12-01

The plumes of Enceladus, and the source of the E-ring in the Saturnian system, easily rank as the major, significant, and unexpected discovery of the Cassini mission. While clearly the source of the E-ring,the nature of the sources and the energetics and dynamics of the plumes and underlying jets remains a subject of intensive study. Refinements of the observations suggest supersonic flow of the primary, water-vapor effluent. Such behavior implies a sonic critical point in the flow beginning from a heated reservoir of vapor, through a constriction, and out at supersonic speeds in the space above the plume/jet channels. Such geometry and thermal conditions mimic that of a de Laval nozzle, such as used in rocket engines for converting chemically heated combustion products into a directional flow. A chamber temperature of 180K suggests an outflow speed as high as 0.8 km/s. With a column density across a jet of ~3 x 1016 cm-2 (about twice that of the broad plume) and a jet width of ~10 km, the implied outflow of water molecules is ~3 x 1010 cm-3 x π/4 (106 cm)2 x 18 amu x 1.66 x 10-27 amu/kg x 8 x 104 cm/s = ~60 kg/s in each constituent jet, of which eight were identified by the Cassini Ultraviolet Imaging Spectrograph (UVIS) during the occultation measurements of the plume region of Enceladus carried out on 24 October 2007.

Regional Modeling of Dust Mass Balance and Radiative Forcing over East Asia using WRF-Chem

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Siyu; Zhao, Chun; Qian, Yun

The Weather Research and Forecasting model with Chemistry (WRF-Chem) is used to investigate the seasonal and annual variations of mineral dust over East Asia during 2007-2011, with a focus on the dust mass balance and radiative forcing. A variety of measurements from in-stu and satellite observations have been used to evaluate simulation results. Generally, WRF-Chem reproduces not only the column variability but also the vertical profile and size distribution of mineral dust over and near the dust source regions of East Asia. We investigate the dust lifecycle and the factors that control the seasonal and spatial variations of dust massmore » balance and radiative forcing over the seven sub-regions of East Asia, i.e. source regions, the Tibetan Plateau, Northern China, Southern China, the ocean outflow region, and Korea-Japan regions. Results show that, over the source regions, transport and dry deposition are the two dominant sinks. Transport contributes to ~30% of the dust sink over the source regions. Dust results in a surface cooling of up to -14 and -10 W m-2, atmospheric warming of up to 20 and 15 W m-2, and TOA cooling of -5 and -8 W m-2 over the two major dust source regions of East Asia, respectively. Over the Tibetan Plateau, transport is the dominant source with a peak in summer. Over identified outflow regions, maximum dust mass loading in spring is contributed by the transport. Dry and wet depositions are the comparably dominant sinks, but wet deposition is larger than dry deposition over the Korea-Japan region, particularly in spring (70% versus 30%). The WRF-Chem simulations can generally capture the measured features of dust aerosols and its radaitve properties and dust mass balance over East Asia, which provides confidence for use in further investigation of dust impact on climate over East Asia.« less

An In Vitro Perfusion System to Enhance Outflow Studies in Mouse Eyes

PubMed Central

Kizhatil, Krishnakumar; Chlebowski, Arthur; Tolman, Nicholas G.; Freeburg, Nelson F.; Ryan, Margaret M.; Shaw, Nicholas N.; Kokini, Alexander D. M.; Marchant, Jeffrey K.; John, Simon W. M.

2016-01-01

Purpose The molecular mechanisms controlling aqueous humor (AQH) outflow and IOP need much further definition. The mouse is a powerful system for characterizing the mechanistic basis of AQH outflow. To enhance outflow studies in mice, we developed a perfusion system that is based on human anterior chamber perfusion culture systems. Our mouse system permits previously impractical experiments. Methods We engineered a computer-controlled, pump-based perfusion system with a platform for mounting whole dissected mouse eyes (minus lens and iris, ∼45% of drainage tissue is perfused). We tested the system's ability to monitor outflow and tested the effects of the outflow-elevating drug, Y27632, a rho-associated protein kinase (ROCK) inhibitor. Finally, we tested the system's ability to detect genetically determined decreases in outflow by determining if deficiency of the candidate genes Nos3 and Cav1 alter outflow. Results Using our system, the outflow facility (C) of C57BL/6J mouse eyes was found to range between 7.7 and 10.4 nl/minutes/mm Hg (corrected for whole eye). Our system readily detected a 74.4% Y27632-induced increase in C. The NOS3 inhibitor L-NG-nitroarginine methyl ester (L-NAME) and a Nos3 null mutation reduced C by 28.3% and 35.8%, respectively. Similarly, in Cav1 null eyes C was reduced by 47.8%. Conclusions We engineered a unique perfusion system that can accurately measure changes in C. We then used the system to show that NOS3 and CAV1 are key components of mechanism(s) controlling outflow. PMID:27701632

PROTOSTELLAR OUTFLOWS AND RADIATIVE FEEDBACK FROM MASSIVE STARS. II. FEEDBACK, STAR-FORMATION EFFICIENCY, AND OUTFLOW BROADENING

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuiper, Rolf; Turner, Neal J.; Yorke, Harold W., E-mail: rolf.kuiper@uni-tuebingen.de, E-mail: Neal.J.Turner@jpl.nasa.gov, E-mail: Harold.W.Yorke@jpl.nasa.gov

2016-11-20

We perform two-dimensional axially symmetric radiation hydrodynamic simulations to assess the impact of outflows and radiative force feedback from massive protostars by varying when the protostellar outflow starts, and to determine the ratio of ejection to accretion rates and the strength of the wide-angle disk wind component. The star-formation efficiency, i.e., the ratio of final stellar mass to initial core mass, is dominated by radiative forces and the ratio of outflow to accretion rates. Increasing this ratio has three effects. First, the protostar grows slower with a lower luminosity at any given time, lowering radiative feedback. Second, bipolar cavities clearedmore » by the outflow become larger, further diminishing radiative feedback on disk and core scales. Third, the higher momentum outflow sweeps up more material from the collapsing envelope, decreasing the protostar's potential mass reservoir via entrainment. The star-formation efficiency varies with the ratio of ejection to accretion rates from 50% in the case of very weak outflows to as low as 20% for very strong outflows. At latitudes between the low-density bipolar cavity and the high-density accretion disk, wide-angle disk winds remove some of the gas, which otherwise would be part of the accretion flow onto the disk; varying the strength of these wide-angle disk winds, however, alters the final star-formation efficiency by only ±6%. For all cases, the opening angle of the bipolar outflow cavity remains below 20° during early protostellar accretion phases, increasing rapidly up to 65° at the onset of radiation pressure feedback.« less

Geometric and Kinematic Structure of the Outflow/Envelope System of L1527 Revealed by Subarcsecond-resolution Observation of CS

NASA Astrophysics Data System (ADS)

Oya, Yoko; Sakai, Nami; Lefloch, Bertrand; López-Sepulcre, Ana; Watanabe, Yoshimasa; Ceccarelli, Cecilia; Yamamoto, Satoshi

2015-10-01

Subarcsecond-resolution images of the rotational line emissions of CS and c-C3H2 obtained toward the low-mass protostar IRAS 04368+2557 in L1527 with the Atacama Large Millimeter/submillimeter Array are investigated to constrain the orientation of the outflow/envelope system. The distribution of CS consists of an envelope component extending from north to south and a faint butterfly shaped outflow component. The kinematic structure of the envelope is well reproduced by a simple ballistic model of an infalling rotating envelope. Although the envelope has a nearly edge-on configuration, we find that the western side of the envelope faces the observer. This configuration is opposite to the direction of the large-scale (˜104 AU) outflow suggested previously from the 12CO (J = 3-2) observation, and to the morphology of infrared reflection near the protostar (˜200 AU). The latter discrepancy could originate from high extinction by the outflow cavity of the western side, or may indicate that the outflow axis is not parallel to the rotation axis of the envelope. Position-velocity diagrams show the accelerated outflow cavity wall, and its kinematic structure in the 2000 AU scale is explained by a standard parabolic model with the inclination angle derived from the analysis of the envelope. The different orientation of the outflow between the small and large scale implies a possibility of precession of the outflow axis. The shape and the velocity of the outflow in the vicinity of the protostar are compared with those of other protostars.

Star formation inside a galactic outflow.

PubMed

Maiolino, R; Russell, H R; Fabian, A C; Carniani, S; Gallagher, R; Cazzoli, S; Arribas, S; Belfiore, F; Bellocchi, E; Colina, L; Cresci, G; Ishibashi, W; Marconi, A; Mannucci, F; Oliva, E; Sturm, E

2017-04-13

Recent observations have revealed massive galactic molecular outflows that may have the physical conditions (high gas densities) required to form stars. Indeed, several recent models predict that such massive outflows may ignite star formation within the outflow itself. This star-formation mode, in which stars form with high radial velocities, could contribute to the morphological evolution of galaxies, to the evolution in size and velocity dispersion of the spheroidal component of galaxies, and would contribute to the population of high-velocity stars, which could even escape the galaxy. Such star formation could provide in situ chemical enrichment of the circumgalactic and intergalactic medium (through supernova explosions of young stars on large orbits), and some models also predict it to contribute substantially to the star-formation rate observed in distant galaxies. Although there exists observational evidence for star formation triggered by outflows or jets into their host galaxy, as a consequence of gas compression, evidence for star formation occurring within galactic outflows is still missing. Here we report spectroscopic observations that unambiguously reveal star formation occurring in a galactic outflow at a redshift of 0.0448. The inferred star-formation rate in the outflow is larger than 15 solar masses per year. Star formation may also be occurring in other galactic outflows, but may have been missed by previous observations owing to the lack of adequate diagnostics.

Quantifying Feedback from Narrow Line Region Outflows in Nearby Active Galaxies. I. Spatially Resolved Mass Outflow Rates for the Seyfert 2 Galaxy Markarian 573

NASA Astrophysics Data System (ADS)

Revalski, M.; Crenshaw, D. M.; Kraemer, S. B.; Fischer, T. C.; Schmitt, H. R.; Machuca, C.

2018-03-01

We present the first spatially resolved mass outflow rate measurements ({\\dot{M}}out}) of the optical emission line gas in the narrow line region (NLR) of a Seyfert 2 galaxy, Markarian 573. Using long slit spectra and [O III] imaging from the Hubble Space Telescope and Apache Point Observatory in conjunction with emission line diagnostics and Cloudy photoionization models, we find a peak outflow rate of {\\dot{M}}out}≈ 3.4 +/- 0.5 {M}ȯ {yr}}-1 at a distance of 210 pc from the central supermassive black hole (SMBH). The outflow extends to distances of 600 pc from the nucleus with a total mass and kinetic energy of M ≈ 2.2 × 106 M ⊙ and E ≈ 5.1 × 1054 erg, revealing the outflows to be more energetic than those in the lower luminosity Seyfert 1 galaxy NGC 4151. The peak outflow rate is an order of magnitude larger than the mass accretion and nuclear outflow rates, indicating local in situ acceleration of the circumnuclear NLR gas. We compare these results to global techniques that quantify an average outflow rate across the NLR, and find the latter are subject to larger uncertainties. These results indicate that spatially resolved observations are critical for probing AGN feedback on scales where circumnuclear star formation occurs.

AGN feedback in action? - outflows and star formation in type 2 AGNs

NASA Astrophysics Data System (ADS)

Woo, Jong-Hak

2017-01-01

We present the statistical constraints on the ionized gas outflows and their connection to star formation, using a large sample of ~110,000 AGNs and star-forming galaxies at z < 0.3. First, we find a dramatic difference of the outflow signatures between AGNs and star-forming galaxies based on the [OIII] emission line kinematics. While the [OIII] velocity and velocity dispersion of star forming galaxies can be entirely accounted by the gravitational potential of host galaxies, AGNs clearly show non-gravitational kinematics, which is comparable to or stronger than the virial motion caused by the gravitational potential. Second, the distribution in the [OIII] velocity - velocity dispersion diagram dramatically expands toward large values with increasing AGN luminosity, implying that the outflows are AGN-driven. Third, the fraction of AGNs with a signature of outflow kinematics, steeply increases with AGN luminosity and Eddington ratio. In particular, the majority of luminous AGNs presents strong non-gravitational kinematics in the [OIII] profile. Interestingly, we find that the specific star formation of non-outflow AGNs is much lower than that of strong outflow AGNs, while the star formation rate of strong outflow AGNs is comparable to that of star forming galaxies. We interpret this trend as a delayed AGN feedback as it takes dynamical time for the outflows to suppress star formation in galactic scales.

Morphological and Hydrodynamic Correlations with Increasing Outflow Facility by Rho-Kinase Inhibitor Y-27632

PubMed Central

Yang, Chen-Yuan Charlie

2014-01-01

Abstract Rho-kinase inhibitors affect actomyosin cytoskeletal networks and have been shown to significantly increase outflow facility and lower intraocular pressure in various animal models and human eyes. This article summarizes common morphological changes in the trabecular meshwork induced by Rho-kinase inhibitors and specifically compares the morphological and hydrodynamic correlations with increased outflow facility by Rho-kinase inhibitor, Y-27632, in bovine, monkey, and human eyes under similar experimental conditions. Interspecies comparison has shown that morphological changes in the juxtacanalicular connective tissue (JCT) of these 3 species were different. However, these different morphological changes in the JCT, no matter if it's separation between the JCT and inner wall in bovine eyes, or separation between the JCT cells or between the JCT cells and their matrix in monkey eyes, or even no separation between the inner wall and the JCT but a more subtle expansion of the JCT in human eyes, appear to correlate with the increased percent change of outflow facility. More importantly, these different morphological changes all resulted in an increase in effective filtration area, which was positively correlated with increased outflow facility in all 3 species. These results suggest a link among changes in outflow facility, tissue architecture, and aqueous outflow pattern. Y-27632 increases outflow facility by redistributing aqueous outflow through a looser and larger area in the JCT. PMID:24460021

Density diagnostics of ionized outflows in active galacitc nuclei

NASA Astrophysics Data System (ADS)

Mao, J.; Kaastra, J.; Mehdipour, M.; Raassen, T.; Gu, L.

2017-10-01

Ionized outflows in Active Galactic Nuclei are thought to influence their nuclear and local galactic environment. However, the distance of outflows with respect to the central engine is poorly constrained, which limits our understanding of the kinetic power by the outflows. Therefore, the impact of AGN outflows on their host galaxies is uncertain. Given the density of the outflows, their distance can be immediately obtained by the definition of the ionization parameter. Here we carry out a theoretical study of density diagnostics of AGN outflows using absorption lines from metastable levels in Be-like to F-like ions. With the new self-consistent photoionization model (PION) in the SPEX code, we are able to calculate ground and metastable level populations. This enable us to determine under what physical conditions these levels are significantly populated. We then identify characteristic transitions from these metastable levels in the X-ray band. Firm detections of absorption lines from such metastable levels are challenging for current grating instruments. The next generation of spectrometers like X-IFU onboard Athena will certainly identify the presence/absence of these density- sensitive absorption lines, thus tightly constraining the location and the kinetic power of AGN outflows.

Scaling Relations Between Warm Galactic Outflows and Their Host Galaxies

NASA Astrophysics Data System (ADS)

Chisholm, John; Tremonti, Christy A.; Leitherer, Claus; Chen, Yanmei; Wofford, Aida; Lundgren, Britt

2015-10-01

We report on a sample of 48 nearby, star-forming galaxies observed with the Cosmic Origin Spectrograph on the Hubble Space Telescope. We measure the kinematics of warm gas in galactic outflows using a combination of four Si ii absorption lines. We use multi-wavelength ancillary data to estimate stellar masses (M*), star formation rates (SFR), circular velocities (vcirc), and morphologies. The galaxies cover four orders of magnitude in M* and SFR, and sample a wide range of morphologies from starbursting mergers to normal star-forming galaxies. We derive 3.0-3.5σ relations between outflow velocity and SFR, M*, and vcirc. The outflow velocities scale as SFR0.08-0.22, {M}*0.12-0.20 and {v}{circ}0.44-0.87, with the range depending on whether we use a maximum or a central velocity to quantify the outflow velocity. After accounting for their increased SFR, mergers drive 32% faster outflows than non-merging galaxies, with all of the highest velocity outflows arising from mergers. Low-mass galaxies (log(M*/ M⊙) < 10.5) lose some low-ionization gas through galactic outflows, while more massive galaxies retain all of their low-ionization gas, unless they undergo a merger.

Analysis of North Atlantic Aircraft Data on Oxygenated Intermediate Species Using an Adapted Regional Chemistry-Transport Model

NASA Technical Reports Server (NTRS)

Chatfield, Robert; Mathur, Rohit; Alapaty, Kiran; Hanna, Adel; Binkowski, Frank; Guan, Hong; Esswein, Robert

2004-01-01

Our study is on the interaction of nitrogen oxides with organics as they are exported from their complex sources in Eastern North America. Both urban and specific industrial emissions contribute the nitrogen of the C-H-O-N compounds that affect the global atmosphere, helping determine both ozone and the self-cleaning radical chemistry of the troposphere mediated by the OH radical. Different industrial sources, urban, and natural emissions contribute the organic C. Peroxyacetyl nitrate, CH3C(double bonds O)OONO2 is the most interesting compound for which we can measure the outflow to the full depth of the Atlantic troposphere. As we adapt the 3-d chemical model to describe outflow for specific periods with sufficient accuracy, we are analyzing some valuable information in the NARE-97 complete airborne dataset. (NARE: North Atlantic Regional Experiment). Ames researchers find that there are substantial puzzles in the ratios of PAN/NO2. Peroxy acetyl nitrate provides one of the major long-distance export pathways for active nitrogen from Eastern North America. It should be closely linked with NO, (defined as the sum NO + NO2) by simple thermal association and decomposition reactions, at least when the ambient temperature is substantially above 5 C.

Contribution of sediment fluxes and transformations to the summer nitrogen budget of an Upper Mississippi River backwater system

USGS Publications Warehouse

James, W.F.; Richardson, W.B.; Soballe, D.M.

2008-01-01

Routing nitrate through backwaters of regulated floodplain rivers to increase retention could decrease loading to nitrogen (N)-sensitive coastal regions. Sediment core determinations of N flux were combined with inflow-outflow fluxes to develop mass balance approximations of N uptake and transformations in a flow-controlled backwater of the Upper Mississippi River (USA). Inflow was the dominant nitrate source (>95%) versus nitrification and varied as a function of source water concentration since flow was constant. Nitrate uptake length increased linearly, while uptake velocity decreased linearly, with increasing inflow concentration to 2 mg l-1, indicating limitation of N uptake by loading. N saturation at higher inflow concentration coincided with maximum uptake capacity, 40% uptake efficiency, and an uptake length 2 times greater than the length of the backwater. Nitrate diffusion and denitrification in sediment accounted for 27% of the backwater nitrate retention, indicating that assimilation by other biota or denitrification on other substrates were the dominant uptake mechanisms. Ammonium export from the backwater was driven by diffusive efflux from the sediment. Ammonium increased from near zero at the inflow to a maximum mid-lake, then declined slightly toward the outflow due to uptake during transport. Ammonium export was small compared to nitrate retention. ?? 2007 Springer Science+Business Media B.V.

Compendium of NASA data base for the Global Tropospheric Experiment's Pacific Exploratory Mission West-A (PEM West-A)

NASA Technical Reports Server (NTRS)

Gregory, G. L.; Scott, A. D., Jr.

1995-01-01

This compendium describes aircraft data that are available from NASA's Pacific Exploratory Mission West-A (PEM West-A). PEM West is a component of the International Global Atmospheric Chemistry's (IGAC) East Asia/North Pacific Regional Study (APARE) project. The PEM- West program encompassed two expeditions to study contrasting meteorological regimes in the Pacific. Objectives of PEM West are to investigate the atmospheric chemistry of ozone over the northwest Pacific -- natural budgets and the impact of anthropogenic sources; and to investigate sulfur chemistry -- continental versus marine sulfur sources. PEM West-A was conducted in September 1991 during which the predominance of tropospheric air is from the mid-Pacific (marine) regions, but (at times) is modified/mixed with Asian continental outflow. PEM West-B was conducted during February 1994, a period characterized by maximum continental outflow. PEM-B data (not included) will become public domain during the Summer of 1995. PEM West-A flight experiments were based at Japan, Hong Kong, and Guam. This document provides a representation of NASA DC-8 aircraft data that are available from NASA Langley's Distributed Active Archive Center (DAAC), which include numerous data such as meteorological observations, modeling products, results from surface studies, satellite observations, and sonde releases.

Compendium of NASA data base for the global tropospheric experiment's Pacific Exploratory Mission West-B (PEM West-B)

NASA Technical Reports Server (NTRS)

Gregory, Gerald L.; Scott, A. Donald, Jr.

1995-01-01

This compendium describes aircraft data that are available from NASA's Pacific Exploratory Mission West-B (PEM West-B). PEM West is a component of the International Global Atmospheric Chemistry's (IGAC) East Asia/North Pacific Regional Study (APARE) project. Objectives of PEM West are to investigate the atmospheric chemistry of ozone over the northwest Pacific -- natural budgets and the impact of anthropogenic/continental sources; and to investigate sulfur chemistry -- continental and marine sulfur sources. The PEM West program encompassed two expeditions. PEM West-A was conducted in September 1991 during which the predominance of tropospheric air was from mid-Pacific (marine) regions, but (at times) was modified by Asian outflow. PEM West-B was conducted during February 1994, a period characterized by maximum Asian outflow. Results from PEM West-A and B are public domain. PEM West-A data are summarized in NASA TM 109177 (published February 1995). Flight experiments were based at Guam, Hong Kong, and Japan. This document provides a representation of NASA DC-8 aircraft data that are available from NASA Langley's Distributed Active Archive Center (DAAC). The DAAC includes numerous other data such as meteorological and modeling products, results from surface studies, satellite observations, and sonde releases.

Arcsecond Resolution Mapping of Sulfur Dioxide Emission in the Circumstellar Envelope of VY Canis Majoris

NASA Astrophysics Data System (ADS)

Fu, Roger R.; Moullet, Arielle; Patel, Nimesh A.; Biersteker, John; Derose, Kimberly L.; Young, Kenneth H.

2012-02-01

We report Submillimeter Array observations of SO2 emission in the circumstellar envelope (CSE) of the red supergiant VY Canis Majoris, with an angular resolution of ≈1''. SO2 emission appears in three distinct outflow regions surrounding the central continuum peak emission that is spatially unresolved. No bipolar structure is noted in the sources. A fourth source of SO2 is identified as a spherical wind centered at the systemic velocity. We estimate the SO2 column density and rotational temperature assuming local thermal equilibrium (LTE) as well as perform non-LTE radiative transfer analysis using RADEX. Column densities of SO2 are found to be ~1016 cm-2 in the outflows and in the spherical wind. Comparison with existing maps of the two parent species OH and SO shows the SO2 distribution to be consistent with that of OH. The abundance ratio f_{SO_{2}}/f_{SO} is greater than unity for all radii larger than 3 × 1016 cm. SO2 is distributed in fragmented clumps compared to SO, PN, and SiS molecules. These observations lend support to specific models of circumstellar chemistry that predict f_{SO_{2}}/f_{SO}>1 and may suggest the role of localized effects such as shocks in the production of SO2 in the CSE.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kwon, Jungmi; Tamura, Motohide; Hough, James H.

Near-infrared imaging polarimetry in the J , H , and K{sub s} bands was carried out for GGD 27 in the dark cloud Lynds 291. Details of an infrared reflection nebula associated with the optical nebulosity GGD 27 and the infrared nebula GGD 27 IRS are presented. Aperture photometry of 1263 point-like sources, detected in all three bands, was used to classify them based on a color–color diagram, and the linear polarization of several hundred sources was determined, with the latter used to map the magnetic field structure around GGD 27. This field, around GGD 27 IRS, appears to bemore » associated with the extended CO outflow of IRAS 18162–2048; however, there are partly distorted or bent components in the field. The Chandrasekhar–Fermi method gives an estimate of the magnetic field strength as ∼90 μ G. A region associated with GGD 27 IRS is discovered to have a circular polarization in the range of ∼2%–11% in the K{sub s} band. The circular polarization has an asymmetric positive/negative pattern and extends out to ∼ 120″ or 1.0 pc. The circular and linear polarization patterns are explained as resulting from a combination of dense inner and fainter outer lobes, suggesting episodic outflow.« less

LINEAR POLARIZATION OF CLASS I METHANOL MASERS IN MASSIVE STAR-FORMING REGIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kang, Ji-hyun; Byun, Do-Young; Kim, Kee-Tae

Class I methanol masers are found to be good tracers of the interaction between outflows from massive young stellar objects with their surrounding media. Although polarization observations of Class II methanol masers have been able to provide information about magnetic fields close to the central (proto)stars, polarization observations of Class I methanol masers are rare, especially at 44 and 95 GHz. We present the results of linear polarization observations of 39 Class I methanol maser sources at 44 and 95 GHz. These two lines are observed simultaneously with one of the 21 m Korean VLBI Network telescopes in single-dish mode.more » Approximately 60% of the observed sources have fractional polarizations of a few percent in at least one transition. This is the first reported detection of linear polarization of the 44 GHz methanol maser. The two maser transitions show similar polarization properties, indicating that they trace similar magnetic environments, although the fraction of the linear polarization is slightly higher at 95 GHz. We discuss the association between the directions of polarization angles and outflows. We also discuss some targets having different polarization properties at both lines, including DR21(OH) and G82.58+0.20, which show the 90° polarization angle flip at 44 GHz.« less

Gravitational wave astronomy - astronomy of the 21st century

NASA Astrophysics Data System (ADS)

Dhurandhar, S. V.

2011-03-01

An enigmatic prediction of Einstein's general theory of relativity is gravitational waves. With the observed decay in the orbit of the Hulse-Taylor binary pulsar agreeing within a fraction of a percent with the theoretically computed decay from Einstein's theory, the existence of gravitational waves was firmly established. Currently there is a worldwide effort to detect gravitational waves with inteferometric gravitational wave observatories or detectors and several such detectors have been built or being built. The initial detectors have reached their design sensitivities and now the effort is on to construct advanced detectors which are expected to detect gravitational waves from astrophysical sources. The era of gravitational wave astronomy has arrived. This article describes the worldwide effort which includes the effort on the Indian front - the IndIGO project -, the principle underlying interferometric detectors both on ground and in space, the principal noise sources that plague such detectors, the astrophysical sources of gravitational waves that one expects to detect by these detectors and some glimpse of the data analysis methods involved in extracting the very weak gravitational wave signals from detector noise.

Gravitational wave astronomy— astronomy of the 21st century

NASA Astrophysics Data System (ADS)

Dhurandhar, S. V.

2011-12-01

An enigmatic prediction of Einstein's general theory of relativity is gravitational waves. With the observed decay in the orbit of the Hulse-Taylor binary pulsar agreeing within a fraction of a percent with the theoretically computed decay from Einstein's theory, the existence of gravitational waves was firmly established. Currently there is a worldwide effort to detect gravitational waves with inteferometric gravitational wave observatories or detectors and several such detectors have been built or are being built. The initial detectors have reached their design sensitivities and now the effort is on to construct advanced detectors which are expected to detect gravitational waves from astrophysical sources. The era of gravitational wave astronomy has arrived. This article describes the worldwide effort which includes the effort on the Indian front— the IndIGO project —, the principle underlying interferometric detectors both on ground and in space, the principal noise sources that plague such detectors, the astrophysical sources of gravitational waves that one expects to detect by these detectors and some glimpse of the data analysis methods involved in extracting the very weak gravitational wave signals from detector noise.

Residence times in river basins as determined by analysis of long-term tritium records

USGS Publications Warehouse

Michel, R.L.

1992-01-01

The US Geological Survey has maintained a network of stations to collect samples for the measurement of tritium concentrations in precipitation and streamflow since the early 1960s. Tritium data from outflow waters of river basins draining 4500-75000 km2 are used to determine average residence times of water within the basins. The basins studied are the Colorado River above Cisco, Utah; the Kissimmee River above Lake Okeechobee, Florida; the Mississippi River above Anoka, Minnesota; the Neuse River above Streets Ferry Bridge near Vanceboro, North Carolina; the Potomac River above Point of Rocks, Maryland; the Sacramento River above Sacramento, California; the Susquehanna River above Harrisburg, Pennsylvania. The basins are modeled with the assumption that the outflow in the river comes from two sources-prompt (within-year) runoff from precipitation, and flow from the long-term reservoirs of the basin. Tritium concentration in the outflow water of the basin is dependent on three factors: (1) tritium concentration in runoff from the long-term reservoir, which depends on the residence time for the reservoir and historical tritium concentrations in precipitation; (2) tritium concentrations in precipitation (the within-year runoff component); (3) relative contributions of flow from the long-term and within-year components. Predicted tritium concentrations for the outflow water in the river basins were calculated for different residence times and for different relative contributions from the two reservoirs. A box model was used to calculate tritium concentrations in the long-term reservoir. Calculated values of outflow tritium concentrations for the basin were regressed against the measured data to obtain a slope as close as possible to 1. These regressions assumed an intercept of zero and were carried out for different values of residence time and reservoir contribution to maximize the fit of modeled versus actual data for all the above rivers. The final slopes of the fitted regression lines ranged from 0.95 to 1.01 (correlation coefficient > 0.96) for the basins studied. Values for the residence time of waters within the basins and average relative contributions of the within-year and long-term reservoirs to outflow were obtained. Values for river basin residence times ranged from 2 years for the Kissimmee River basin to 20 years for the Potomac River basin. The residence times indicate the time scale in which the basin responds to anthropogenic inputs. The modeled tritium concentrations for the basins also furnish input data for urban and agricultural settings where these river waters are used. ?? 1992.

What Fraction of Active Galaxies Actually Show Outflows?

NASA Astrophysics Data System (ADS)

Ganguly, Rajib; Brotherton, M. S.

2007-12-01

Outflows from active galactic nuclei (AGNs) seem to be common and are thought to be important from a variety of perspectives: as an agent of chemical enhancement of the interstellar and intergalactic media, as an agent of angular momentum removal from the accreting central engine, and as an agent limiting star formation in starbursting systems by blowing out gas and dust from the host galaxy. To understand these processes, we must determine what fraction of AGNs feature outflows and understand what forms they take. We examine recent surveys of outflows detected in ultraviolet absorption over the entire range of velocities and velocity widths (i.e., broad absorption lines, associated absorption lines, and high-velocity narrow absorption lines). While the fraction of specific forms of outflows depends on AGN properties, the overall fraction displaying outflows is fairly constant, approximately 60%, over many orders of magnitude in luminosity. We discuss implications of this result and ways to refine our understanding of outflows. We acknowledge support from the US National Science Foundation through grant AST 05-07781.

The very faint X-ray binary IGR J17062-6143: a truncated disc, no pulsations, and a possible outflow

NASA Astrophysics Data System (ADS)

van den Eijnden, J.; Degenaar, N.; Pinto, C.; Patruno, A.; Wette, K.; Messenger, C.; Hernández Santisteban, J. V.; Wijnands, R.; Miller, J. M.; Altamirano, D.; Paerels, F.; Chakrabarty, D.; Fabian, A. C.

2018-04-01

We present a comprehensive X-ray study of the neutron star low-mass X-ray binary IGR J17062-6143, which has been accreting at low luminosities since its discovery in 2006. Analysing NuSTAR, XMM-Newton, and Swift observations, we investigate the very faint nature of this source through three approaches: modelling the relativistic reflection spectrum to constrain the accretion geometry, performing high-resolution X-ray spectroscopy to search for an outflow, and searching for the recently reported millisecond X-ray pulsations. We find a strongly truncated accretion disc at 77^{+22}_{-18} gravitational radii (˜164 km) assuming a high inclination, although a low inclination and a disc extending to the neutron star cannot be excluded. The high-resolution spectroscopy reveals evidence for oxygen-rich circumbinary material, possibly resulting from a blueshifted, collisionally ionized outflow. Finally, we do not detect any pulsations. We discuss these results in the broader context of possible explanations for the persistent faint nature of weakly accreting neutron stars. The results are consistent with both an ultra-compact binary orbit and a magnetically truncated accretion flow, although both cannot be unambiguously inferred. We also discuss the nature of the donor star and conclude that it is likely a CO or O-Ne-Mg white dwarf, consistent with recent multiwavelength modelling.

RESOLVING THE GEOMETRY OF THE INNERMOST RELATIVISTIC JETS IN ACTIVE GALACTIC NUCLEI

DOE Office of Scientific and Technical Information (OSTI.GOV)

Algaba, J. C.; Lee, S. S.; Nakamura, M.

2017-01-01

In the current paradigm, it is believed that the compact VLBI radio core of radio-loud active galactic nuclei (AGNs) represents the innermost upstream regions of relativistic outflows. These regions of AGN jets have generally been modeled by a conical outflow with a roughly constant opening angle and flow speed. Nonetheless, some works suggest that a parabolic geometry would be more appropriate to fit the high energy spectral distribution properties and it has been recently found that, at least in some nearby radio galaxies, the geometry of the innermost regions of the jet is parabolic. We compile here multi-frequency core sizes of archivalmore » data to investigate the typically unresolved upstream regions of the jet geometry of a sample of 56 radio-loud AGNs. Data combined from the sources considered here are not consistent with the classic picture of a conical jet starting in the vicinity of the super-massive black hole (SMBH), and may exclude a pure parabolic outflow solution, but rather suggest an intermediate solution with quasi-parabolic streams, which are frequently seen in numerical simulations. Inspection of the large opening angles near the SMBH and the range of the Lorentz factors derived from our results support our analyses. Our result suggests that the conical jet paradigm in AGNs needs to be re-examined by millimeter/sub-millimeter VLBI observations.« less

AN IONIZED OUTFLOW FROM AB AUR, A HERBIG AE STAR WITH A TRANSITIONAL DISK

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rodríguez, Luis F.; Zapata, Luis A.; Ortiz-León, Gisela N.

AB Aur is a Herbig Ae star with a transitional disk. Transitional disks present substantial dust clearing in their inner regions, most probably because of the formation of one or more planets, although other explanations are still viable. In transitional objects, accretion is found to be about an order of magnitude smaller than in classical full disks. Since accretion is believed to be correlated with outflow activity, centimeter free-free jets are expected to be present in association with these systems, at weaker levels than in classical protoplanetary (full) systems. We present new observations of the centimeter radio emission associated withmore » the inner regions of AB Aur and conclude that the morphology, orientation, spectral index, and lack of temporal variability of the centimeter source imply the presence of a collimated, ionized outflow. The radio luminosity of this radio jet is, however, about 20 times smaller than that expected for a classical system of similar bolometric luminosity. We conclude that centimeter continuum emission is present in association with stars with transitional disks, but at levels than are becoming detectable only with the upgraded radio arrays. On the other hand, assuming that the jet velocity is 300 km s{sup –1}, we find that the ratio of mass loss rate to accretion rate in AB Aur is ∼0.1, similar to that found for less evolved systems.« less

Septation and separation within the outflow tract of the developing heart

PubMed Central

Webb, Sandra; Qayyum, Sonia R; Anderson, Robert H; Lamers, Wouter H; Richardson, Michael K

2003-01-01

The developmental anatomy of the ventricular outlets and intrapericardial arterial trunks is a source of considerable confusion. First, major problems exist because of the multiple names and definitions used to describe this region of the heart as it develops. Second, there is no agreement on the boundaries of the described components, nor on the number of ridges or cushions to be found dividing the outflow tract, and the pattern of their fusion. Evidence is also lacking concerning the role of the fused cushions relative to that of the so-called aortopulmonary septum in separating the intrapericardial components of the great arterial trunks. In this review, we discuss the existing problems, as we see them, in the context of developmental and postnatal morphology. We concentrate, in particular, on the changes in the nature of the wall of the outflow tract, which is initially myocardial throughout its length. Key features that, thus far, do not seem to have received appropriate attention are the origin, and mode of separation, of the intrapericardial portions of the arterial trunks, and the formation of the walls of the aortic and pulmonary valvar sinuses. Also as yet undetermined is the formation of the free-standing muscular subpulmonary infundibulum, the mechanism of its separation from the aortic valvar sinuses, and its differentiation, if any, from the muscular ventricular outlet septum. PMID:12739611

Evaluation of Peripheral Blood Circulation Disorder in Scleroderma Patients Using an Optical Sensor with a Pressurization Mechanism

PubMed Central

Yamakoshi, Yoshiki

2016-01-01

Blood circulation function of peripheral blood vessels in skin dermis was evaluated employing an optical sensor with a pressurization mechanism using the blood outflow and reflow characteristics. The device contains a light source and an optical sensor. When applied to the skin surface, it first exerts the primary pressure (higher than the systolic blood pressure), causing an outflow of blood from the dermal peripheral blood vessels. After two heartbeats, the pressure is lowered (secondary pressure) and blood reflows into the peripheral blood vessels. Hemoglobin concentration, which changes during blood outflow and reflow, is derived from the received light intensity using the Beer–Lambert law. This method was evaluated in 26 healthy female volunteers and 26 female scleroderma patients. In order to evaluate the blood circulation function of the peripheral blood vessels of scleroderma patients, pressurization sequence which consists of primary pressure followed by secondary pressure was adopted. Blood reflow during the first heartbeat period after applying the secondary pressure of 40mmHg was (mean±SD) 0.059±0.05%mm for scleroderma patients and 0.173±0.104%mm for healthy volunteers. Blood reflow was significantly lower in scleroderma patients than in healthy volunteers (p<0.05). This result indicates that the information necessary for assessing blood circulation disorder of peripheral blood vessels in scleroderma patients is objectively obtained by the proposed method. PMID:27479094

Evaluation of Peripheral Blood Circulation Disorder in Scleroderma Patients Using an Optical Sensor with a Pressurization Mechanism.

PubMed

Yamakoshi, Yoshiki; Motegi, Sei-Ichiro; Ishikawa, Osamu

2016-01-01

Blood circulation function of peripheral blood vessels in skin dermis was evaluated employing an optical sensor with a pressurization mechanism using the blood outflow and reflow characteristics. The device contains a light source and an optical sensor. When applied to the skin surface, it first exerts the primary pressure (higher than the systolic blood pressure), causing an outflow of blood from the dermal peripheral blood vessels. After two heartbeats, the pressure is lowered (secondary pressure) and blood reflows into the peripheral blood vessels. Hemoglobin concentration, which changes during blood outflow and reflow, is derived from the received light intensity using the Beer-Lambert law. This method was evaluated in 26 healthy female volunteers and 26 female scleroderma patients. In order to evaluate the blood circulation function of the peripheral blood vessels of scleroderma patients, pressurization sequence which consists of primary pressure followed by secondary pressure was adopted. Blood reflow during the first heartbeat period after applying the secondary pressure of 40mmHg was (mean±SD) 0.059±0.05%mm for scleroderma patients and 0.173±0.104%mm for healthy volunteers. Blood reflow was significantly lower in scleroderma patients than in healthy volunteers (p<0.05). This result indicates that the information necessary for assessing blood circulation disorder of peripheral blood vessels in scleroderma patients is objectively obtained by the proposed method.

Unveiling the molecular bipolar outflow of the peculiar red supergiant VY Canis Majoris

NASA Astrophysics Data System (ADS)

Shinnaga, Hiroko; Claussen, Mark J.; Lim, Jeremy; Dinh-van-Trung; Tsuboi, Masato

2003-04-01

We carried out polarimetric spectral-line imaging of the molecular outflow of the peculiar red supergiant VY Canis Majoris in SiO J=1-0 line in the ground vibrational state, which contains highly linearly-polarized velocity components, using the Very Large Array. We succeeded in unveiling the highly linearly polarized bipolar outflow for the first time at subarcsecond spatial resolution. The results clearly show that the direction of linear polarization of the brightest maser components is parallel to the outflow axis. The results strongly suggest that the linear polarization of the SiO maser is closely related to the outflow phenomena of the star. Furthermore, the results indicate that the linear polarization observed in the optical and infrared also occur due to the outflow phenomena.

Lipid-sensors, enigmatic-orphan and orphan nuclear receptors as therapeutic targets in breast-cancer.

PubMed

Garattini, Enrico; Bolis, Marco; Gianni', Maurizio; Paroni, Gabriela; Fratelli, Maddalena; Terao, Mineko

2016-07-05

Breast-cancer is heterogeneous and consists of various groups with different biological characteristics. Innovative pharmacological approaches accounting for this heterogeneity are needed. The forty eight human Nuclear-Hormone-Receptors are ligand-dependent transcription-factors and are classified into Endocrine-Receptors, Adopted-Orphan-Receptors (Lipid-sensors and Enigmatic-Orphans) and Orphan-receptors. Nuclear-Receptors represent ideal targets for the design/synthesis of pharmacological ligands. We provide an overview of the literature available on the expression and potential role played by Lipid-sensors, Enigmatic-Orphans and Orphan-Receptors in breast-cancer. The data are complemented by an analysis of the expression levels of each selected Nuclear-Receptor in the PAM50 breast-cancer groups, following re-elaboration of the data publicly available. The major aim is to support the idea that some of the Nuclear-Receptors represent largely unexploited therapeutic-targets in breast-cancer treatment/chemo-prevention. On the basis of our analysis, we conclude that the Lipid-Sensors, NR1C3, NR1H2 and NR1H3 are likely to be onco-suppressors in breast-cancer. The Enigmatic-Orphans, NR1F1 NR2A1 and NR3B3 as well as the Orphan-Receptors, NR0B1, NR0B2, NR1D1, NR2F1, NR2F2 and NR4A3 exert a similar action. These Nuclear-Receptors represent candidates for the development of therapeutic strategies aimed at increasing their expression or activating them in tumor cells. The group of Nuclear-Receptors endowed with potential oncogenic properties consists of the Lipid-Sensors, NR1C2 and NR1I2, the Enigmatic-Orphans, NR1F3, NR3B1 and NR5A2, as well as the Orphan-Receptors, NR2E1, NR2E3 and NR6A1. These oncogenic Nuclear-Receptors should be targeted with selective antagonists, reverse-agonists or agents/strategies capable of reducing their expression in breast-cancer cells.

Evidence for ultra-fast outflows in radio-quiet AGNs. I. Detection and statistical incidence of Fe K-shell absorption lines

NASA Astrophysics Data System (ADS)

Tombesi, F.; Cappi, M.; Reeves, J. N.; Palumbo, G. G. C.; Yaqoob, T.; Braito, V.; Dadina, M.

2010-10-01

Context. Blue-shifted Fe K absorption lines have been detected in recent years between 7 and 10 keV in the X-ray spectra of several radio-quiet AGNs. The derived blue-shifted velocities of the lines can often reach mildly relativistic values, up to 0.2-0.4c. These findings are important because they suggest the presence of a previously unknown massive and highly ionized absorbing material outflowing from their nuclei, possibly connected with accretion disk winds/outflows. Aims: The scope of the present work is to statistically quantify the parameters and incidence of the blue-shifted Fe K absorption lines through a uniform analysis on a large sample of radio-quiet AGNs. This allows us to assess their global detection significance and to overcome any possible publication bias. Methods: We performed a blind search for narrow absorption features at energies greater than 6.4 keV in a sample of 42 radio-quiet AGNs observed with XMM-Newton. A simple uniform model composed by an absorbed power-law plus Gaussian emission and absorption lines provided a good fit for all the data sets. We derived the absorption lines parameters and calculated their detailed detection significance making use of the classical F-test and extensive Monte Carlo simulations. Results: We detect 36 narrow absorption lines on a total of 101 XMM-Newton EPIC pn observations. The number of absorption lines at rest-frame energies higher than 7 keV is 22. Their global probability to be generated by random fluctuations is very low, less than 3 × 10-8, and their detection have been independently confirmed by a spectral analysis of the MOS data, with associated random probability <10-7. We identify the lines as Fe XXV and Fe XXVI K-shell resonant absorption. They are systematically blue-shifted, with a velocity distribution ranging from zero up to ~0.3c, with a peak and mean value at ~0.1c. We detect variability of the lines on both EWs and blue-shifted velocities among different XMM-Newton observations even on time-scales as short as a few days, possibly suggesting somewhat compact absorbers. Moreover, we find no significant correlation between the cosmological red-shifts of the sources and the lines blue-shifted velocities, ruling out any systematic contamination by local absorption. If we define ultra-fast outflows (UFOs) those highly ionized absorbers with outflow velocities higher than 104 km s-1, then the majority of the lines are consistent with being associated to UFOs and the fraction of objects with detected UFOs in the whole sample is at least ~35%. This fraction is similar for type 1 and type 2 sources. The global covering fraction of the absorbers is consequently estimated to be in the range C ˜ 0.4-0.6, thereby implying large opening angles. Conclusions: From our systematic X-ray spectral analysis on a large sample of radio-quiet AGNs we have been able to clearly assess the global veracity of the blue-shifted Fe K absorption lines at E > 7 keV and to overcome their publication bias. These lines indicate that UFOs are a rather common phenomenon observable in the central regions of these sources and they are probably the direct signature of AGN accretion disk winds/ejecta. The detailed photo-ionization modeling of these absorbers is presented in a companion paper. Appendices are only available in electronic form at http://www.aanda.org

Classification of hydrogeologic areas and hydrogeologic flow systems in the basin and range physiographic province, southwestern United States

USGS Publications Warehouse

Anning, David W.; Konieczki, Alice D.

2005-01-01

The hydrogeology of the Basin and Range Physiographic Province in parts of Arizona, California, New Mexico, Utah, and most of Nevada was classified at basin and larger scales to facilitate information transfer and to provide a synthesis of results from many previous hydrologic investigations. A conceptual model for the spatial hierarchy of the hydrogeology was developed for the Basin and Range Physiographic Province and consists, in order of increasing spatial scale, of hydrogeologic components, hydrogeologic areas, hydrogeologic flow systems, and hydrogeologic regions. This hierarchy formed a framework for hydrogeologic classification. Hydrogeologic areas consist of coincident ground-water and surface-water basins and were delineated on the basis of existing sets of basin boundaries that were used in past investigations by State and Federal government agencies. Within the study area, 344 hydrogeologic areas were identified and delineated. This set of basins not only provides a framework for the classification developed in this report, but also has value for regional and subregional purposes of inventory, study, analysis, and planning throughout the Basin and Range Physiographic Province. The fact that nearly all of the province is delineated by the hydrogeologic areas makes this set well suited to support regional-scale investigations. Hydrogeologic areas are conceptualized as a control volume consisting of three hydrogeologic components: the soils and streams, basin fill, and consolidated rocks. The soils and streams hydrogeologic component consists of all surface-water bodies and soils extending to the bottom of the plant root zone. The basin-fill hydrogeologic component consists of unconsolidated and semiconsolidated sediment deposited in the structural basin. The consolidated-rocks hydrogeologic component consists of the crystalline and sedimentary rocks that form the mountain blocks and basement rock of the structural basin. Hydrogeologic areas were classified into 19 groups through a cluster analysis of 8 characteristics of each area's hydrologic system. Six characteristics represented the inflows and outflows of water through the soils and streams, basin fill, and consolidated rocks, and can be used to determine the hydrogeologic area's position in a hydrogeologic flow system. Source-, link-, and sink-type hydrogeologic areas have outflow but not inflow, inflow and outflow, and inflow but not outflow, respectively, through one or more of the three hydrogeologic components. Isolated hydrogeologic areas have no inflow or outflow through any of the three hydrogeologic components. The remaining two characteristics are indexes that represent natural recharge and discharge processes and anthropogenic recharge and discharge processes occurring in the hydrogeologic area. Of the 19 groups of hydrogeologic areas, 1 consisted of predominantly isolated-type hydrogeologic areas, 7 consisted of source-type hydrogeologic areas, 9 consisted of link-type hydrogeologic areas, and 2 consisted of sink-type hydrogeologic areas. Groups comprising the source-, link-, and sink-type hydrogeologic areas can be distinguished between each other on the basis of the hydrogeologic component(s) through which interbasin flow occurs, as well as typical values for the two indexes. Conceptual models of the hydrologic systems of a representative hydrogeologic area for each group were developed to help distinguish groups and to synthesize the variation in hydrogeologic systems in the Basin and Range Physiographic Province. Hydrogeologic flow systems consist of either a single isolated hydrogeologic area or a series of multiple hydrogeologic areas that are hydraulically connected through interbasin flows. A total of 54 hydrogeologic flow systems were identified and classified into 9 groups. One group consisted of single isolated hydrogeologic areas. The remaining eight groups consisted of multiple hydrogeologic areas and were distinguished o

Properties of the molecular gas in the fast outflow in the Seyfert galaxy IC 5063

NASA Astrophysics Data System (ADS)

Oosterloo, Tom; Raymond Oonk, J. B.; Morganti, Raffaella; Combes, Françoise; Dasyra, Kalliopi; Salomé, Philippe; Vlahakis, Nektarios; Tadhunter, Clive

2017-12-01

We present a detailed study of the properties of the molecular gas in the fast outflow driven by the active galactic nucleus (AGN) in the nearby radio-loud Seyfert galaxy IC 5063. By using ALMA observations of a number of tracers of the molecular gas (12CO(1-0), 12CO(2-1), 12CO(3-2), 13CO(2-1) and HCO+(4-3)), we map the differences in excitation, density and temperature of the gas as function of position and kinematics. The results show that in the immediate vicinity of the radio jet, a fast outflow, with velocities up to 800 km s-1, is occurring of which the gas has high excitation with excitation temperatures in the range 30-55 K, demonstrating the direct impact of the jet on the ISM. The relative brightness of the 12CO lines, as well as that of 13CO(2-1) vs. 12CO(2-1), show that the outflow is optically thin. We estimate the mass of the molecular outflow to be at least 1.2 × 106 M⊙ and likely to be a factor between two and three larger than this value. This is similar to that of the outflow of atomic gas, but much larger than that of the ionised outflow, showing that the outflow in IC 5063 is dominated by cold gas. The total mass outflow rate we estimated to be 12 M⊙ yr-1. The mass of the outflow is much smaller than the total gas mass of the ISM of IC 5063. Therefore, although the influence of the AGN and its radio jet is very significant in the inner regions of IC 5063, globally speaking the impact will be very modest. We used RADEX non-LTE modelling to explore the physical conditions of the molecular gas in the outflow. Models with the outflowing gas being quite clumpy give the most consistent results and our preferred solutions have kinetic temperatures in the range 20-100 K and densities between 105 and 106 cm-3. The resulting pressures are 106-107.5 K cm-3, about two orders of magnitude higher than in the outer quiescent disk. The highest densities and temperatures are found in the regions with the fastest outflow. The results strongly suggest that the outflow in IC 5063 is driven by the radio plasma jet expanding into a clumpy gaseous medium and creating a cocoon of (shocked) gas which is pushed away from the jet axis resulting in a lateral outflow, very similar to what is predicted by numerical simulations.

Solar forcing, and ionospheric ion outflow from Venus, Earth and Mars - A comparison

NASA Astrophysics Data System (ADS)

Lundin, R. N.

2012-12-01

Solar forcing by e.g. EUV radiation and the solar wind leads to outflow and escape of ionospheric ions from Earth, Venus and Mars. In-situ measurements in the Earth's space environment have demonstrated that the ion escape rate correlates with the magnitude of solar forcing, i.e. high solar EUV and solar wind forcing leads to enhanced escape rates. The Terrestrial outflow is dominated by H+ and O+ suggesting that the ultimate origin of outflowing ions is water. Recent measurements from the two arid planets Mars and Venus, their atmospheres dominated by CO2, display characteristics similar to that of the Earth - an outflow dominated by hydrogen (H+) and oxygen (O+, O2+) ions. Despite major differences in atmospheric composition, the composition of the ion outflow from Earth and Venus is very similar, i.e. H+ and O+ dominates and the outflow has a stoichiometric H/O ratio of close to 2. The latter implies escape of water. The ion outflow from Mars is dominated by O+, O2+, and H+. Here the stoichiometric ratio between hydrogen and oxygen ion is ≈1, implying that if the ion outflow originates from water, about half of the hydrogen mass disappears by other means. The primary origin of the ion outflow from Earth, Venus and Mars is a complex issue. Nevertheless, a predominant hydrogen and oxygen loss implies that water can easily escape planets orbiting close to the Sun, while Carbon-based molecules (e.g. CO2) resides more easily. Observations shows that the outflow of e.g. CO+ and CO2+ from Mars and Venus is minute compared to the outflow of hydrogen and oxygen ions. Magnetic shielding is an issue affecting the net ion outflow and escape from a planet, because acceleration processes are also the characteristics of magnetized plasmas. Recent findings suggests that, despite magnetic field pile-up at Mars and Venus, the stand-off distance is insufficient to prohibit a direct interaction between the solar wind and the magnetized ionospheric plasma in the induced magnetospheres of Mars and Venus. On the other hand, a planetary magnetic field, such as the Earth's dipole field and the Martian multipole crustal field, may foster shielding as well as plasma acceleration. However, in this case the ion acceleration may be confined in closed planetary magnetic flux tubes, leading to a low escape rates.

Rapid Changes in the Structure of the BN Object

NASA Technical Reports Server (NTRS)

Danchi, William C.; Gezari, D. Y.; Greenhill, L. J.; Najita, J.; Monnier, J. D.; Tuthill, P. G.; Wishnow, E. H.; Townes, C. H.; Fisher, Richard R. (Technical Monitor)

2001-01-01

The BN/KL region in Orion is the archetypal region of high-mass star formation, radiating approx. 10(sup)5 Lsun and displaying promininent bulk outflows. In particular, there is no certain identification of the sources responsible for the high luminosity and outflows, and is the origin of a major explosive event (Shultz et al. 1999, ApJ, 511, 282). Using 18.7 and 12.5 micron data from observations in December 1999 and October 2000 made at the Keck I telescope, we discovered that the BN Object has a companion previously seen only at radio wavelengths (Menten & Reid 1995, ApJ, 445, L157). We call this companion B2 and it is about 1.5 arcsec West of the bright component. We also see changes in the shape of BN and the emission of "blobs" or "bullets" of material. While B2 remains unchanged and in the same place between the two epochs, there is an additional structure in BN to the South-South-East and the North-East, as well as a finger of material pointing North from B2 itself. Such a change has not been seen before in the infrared. We have looked very carefully at these images, calibrator images taken within a few minutes of the source images, as well as our previous images and cannot find any technical faults with the data. We explore the implications of these results, in particular, can these features be connected with previously observed "bullets" or "fingers" (see Allen & Burton 1993, for example), making BN a source for the bullets, implying they are not from IRc2 as previously thought? Or could they be produced by an interaction between material from BN and other sources such as IRc2?

ALMA Observations of Dust Polarization and Molecular Line Emission from the Class 0 Protostellar Source Serpens SMM1

NASA Astrophysics Data System (ADS)

Hull, Charles L. H.; Girart, Josep M.; Tychoniec, Łukasz; Rao, Ramprasad; Cortés, Paulo C.; Pokhrel, Riwaj; Zhang, Qizhou; Houde, Martin; Dunham, Michael M.; Kristensen, Lars E.; Lai, Shih-Ping; Li, Zhi-Yun; Plambeck, Richard L.

2017-10-01

We present high angular resolution dust polarization and molecular line observations carried out with the Atacama Large Millimeter/submillimeter Array (ALMA) toward the Class 0 protostar Serpens SMM1. By complementing these observations with new polarization observations from the Submillimeter Array (SMA) and archival data from the Combined Array for Research in Millimeter-wave Astronomy (CARMA) and the James Clerk Maxwell Telescopes (JCMT), we can compare the magnetic field orientations at different spatial scales. We find major changes in the magnetic field orientation between large (˜0.1 pc) scales—where the magnetic field is oriented E-W, perpendicular to the major axis of the dusty filament where SMM1 is embedded—and the intermediate and small scales probed by CARMA (˜1000 au resolution), the SMA (˜350 au resolution), and ALMA (˜140 au resolution). The ALMA maps reveal that the redshifted lobe of the bipolar outflow is shaping the magnetic field in SMM1 on the southeast side of the source; however, on the northwestern side and elsewhere in the source, low-velocity shocks may be causing the observed chaotic magnetic field pattern. High-spatial-resolution continuum and spectral-line observations also reveal a tight (˜130 au) protobinary system in SMM1-b, the eastern component of which is launching an extremely high-velocity, one-sided jet visible in both {CO}(J=2\\to 1) and {SiO}(J=5\\to 4); however, that jet does not appear to be shaping the magnetic field. These observations show that with the sensitivity and resolution of ALMA, we can now begin to understand the role that feedback (e.g., from protostellar outflows) plays in shaping the magnetic field in very young, star-forming sources like SMM1.

A51F-0123: Model Analysis of Tropospheric Aerosol Variability and Sources over the North Atlantic During NAAMES 2015-2016

NASA Technical Reports Server (NTRS)

Liu, Hongyu; Moore, Richard; Hostetler, Chris A.; Ferrare, Richard Anthony; Fairlie, Thomas Duncan; Hu, Youngxiang; Chen, Gao; Hair, Johnathan W.; Johnson, Matthew S.

2016-01-01

The North Atlantic Aerosols and Marine Ecosystems Study (NAAMES) is a five-year Earth-Venture Suborbital-2 Mission to characterize the plankton ecosystems and their influences on remote marine aerosols, boundary layer clouds, and their implications for climate in the North Atlantic. While marine-sourced aerosols have been shown to make important contributions to surface aerosol loading, cloud condensation nuclei and ice nuclei concentrations over remote marine and coastal regions, it is still a challenge to differentiate the marine biogenic aerosol signal from the strong influence of continental pollution outflow. We examine here the spatiotemporal variability and quantify the sources of tropospheric aerosols over the North Atlantic during the first two phases (November 2015 and May-June 2016) of NAAMES using a state-of-the-art chemical transport model (GEOS-Chem). The model is driven by the Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2) from the NASA Global Modeling and Assimilation Office (GMAO). It includes sulfate-nitrate-ammonium aerosol thermodynamics coupled to ozone-NOx-hydrocarbon-aerosol chemistry, mineral dust, sea salt, elemental and organic carbon aerosols, and especially a recently implemented parameterization for the marine primary organic aerosol emission. The simulated aerosols over the North Atlantic are evaluated with available satellite (e.g., MODIS) observations of aerosol optical depths (AOD), and aircraft and ship aerosol measurements. We diagnose transport pathways for continental pollution outflow over the North Atlantic using carbon monoxide, an excellent tracer for anthropogenic pollution transport. We also conduct model perturbation experiments to quantify the relative contributions of terrestrial and oceanic sources to the aerosol loading, AOD, and their variability over the North Atlantic.

XMM-Newton Detection of a Delayed X-ray Eruption from V838 Monocerotis

NASA Astrophysics Data System (ADS)

Antonini, Fabio; Montez, R., Jr.; Kastner, J.; Bond, H. E.; Soker, N.; Tylenda, R.; Starrfield, S.

2010-01-01

The star V838 Mon, discovered undergoing an outburst at the beginning of January 2002, is one of the most enigmatic objects observed in stellar astrophysics in recent decades. We report the XMM-Newton/EPIC detection in 2008 March of a pair of spatially confused X-ray sources in the vicinity of V838 Mon. Spectral/spatial analysis demonstrates the presence of a relatively hard, luminous source that is spatially coincident with V838 Mon itself, and a second, more luminous source located 8'' south of V838 Mon (projected separation 0.2pc if at the 6 kpc distance of V838 Mon). Neither source was detected in a Chandra/ACIS-S observation obtained about one year after outburst. The inferred X-ray luminosity and temperature of the hard source component at the position of V838 Mon, as well as its delayed appearance, appear consistent with a stellar merger scenario for the optical/IR outburst of V838 Mon. Further X-ray observations of V838 Mon are warranted, to confirm the position(s) of the source(s) in the vicinity of V838 Mon and to establish their long- and short-term temporal behavior.This research has been supported via NASA/GSFC XMM/Newton Guest Observer Facility grant NNX08AD91G to RIT (and associated subcontracts to STScI and the University of Arizona).

Long-Term Results of Stent Placement in Patients with Outflow Block After Living-Donor-Liver Transplantation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fujimori, Masashi, E-mail: fujimorim@clin.medic.mie-u.ac.jp; Yamakado, Koichiro, E-mail: yamakado47@gmail.com; Takaki, Haruyuki, E-mail: takaki-h@clin.medic.mie-u.ac.jp

PurposeTo evaluate long-term results of stent placement retrospectively in patients with outflow block after living-donor-liver transplantation (LDLT).Materials and MethodsFor this institutional review board approved retrospective study conducted during 2002–2012, stents were placed in outflow veins in 15 patients (11.3 %, 15/133) (12 men; 3 female) in whom outflow block developed after LDLT. Their mean age was 52.3 years ± 15.3 (SD) (range, 4–69 years). Venous stenosis with a pressure gradient ≥5 mmHg (outflow block) was observed in the inferior vena cava in seven patients, hepatic vein in seven patients, and both in one patient. Technical success, change in a pressure gradient and clinical manifestations, and complicationsmore » were evaluated. Overall survival of 15 patients undergoing outflow block stenting was compared with that of 116 patients without outflow block after LDLT.ResultsStents were placed across the outflow block veins without complications, lowering the pressure gradient ≤ 3 mmHg in all patients (100 %, 15/15). Clinical manifestations improved in 11 patients (73.3 %, 11/15), and all were discharged from the hospital. However, they did not improve in the other 4 patients (26.7 %, 4/15) who died in the hospital 1.0–3.7 months after stenting (mean, 2.0 ± 1.2 months). No significant difference in 5-year survival rates was found between patients with and without outflow block after LDLT (61.1 vs. 72.2 %, p = .405).ConclusionStenting is a feasible, safe, and useful therapeutic option to resolve outflow block following LDLT, providing equal survival to that of patients without outflow block.« less

Quantifying the AGN-driven outflows in ULIRGs (QUADROS) III: Measurements of the radii and kinetic powers of 8 near-nuclear outflows

NASA Astrophysics Data System (ADS)

Spence, R. A. W.; Tadhunter, C. N.; Rose, M.; Rodríguez Zaurín, J.

2018-05-01

As part of the QUADROS project to quantify the impact of AGN-driven outflows in rapidly evolving galaxies in the local universe, we present observations of 8 nearby ULIRGs (0.04 < z < 0.2) taken with the ISIS spectrograph on the William Herschel Telescope (WHT), and also summarize the results of the project as a whole. Consistent with Rose et al. (2018), we find that the outflow regions are compact (0.08 < R_{[O III]} < 1.5 kpc), and the electron densities measured using the [S II], [O II] trans-auroral emission-line ratios are relatively high (2.5 < log ne (cm-3) < 4.5, median log ne (cm-3) ˜ 3.1). Many of the outflow regions are also significantly reddened (median E(B - V) ˜ 0.5). Assuming that the de-projected outflow velocities are represented by the 5^{th} percentile velocities (v05) of the broad, blueshifted components of [O III] λ5007, we calculate relatively modest mass outflow rates (0.1 < \\dot{M} < 20 M⊙ yr-1, median \\dot{M} ˜ 2 M⊙ yr-1), and find kinetic powers as a fraction of the AGN bolometric luminosity (\\dot{F} = \\dot{E}/L_bol) in the range 0.02 < \\dot{F} < 3 per cent, median \\dot{F} ˜ 0.3 per cent). The latter estimates are in line with the predictions of multi-stage outflow models, or single-stage models in which only a modest fraction of the initial kinetic power of the inner disk winds is transferred to the larger-scale outflows. Considering the QUADROS sample as a whole, we find no clear evidence for correlations between the properties of the outflows and the bolometric luminosities of the AGN, albeit based on a sample that covers a relatively small range in Lbol. Overall, our results suggest that there is a significant intrinsic scatter in outflow properties of ULIRGs for a given AGN luminosity.

Quasars Outflows As A Function of SED - An Empirical Approach

NASA Astrophysics Data System (ADS)

Richmond, Joseph M.; Ganguly, Rajib

2015-08-01

Feedback from quasars (jets, outflows, and luminosity) is now recognized as a vital phase in describing galaxy evolution, growth, and star formation efficiency. Regarding outflows, roughly 60% are observed to have outflowing gas appearing at large velocities and with a variety of velocity dispersions. The most extreme observed form of these outflows appears in the ultraviolet spectrum of 15-20% of objects. Understanding the physics of these outflows is important for both astrophysical and cosmological reasons. Establishing empirical relationships to test the theoretical models of how these outflows are driven (and hence, how they impact their surroundings) is currently plagued by having too few objects, where other parameters like the black hole mass or accretion rate, may add to the scatter. We aim to fix this by using a systematic study of a large sample of objects. As a follow up to a previous study, we have identified a sample of nearly 11000 z=1.7-2 quasars using archived data from the Sloan Digital Sky Survey (Data Release 7), of which roughly 4400 appear to show outflows according to the visual inspection. The specific redshift range is chosen to feature both the Mg II 2800 emission line as well as wavelengths extending to nearly 20,000 km/s blueward of the C IV 1549 emission line. Our goals for this study are: (1) To temper our visual inspection schemes with a more automated, computer-driven scheme; (2) To measure the properties of the outflows (velocity, velocity dispersion, equivalent width, ionization); (3) To supplement the SDSS spectra with photometric measurements from GALEX, 2MASS, and WISE to further characterize the spectral energy distributions (SEDs) and dust content; (4) To form spectral composites to investigate possible SED changes with outflow properties; and (5) To use published estimates of the quasar physical properties (black hole mass, accretion rate, etc.) to fully establish in an empirical way the complex dependencies between the properties of the outflow, and the physical properties of the system.

Effectiveness of a stormwater collection and detention system for reducing constituent loads from bridge runoff in Pinellas County, Florida

USGS Publications Warehouse

Stoker, Y.E.

1996-01-01

The quantity and quality of stormwater runoff from the Bayside Bridge were evaluated to determine the effectiveness of the stormwater collection and detention pond system of the bridge in reducing constituent loads to Old Tampa Bay. Water-quality samples of stormwater runoff from the bridge and outflow from the detention pond were collected during and after selected storms. These samples were used to compute loads for selected constituents. Stormwater on the Bayside Bridge drained rapidly during rain events. The volume of stormwater runoff from 24 storms measured during the study ranged from 4,086 to 103,705 cubic feet. Storms were most frequent during July through September and were least frequent from February through May. Concentrations of most constituents in stormwater runoff before the bridge opened to traffic were less than or equal to concentrations measured after the bridge was opened to traffic. However, concentrations of arsenic in the outflow from the detention pond generally were greater before the bridge opened than concentrations after, and concentrations of orthophosphorus in the stormwater runoff and outflow from the pond were greater before the bridge opened than during over half the sampled storms after the bridge opened. Concentrations of most constituents measured in stormwater runoff from the bridge were greatest at the beginning of the storm and decreased as the storm continued. Variations in suspended solids, nutrients, and trace element concentrations were not always concurrent with each other. The source of the measured constituent (rainfall or road debris) and the phase of the constituent (suspended or dissolved) probably affected the timing of concentration changes. The quality of stormwater runoff from the Bayside Bridge varied with total runoff volume, with the length of the dry period before the storm, and with season. Average concentrations of suspended solids, ammonia plus organic nitrogen, nitrite plus nitrate nitrogen, orthophosphorus, phosphorus, total organic carbon, aluminum, arsenic, copper, and zinc in stormwater runoff generally were inversely related to runoff volume. The quality of outflow from the detention pond also varied during a storm event and with season. Maximum concentrations generally occurred near the beginning of a storm, and decreased as the storm continued. Maximum concentrations of many constituents occurred in June and July 1995. During the summer months, pH exceeded 9.0 while inorganic nitrogen concentrations were very low. These high pH values and low inorganic nitrogen concentrations are most likely associated with photosynthesis by algae or aquatic plants in the pond. Concentrations of nitrogen, phosphorus, and nickel in stormwater runoff were correlated with total organic carbon concentrations. Concentrations of chromium, copper, iron, nickel, lead, and zinc in stormwater runoff were correlated with aluminum concentrations. The source of these metals is probably the bridge materials and metallic debris from vehicles. The northern detention pond system of the Bayside Bridge effectively reduced concentrations of suspended solids, ammonia nitrogen, nitrite plus nitrate nitrogen, phosphorus, aluminum, cadmium, chromium, copper, iron, lead, nickel, and zinc in stormwater runoff before water discharged from the pond. However, concentrations of ammonia plus organic nitrogen, organic carbon, arsenic, and values for alkalinity, pH, and specific conductance generally were greater in outflow from the pond than in stormwater runoff from the bridge. Stormwater runoff and pond outflow for three storm events were evaluated to determine the effectiveness of the detention pond system in removing selected constituents from the stormwater runoff. Most constituents and constituent loads were reduced in the outflow from the pond. Suspended solids loads were reduced about 30 to 45 percent, inorganic nitrogen loads were reduced by about 60 to 90 percent, and loads of most trace elements

A Study of PG Quasar-Driven Outflows with COS

NASA Astrophysics Data System (ADS)

Hamann, Frederick

2013-10-01

Quasar outflows are an important part of the quasar phenomenon, but many questions remain about their energetics, physical properties and the role they might play in providing feedback to host galaxy evolution. We searched our own COS far-UV observations from the QUEST survey and other large COS programs to find a sample of 6 bright PG quasars with broad {FWHM > 400 km/s} high velocity {v > 1000 km/s} absorption lines that clearly form in quasar-driven winds. These quasars can fill an important gap in our understanding between local Seyferts with low-speed winds and high-redshift quasars with extreme BAL outflows. They are also well-studied at other wavelengths, with some evidence for the quasars driving galaxy-scale blowouts and shutting down star formation. But almost nothing is known about the quasar outflows themselves. We propose a detailed study of these 6 outflow quasars using new COS FUV observations to 1} expand the existing wavelength coverage across critical lines that are diagnostic of the outflow physical conditions, kinetic energies, and metallicities, and 2} check for line variability as an indicator of the outflow structure and locations. This quasar sample includes unusual cases with many low-abundance {PV 1118,1128 and SIV 1063} and excited-state lines {SIV 1073*, CIII* 1175, CII* 1335} that will provide unprecedented constraints on the outflow properties, plus the first known OVI-only mini-BAL outflow {no lower ions detected} for which we will cover NeVIII 770,780 to probe the highest ionization gas. The high FUV sensitivity of COS is uniquely able to measure this wide range of outflow lines in low-redshift quasars with no Lya forest contamination.

Transport pathways for Asian pollution outflow over the Pacific: Interannual and seasonal variations

NASA Astrophysics Data System (ADS)

Liu, Hongyu; Jacob, Daniel J.; Bey, Isabelle; Yantosca, Robert M.; Duncan, Bryan N.; Sachse, Glen W.

2003-10-01

The meteorological pathways contributing to Asian pollution outflow over the Pacific are examined with a global three-dimensional model analysis of CO observations from the Transport and Chemical Evolution over the Pacific (TRACE-P) aircraft mission (February-April 2001). The model is used also to place the TRACE-P observations in an interannual (1994-2001) and seasonal context. The major process driving Asian pollution outflow in spring is frontal lifting ahead of southeastward-moving cold fronts (the leading edge of cold surges) and transport in the boundary layer behind the cold fronts. Orographic lifting over central and eastern China combines with the cold fronts to promote the transport of Chinese pollution to the free troposphere. Outflow of seasonal biomass burning in Southeast Asia during spring takes place mostly by deep convection but also by northeastward transport and frontal lifting, mixing with the anthropogenic outflow. Boundary layer outflow over the western Pacific is largely devoid of biomass burning influence. European and African (biomass burning) plumes in Asian outflow during TRACE-P were weak (<60 ppbv and 20 ppbv CO, respectively) and were not detectable in the observations because of superposition of the much larger Asian pollution signal. Spring 2001 (La Niña) was characterized by unusually frequent cold surge events in the Asian Pacific rim and strong convection in Southeast Asia, leading to unusually strong boundary layer outflow of anthropogenic emissions and convective outflow of biomass burning emissions in the upper troposphere. The Asian outflow flux of CO to the Pacific is found to vary seasonally by a factor of 3-4 (maximum in March and minimum in summer). The March maximum results from frequent cold surge events and seasonal biomass burning emissions.

Quenching star formation with quasar outflows launched by trapped IR radiation

NASA Astrophysics Data System (ADS)

Costa, Tiago; Rosdahl, Joakim; Sijacki, Debora; Haehnelt, Martin G.

2018-06-01

We present cosmological radiation-hydrodynamic simulations, performed with the code RAMSES-RT, of radiatively-driven outflows in a massive quasar host halo at z = 6. Our simulations include both single- and multi-scattered radiation pressure on dust from a quasar and are compared against simulations performed with thermal feedback. For radiation pressure-driving, we show that there is a critical quasar luminosity above which a galactic outflow is launched, set by the equilibrium of gravitational and radiation forces. While this critical luminosity is unrealistically high in the single-scattering limit for plausible black hole masses, it is in line with a ≈ 3 × 10^9 M_⊙ black hole accreting at its Eddington limit, if infrared (IR) multi-scattering radiation pressure is included. The outflows are fast (v ≳ 1000 km s^{-1}) and strongly mass-loaded with peak mass outflow rates ≈ 10^3 - 10^4 M_⊙ yr^{-1}, but short-lived (< 10 Myr). Outflowing material is multi-phase, though predominantly composed of cool gas, forming via a thermal instability in the shocked swept-up component. Radiation pressure- and thermally-driven outflows both affect their host galaxies significantly, but in different, complementary ways. Thermally-driven outflows couple more efficiently to diffuse halo gas, generating more powerful, hotter and more volume-filling outflows. IR radiation, through its ability to penetrate dense gas via diffusion, is more efficient at ejecting gas from the bulge. The combination of gas ejection through outflows with internal pressurisation by trapped IR radiation leads to a complete shut down of star formation in the bulge. We hence argue that radiation pressure-driven feedback may be an important ingredient in regulating star formation in compact starbursts, especially during the quasar's `obscured' phase.

Transport Pathways for Asian Pollution Outflow Over the Pacific: Interannual and Seasonal Variations

NASA Technical Reports Server (NTRS)

Liu, Hong-Yu; Jacob, Daniel J.; Bey, Isabelle; Yantosca, Robert M.; Duncan, Bryan N.; Sachse, Glen W.

2003-01-01

The meteorological pathways contributing to Asian pollution outflow over the Pacific are examined with a global three-dimensional model analysis of CO observations from the Transport and Chemical Evolution over the Pacific (TRACE-P) aircraft mission (February-April 2001). The model is used also to place the TRACE-P observations in an interannual (1994-2001) and seasonal context. The major process driving Asian pollution outflow in spring is frontal lifting ahead of southeastward-moving cold fronts (the leading edge of cold surges) and transport in the boundary layer behind the cold fronts. Orographic lifting over central and eastern China combines with the cold fronts to promote the transport of Chinese pollution to the free troposphere. Outflow of seasonal biomass burning in Southeast Asia during spring takes place mostly by deep convection but also by northeastward transport and frontal lifting, mixing with the anthropogenic outflow. Boundary layer outflow over the western Pacific is largely devoid of biomass burning influence. European and African (biomass burning) plumes in Asian outflow during TRACE-P were weak (less than 60 ppbv and 20 ppbv CO, respectively) and were not detectable in the observations because of superposition of the much larger Asian pollution signal. Spring 2001 (La Nina) was characterized by unusually frequent cold surge events in the Asian Pacific rim and strong convection in Southeast Asia, leading to unusually strong boundary layer outflow of anthropogenic emissions and convective outflow of biomass burning emissions in the upper troposphere. The Asian outflow flux of CO to the Pacific is found to vary seasonally by a factor of 3-4 (maximum in March and minimum in summer). The March maximum results from frequent cold surge events and seasonal biomass burning emissions.

Transport and outflow to the North Atlantic in the lower marine troposphere during ICARTT 2004

NASA Astrophysics Data System (ADS)

Davis, S. R.; Talbot, R.; Mao, H.

2012-01-01

An analysis of pollution plumes emitted from sources in the Northeastern US was based on observations from the International Consortium for Atmospheric Research on Transport and Transformation (ICARTT) 2004 field campaign. Particular attention was given to the relation of these plumes to coastal transport patterns in lower tropospheric layers throughout the Gulf of Maine (GOM) and their contribution to large-scale pollution outflow from the North American continent. Using measurements obtained during a series of flights of the NOAA WP-3D and the NASA DC-8, a unique quasi-lagrangian case study was conducted for a freshly emitted plume emanating from the New York City source region in late July 2004. The initial development of this plume stemmed from the accumulation of boundary layer pollutants within a coastal residual layer where weak synoptic forcing triggered its advection by mean southwesterly flow. As the plume tracked into the GOM, analysis showed that the plume layer vertical structure evolved into an internal boundary layer form, with signatures of steep vertical gradients in temperature, moisture and wind speed often resulting in periodic turbulence. This structure remained well-defined during the plume study, allowing for the detachment of the plume layer from the surface and thus minimal deposition and plume-sea surface exchange. In contrast, lateral mixing with other low-level plumes was significant during its transit and facilitated in part by persistent shear driven turbulence which further contributed to the high spatial variability in trace gas mixing ratios. The impact of the plume inland was assessed using observations from the AIRMAP air quality network. This impact was noticeably detected as a contribution to poor surface ozone conditions and significant elevations of other major pollutants to levels equaling the highest observed that summer. Further contributions to larger-scale outflow across the North Atlantic was also observed and analyzed.

Water mass modification at the Agulhas retroflection: chlorofluoromethane studies

NASA Astrophysics Data System (ADS)

Fine, Rana A.; Warner, Mark J.; Weiss, Ray F.

1988-03-01

Chlorofluoromethane (CFM) and hydrographic data from the 1983 Agulhas Retroflection cruise are used to show the importance of the region in ventilating thermocline and Intermediate Waters of the southwest Indian ocean gyre. Generally South Atlantic waters are more recently ventilated by at least two years than those of the South Indian Ocean, probably because the latter are farther downstream from the source regions near the South Atlantic subantarctic sector. A two-component mixing model shows that the outflow from the Agulhas Retroflection (14-4°C) was composed of South Indian water and at least 23% South Atlantic water. However, at the density of Indian sector Subantarctic Mode Water the inflow into the Agulhas Retroflection was well preserved in the outflow, and the South Atlantic and Indian waters appear to be ventilated by different water masses. In addition, strong interleaving was found throughout the survey area (between 14 and 4°C), characterized by correlations of negative salinity anomalies with high CFM concentrations. At the density of Antarctic Intermediate Water (AAIW) there was interleaving of both low salinity water and higher salinity Red Sea Water. Using estimates of past atmospheric ratios of two CFMs, we calculate that AAIW within the retroflection was 50-75% diluted by mixing with CFM-free water since leaving the source region. Results from the two-component mixing model, which show substantial contributions of South Atlantic water in the outflow, suggest that the return flow for the 10 Sv leakage of Indian Ocean water via the Agulhas Current into the South Atlantic [ GORDON (1985) Science, 227, 1030-1033; GORDONet al. (1987) Deep-Sea Research, 34, 565-600] is occurring at thermocline and intermediate depths. A combination of active mixing in this region and similarity in the ventilation processes may be the reason that the South Atlantic and Indian thermoclines are coincident in temperature and salinity space (between 15 and 7°C) as noted by Gordon.

Ultrafast outflows in radio-loud active galactic nuclei

NASA Astrophysics Data System (ADS)

Tombesi, F.; Tazaki, F.; Mushotzky, R. F.; Ueda, Y.; Cappi, M.; Gofford, J.; Reeves, J. N.; Guainazzi, M.

2014-09-01

Recent X-ray observations show absorbing winds with velocities up to mildly relativistic values of the order of ˜0.1c in a limited sample of six broad-line radio galaxies. They are observed as blueshifted Fe XXV-XXVI K-shell absorption lines, similarly to the ultrafast outflows (UFOs) reported in Seyferts and quasars. In this work we extend the search for such Fe K absorption lines to a larger sample of 26 radio-loud active galactic nuclei (AGN) observed with XMM-Newton and Suzaku. The sample is drawn from the Swift Burst Alert Telescope 58-month catalogue and blazars are excluded. X-ray bright Fanaroff-Riley Class II radio galaxies constitute the majority of the sources. Combining the results of this analysis with those in the literature we find that UFOs are detected in >27 per cent of the sources. However, correcting for the number of spectra with insufficient signal-to-noise ratio, we can estimate that the incidence of UFOs is this sample of radio-loud AGN is likely in the range f ≃ (50 ± 20) per cent. A photoionization modelling of the absorption lines with XSTAR allows us to estimate the distribution of their main parameters. The observed outflow velocities are broadly distributed between vout ≲ 1000 km s-1 and vout ≃ 0.4c, with mean and median values of vout ≃ 0.133c and vout ≃ 0.117c, respectively. The material is highly ionized, with an average ionization parameter of logξ ≃ 4.5 erg s-1 cm, and the column densities are larger than NH > 1022 cm-2. Overall, these characteristics are consistent with the presence of complex accretion disc winds in a significant fraction of radio-loud AGN and demonstrate that the presence of relativistic jets does not preclude the existence of winds, in accordance with several theoretical models.

Exploring molecular complexity with ALMA (EMoCA): Detection of three new hot cores in Sagittarius B2(N)

NASA Astrophysics Data System (ADS)

Bonfand, M.; Belloche, A.; Menten, K. M.; Garrod, R. T.; Müller, H. S. P.

2017-08-01

Context. The Sagittarius B2 molecular cloud contains several sites forming high-mass stars. Sgr B2(N) is one of its main centers of activity. It hosts several compact and ultra-compact HII regions, as well as two known hot molecular cores (Sgr B2(N1) and Sgr B2(N2)) in the early stage of the high-mass star formation process, where complex organic molecules (COMs) are detected in the gas phase. Aims: Our goal is to use the high sensitivity of the Atacama Large Millimeter/submillimeter Array (ALMA) to characterize the hot core population in Sgr B2(N) and thereby shed new light on the star formation process in this star-forming region. Methods: We use a complete 3 mm spectral line survey conducted with ALMA to search for faint hot cores in the Sgr B2(N) region. The chemical composition of the detected sources and the column densities are derived by modeling the whole spectra under the assumption of local thermodynamic equilibrium. Population diagrams are constructed to fit rotational temperatures. Integrated intensity maps are produced to derive the peak position and fit the size of each molecule's emission distribution. The kinematic structure of the hot cores is investigated by analyzing the line wing emission of typical outflow tracers. The H2 column densities are computed from ALMA and SMA continuum emission maps. Results: We report the discovery of three new hot cores in Sgr B2(N) that we call Sgr B2(N3), Sgr B2(N4), and Sgr B2(N5). The three sources are associated with class II methanol masers, well known tracers of high-mass star formation, and Sgr B2(N5), also with a UCHII region. Their H2 column densities are found to be between approximately 16 and 36 times lower than the one of the main hot core Sgr B2(N1). The spectra of these new hot cores have spectral line densities of 11 up to 31 emission lines per GHz above the 7σ level, assigned to 22-25 molecules plus 13-20 less abundant isotopologs. We derive rotational temperatures of approximately 140-180 K for the three new hot cores and mean source sizes of 0.4″ for Sgr B2(N3) and 1.0″ for Sgr B2(N4) and Sgr B2(N5). The chemical composition of Sgr B2(N3), Sgr B2(N4), and Sgr B2(N5) is very similar, but it differs from that of Sgr B2(N2). Finally, Sgr B2(N3) and Sgr B2(N5) show high-velocity wing emission in typical outflow tracers, with a bipolar morphology in their integrated intensity maps suggesting the presence of an outflow, like in Sgr B2(N1). No sign of an outflow is found around Sgr B2(N2) and Sgr B2(N4). We derive statistical lifetimes of 4 × 104 yr for the class II methanol maser phase and 6 × 104 yr for the hot core phase in Sgr B2(N). Conclusions: The associations of the hot cores with class II methanol masers, outflows, and/or UCHII regions tentatively suggest the following age sequence: Sgr B2(N4), Sgr B2(N3), SgrB2(N5), Sgr B2(N1). The status of Sgr B2(N2) is unclear. It may contain two distinct sources, a UCHII region and a very young hot core.

AGN outflows and feedback twenty years on

NASA Astrophysics Data System (ADS)

Harrison, C. M.; Costa, T.; Tadhunter, C. N.; Flütsch, A.; Kakkad, D.; Perna, M.; Vietri, G.

2018-03-01

It is twenty years since the seminal works by Magorrian and co-authors and by Silk and Rees, which, along with other related work, ignited an explosion of publications connecting active galactic nucleus (AGN)-driven outflows to galaxy evolution. With a surge in observations of AGN outflows, studies are attempting to test AGN feedback models directly using the outflow properties. With a focus on outflows traced by optical and CO emission lines, we discuss significant challenges that greatly complicate this task, from both an observational and theoretical perspective. We highlight the observational uncertainties involved and the assumptions required when deriving kinetic coupling efficiencies (that is, outflow kinetic power as a fraction of AGN luminosity) from typical observations. Based on recent models we demonstrate that extreme caution should be taken when comparing observationally derived kinetic coupling efficiencies to coupling efficiencies from fiducial feedback models.

Broad Redshifted Line as a Signature of Outflow

NASA Astrophysics Data System (ADS)

Titarchuk, Lev; Kazanas, Demos; Becker, Peter A.

2003-11-01

We formulate and solve the diffusion problem of line photon propagation in a bulk outflow from a compact object (black hole or neutron star) using a generic assumption regarding the distribution of line photons within the outflow. Thomson scattering of the line photons within the expanding flow leads to a decrease of their energy which is of first order in v/c, where v is the outflow velocity and c is the speed of light. We demonstrate that the emergent line profile is closely related to the time distribution of photons diffusing through the flow (the light curve) and consists of a broad redshifted feature. We analyzed the line profiles for the general case of outflow density distribution. We emphasize that the redshifted lines are intrinsic properties of the powerful outflow that are supposed to be in many compact objects.

Broad Red-Shifted Lines as a Signature of Outflow

NASA Astrophysics Data System (ADS)

Kazanas, Demosthenes; Titarchuk, Lev; Becker, Peter A.

2004-07-01

We formulate and solve the diffusion problem of line photon propagation in a bulk outflow from a compact object (black hole or neutron star) using a generic assumption regarding the distribution of line photons within the outflow. Thomson scattering of the line photons within the expanding flow leads to a decrease of their energy which is of first order in v/c, where v is the outflow velocity and c the speed of light. We demonstrate that the emergent line profile is closely related to the time distribution of photons diffusing through the flow (the light curve) and consists of a broad redshifted feature. We analyzed the line profiles for the general case of outflow density distribution. We emphasize that the redshifted lines are intrinsic properties of the powerful outflow that are supposed to be in many compact objects.

Broad Red-Shifted Lines as a Signature of Outflows

NASA Astrophysics Data System (ADS)

Titarchuck, Lev; Kazanas, Demos; Becker, Peter A.

2006-02-01

We formulate and solve the diffusion problem of line photon propagation in a bulk outflow from a compact object (black hole or neutron star) using a generic assumption regarding the distribution of line photons within the outflow. Thomson scattering of the line photons within the expanding flow leads to a decrease of their energy which is of first order in υ/c, where υ the outflow velocity and c is the speed of light. We demonstrate that the emergent line profile is closely related to the time distribution of photons diffusing through the flow (the light curve) and consists of a broad redshifted feature. We analyzed the line profiles for the general case of outflow density distribution. We emphasize that the redshifted lines are intrinsic properties of the powerful outflow that are supposed to be in many compact objects.

The Simbol-X Perspective on the Physics of Quasar Outflows

NASA Astrophysics Data System (ADS)

Giustini, M.; Cappi, M.; Vignali, C.; Palumbo, G. G. C.; Fiore, F.; Malaguti, G.

2009-05-01

There is increasing evidence that quasar outflows may play a key role in providing the feedback between AGN/QSOs and their surrounding (and feeding) media, in regulating the central supermassive black hole growth and the galaxy formation and, on larger scales, in shaping the growth of cosmic structures (see e.g. [1]). X-ray observations of quasar outflows are crucial to probe their innermost parts and assess the global energetics entrained in the outflow by studying its most extreme (in terms of velocity, ionization state, mass outflow rate) phases. Simbol-X-with its high effective area in the Fe K energy band and above-will allow the detection and the characterization of powerful outflows in bright, nearby AGN and notably also in moderately faint AGN, thus shedding light on feedback processes in these objects.

Investigations of protostellar outflow launching and gas entrainment: Hydrodynamic simulations and molecular emission

DOE Office of Scientific and Technical Information (OSTI.GOV)

Offner, Stella S. R.; Arce, Héctor G., E-mail: stella.offner@yale.edu

2014-03-20

We investigate protostellar outflow evolution, gas entrainment, and star formation efficiency using radiation-hydrodynamic simulations of isolated, turbulent low-mass cores. We adopt an X-wind launching model, in which the outflow rate is coupled to the instantaneous protostellar accretion rate and evolution. We vary the outflow collimation angle from θ = 0.01-0.1 and find that even well-collimated outflows effectively sweep up and entrain significant core mass. The Stage 0 lifetime ranges from 0.14-0.19 Myr, which is similar to the observed Class 0 lifetime. The star formation efficiency of the cores spans 0.41-0.51. In all cases, the outflows drive strong turbulence in themore » surrounding material. Although the initial core turbulence is purely solenoidal by construction, the simulations converge to approximate equipartition between solenoidal and compressive motions due to a combination of outflow driving and collapse. When compared to simulation of a cluster of protostars, which is not gravitationally centrally condensed, we find that the outflows drive motions that are mainly solenoidal. The final turbulent velocity dispersion is about twice the initial value of the cores, indicating that an individual outflow is easily able to replenish turbulent motions on sub-parsec scales. We post-process the simulations to produce synthetic molecular line emission maps of {sup 12}CO, {sup 13}CO, and C{sup 18}O and evaluate how well these tracers reproduce the underlying mass and velocity structure.« less

Full-Sun observations for identifying the source of the slow solar wind

PubMed Central

Brooks, David H.; Ugarte-Urra, Ignacio; Warren, Harry P.

2015-01-01

Fast (>700 km s−1) and slow (~400 km s−1) winds stream from the Sun, permeate the heliosphere and influence the near-Earth environment. While the fast wind is known to emanate primarily from polar coronal holes, the source of the slow wind remains unknown. Here we identify possible sites of origin using a slow solar wind source map of the entire Sun, which we construct from specially designed, full-disk observations from the Hinode satellite, and a magnetic field model. Our map provides a full-Sun observation that combines three key ingredients for identifying the sources: velocity, plasma composition and magnetic topology and shows them as solar wind composition plasma outflowing on open magnetic field lines. The area coverage of the identified sources is large enough that the sum of their mass contributions can explain a significant fraction of the mass loss rate of the solar wind. PMID:25562705

Spectroscopic Confirmation of Young Planetary-mass Companions on Wide Orbits

NASA Astrophysics Data System (ADS)

Bowler, Brendan P.; Liu, Michael C.; Kraus, Adam L.; Mann, Andrew W.

2014-03-01

We present moderate-resolution (R ~ 4000-5000) near-infrared integral field spectroscopy of the young (1-5 Myr) 6-14 M Jup companions ROXs 42B b and FW Tau b obtained with Keck/OSIRIS and Gemini-North/NIFS. The spectrum of ROXs 42B b exhibits clear signs of low surface gravity common to young L dwarfs, confirming its extreme youth, cool temperature, and low mass. Overall, it closely resembles the free-floating 4-7 M Jup L-type Taurus member 2MASS J04373705+2331080. The companion to FW Tau AB is more enigmatic. Our optical and near-infrared spectra show strong evidence of outflow activity and disk accretion in the form of line emission from [S II], [O I], Hα, Ca II, [Fe II], Paβ, and H2. The molecular hydrogen emission is spatially resolved as a single lobe that stretches ≈0.''1 (15 AU). Although the extended emission is not kinematically resolved in our data, its morphology resembles shock-excited H2 jets primarily seen in young Class 0 and Class I sources. The near-infrared continuum of FW Tau b is mostly flat and lacks the deep absorption features expected for a cool, late-type object. This may be a result of accretion-induced veiling, especially in light of its strong and sustained Hα emission (EW(Hα) >~ 290 Å). Alternatively, FW Tau b may be a slightly warmer (M5-M8) accreting low-mass star or brown dwarf (0.03-0.15 M ⊙) with an edge-on disk. Regardless, its young evolutionary stage is in stark contrast to its Class III host FW Tau AB, indicating a more rapid disk clearing timescale for the host binary system than for its wide companion. Finally, we present near-infrared spectra of the young (~2-10 Myr) low-mass (12-15 M Jup) companions GSC 6214-210 B and SR 12 C and find they best resemble low-gravity M9.5 and M9 substellar templates. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

Combined technetium radioisotope penile plethysmography and xenon washout: A technique for evaluating corpora cavernosal inflow and outflow during early tumescence

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schwartz, A.N.; Graham, M.M.

1991-03-01

Combined technetium radioisotope penile plethysmography and xenon washout is a new technique that measures both corporal arterial inflow and venous sinusoidal outflow during early tumescence in patients with erectile dysfunction. Fourteen patients were studied using 99mTc-RBCs to measure inflow and 133Xe or 127Xe in saline to measure outflow. Tumescence was induced by injecting papaverine intracorporally. Peak corporal rates corrected for inflow (r = 0.88) and uncorrected for outflow (r = 0.91) and change in volume over 2 min centered around peak inflow (r = 0.96) all correlated with angiography. Outflow measurements did not correlate with intracorporal resistance. Thus, outflow ratesmore » alone could not be used to predict venous sinusoidal competence. Normal inflow rate is greater than 20 ml/min; probable normal 12-20; indeterminate inflow 7-12; and abnormal inflow less than 7 ml/min. Technetium-99m radioisotope penile plethysmography and xenon washout can be performed together and both provide a method for simultaneously evaluating the relationship between corporal inflow and outflow rates in patients with erectile dysfunction.« less

X-Ray Evidence for the Accretion Disc-Outflow Connection in 3C 111

NASA Technical Reports Server (NTRS)

Tombesi, Frank; Sambruna, R. M.; Reeves, J. N.; Reynolds, C. S.; Braito, V.

2011-01-01

We present the spectral analysis of three Suzaku X-ray Imaging Spectrometer observations of 3C III requested to monitor the predicted variability of its ultrafast outflow on approximately 7 d time-scales. We detect an ionized iron emission line in the first observation and a blueshifted absorption line in the second, when the flux is approximately 30 per cent higher. The location of the material is constrained at less than 0.006 pc from the variability. Detailed modelling supports an identification with ionized reflection off the accretion disc at approximately 20-100rg from the black hole and a highly ionized and massive ultrafast outflow with velocity approximately 0.1c, respectively. The outflow is most probably accelerated by radiation pressure, but additional magnetic thrust cannot be excluded. The measured high outflow rate and mechanical energy support the claims that disc outflows may have a significant feedback role. This work provides the first direct evidence for an accretion disc-outflow connection in a radio-loud active galactic nucleus, possibly linked also to the jet activity.

Protostellar Outflows Mapped with ALMA and Techniques to Include Short Spacings

NASA Astrophysics Data System (ADS)

Plunkett, Adele

2018-01-01

Protostellar outflows are early signs of star formation, yet in cluster environments - common sites of star formation - their role and interaction with surrounding gas are complicated. Protostellar outflows are interesting and complex because they connect protostars (scales 10s au) to the surrounding gas environment (few pc), and their morphology constrains launching and/or accretion modes. A complete outflow study must use observing methods that recover several orders of magnitude of spatial scales, ideally with sub-arcsecond resolution and mapping over a few parsecs. ALMA provides high-resolution observations of outflows, and in some cases outflows have been mapped in clusters. Combining with observations using the Total Power array is possible, but challenging, and a large single dish telescope providing more overlap in uv space is advantageous. In this presentation I show protostellar outflows observed with ALMA using 12m, 7m, and To tal Power arrays. With a new CASA tool TP2VIS we create total power ``visibility'' data and perform joint imaging and deconvolution of interferometry and single dish data. TP2VIS will ultimately provide synergy between ALMA and AtLAST data.

AN ENIGMATIC POINT-LIKE FEATURE WITHIN THE HD 169142 TRANSITIONAL DISK ,

DOE Office of Scientific and Technical Information (OSTI.GOV)

Biller, Beth A.; Males, Jared; Morzinski, Katie

2014-09-01

We report the detection of a faint point-like feature possibly related to ongoing planet-formation in the disk of the transition disk star HD 169142. The point-like feature has a Δmag(L) ∼ 6.4, at a separation of ∼0.''11 and position angle ∼0°. Given its lack of an H or K{sub S} counterpart despite its relative brightness, this candidate cannot be explained by purely photospheric emission and must be a disk feature heated by an as yet unknown source. Its extremely red colors make it highly unlikely to be a background object, but future multi-wavelength follow up is necessary for confirmation and characterization ofmore » this feature.« less

The mythic species Issus analis Brullé, 1833 (Hemiptera, Fulgoroidea, Issidae): still an enigmatic taxon.

PubMed

Gnezdilov, Vladimir M; Bourgoin, Thierry

2017-01-04

One Issidae specimen stored in Paris museum historical collections is reported as holotype of Issus analis Brullé, 1833. From the original description, which is confirmed by study of this specimen, the species is moved to the genus Zopherisca Emeljanov, 2001 under a new combination Zopherisca analis (Brullé, 1833), comb. n. Date of description is discussed and modified from 1832 to 1833 accordingly. Unfortunately being a female as type specimen, the species remains quite enigmatic until some molecular analsysis could be undertaken on this old material.

Eta Carinae: Enigmatic Eta Carinae

NASA Astrophysics Data System (ADS)

Pittard, J. M.

2003-02-01

Eta Carinae is perhaps the most massive and luminous star in our galaxy, and is also one of the most enigmatic. Despite over a century and a half of study since an enormous eruption which expelled several solar masses of material into interstellar space, and which guaranteed its infamy, astronomers have struggled to understand its true nature. With a key event in the cycle of this star expected during the summer of 2003, an unprecedented programme of observations has been organized by astronomers around the world. Eta Carinae may at last be about to reveal some of its most fundamental secrets.

The multi-phase winds of Markarian 231: from the hot, nuclear, ultra-fast wind to the galaxy-scale, molecular outflow

NASA Astrophysics Data System (ADS)

Feruglio, C.; Fiore, F.; Carniani, S.; Piconcelli, E.; Zappacosta, L.; Bongiorno, A.; Cicone, C.; Maiolino, R.; Marconi, A.; Menci, N.; Puccetti, S.; Veilleux, S.

2015-11-01

Mrk 231 is a nearby ultra-luminous IR galaxy exhibiting a kpc-scale, multi-phase AGN-driven outflow. This galaxy represents the best target to investigate in detail the morphology and energetics of powerful outflows, as well as their still poorly-understood expansion mechanism and impact on the host galaxy. In this work, we present the best sensitivity and angular resolution maps of the molecular disk and outflow of Mrk 231, as traced by CO(2-1) and (3-2) observations obtained with the IRAM/PdBI. In addition, we analyze archival deep Chandra and NuSTAR X-ray observations. We use this unprecedented combination of multi-wavelength data sets to constrain the physical properties of both the molecular disk and outflow, the presence of a highly-ionized ultra-fast nuclear wind, and their connection. The molecular CO(2-1) outflow has a size of 1 kpc, and extends in all directions around the nucleus, being more prominent along the south-west to north-east direction, suggesting a wide-angle biconical geometry. The maximum projected velocity of the outflow is nearly constant out to 1 kpc, thus implying that the density of the outflowing material must decrease from the nucleus outwards as r-2. This suggests that either a large part of the gas leaves the flow during its expansion or that the bulk of the outflow has not yet reached out to 1 kpc, thus implying a limit on its age of 1 Myr. Mapping the mass and energy rates of the molecular outflow yields dot {M} OF = [500-1000] M⊙ yr-1 and Ėkin,OF = [7-10] × 1043 erg s-1. The total kinetic energy of the outflow is Ekin,OF is of the same order of the total energy of the molecular disk, Edisk. Remarkably, our analysis of the X-ray data reveals a nuclear ultra-fast outflow (UFO) with velocity -20 000 km s-1, dot {M}UFO = [0.3-2.1] M⊙ yr-1, and momentum load dot {P}UFO/ dot {P}rad = [0.2-1.6]. We find Ėkin,UFO Ėkin,OF as predicted for outflows undergoing an energy conserving expansion. This suggests that most of the UFO kinetic energy is transferred to mechanical energy of the kpc-scale outflow, strongly supporting that the energy released during accretion of matter onto super-massive black holes is the ultimate driver of giant massive outflows. The momentum flux dot {P}OF derived for the large scale outflows in Mrk 231 enables us to estimate a momentum boost dot {P}OF/ dot {P} UFO ≈ [30-60]. The ratios Ėkin,UFO/Lbol,AGN = [1-5] % and Ėkin,OF/Lbol,AGN = [1-3] % agree with the requirements of the most popular models of AGN feedback. Based on observations carried out with the IRAM Plateau de Bure Interferometer. IRAM is supported by INSU/CNRS (France), MPG (Germany) and IGN (Spain), and with Chandra and NuSTAR observatories.

Probing Cosmic Infrared Sources: A Computer Modeling Approach

DTIC Science & Technology

1992-06-01

developed to study various physical phenomena involving dust grains, e.g., molecule formation on grains, grain formation in expanding circumstellar...EVALUATION OF METHODS OF ANALYSIS IN INFRARED ASTR9?NOMY 16 4.0 THEORETICAL STUDIES INVOLVING DUST GRAINS., 16 4.1 Theory of Molecule Formation on Dust Grains...17 4.2 Modeling Grain Formation in Stellar Outflows 7 18 4.3 Infrared Emission from Fractal Grains * 19 4.4 Photochemistry in Circumstellar Envelopes

Red Sea Outflow Experiment (REDSOX): DLD2 RAFOS Float Data Report February 2001 - March 2003

DTIC Science & Technology

2005-01-01

1 2. Description of the DLD2 Float and Dual-Release System ................................................................... 2 3. Sound Sources...processing are described in detail. 2. Description of the DLD2 Float and Dual-Release System The DLD2 is a second-generation RAFOS (Ranging And Fixing Of...Sound) float with several improvements over the traditional RAFOS float (see Rossby et al., 1986, for a complete description of the RAFOS system ). A

Velocities of gas in star-forming regions

NASA Astrophysics Data System (ADS)

Nissen, H. D.; Gustafsson, M.; Field, D.; Lemaire, J. L.; Clénet, Y.; Rouan, D.

2007-12-01

We present high spatial (0.18") and velocity (<2 km/s) resolution observations of the central 1'x1' of OMC1. We identify a large number of shock features and determine radial velocity, position angle and emission brightness for each of these features. Using this dataset we analyze the kinematic properties of the inner square arcminute of OMC1, identifying among other things the IR signature of a massive outflow originating from source I.

3D Reconstruction of the Source and Scale of Buried Young Flood Channels on Mars

NASA Astrophysics Data System (ADS)

Morgan, Gareth A.; Campbell, Bruce A.; Carter, Lynn M.; Plaut, Jeffrey J.; Phillips, Roger J.

2013-05-01

Outflow channels on Mars are interpreted as the product of gigantic floods due to the catastrophic eruption of groundwater that may also have initiated episodes of climate change. Marte Vallis, the largest of the young martian outflow channels (<500 million years old), is embayed by lava flows that hinder detailed studies and comparisons with older channel systems. Understanding Marte Vallis is essential to our assessment of recent Mars hydrologic activity during a period otherwise considered to be cold and dry. Using data from the Shallow Radar sounder on the Mars Reconnaissance Orbiter, we present a three-dimensional (3D) reconstruction of buried channels on Mars and provide estimates of paleohydrologic parameters. Our work shows that Cerberus Fossae provided the waters that carved Marte Vallis, and it extended an additional 180 kilometers to the east before the emplacement of the younger lava flows. We identified two stages of channel incision and determined that channel depths were more than twice those of previous estimates.

Simulations of the Cleft Ion Fountain outflows resulting from the passage of Storm Enhanced Density (SED) plasma flux tubes through the dayside cleft auroral processes region

NASA Astrophysics Data System (ADS)

Horwitz, James; Zeng, Wen

2007-10-01

Foster et al. [2002] reported elevated ionospheric density regions convected from subauroral plasmaspheric regions toward noon, in association with convection of plasmaspheric tails. These Storm Enhanced Density (SED) regions could supply cleft ion fountain outflows. Here, we will utilize our Dynamic Fluid Kinetic (DyFK) model to simulate the entry of a high-density ``plasmasphere-like'' flux tube entering the cleft region and subjected to an episode of wave-driven transverse ion heating. It is found that the O^+ ion density at higher altitudes increases and the density at lower altitudes decreases, following this heating episode, indicating increased fluxes of O^+ ions from the ionospheric source gain sufficient energy to reach higher altitudes after the effects of transverse wave heating. Foster, J. C., P. J. Erickson, A. J. Coster, J. Goldstein, and F. J. Rich, Ionospheric signatures of plasmaspheric tails, Geophys. Res. Lett., 29(13), 1623, doi:10.1029/2002GL015067, 2002.

3D reconstruction of the source and scale of buried young flood channels on Mars.

PubMed

Morgan, Gareth A; Campbell, Bruce A; Carter, Lynn M; Plaut, Jeffrey J; Phillips, Roger J

2013-05-03

Outflow channels on Mars are interpreted as the product of gigantic floods due to the catastrophic eruption of groundwater that may also have initiated episodes of climate change. Marte Vallis, the largest of the young martian outflow channels (<500 million years old), is embayed by lava flows that hinder detailed studies and comparisons with older channel systems. Understanding Marte Vallis is essential to our assessment of recent Mars hydrologic activity during a period otherwise considered to be cold and dry. Using data from the Shallow Radar sounder on the Mars Reconnaissance Orbiter, we present a three-dimensional (3D) reconstruction of buried channels on Mars and provide estimates of paleohydrologic parameters. Our work shows that Cerberus Fossae provided the waters that carved Marte Vallis, and it extended an additional 180 kilometers to the east before the emplacement of the younger lava flows. We identified two stages of channel incision and determined that channel depths were more than twice those of previous estimates.

Images and Spectra of Time Dependent Two Component Advective Flow in Presence of Outflows

NASA Astrophysics Data System (ADS)

Chatterjee, Arka; Chakrabarti, Sandip K.; Ghosh, Himadri; Garain, Sudip K.

2018-05-01

Two Component Advective Flow (TCAF) successfully explains the spectral and temporal properties of outbursting or persistent sources. Images of static TCAF with Compton cloud or CENtrifugal pressure supported Boundary Layer (CENBOL) due to gravitational bending of photons have been studied before. In this paper, we study time dependent images of advective flows around a Schwarzschild black hole which include cooling effects due to Comptonization of soft photons from a Keplerian disks well as the self-consistently produced jets and outflows. We show the overall image of the disk-jet system after convolving with a typical beamwidth. A long exposure image with time dependent system need not show the black hole horizon conspicuously, unless one is looking at a soft state with no jet or the system along the jet axis. Assuming these disk-jet configurations are relevant to radio emitting systems also, our results would be useful to look for event horizons in high accretion rate Supermassive Black Holes in Seyfert galaxies, RL Quasars.

Solar Illumination Control of the Polar Wind

NASA Astrophysics Data System (ADS)

Maes, L.; Maggiolo, R.; De Keyser, J.; André, M.; Eriksson, A. I.; Haaland, S.; Li, K.; Poedts, S.

2017-11-01

Polar wind outflow is an important process through which the ionosphere supplies plasma to the magnetosphere. The main source of energy driving the polar wind is solar illumination of the ionosphere. As a result, many studies have found a relation between polar wind flux densities and solar EUV intensity, but less is known about their relation to the solar zenith angle at the ionospheric origin, certainly at higher altitudes. The low energy of the outflowing particles and spacecraft charging means it is very difficult to measure the polar wind at high altitudes. We take advantage of an alternative method that allows estimations of the polar wind flux densities far in the lobes. We analyze measurements made by the Cluster spacecraft at altitudes from 4 up to 20 RE. We observe a strong dependence on the solar zenith angle in the ion flux density and see that both the ion velocity and density exhibit a solar zenith angle dependence as well. We also find a seasonal variation of the flux density.

Magnetically driven jets and winds: Exact solutions

NASA Technical Reports Server (NTRS)

Contopoulos, J.; Lovelace, R. V. E.

1994-01-01

We present a general class of self-similar solutions of the full set of MHD equations that include matter flow, electromagnetic fields, pressure, and gravity. The solutions represent axisymmetric, time-independent, nonrelativistic, ideal, magnetohydrodynamic, collimated outflows (jet and winds) from magnetized accretion disks around compact objects. The magnetic field extracts angular momentum from the disk, accelerates the outflows perpedicular to the disk, and provides collimation at large distances. The terminal outflow velocities are of the order of or greater than the rotational velocity of the disk at the base of the flow. When a nonzero electric current flows along the jet, the outflow radius oscillates with axial distance, whereas when the total electric current is zero (with the return current flowing across the jet's cross section), the outflow radius increase to a maximum and then decreases. The method can also be applied to relativistic outflows.

OUTFLOW AND METALLICITY IN THE BROAD-LINE REGION OF LOW-REDSHIFT ACTIVE GALACTIC NUCLEI

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shin, Jaejin; Woo, Jong-Hak; Nagao, Tohru

2017-01-20

Outflows in active galactic nuclei (AGNs) are crucial to understand in investigating the co-evolution of supermassive black holes (SMBHs) and their host galaxies since outflows may play an important role as an AGN feedback mechanism. Based on archival UV spectra obtained with the Hubble Space Telescope and IUE , we investigate outflows in the broad-line region (BLR) in low-redshift AGNs ( z < 0.4) through detailed analysis of the velocity profile of the C iv emission line. We find a dependence of the outflow strength on the Eddington ratio and the BLR metallicity in our low-redshift AGN sample, which ismore » consistent with earlier results obtained for high-redshift quasars. These results suggest that BLR outflows, gas accretion onto SMBHs, and past star formation activity in host galaxies are physically related in low-redshift AGNs as in powerful high-redshift quasars.« less

Transport and Chemical Evolution over the Pacific (TRACE-P) aircraft mission: Design, execution, and first results

NASA Astrophysics Data System (ADS)

Jacob, Daniel J.; Crawford, James H.; Kleb, Mary M.; Connors, Vickie S.; Bendura, Richard J.; Raper, James L.; Sachse, Glen W.; Gille, John C.; Emmons, Louisa; Heald, Colette L.

2003-10-01

The NASA Transport and Chemical Evolution over the Pacific (TRACE-P) aircraft mission was conducted in February-April 2001 over the NW Pacific (1) to characterize the Asian chemical outflow and relate it quantitatively to its sources and (2) to determine its chemical evolution. It used two aircraft, a DC-8 and a P-3B, operating out of Hong Kong and Yokota Air Force Base (near Tokyo), with secondary sites in Hawaii, Wake Island, Guam, Okinawa, and Midway. The aircraft carried instrumentation for measurements of long-lived greenhouse gases, ozone and its precursors, aerosols and their precursors, related species, and chemical tracers. Five chemical transport models (CTMs) were used for chemical forecasting. Customized bottom-up emission inventories for East Asia were generated prior to the mission to support chemical forecasting and to serve as a priori for evaluation with the aircraft data. Validation flights were conducted for the Measurements Of Pollution In The Troposphere (MOPITT) satellite instrument and revealed little bias (6 ± 2%) in the MOPITT measurements of CO columns. A major event of transpacific Asian pollution was characterized through combined analysis of TRACE-P and MOPITT data. The TRACE-P observations showed that cold fronts sweeping across East Asia and the associated warm conveyor belts (WCBs) are the dominant pathway for Asian outflow to the Pacific in spring. The WCBs lift both anthropogenic and biomass burning (SE Asia) effluents to the free troposphere, resulting in complex chemical signatures. The TRACE-P data are in general consistent with a priori emission inventories, lending confidence in our ability to quantify Asian emissions from socioeconomic data and emission factors. However, the residential combustion source in rural China was found to be much larger than the a priori, and there were also unexplained chemical enhancements (HCN, CH3Cl, OCS, alkylnitrates) in Chinese urban plumes. The Asian source of CCl4 was found to be much higher than government estimates. Measurements of HCN and CH3CN indicated a dominant biomass burning source and ocean sink for both gases. Large fractions of sulfate and nitrate were found to be present in dust aerosols. Photochemical activity in the Asian outflow was strongly reduced by aerosol attenuation of UV radiation, with major implications for the concentrations of HOx radicals. New particle formation, apparently from ternary nucleation involving NH3, was observed in Chinese urban plumes.

Transport and Chemical Evolution over the Pacific (TRACE-P)Aircraft Mission: Design, Execution, and First Results

NASA Technical Reports Server (NTRS)

Jacob, Daniel J.; Crawford, James H.; Kleb, Mary M.; Connors, Vickie S.; Bendura, Richard J.; Raper, James L.; Sachse, Glen W.; Gille, John C.; Emmons, Louisa; Heald, Colette L.

2003-01-01

The NASA Transport and Chemical Evolution over the Pacific (TRACE-P) aircraft mission was conducted in February-April 2001 over the NW Pacific (1) to characterize the Asian chemical outflow and relate it quantitatively to its sources and (2) to determine its chemical evolution. It used two aircraft, a DC-8 and a P-3B, operating out of Hong Kong and Yokota Air Force Base (near Tokyo), with secondary sites in Hawaii, Wake Island, Guam, Okinawa, and Midway. The aircraft carried instrumentation for measurements of long-lived greenhouse gases, ozone and its precursors, aerosols and their precursors, related species, and chemical tracers. Five chemical transport models (CTMs) were used for chemical forecasting. Customized bottom-up emission inventories for East Asia were generated prior to the mission to support chemical forecasting and to serve as a priori for evaluation with the aircraft data. Validation flights were conducted for the Measurements Of Pollution In The Troposphere (MOPITT) satellite instrument and revealed little bias (6 plus or minus 2%) in the MOPITT measurements of CO columns. A major event of transpacific Asian pollution was characterized through combined analysis of TRACE-P and MOPITT data. The TRACE-P observations showed that cold fronts sweeping across East Asia and the associated warm conveyor belts (WCBs) are the dominant pathway for Asian outflow to the Pacific in spring. The WCBs lift both anthropogenic and biomass burning (SE Asia) effluents to the free troposphere, resulting in complex chemical signatures. The TRACE-P data are in general consistent with a priori emission inventories, lending confidence in our ability to quantify Asian emissions from socioeconomic data and emission factors. However, the residential combustion source in rural China was found to be much larger than the a priori, and there were also unexplained chemical enhancements (HCN, CH3Cl, OCS, alkylnitrates) in Chinese urban plumes. The Asian source of CCl4 was found to be much higher than government estimates. Measurements of HCN and CH3CN indicated a dominant biomass burning source and ocean sink for both gases. Large fractions of sulfate and nitrate were found to be present in dust aerosols. Photochemical activity in the Asian outflow was strongly reduced by aerosol attenuation of UV radiation, with major implications for the concentrations of HOx, radicals. New particle formation, apparently from ternary nucleation involving NH3, was observed in Chinese urban plumes.

Protostellar jets in the NIR: interaction with the ISM and correlation with the exciting source evolutionary phase

NASA Astrophysics Data System (ADS)

Caratti o Garatti, Alessio

2006-03-01

I present an in-depth near-IR (NIR) analysis of a sample of H2 jets from young embedded sources to compare the physical, kinematical properties and cooling mechanisms of the different flows. The sample comprises 23 outflows driven by Class 0 and I sources having low-intermediate solar luminosity (1-600 L(sun)). For such an analysis, I have utilized narrow band images centered on the H2 (2.12 micron) and [FeII] (1.64 micron) spectral lines, low resolution spectra (R~600) in the range 1-2.5 micron and high resolution spectra (R~10000) centered on H2 (2.12 micron) and [FeII] (1.64 micron) lines. At NIR wavelengths these two tracers (H2,[FeII]) are the main coolants of the gas, that is excited by strong radiative shocks. Narrow band images have been used to detect such shocked regions in both ionic and molecular components. [FeII] have been observed in ~74% of the outflows which in some cases indicate the presence of embedded Herbig Haro (HH) like objects. H2 line ratios have been used to estimate the visual extinction and the average temperature of the molecular gas. A(V) values range from ~2 to ~15 mag, while average temperatures range between ~2000 and ~4000 K. In several knots, however, a stratification of temperatures is found with maximum values up to 5000 K. Such a stratification is more commonly observed in those knots which also show [FeII] emission, while a thermalized gas at a single temperature is generally found in knots emitting only in molecular lines. Combining narrow band imaging with the parameters derived from the spectroscopic analysis, it was possible to measure the total luminosity of the H2 and [FeII] shocked regions (L(H2) and L([FeII])) in each flow. H2 is the major NIR coolant with an average L(H2)/L([FeII]) ratio of ~10^2. About 83% of the sources have a L(H2)/L(bol) ratio ~0.04, irrespective of the Class of the driving source, while a smaller group of sources (mostly Class I) have L(H2)/L(bol) an order of magnitude smaller. Such a separation reveals the non-homogeneous behaviour of Cl ass I, where sources with very different outflow activity can be found. These less luminous jets are originated by older sources, where L(bol) is not dominated anymore by the accretion luminosity. This is confirmed by a further analysis conducted on jets from six intermediate and high mass sources, four of them not included in the original sample. They have a faster evolution with respect to the low mass ones and thus only a fraction of their L(bol) is due to the accretion luminosity. For these objects I find a defined separation between the two Classes in the L(H2)-L(bol) plot. Viceversa, there is a straight correlation between L(H2) and L(acc) for all these sources. Finally, I compare the derived jet physical parameters to theoretical shock models. The observed H2 emission in the HH objects can be mostly reproduced by models of J-type shocks with magnetic precursors.

MOLECULAR OUTFLOWS FROM THE PROTOCLUSTER SERPENS SOUTH

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nakamura, Fumitaka; Higuchi, Aya; Sugitani, Kohji

2011-08-20

We present the results of CO (J = 3-2) and HCO{sup +} (J = 4-3) mapping observations toward a nearby embedded cluster, Serpens South, using the ASTE 10 m telescope. Our CO (J = 3-2) map reveals that many outflows are crowded in the dense cluster-forming clump that can be recognized as an HCO{sup +} clump with a size of {approx}0.2 pc and mass of {approx}80 M{sub sun}. The clump contains several subfragments with sizes of {approx}0.05 pc. By comparing the CO (J = 3-2) map with the 1.1 mm dust continuum image taken by AzTEC on ASTE, we findmore » that the spatial extents of the outflow lobes are sometimes anti-correlated with the distribution of the dense gas, and some of the outflow lobes apparently collide with the dense gas. The total outflow mass, momentum, and energy are estimated to be 0.6 M{sub sun}, 8 M{sub sun} km s{sup -1}, and 64 M{sub sun} km{sup 2} s{sup -2}, respectively. The energy injection rate due to the outflows is comparable to the turbulence dissipation rate in the clump, implying that the protostellar outflows can maintain the supersonic turbulence in this region. The total outflow energy seems only about 10% of the clump gravitational energy. We conclude that the current outflow activity is not enough to destroy the whole cluster-forming clump, and therefore star formation is likely to continue for several or many local dynamical times.« less

Determination of volume-time curves for the right ventricle and its outflow tract for functional analyses.

PubMed

Gabbert, Dominik D; Entenmann, Andreas; Jerosch-Herold, Michael; Frettlöh, Felicitas; Hart, Christopher; Voges, Inga; Pham, Minh; Andrade, Ana; Pardun, Eileen; Wegner, P; Hansen, Traudel; Kramer, Hans-Heiner; Rickers, Carsten

2013-12-01

The determination of right ventricular volumes and function is of increasing interest for the postoperative care of patients with congenital heart defects. The presentation of volumetry data in terms of volume-time curves allows a comprehensive functional assessment. By using manual contour tracing, the generation of volume-time curves is exceedingly time-consuming. This study describes a fast and precise method for determining volume-time curves for the right ventricle and for the right ventricular outflow tract. The method applies contour detection and includes a feature for identifying the right ventricular outflow tract volume. The segregation of the outflow tract is performed by four-dimensional curved smooth boundary surfaces defined by prespecified anatomical landmarks. The comparison with manual contour tracing demonstrates that the method is accurate and improves the precision of the measurement. Compared to manual contour tracing the bias is <0.1% ± 4.1% (right ventricle) and -2.6% ± 20.0% (right ventricular outflow tract). The standard deviations of inter- and intraobserver variabilities for determining the volume of the right ventricular outflow tract are reduced to less than half the values of manual contour tracing. The time consumption per patient is reduced from 341 ± 80 min (right ventricle) and 56 ± 11 min (right ventricular outflow tract) using manual contour tracing to 46 ± 9 min for a combined analysis of right ventricle and right ventricular outflow tract. The analysis of volume-time curves for the right ventricle and its outflow tract discloses new evaluation methods in clinical routine and science. Copyright © 2013 Wiley Periodicals, Inc.

Dense Molecular Gas Tracers in the Outflow of the Starburst Galaxy NGC 253

NASA Astrophysics Data System (ADS)

Walter, Fabian; Bolatto, Alberto D.; Leroy, Adam K.; Veilleux, Sylvain; Warren, Steven R.; Hodge, Jacqueline; Levy, Rebecca C.; Meier, David S.; Ostriker, Eve C.; Ott, Jürgen; Rosolowsky, Erik; Scoville, Nick; Weiss, Axel; Zschaechner, Laura; Zwaan, Martin

2017-02-01

We present a detailed study of a molecular outflow feature in the nearby starburst galaxy NGC 253 using ALMA. We find that this feature is clearly associated with the edge of NGC 253's prominent ionized outflow, has a projected length of ˜300 pc, with a width of ˜50 pc, and a velocity dispersion of ˜40 km s-1, which is consistent with an ejection from the disk about 1 Myr ago. The kinematics of the molecular gas in this feature can be interpreted (albeit not uniquely) as accelerating at a rate of 1 km s-1 pc-1. In this scenario, the gas is approaching an escape velocity at the last measured point. Strikingly, bright tracers of dense molecular gas (HCN, CN, HCO+, CS) are also detected in the molecular outflow: we measure an HCN(1-0)/CO(1-0) line ratio of ˜ 1/10 in the outflow, similar to that in the central starburst region of NGC 253 and other starburst galaxies. By contrast, the HCN/CO line ratio in the NGC 253 disk is significantly lower (˜ 1/30), similar to other nearby galaxy disks. This strongly suggests that the streamer gas originates from the starburst, and that its physical state does not change significantly over timescales of ˜1 Myr during its entrainment in the outflow. Simple calculations indicate that radiation pressure is not the main mechanism for driving the outflow. The presence of such dense material in molecular outflows needs to be accounted for in simulations of galactic outflows.

Powerful Molecular Outflows in Nearby Active Galaxies

NASA Astrophysics Data System (ADS)

Veilleux, Sylvain; Meléndez, Marcio

2014-07-01

We report the results from a systematic search for molecular (OH 119 μm) outflows with Herschel-PACS† in a sample of 43 nearby (z < 0.3) galaxy mergers, mostly ultraluminous infrared galaxies (ULIRGs) and QSOs. We find that the character of the OH feature (strength of the absorption relative to the emission) correlates with that of the 9.7-μm silicate feature, a measure of obscuration in ULIRGs. Unambiguous evidence for molecular outflows, based on the detection of OH absorption profiles with median velocities more blueshifted than -50 km s-1, is seen in 26 (70%) of the 37 OH-detected targets, suggesting a wide-angle (~ 145°) outflow geometry. Conversely, unambiguous evidence for molecular inflows, based on the detection of OH absorption profiles with median velocities more redshifted than +50 km s-1, is seen in only 4 objects, suggesting a planar or filamentary geometry for the inflowing gas. Terminal outflow velocities of ~ -1000 km s-1 are measured in several objects, but median outflow velocities are typically ~ -200 km s-1. While the outflow velocities show no statistically significant dependence on the star formation rate, they are distinctly more blueshifted among systems with large AGN fractions and luminosities [log (L AGN/L ⊙) >= 11.8 +/- 0.3]. The quasars in these systems play a dominant role in driving the molecular outflows. In contrast, the most AGN dominated systems, where OH is seen purely in emission, show relatively modest OH line widths, despite their large AGN luminosities, perhaps indicating that molecular outflows subside once the quasar has cleared a path through the obscuring material.

Shining a light on galactic outflows: photoionized outflows

NASA Astrophysics Data System (ADS)

Chisholm, John; Tremonti, Christy A.; Leitherer, Claus; Chen, Yanmei; Wofford, Aida

2016-04-01

We study the ionization structure of galactic outflows in 37 nearby, star-forming galaxies with the Cosmic Origins Spectrograph on the Hubble Space Telescope. We use the O I, Si II, Si III, and Si IV ultraviolet absorption lines to characterize the different ionization states of outflowing gas. We measure the equivalent widths, line widths, and outflow velocities of the four transitions, and find shallow scaling relations between them and galactic stellar mass and star formation rate. Regardless of the ionization potential, lines of similar strength have similar velocities and line widths, indicating that the four transitions can be modelled as a comoving phase. The Si equivalent width ratios (e.g. Si IV/Si II) have low dispersion, and little variation with stellar mass; while ratios with O I and Si vary by a factor of 2 for a given stellar mass. Photoionization models reproduce these equivalent width ratios, while shock models under predict the relative amount of high ionization gas. The photoionization models constrain the ionization parameter (U) between -2.25 < log (U) < -1.5, and require that the outflow metallicities are greater than 0.5 Z⊙. We derive ionization fractions for the transitions, and show that the range of ionization parameters and stellar metallicities leads to a factor of 1.15-10 variation in the ionization fractions. Historically, mass outflow rates are calculated by converting a column density measurement from a single metal ion into a total hydrogen column density using an ionization fraction, thus mass outflow rates are sensitive to the assumed ionization structure of the outflow.

Segmental Versican Expression in the Trabecular Meshwork and Involvement in Outflow Facility

PubMed Central

Keller, Kate E.; Bradley, John M.; Vranka, Janice A.

2011-01-01

Purpose. Versican is a large proteoglycan with numerous chondroitin sulfate (CS) glycosaminoglycan (GAG) side chains attached. To assess versican's potential contributions to aqueous humor outflow resistance, its segmental distribution in the trabecular meshwork (TM) and the effect on outflow facility of silencing the versican gene were evaluated. Methods. Fluorescent quantum dots (Qdots) were perfused to label outflow pathways of anterior segments. Immunofluorescence with confocal microscopy and quantitative RT-PCR were used to determine versican protein and mRNA distribution relative to Qdot-labeled regions. Lentiviral delivery of shRNA-silencing cassettes to TM cells in perfused anterior segment cultures was used to evaluate the involvement of versican and CS GAG chains in outflow facility. Results. Qdot uptake by TM cells showed considerable segmental variability in both human and porcine outflow pathways. Regional levels of Qdot labeling were inversely related to versican protein and mRNA levels; versican levels were relatively high in sparsely Qdot-labeled regions and low in densely labeled regions. Versican silencing decreased outflow facility in human and increased facility in porcine anterior segments. However, RNAi silencing of ChGn, an enzyme unique to CS GAG biosynthesis, increased outflow facility in both species. The fibrillar pattern of versican immunostaining in the TM juxtacanalicular region was disrupted after versican silencing in perfusion culture. Conclusions. Versican appears to be a central component of the outflow resistance, where it may organize GAGs and other ECM components to facilitate and control open flow channels in the TM. However, the exact molecular organization of this resistance appears to differ between human and porcine eyes. PMID:21596823

Feeding the fire: tracing the mass-loading of 107 K galactic outflows with O VI absorption

NASA Astrophysics Data System (ADS)

Chisholm, J.; Bordoloi, R.; Rigby, J. R.; Bayliss, M.

2018-02-01

Galactic outflows regulate the amount of gas galaxies convert into stars. However, it is difficult to measure the mass outflows remove because they span a large range of temperatures and phases. Here, we study the rest-frame ultraviolet spectrum of a lensed galaxy at z ˜ 2.9 with prominent interstellar absorption lines from O I, tracing neutral gas, up to O VI, tracing transitional phase gas. The O VI profile mimics weak low-ionization profiles at low velocities, and strong saturated profiles at high velocities. These trends indicate that O VI gas is co-spatial with the low-ionization gas. Further, at velocities blueward of -200 km s-1 the column density of the low-ionization outflow rapidly drops while the O VI column density rises, suggesting that O VI is created as the low-ionization gas is destroyed. Photoionization models do not reproduce the observed O VI, but adequately match the low-ionization gas, indicating that the phases have different formation mechanisms. Photoionized outflows are more massive than O VI outflows for most of the observed velocities, although the O VI mass outflow rate exceeds the photoionized outflow at velocities above the galaxy's escape velocity. Therefore, most gas capable of escaping the galaxy is in a hot outflow phase. We suggest that the O VI absorption is a temporary by-product of conduction transferring mass from the photoionized phase to an unobserved hot wind, and discuss how this mass-loading impacts the observed circum-galactic medium.

Acoustic emission testing on an F/A-18 E/F titanium bulkhead

NASA Astrophysics Data System (ADS)

Martin, Christopher A.; Van Way, Craig B.; Lockyer, Allen J.; Kudva, Jayanth N.; Ziola, Steve M.

1995-04-01

An important opportunity recently transpired at Northrop Grumman Corporation to instrument an F/A - 18 E/F titanium bulkhead with broad band acoustic emission sensors during a scheduled structural fatigue test. The overall intention of this effort was to investigate the potential for detecting crack propagation using acoustic transmission signals for a large structural component. Key areas of experimentation and experience included (1) acoustic noise characterization, (2) separation of crack signals from extraneous noise, (3) source location accuracy, and (4) methods of acoustic transducer attachment. Fatigue cracking was observed and monitored by strategically placed acoustic emission sensors. The outcome of the testing indicated that accurate source location still remains enigmatic for non-specialist engineering personnel especially at this level of structural complexity. However, contrary to preconceived expectations, crack events could be readily separated from extraneous noise. A further dividend from the investigation materialized in the form of close correspondence between frequency domain waveforms of the bulkhead test specimen tested and earlier work with thick plates.

More shock recovery experiments on mesosiderite analogs

NASA Technical Reports Server (NTRS)

Rowan, L. R.; Mittlefehldt, D. W.

1994-01-01

Mesosiderites, a small but unique group of stony-iron meteorites with affinities to howardites, eucrites, and pallasites, remain enigmatic in terms of their petrogenesis. They are composed of approximately equal weight proportions of Fe-Ni metal plus troilite and gabbroic, basaltic, and orthopyroxenitic materials. The metal and silicates, which display variable grain sizes and shapes, are delicately intermingled, forming irregular grain boundaries that have been attributed to a wide range of origins from subsolidus metamorphism to supersolidus igneous processes. Perhaps the most relevant question regarding the petrogenesis of mesosiderites is: what is the source and duration of heating that could produce the unequilibrated textures and chemistry of these meteorites? A leading candidate appears to be impacts of metallic core fragments with a differentiated asteroidal surface. This provides not only a suitable source of heat, but also the metal component uniquely required by mesosiderites. A series of shock recovery experiments on mesosiderite analogs has been continued. Textural and chemical similarities have been found that support an impact-derived origin for these unusual meteorites.

Maja Valley and the Chryse outflow complex sites

NASA Technical Reports Server (NTRS)

Rice, Jim W.

1994-01-01

This candidate landing site is located at 19 deg N, 53.5 deg W near the mouth of a major outflow channel. Maja Valles, and two 'valley network' channel systems, Maumee and Vedra Valles. The following objectives are to be analyzed in this region: (1) origin and paleohydrology of outflow and valley network channels; (2) fan delta complex composition (the deposit located in this area is one of the few identified at the mouth s of any channels on the planet); and (3) analysis of any paleolake sediments (carbonates, evaporites). The primary objectives of the Chryse Outflow Complex region (Ares, Tiu, Mawrth, Simud, and Shalbatana Valles) would be outflow channel dynamics (paleohydrology) of five different channel systems.

Long-range transport and mixing of aerosol sources during the 2013 North American biomass burning episode: analysis of multiple lidar observations in the western Mediterranean basin

NASA Astrophysics Data System (ADS)

Ancellet, Gerard; Pelon, Jacques; Totems, Julien; Chazette, Patrick; Bazureau, Ariane; Sicard, Michaël; Di Iorio, Tatiana; Dulac, Francois; Mallet, Marc

2016-04-01

Long-range transport of biomass burning (BB) aerosols between North America and the Mediterranean region took place in June 2013. A large number of ground-based and airborne lidar measurements were deployed in the western Mediterranean during the Chemistry-AeRosol Mediterranean EXperiment (ChArMEx) intensive observation period. A detailed analysis of the potential North American aerosol sources is conducted including the assessment of their transport to Europe using forward simulations of the FLEXPART Lagrangian particle dispersion model initialized using satellite observations by MODIS and CALIOP. The three-dimensional structure of the aerosol distribution in the ChArMEx domain observed by the ground-based lidars (Minorca, Barcelona and Lampedusa), a Falcon-20 aircraft flight and three CALIOP tracks, agrees very well with the model simulation of the three major sources considered in this work: Canadian and Colorado fires, a dust storm from western US and the contribution of Saharan dust streamers advected from the North Atlantic trade wind region into the westerlies region. Four aerosol types were identified using the optical properties of the observed aerosol layers (aerosol depolarization ratio, lidar ratio) and the transport model analysis of the contribution of each aerosol source: (i) pure BB layer, (ii) weakly dusty BB, (iii) significant mixture of BB and dust transported from the trade wind region, and (iv) the outflow of Saharan dust by the subtropical jet and not mixed with BB aerosol. The contribution of the Canadian fires is the major aerosol source during this episode while mixing of dust and BB is only significant at an altitude above 5 km. The mixing corresponds to a 20-30 % dust contribution in the total aerosol backscatter. The comparison with the MODIS aerosol optical depth horizontal distribution during this episode over the western Mediterranean Sea shows that the Canadian fire contributions were as large as the direct northward dust outflow from Sahara.

Long range transport and mixing of aerosol sources during the 2013 North American biomass burning episode: analysis of multiple lidar observations in the Western Mediterranean basin

NASA Astrophysics Data System (ADS)

Ancellet, G.; Pelon, J.; Totems, J.; Chazette, P.; Bazureau, A.; Sicard, M.; Di Iorio, T.; Dulac, F.; Mallet, M.

2015-11-01

Long range transport of biomass burning (BB) aerosols between North America and the Mediterranean region took place in June 2013. A large number of ground based and airborne lidar measurements were deployed in the Western Mediterranean during the Chemistry-AeRosol Mediterranean EXperiment (ChArMEx) intensive observation period. A detailed analysis of the potential North American aerosol sources is conducted including the assessment of their transport to Europe using forward simulations of the FLEXPART Lagrangian particle dispersion model initialized using satellite observations by MODIS and CALIOP. The three dimensional structure of the aerosol distribution in the ChArMEx domain observed by the ground-based lidars (Menorca, Barcelona and Lampedusa), a Falcon-20 aircraft flight and three CALIOP tracks, agree very well with the model simulation of the three major sources considered in this work: Canadian and Colorado fires, a dust storm from Western US and the contribution of Saharan dust streamers advected from the North Atlantic trade wind region into the Westerlies region. Four aerosol types were identified using the optical properties of the observed aerosol layers (aerosol depolarization ratio, lidar ratio) and the transport model analysis of the contribution of each aerosol source: (I) pure BB layer, (II) weakly dusty BB, (III) significant mixture of BB and dust transported from the trade wind region (IV) the outflow of Saharan dust by the subtropical jet and not mixed with BB aerosol. The contribution of the Canadian fires is the major aerosol source during this episode while mixing of dust and BB is only significant at altitude above 5 km. The mixing corresponds to a 20-30 % dust contribution in the total aerosol backscatter. The comparison with the MODIS AOD horizontal distribution during this episode over the Western Mediterranean sea shows that the Canadian fires contribution were as large as the direct northward dust outflow from Sahara.

Stable carbon and nitrogen isotopic compositions of ambient aerosols collected from Okinawa Island in the western North Pacific Rim, an outflow region of Asian dusts and pollutants

NASA Astrophysics Data System (ADS)

Kunwar, Bhagawati; Kawamura, Kimitaka; Zhu, Chunmao

2016-04-01

Stable carbon (δ13C) and nitrogen (δ15N) isotope ratios were measured for total carbon (TC) and nitrogen (TN), respectively, in aerosol (TSP) samples collected at Cape Hedo, Okinawa, an outflow region of Asian pollutants, during 2009-2010. The averaged δ13C and δ15N ratios are -22.2‰ and +12.5‰, respectively. The δ13C values are similar in both spring (-22.5‰) and winter (-22.5‰), suggesting the similar sources and/or source regions. We found that δ13C from Okinawa aerosols are ca. 2‰ higher than those reported from Chinese megacities probably due to photochemical aging of organic aerosols. A strong correlation (r = 0.81) was found between nss-Ca and TSP, suggesting that springtime aerosols are influenced from Asian dusts. However, carbonates in the Asian dusts were titrated with acidic species such as sulfuric acid and oxalic acid during atmospheric transport although two samples suggested the presence of remaining carbonate. No correlations were found between δ13C and tracer compounds (levoglucosan, elemental carbon, oxalic acid, and Na+). During winter and spring, coal burning is significant source in China. Based on isotopic mass balance, contribution of coal burning origin particles to total aerosol carbon was estimated as ca. 97% in winter, which is probably associated with the high emissions in China. Contribution of NO3- to TN was on average 45% whereas that of NH4+ was 18%. These results suggest that vehicular exhaust is an important source of TN in Okinawa aerosols. Concentration of water-soluble organic nitrogen (WSON) is higher in summer, suggesting that WSON is more emitted from the ocean in warmer season whereas inorganic nitrogen is more emitted in winter and spring from pollution sources in the Asian continent.

Physics from Time Variability of the VHE Blazar PKS 2155-304

NASA Astrophysics Data System (ADS)

Barres de Almeida, Ulisses

2010-10-01

Blazars are the principal extragalactic sources of very high energy gamma-ray emission in the Universe. These objects constitute a sub-class of Active Galactic Nuclei whose emission is dominated by Doppler boosted non-thermal radiation from plasma outflow- ing at relativistic speeds from the central engine. This plasma outflow happens in the form of large-scale collimated structures called jets, which can extend for Mpc in length and transport energy from the central engine of the galaxy to the larger scale intergalac- tic medium. Over thirty such sources have been discovered to date by ground-based gamma-ray telescopes such as H.E.S.S., and PKS 2155-304 is the prototypical southern- hemisphere representative of this population of objects. In this thesis we have studied in detail some aspects of the temporal variability of the jet emission from PKS 2155-304, combining coordinated observations across the electro- magnetic spectrum, from optical polarimetric measurements to X-ray and ground-based gamma-ray data. The temporal properties of the dataset allowed us to derive important physical information about the structure and emission mechanisms of the source and put constraints to the location of the sites of VHE emission and particle acceleration within the jet. We have also derived a sensitive statistical measure, called Kolmogorov distance, which we applied to the large outburst observed from PKS 2155-304 in July 2006, to de- rive the most stringent constraints to date on limits for the violation of Lorentz invariance induced by quantum-gravity effects from AGN measurements.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matsui, H.; Koike, Makoto; Kondo, Yutaka

Organic aerosol (OA) simulations using the volatility basis-set approach were made for East Asia and its outflow region. Model simulations were evaluated through comparisons with OA measured by aerosol mass spectrometers in and around Tokyo (at Komaba and Kisai in summer 2003 and 2004) and over the outflow region in East Asia (at Fukue and Hedo in spring 2009). The simulations with aging processes of organic vapors reasonably well reproduced mass concentrations, temporal variations, and formation efficiency of observed OA at all sites. As OA mass was severely underestimated in the simulations without the aging processes, the oxidations of organicmore » vapors are essential for reasonable OA simulations over East Asia. By considering the aging processes, simulated OA concentrations considerably increased from 0.24 to 1.28 µg m-3 in the boundary layer over the whole of East Asia. OA formed from the interaction of anthropogenic and biogenic sources was also enhanced by the aging processes. The fraction of controllable OA was estimated to be 87 % of total OA over the whole of East Asia, showing that most of the OA in our simulations formed anthropogenically (controllable). A large portion of biogenic secondary OA (78 % of biogenic secondary OA) formed through the influence of anthropogenic sources. The high fraction of controllable OA in our simulations is likely because anthropogenic emissions are dominant over East Asia and OA formation is enhanced by anthropogenic sources and their aging processes. Both the amounts (from 0.18 to 1.12 µg m-3) and the fraction (from 75 % to 87 %) of controllable OA were increased by aging processes of organic vapors over East Asia.« less

The Hunt for Red Quasars: Luminous Obscured Black Hole Growth Unveiled in the Stripe 82 X-Ray Survey

NASA Astrophysics Data System (ADS)

LaMassa, Stephanie M.; Glikman, Eilat; Brusa, Marcella; Rigby, Jane R.; Tasnim Ananna, Tonima; Stern, Daniel; Lira, Paulina; Urry, C. Megan; Salvato, Mara; Alexandroff, Rachael; Allevato, Viola; Cardamone, Carolin; Civano, Francesca; Coppi, Paolo; Farrah, Duncan; Komossa, S.; Lanzuisi, Giorgio; Marchesi, Stefano; Richards, Gordon; Trakhtenbrot, Benny; Treister, Ezequiel

2017-10-01

We present results of a ground-based near-infrared campaign with Palomar TripleSpec, Keck NIRSPEC, and Gemini GNIRS to target two samples of reddened active galactic nucleus (AGN) candidates from the 31 deg2 Stripe 82 X-ray survey. One sample, which is ˜89% complete to K< 16 (Vega), consists of eight confirmed AGNs, four of which were identified with our follow-up program, and is selected to have red R - K colors (> 4, Vega). The fainter sample (K> 17, Vega) represents a pilot program to follow-up four sources from a parent sample of 34 that are not detected in the single-epoch SDSS catalog and have WISE quasar colors. All 12 sources are broad-line AGNs (at least one permitted emission line has an FWHM exceeding 1300 km s-1) and span a redshift range 0.59< z< 2.5. Half the (R - K)-selected AGNs have features in their spectra suggestive of outflows. When comparing these sources to a matched sample of blue Type 1 AGNs, we find that the reddened AGNs are more distant (z> 0.5), and a greater percentage have high X-ray luminosities ({L}{{X},{full}}> {10}44 erg s-1). Such outflows and high luminosities may be consistent with the paradigm that reddened broad-line AGNs represent a transitory phase in AGN evolution as described by the major merger model for black hole growth. Results from our pilot program demonstrate proof of concept that our selection technique is successful in discovering reddened quasars at z> 1 missed by optical surveys.

Sources of tropospheric ozone along the Asian Pacific Rim: An analysis of ozonesonde observations

NASA Astrophysics Data System (ADS)

Liu, Hongyu; Jacob, Daniel J.; Chan, Lo Yin; Oltmans, Samuel J.; Bey, Isabelle; Yantosca, Robert M.; Harris, Joyce M.; Duncan, Bryan N.; Martin, Randall V.

2002-11-01

The sources contributing to tropospheric ozone over the Asian Pacific Rim in different seasons are quantified by analysis of Hong Kong and Japanese ozonesonde observations with a global three-dimensional (3-D) chemical transport model (GEOS-CHEM) driven by assimilated meteorological observations. Particular focus is placed on the extensive observations available from Hong Kong in 1996. In the middle-upper troposphere (MT-UT), maximum Asian pollution influence along the Pacific Rim occurs in summer, reflecting rapid convective transport of surface pollution. In the lower troposphere (LT) the season of maximum Asian pollution influence shifts to summer at midlatitudes from fall at low latitudes due to monsoonal influence. The UT ozone minimum and high variability observed over Hong Kong in winter reflects frequent tropical intrusions alternating with stratospheric intrusions. Asian biomass burning makes a major contribution to ozone at <32°N in spring. Maximum European pollution influence (<5 ppbv) occurs in spring in the LT. North American pollution influence exceeds European influence in the UT-MT, reflecting the uplift from convection and the warm conveyor belts over the eastern seaboard of North America. African outflow makes a major contribution to ozone in the low-latitude MT-UT over the Pacific Rim during November-April. Lightning influence over the Pacific Rim is minimum in summer due to westward UT transport at low latitudes associated with the Tibetan anticyclone. The Asian outflow flux of ozone to the Pacific is maximum in spring and fall and includes a major contribution from Asian anthropogenic sources year-round.

Sources of Tropospheric Ozone along the Asian Pacific Rim: An Analysis of Ozonesonde Observations

NASA Technical Reports Server (NTRS)

Liu, Hong-Yu; Jacob, Daniel J.; Chan, Lo Yin; Oltmans, Samuel J.; Bey, Isabelle; Yantosca, Robert M.; Harris, Joyce M.; Duncan, Bryan N.; Martin, Randall V.

2002-01-01

The sources contributing to tropospheric ozone over the Asian Pacific Rim in different seasons are quantified by analysis of Hong Kong and Japanese ozonesonde observations with a global three-dimensional (3-D) chemical transport model (GEOS-CHEM) driven by assimilated meteorological observations. Particular focus is placed on the extensive observations available from Hong Kong in 1996. In the middle-upper troposphere (MT- UT), maximum Asian pollution influence along the Pacific Rim occurs in summer, reflecting rapid convective transport of surface pollution. In the lower troposphere (LT) the season of maximum Asian pollution influence shifts to summer at midlatitudes from fall at low latitudes due to monsoonal influence. The UT ozone minimum and high variability observed over Hong Kong in winter reflects frequent tropical intrusions alternating with stratospheric intrusions. Asian biomass burning makes a major contribution to ozone at less than 32 deg.N in spring. Maximum European pollution influence (less than 5 ppbv) occurs in spring in the LT. North American pollution influence exceeds European influence in the UT-MT, reflecting the uplift from convection and the warm conveyor belts over the eastern seaboard of North America. African outflow makes a major contribution to ozone in the low-latitude MT-UT over the Pacific Rim during November- April. Lightning influence over the Pacific Rim is minimum in summer due to westward UT transport at low latitudes associated with the Tibetan anticyclone. The Asian outflow flux of ozone to the Pacific is maximum in spring and fall and includes a major contribution from Asian anthropogenic sources year-round.

Simulation of California's Major Reservoirs Outflow Using Data Mining Technique

NASA Astrophysics Data System (ADS)

Yang, T.; Gao, X.; Sorooshian, S.

2014-12-01

The reservoir's outflow is controlled by reservoir operators, which is different from the upstream inflow. The outflow is more important than the reservoir's inflow for the downstream water users. In order to simulate the complicated reservoir operation and extract the outflow decision making patterns for California's 12 major reservoirs, we build a data-driven, computer-based ("artificial intelligent") reservoir decision making tool, using decision regression and classification tree approach. This is a well-developed statistical and graphical modeling methodology in the field of data mining. A shuffled cross validation approach is also employed to extract the outflow decision making patterns and rules based on the selected decision variables (inflow amount, precipitation, timing, water type year etc.). To show the accuracy of the model, a verification study is carried out comparing the model-generated outflow decisions ("artificial intelligent" decisions) with that made by reservoir operators (human decisions). The simulation results show that the machine-generated outflow decisions are very similar to the real reservoir operators' decisions. This conclusion is based on statistical evaluations using the Nash-Sutcliffe test. The proposed model is able to detect the most influential variables and their weights when the reservoir operators make an outflow decision. While the proposed approach was firstly applied and tested on California's 12 major reservoirs, the method is universally adaptable to other reservoir systems.

The small observed scale of AGN-driven outflows, and inside-out disc quenching

NASA Astrophysics Data System (ADS)

Zubovas, Kastytis; King, Andrew

2016-11-01

Observations of massive outflows with detectable central active galactic nuclei (AGN) typically find them within radii ≲10 kpc. We show that this apparent size restriction is a natural result of AGN driving if this process injects total energy only of the order of the gas binding energy to the outflow, and the AGN varies over time (`flickers') as suggested in recent work. After the end of all AGN activity, the outflow continues to expand to larger radii, powered by the thermal expansion of the remnant-shocked AGN wind. We suggest that on average, outflows should be detected further from the nucleus in more massive galaxies. In massive gas-rich galaxies, these could be several tens of kpc in radius. We also consider the effect that pressure of such outflows has on a galaxy disc. In moderately gas-rich discs, with gas-to-baryon fraction <0.2, the outflow may induce star formation significant enough to be distinguished from quiescent by an apparently different normalization of the Kennicutt-Schmidt law. The star formation enhancement is probably stronger in the outskirts of galaxy discs, so coasting outflows might be detected by their effects upon the disc even after the driving AGN has shut off. We compare our results to the recent inference of inside-out quenching of star formation in galaxy discs.

Cold Ion Outflow Modulated by the Solar Wind Energy Input and Tilt of the Geomagnetic Dipole

NASA Astrophysics Data System (ADS)

Li, Kun; Wei, Y.; André, M.; Eriksson, A.; Haaland, S.; Kronberg, E. A.; Nilsson, H.; Maes, L.; Rong, Z. J.; Wan, W. X.

2017-10-01

The solar wind energy input into the Earth's magnetosphere-ionosphere system drives ionospheric outflow, which plays an important role in both the magnetospheric dynamics and evolution of the atmosphere. However, little is known about the cold ion outflow with energies lower than a few tens of eV, as the direct measurement of cold ions is difficult because a spacecraft gains a positive electric charge due to the photoemission effect, which prevents cold ions from reaching the onboard detectors. A recent breakthrough in the measurement technique using Cluster spacecraft revealed that cold ions dominate the ion population in the magnetosphere. This new technique yields a comprehensive data set containing measurements of the velocities and densities of cold ions for the years 2001-2010. In this paper, this data set is used to analyze the cold ion outflow from the ionosphere. We found that about 0.1% of the solar wind energy input is transformed to the kinetic energy of cold ion outflow at the topside ionosphere. We also found that the geomagnetic dipole tilt can significantly affect the density of cold ion outflow, modulating the outflow rate of cold ion kinetic energy. These results give us clues to study the evolution of ionospheric outflow with changing global magnetic field and solar wind condition in the history.

Do changes in climate and land use pose a risk to the future water availability of Mediterranean Lakes?

NASA Astrophysics Data System (ADS)

Bucak, T.; Trolle, D.; Andersen, H. E.; Thodsen, H.; Erdoğan, Ş.; Levi, E. E.; Filiz, N.; Jeppesen, E.; Beklioğlu, M.

2016-12-01

Inter- and intra-annual water level fluctuations and change in water flow regime are intrinsic characteristics of Mediterranean lakes. However, considering the climate change projections for the water-limited Mediterranean region where potential evapotranspiration exceeds precipitation and with increased air temperatures and decreased precipitation, more dramatic water level declines in lakes and severe water scarcity problems are expected to occur in the future. Our study lake, Lake Beyşehir, the largest freshwater lake in the Mediterranean basin, is - like other Mediterranean lakes - under pressure due to water abstraction for irrigated crop farming and climatic changes, and integrated water level management is therefore required. We used an integrated modeling approach to predict the future lake water level of Lake Beyşehir in response to the future changes in both climate and, potentially, land use by linking the catchment model Soil and Water Assessment Tool (SWAT) with a Support Vector Machine Regression model (ɛ-SVR). We found that climate change projections caused enhanced potential evapotranspiration and reduced total runoff, whereas the effects of various land use scenarios within the catchment were comparatively minor. In all climate scenarios applied in the ɛ-SVR model, changes in hydrological processes caused a water level reduction, predicting that the lake may dry out already in the 2040s with the current outflow regulation considering the most pessimistic scenario. Based on model runs with optimum outflow management, a 9-60% reduction in outflow withdrawal is needed to prevent the lake from drying out by the end of this century. Our results indicate that shallow Mediterranean lakes may face a severe risk of drying out and loss of ecosystem value in near future if the current intense water abstraction is maintained. Therefore, we conclude that outflow management in water-limited regions in a warmer and drier future and sustainable use of water sources are vitally important to sustain lake ecosystems and their ecosystem services.

Use of models to map potential capture of surface water

USGS Publications Warehouse

Leake, Stanley A.

2006-01-01

The effects of ground-water withdrawals on surface-water resources and riparian vegetation have become important considerations in water-availability studies. Ground water withdrawn by a well initially comes from storage around the well, but with time can eventually increase inflow to the aquifer and (or) decrease natural outflow from the aquifer. This increased inflow and decreased outflow is referred to as “capture.” For a given time, capture can be expressed as a fraction of withdrawal rate that is accounted for as increased rates of inflow and decreased rates of outflow. The time frames over which capture might occur at different locations commonly are not well understood by resource managers. A ground-water model, however, can be used to map potential capture for areas and times of interest. The maps can help managers visualize the possible timing of capture over large regions. The first step in the procedure to map potential capture is to run a ground-water model in steady-state mode without withdrawals to establish baseline total flow rates at all sources and sinks. The next step is to select a time frame and appropriate withdrawal rate for computing capture. For regional aquifers, time frames of decades to centuries may be appropriate. The model is then run repeatedly in transient mode, each run with one well in a different model cell in an area of interest. Differences in inflow and outflow rates from the baseline conditions for each model run are computed and saved. The differences in individual components are summed and divided by the withdrawal rate to obtain a single capture fraction for each cell. Values are contoured to depict capture fractions for the time of interest. Considerations in carrying out the analysis include use of realistic physical boundaries in the model, understanding the degree of linearity of the model, selection of an appropriate time frame and withdrawal rate, and minimizing error in the global mass balance of the model.

NuSTAR View of the Black Hole Wind in the Galaxy Merger IRAS F11119+3257

NASA Astrophysics Data System (ADS)

Tombesi, F.; Veilleux, S.; Meléndez, M.; Lohfink, A.; Reeves, J. N.; Piconcelli, E.; Fiore, F.; Feruglio, C.

2017-12-01

Galactic winds driven by active galactic nuclei (AGNs) have been invoked to play a fundamental role in the co-evolution between supermassive black holes and their host galaxies. Finding observational evidence of such feedback mechanisms is of crucial importance and it requires a multi-wavelength approach in order to compare winds at different scales and phases. In Tombesi et al., we reported the detection of a powerful ultra-fast outflow (UFO) in the Suzaku X-ray spectrum of the ultra-luminous infrared galaxy IRAS F11119+3257. The comparison with a galaxy-scale OH molecular outflow observed with Herschel in the same source supported the energy-conserving scenario for AGN feedback. The main objective of this work is to perform an independent check of the Suzaku results using the higher sensitivity and wider X-ray continuum coverage of NuSTAR. We clearly detect a highly ionized Fe K UFO in the 100 ks NuSTAR spectrum with parameters N H = (3.2 ± 1.5) × 1024 cm-2, log ξ = {4.0}-0.3+1.2 erg s-1 cm, and {v}{out}={0.253}-0.118+0.061c. The launching radius is likely at a distance of r ≥ 16r s from the black hole. The mass outflow rate is in the range of {\\dot{M}}{out} ≃ 0.5-2 M ⊙ yr-1. The UFO momentum rate and power are {\\dot{P}}{out} ≃ 0.5-2 L AGN/c and {\\dot{E}}{out} ≃ 7%-27% L AGN, respectively. The UFO parameters are consistent between the 2013 Suzaku and the 2015 NuSTAR observations. Only the column density is found to be variable, possibly suggesting a clumpy wind. The comparison with the energetics of molecular outflows estimated in infrared and millimeter wavelengths support a connection between the nuclear and galaxy-scale winds in luminous AGNs.