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Sample records for active region formed

  1. Broca's region and Visual Word Form Area activation differ during a predictive Stroop task.

    PubMed

    Wallentin, Mikkel; Gravholt, Claus Højbjerg; Skakkebæk, Anne

    2015-12-01

    Competing theories attempt to explain the function of Broca's area in single word processing. Studies have found the region to be more active during processing of pseudo words than real words and during infrequent words relative to frequent words and during Stroop (incongruent) color words compared to Non-Stroop (congruent) words. Two related theories explain these findings as reflecting either "cognitive control" processing in the face of conflicting input or a linguistic prediction error signal, based on a predictive coding approach. The latter implies that processing cost refers to violations of expectations based on the statistical distributions of input. In this fMRI experiment we attempted to disentangle single word processing cost originating from cognitive conflict and that stemming from predictive expectation violation. Participants (N = 49) responded to whether the words "GREEN" or "RED" were displayed in green or red (incongruent vs congruent colors). One of the colors, however, was presented three times as often as the other, making it possible to study both congruency and frequency effects independently. Auditory stimuli saying "GREEN" or "RED" had the same distribution, making it possible to study frequency effects across modalities. We found significant behavioral effects of both incongruency and frequency. A significant effect (p < .05 FWE) of incongruency was found in Broca's region, but no effect of frequency was observed and no interaction. Conjoined effects of incongruency and frequency were found in parietal regions as well as in the Visual Word Form Area (VWFA). No interaction between perceptual modality and frequency was found in VWFA suggesting that the region is not strictly visual. These findings speak against a strong version of the prediction error processing hypothesis in Broca's region. They support the idea that prediction error processes in the intermediate timeframe are allocated to more posterior parts of the brain. Copyright

  2. Star Forming Regions in Cassiopeia

    NASA Astrophysics Data System (ADS)

    Kun, M.

    2008-12-01

    This chapter describes the Galactic star forming regions in the constellation Cassiopeia, in the Galactic coordinate range 120° ⪉ l ⪉ 130°, -5° ⪉ b ⪉ 15°. At |b| > 10° the nearby clouds L 1333 and L 1340 are found in this region. The local arm of the Galaxy in Cassiopeia contains only a few star forming regions, smaller and less active than the OB associations of the neighboring Cepheus. Five members of this system, LkHα 198 and its environment, L 1287, L 1293, L 1302/NGC 255, and S 187 are discussed. Several more distant OB associations and giant star forming regions in Cassiopeia are associated with the Perseus arm at 2.0--3.0 kpc. Among these, the Herbig Be star MWC 1080 is discussed in this chapter.

  3. Observational analysis of the physical conditions in galactic and extragalactic active star forming regions

    NASA Astrophysics Data System (ADS)

    Kristensen, L. E.

    2007-10-01

    In my thesis observations of near-infrared rovibrational H_2 emission in active star-forming regions are presented and analysed. The main subject of this work concerns new observations of the Orion Molecular Cloud (OMC1) and in particular the BN-KL region. Data consist of images of individual H_2 lines with high spatial resolution obtained both at the Canada-France-Hawaii Telescope and at the ESO Very Large Telescope (VLT). With the high spatial resolution of the VLT it is possible to analyse in detail (down to 60 AU ~ 0.13") individual objects in the region. I have also analysed H_2 and [FeII] emission from outflows in two dark clouds (Bok globules BHR71 and BHR137) and a high excitation blob in the Magellanic Clouds (N159-5). In the latter, data consist of long-slit spectra obtained at the ESO-VLT. In order to facilitate this work I ran a large grid of ~25000 shock models, producing almost 400 Gb of results. These models are state-of-the-art and there is a large number of free parameters which can be adjusted. A big part of my project has been to analyse the results from this grid and make it publically available. Furthermore, as it turned out, not all results are equally reliable and I have had to develop methods for checking the consistency of the wealth of results obtained. But with the model results and a sound knowledge of shock physics it is now relatively straightforward to interpret the H_2 and [FeII] data. The models allow me to predict the large-scale physical conditions in OMC1 such as density, shock velocities, magnetic field strengths, etc. Overall the preshock density is of the order of ~10^5-10^7 cm(-3) and shock velocities are in the interval 10-40 km/s. Another very interesting result is a new method developed for analysing bow shocks observed at high spatial resolution. For one isolated bow shock in OMC1 I predict a shock velocity of 50 km/s and a preshock density of the order of 5x10^5 cm(-3). The 3D velocity has recently been measured to 55 km

  4. Star Formation Activity Beyond the Outer Arm. I. WISE-selected Candidate Star-forming Regions

    NASA Astrophysics Data System (ADS)

    Izumi, Natsuko; Kobayashi, Naoto; Yasui, Chikako; Saito, Masao; Hamano, Satoshi

    2017-10-01

    The outer Galaxy beyond the Outer Arm provides a good opportunity to study star formation in an environment significantly different from that in the solar neighborhood. However, star-forming regions in the outer Galaxy have never been comprehensively studied or cataloged because of the difficulties in detecting them at such large distances. We studied 33 known young star-forming regions associated with 13 molecular clouds at R G ≥ 13.5 kpc in the outer Galaxy with data from the Wide-field Infrared Survey Explorer (WISE) mid-infrared all-sky survey. From their color distribution, we developed a simple identification criterion of star-forming regions in the outer Galaxy with the WISE color. We applied the criterion to all the WISE sources in the molecular clouds in the outer Galaxy at R G ≥ 13.5 kpc detected with the Five College Radio Astronomy Observatory (FCRAO) 12CO survey of the outer Galaxy, of which the survey region is 102.°49 ≤ l ≤ 141.°54, ‑3.°03 ≤ b ≤ 5.°41, and successfully identified 711 new candidate star-forming regions in 240 molecular clouds. The large number of samples enables us to perform the statistical study of star formation properties in the outer Galaxy for the first time. This study is crucial to investigate the fundamental star formation properties, including star formation rate, star formation efficiency, and initial mass function, in a primordial environment such as the early phase of the Galaxy formation.

  5. Star Forming Regions in Cepheus

    NASA Astrophysics Data System (ADS)

    Kun, M.; Kiss, Z. T.; Balog, Z.

    2008-12-01

    The northern Milky Way in the constellation of Cepheus (100° ≤ l ≤ 120°; 0° ≤ b ≤ 20°) contains several star forming regions. The molecular clouds of the Cepheus Flare region at b > 10°, are sites of low and intermediate mass star formation located between 200 and 450 pc from the Sun. Three nearby OB associations, Cep OB2, Cep OB3, Cep OB4, located at 600--800 pc, are eac= h involved in forming stars, like the well known high mass star forming regio= n S 140 at 900 pc. The reflection nebula NGC 7129 around 1 kpc harbors young, compact clusters of low and intermediate mass stars. The giant star forming complex NGC 7538 and the young open cluster NGC 7380, associated with the Perseus arm, are located at d > 2 kpc.

  6. Star-forming Activity in the H II Regions Associated with the IRAS 17160-3707 Complex

    NASA Astrophysics Data System (ADS)

    Nandakumar, G.; Veena, V. S.; Vig, S.; Tej, A.; Ghosh, S. K.; Ojha, D. K.

    2016-11-01

    We present a multiwavelength investigation of star formation activity toward the southern H ii regions associated with IRAS 17160-3707, located at a distance of 6.2 kpc with a bolometric luminosity of 8.3 × 105 L ⊙. The ionized gas distribution and dust clumps in the parental molecular cloud are examined in detail using measurements at infrared, submillimeter and radio wavelengths. The radio continuum images at 1280 and 610 MHz obtained using the Giant Metrewave Radio Telescope reveal the presence of multiple compact sources as well as nebulous emission. At submillimeter wavelengths, we identify seven dust clumps and estimate their physical properties such as temperature: 24-30 K, mass: 300-4800 M ⊙ and luminosity: 9-317 × 102 L ⊙ using modified blackbody fits to the spectral energy distributions (SEDs) between 70 and 870 μm. We find 24 young stellar objects (YSOs) in the mid-infrared, with a few of them coincident with the compact radio sources. The SEDs of the YSOs have been fitted by the Robitaille models and the results indicate that those having radio compact sources as counterparts host massive objects in early evolutionary stages with best fit age ≤0.2 Myr. We compare the relative evolutionary stages of clumps using various signposts such as masers, ionized gas, presence of YSOs and infrared nebulosity, and find six massive star-forming clumps and one quiescent clump. Of the former, five are in a relatively advanced stage and one in an earlier stage.

  7. Forming Polymers. Learning Activity.

    ERIC Educational Resources Information Center

    Shackelford, Ray

    1997-01-01

    Offers a technology education activity on the subject of manufacturing processes. Includes background information, concepts presented, objectives, equipment list, procedures, and suggested follow-up activities. (JOW)

  8. Rapid intranasal delivery of chloramphenicol acetyltransferase in the active form to different brain regions as a model for enzyme therapy in the CNS.

    PubMed

    Appu, Abhilash P; Arun, Peethambaran; Krishnan, Jishnu K S; Moffett, John R; Namboodiri, Aryan M A

    2016-02-01

    The blood brain barrier (BBB) is critical for maintaining central nervous system (CNS) homeostasis by restricting entry of potentially toxic substances. However, the BBB is a major obstacle in the treatment of neurotoxicity and neurological disorders due to the restrictive nature of the barrier to many medications. Intranasal delivery of active enzymes to the brain has therapeutic potential for the treatment of numerous CNS enzyme deficiency disorders and CNS toxicity caused by chemical threat agents. The aim of this work is to provide a sensitive model system for analyzing the rapid delivery of active enzymes into various regions of the brain with therapeutic bioavailability. We tested intranasal delivery of chloramphenicol acetyltransferase (CAT), a relatively large (75kD) enzyme, in its active form into different regions of the brain. CAT was delivered intranasally to anaesthetized rats and enzyme activity was measured in different regions using a highly specific High Performance Thin Layer Chromatography (HP-TLC)-radiometry coupled assay. Active enzyme reached all examined areas of the brain within 15min (the earliest time point tested). In addition, the yield of enzyme activity in the brain was almost doubled in the brains of rats pre-treated with matrix metalloproteinase-9 (MMP-9). Intranasal administration of active enzymes in conjunction with MMP-9 to the CNS is both rapid and effective. The present results suggest that intranasal enzyme therapy is a promising method for counteracting CNS chemical threat poisoning, as well as for treating CNS enzyme deficiency disorders. Published by Elsevier B.V.

  9. Carbon Dioxide in Star-forming Regions.

    PubMed

    Charnley; Kaufman

    2000-02-01

    We consider the gas-phase chemistry of CO2 molecules in active regions. We show that CO2 molecules evaporated from dust in hot cores cannot be efficiently destroyed and are in fact copiously produced in cooler gas. When CO2-rich ices are sputtered in strong MHD shock waves, the increase in atomic hydrogen, due to H2 dissociation by ion-neutral streaming, means that CO2 can be depleted by factors of approximately 500 from its injected abundance. We find that a critical shock speed exists at higher preshock densities below which CO2 molecules can be efficiently sputtered but survive in the postshock gas. These calculations offer an explanation for the low gas/solid CO2 ratios detected by the Infrared Space Observatory in star-forming cores as being due to shock destruction followed by partial reformation in warm gas. The presence of high abundances of CO2 in the strongly shocked Galactic center clouds Sgr B2 and Sgr A also find a tentative explanation in this scenario. Shock activity plays an important role in determining the chemistry of star-forming regions, and we suggest that most hot cores are in fact shocked cores.

  10. Rapid intranasal delivery of chloramphenicol acetyltransferase in the active form to different brain regions as a model for enzyme therapy in the CNS

    PubMed Central

    Appu, Abhilash P; Arun, Peethambaran; Krishnan, Jishnu K. S.; Moffett, John R.; Namboodiri, Aryan M. A.

    2015-01-01

    Background The blood brain barrier (BBB) is critical for maintaining central nervous system (CNS) homeostasis by restricting entry of potentially toxic substances. However, the BBB is a major obstacle in the treatment of neurotoxicity and neurological disorders due to the restrictive nature of the barrier to many medications. Intranasal delivery of active enzymes to the brain has therapeutic potential for the treatment of numerous CNS enzyme deficiency disorders and CNS toxicity caused by chemical threat agents. New method The aim of this work is to provide a sensitive model system for analyzing the rapid delivery of active enzymes into various regions of the brain with therapeutic bioavailability. Results We tested intranasal delivery of chloramphenicol acetyltransferase (CAT), a relatively large (75 kD) enzyme, in its active form into different regions of the brain. CAT was delivered intranasally to anaesthetized rats and enzyme activity was measured in different regions using a highly specific High Performance Thin Layer Chromatography (HP-TLC)-radiometry coupled assay. Active enzyme reached all examined areas of the brain within 15 min (the earliest time point tested). In addition, the yield of enzyme activity in the brain was almost doubled in the brains of rats pre-treated with matrix metalloproteinase-9 (MMP-9). Comparison with existing method (s) Intranasal administration of active enzymes in conjunction with MMP-9 to the CNS is both rapid and effective. Conclusion The present results suggest that intranasal enzyme therapy is a promising method for counteracting CNS chemical threat poisoning, as well as for treating CNS enzyme deficiency disorders. PMID:26688469

  11. Active Regions Blossoming

    NASA Image and Video Library

    2015-10-28

    As a pair of active regions began to rotate into view, their towering magnetic field lines above them bloomed into a dazzling display of twisting arches (Oct. 27-28, 2015). Some of the lines reached over and connected with the neighboring active region. Active regions are usually the source of solar storms. The images were taken in a wavelength of extreme ultraviolet light. http://photojournal.jpl.nasa.gov/catalog/PIA20048

  12. Z-DNA-forming sites identified by ChIP-Seq are associated with actively transcribed regions in the human genome.

    PubMed

    Shin, So-I; Ham, Seokjin; Park, Jihwan; Seo, Seong Hye; Lim, Chae Hyun; Jeon, Hyeongrin; Huh, Jounghyun; Roh, Tae-Young

    2016-07-03

    Z-DNA, a left-handed double helical DNA is structurally different from the most abundant B-DNA. Z-DNA has been known to play a significant role in transcription and genome stability but the biological meaning and positions of Z-DNA-forming sites (ZFSs) in the human genome has not been fully explored. To obtain genome-wide map of ZFSs, Zaa with two Z-DNA-binding domains was used for ChIP-Seq analysis. A total of 391 ZFSs were found and their functions were examined in vivo A large portion of ZFSs was enriched in the promoter regions and contain sequences with high potential to form Z-DNA. Genes containing ZFSs were occupied by RNA polymerase II at the promoters and showed high levels of expression. Moreover, ZFSs were significantly related to active histone marks such as H3K4me3 and H3K9ac. The association of Z-DNA with active transcription was confirmed by the reporter assay system. Overall, our results suggest that Z-DNA formation depends on chromatin structure as well as sequence composition, and is associated with active transcription in human cells. The global information about ZFSs positioning will provide a useful resource for further understanding of DNA structure-dependent transcriptional regulation. © The Author 2016. Published by Oxford University Press on behalf of Kazusa DNA Research Institute.

  13. Gyrating Active Region

    NASA Image and Video Library

    2017-01-26

    On Jan. 20, 2017, NASA Solar Dynamics Observatory captured a small area of the sun highlighted three active region. Over half a day this active region sent dark swirls of plasma and bright magnetic arches twisting and turning above it. All the activity in the three areas was driven by competing magnetic forces. The dynamic action was observed in a wavelength of extreme ultraviolet light. Movies are available at http://photojournal.jpl.nasa.gov/catalog/PIA11703

  14. Active Regions' Magnetic Connection

    NASA Image and Video Library

    2017-05-22

    Several bright bands of plasma connect from one active region to another, even though they are tens of thousands of miles away from each other (May 17-18, 2017). Active regions are, by their nature, strong magnetic areas with north and south poles. The plasma consists of charged particles that stream along the magnetic field lines between these two regions. These connecting lines are clearly visible in this wavelength of extreme ultraviolet light. Other loops and strands of bright plasma can be seen rising up and out of smaller active regions as well. The video covers about one day's worth of activity. Movies are available at https://photojournal.jpl.nasa.gov/catalog/PIA21638

  15. Molecular Outflows in Massive Star Forming Regions

    NASA Astrophysics Data System (ADS)

    Cunningham, Nichol

    2015-11-01

    This thesis presents millimetre continuum and molecular line observations exploring the properties of molecular outflows towards massive star forming regions. Massive stars produce some of the most energetic phenomena in the Galaxy, yet we still do not have a comprehensive understanding of how they actually form. Outflows are known to play a key role in this formation process and their properties, particularly how they change depending on the mass, luminosity and evolution of the driving source can shed light on how massive stars actually form. This thesis presents observations at both high (SMA 3 arcsecond) and low (JCMT 15 arcsecond) spatial resolution of the known jet/outflow tracers, SiO and 12CO, towards a sample massive star forming region drawn from the RMS survey. Furthermore, the presence of infall signatures is explored through observations of HCO+ and H13CO+, and the hot core nature of the regions is probed using tracers such as CH3CN, HC3N and CH3OH. SiO is detected towards approximately 50% of the massive young stellar objects and HII regions in the JCMT sample. The detection of SiO appears to be linked to the age of the RMS source, with the likely younger sources showing a stronger dependence with SiO. The presence of SiO also appears to be linked to the CO velocity, with SiO more efficiently tracing sources with higher velocity dispersions. In the MOPRA observations towards a sample of 33 RMS sources, CH3CN is detected towards 66% of the sources, with the redder likely younger sources having the largest rotational temperatures. This thesis presents the first interferometric SiO (5-4) and 12CO (2-1) observations, taken with the SMA, towards the massive star forming region G203.3166/NGC 2264-C. In this intermediate/massive star forming cluster, SiO is again tracing the youngest sources. Both the SiO and 12CO emission trace two bipolar, high velocity outflows towards the mm brightest, IR-dark, likely youngest sources in this reg! ion. In contrast the IR

  16. Energized Active Regions

    NASA Image and Video Library

    2017-06-02

    A pair of relatively small (but frenetic) active regions rotated into view, spouting off numerous small flares and sweeping loops of plasma (May 31-June 2, 2017). At first, only the one active region was observed, but mid-way though the video clip a second one behind the first can be picked out. The dynamic regions were easily the most remarkable areas on the sun during this 42-hour period. The images were taken in a wavelength of extreme ultraviolet light. Movies are available at https://photojournal.jpl.nasa.gov/catalog/PIA21756

  17. Agitated Active Region

    NASA Image and Video Library

    2016-10-11

    An active region just rotating into view gave us a perfect view of the tussle of magnetic field lines above it (Oct. 10-11, 2016). The particles spiraling along the magnetic field lines become visible in extreme ultraviolet light, helping us to see the struggle going on. There were no eruptions during this period, although active regions are usually the source for solar storms. The video clip covers just one day's worth of activity. Movies are available at http://photojournal.jpl.nasa.gov/catalog/PIA21109

  18. Active superconducting devices formed of thin films

    DOEpatents

    Martens, Jon S.; Beyer, James B.; Nordman, James E.; Hohenwarter, Gert K. G.

    1991-05-28

    Active superconducting devices are formed of thin films of superconductor which include a main conduction channel which has an active weak link region. The weak link region is composed of an array of links of thin film superconductor spaced from one another by voids and selected in size and thickness such that magnetic flux can propagate across the weak link region when it is superconducting. Magnetic flux applied to the weak link region will propagate across the array of links causing localized loss of superconductivity in the links and changing the effective resistance across the links. The magnetic flux can be applied from a control line formed of a superconducting film deposited coplanar with the main conduction channel and weak link region on a substrate. The devices can be formed of any type to superconductor but are particularly well suited to the high temperature superconductors since the devices can be entirely formed from coplanar films with no overlying regions. The devices can be utilized for a variety of electrical components, including switching circuits, amplifiers, oscillators and modulators, and are well suited to microwave frequency applications.

  19. Jumpy Active Region

    NASA Image and Video Library

    2017-01-03

    A close-up view of one day in the life of a rather small active region shows the agitation and dynamism of its magnetic field (Dec. 21, 2016). This wavelength of extreme ultraviolet light reveals particles as they spin along the cascading arches of magnetic field lines above the active region. Some darker plasma rises up and spins around at the edge of the sun near the end of the video clip also being pulled by unseen magnetic forces. Movies are available at http://photojournal.jpl.nasa.gov/catalog/PIA15032

  20. [Molecular spectral diagnosis of star forming regions].

    PubMed

    Xi, S; Qin, S; Deng, L; Yang, J

    2001-08-01

    Stars are the basic building blocks of our universe, therefore it is one of the most important research topics in astrophysics to understand the origin and the early evolution of these objects. The current picture is that stars are formed during the collapse of a large enough self-gravitating interstellar molecular cloud. The early collapse gives birth to a fetus of a star, which is surrounded by a rotating accretion disk. The proto-star accretes interstellar matter through the disk which in turn transfer the accumulated matter to the central proto-star, then the star gets weight during the process. Observation shows that gorgeous ejection of matter always come along with the accretion process. In the presence of disks, these outflows usually escape from the system along the axis of the disk, forming so called bipolar outflows. Typical tracers of these activities are rich molecules such as CO, SiC2, C3H, C3H2 etc. Observationally, such typical molecular outflows can be detected using Doppler effect by spectroscopic measurements. Using the 13.7 m radio telescope in Delingha station of Purple Mountain Observatory, we performed a survey for 12 low temperature IRAS objects, some of the sources show high velocity properties. Detailed analysis of the Doppler profiles of IRS34 is presented. Star forming activities are clearly seen in this field.

  1. Disk Evaporation in Star Forming Regions

    NASA Technical Reports Server (NTRS)

    Hollenbach, David; DeVincenzi, Donald L. (Technical Monitor)

    2000-01-01

    Young stars produce sufficient ultraviolet photon luminosity and mechanical luminosity in their winds to significantly affect the structure and evolution of the accretion disks surrounding them. The Lyman continuum photons create a nearly static, ionized, isothermal 10(exp 4) K atmosphere forms above the neutral disk at small distances from the star. Further out, they create a photoevaporative flow which relatively rapidly destroys the disk. The resulting slow (10-50 km/s) ionized outflow, which persists for approx. greater than 10(exp 5) years for disk masses M(sub d) approx. 0.3M(sub *), may explain the observational characteristics of many ultracompact HII regions. We compare model results to the observed radio free-free spectra and luminosities of ultracompact HII regions and to the interesting source MWC349, which is observed to produce hydrogen masers. We apply the results to Ae and Be stars in order to determine the lifetimes of disks around such stars. We also apply the results to the early solar nebula to explain the the dispersal of the solar nebula and the differences in hydrogen content in the giant planets. Finally, we model the small bright objects ("proplyds") observed in the Orion Nebula as disks around young, low mass stars which are externally illuminated by the UV photons from the nearby massive star Theta(sup 1) C.

  2. Disk Evaporation in Star Forming Regions

    NASA Technical Reports Server (NTRS)

    Hollenbach, David; DeVincenzi, Donald L. (Technical Monitor)

    2000-01-01

    Young stars produce sufficient ultraviolet photon luminosity and mechanical luminosity in their winds to significantly affect the structure and evolution of the accretion disks surrounding them. The Lyman continuum photons create a nearly static, ionized, isothermal 10(exp 4) K atmosphere forms above the neutral disk at small distances from the star. Further out, they create a photoevaporative flow which relatively rapidly destroys the disk. The resulting slow (10-50 km/s) ionized outflow, which persists for approx. greater than 10(exp 5) years for disk masses M(sub d) approx. 0.3M(sub *), may explain the observational characteristics of many ultracompact HII regions. We compare model results to the observed radio free-free spectra and luminosities of ultracompact HII regions and to the interesting source MWC349, which is observed to produce hydrogen masers. We apply the results to Ae and Be stars in order to determine the lifetimes of disks around such stars. We also apply the results to the early solar nebula to explain the the dispersal of the solar nebula and the differences in hydrogen content in the giant planets. Finally, we model the small bright objects ("proplyds") observed in the Orion Nebula as disks around young, low mass stars which are externally illuminated by the UV photons from the nearby massive star Theta(sup 1) C.

  3. Active region seismology

    NASA Technical Reports Server (NTRS)

    Bogdan, Tom; Braun, D. C.

    1995-01-01

    Active region seismology is concerned with the determination and interpretation of the interaction of the solar acoustic oscillations with near-surface target structures, such as magnetic flux concentration, sunspots, and plage. Recent observations made with a high spatial resolution and a long temporal duration enabled measurements of the scattering matrix for sunspots and solar active regions to be carried out as a function of the mode properties. Based on this information, the amount of p-mode absorption, partial-wave phase shift, and mode mixing introduced by the sunspot, could be determined. In addition, the possibility of detecting the presence of completely submerged magnetic fields was raised, and new procedures for performing acoustic holography of the solar interior are being developed. The accumulating evidence points to the mode conversion of p-modes to various magneto-atmospheric waves within the magnetic flux concentration as being the unifying physical mechanism responsible for these diverse phenomena.

  4. Tangled up Active Region

    NASA Image and Video Library

    2017-09-27

    This close-up image of the sun presents an active region in profile as it rotated out of view. We can observe both the bright arching field lines and smaller pieces of darker matter in their midst being pulled back and forth just above the Sun's surface over about 36 hours (July 20-22, 2011). Both of these physical responses were caused by strong, tangled magnetic forces that are constantly evolving and reorganizing within the active region. Other active regions can be seen in the foreground as well. The image and movie were taken in extreme ultraviolet light of ionized iron heated to one million degrees. To view a hd video of this event go here: www.flickr.com/photos/gsfc/6006013038 Credit: NASA/GSFC/SDO NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

  5. Extreme Variables in Star Forming Regions

    NASA Astrophysics Data System (ADS)

    Contreras Peña, Carlos Eduardo

    2015-01-01

    in two multi-epoch infrared surveys: the UKIDSS Galactic Plane Survey (GPS) and the Vista Variables in the Via Lactea (VVV). In order to further investigate the nature of the selected variable stars, we use photometric information arising from public surveys at near- to far-infrared wavelengths. In addition we have performed spectroscopic and photometric follow-up for a large subset of the samples arising from GPS and VVV. We analyse the widely separated two-epoch K-band photometry in the 5th, 7th and 8th data releases of the UKIDSS Galactic Plane Survey. We find 71 stars with ΔK > 1 mag, including 2 previously known OH/IR stars and a Nova. Even though the mid-plane is mostly excluded from the dataset, we find the majority (66%) of our sample to be within known star forming regions (SFRs), with two large concentrations in the Serpens OB2 association (11 stars) and the Cygnus-X complex (27 stars). The analysis of the multi-epoch K-band photometry of 2010-2012 data from VVV covering the Galactic disc at |b| < 1° yields 816 high amplitude variables, which include known variables of different classes such as high mass X-ray binaries, Novae and eclipsing binaries among others. Remarkably, 65% of the sample are found concentrated towards areas of star formation, similar to the results from GPS. In both surveys, sources in SFRs show spectral energy distributions (SEDs) that support classification as YSOs. This indicates that YSOs dominate the Galactic population of high amplitude infrared variable stars at low luminosities and therefore likely dominate the total high amplitude population. Spectroscopic follow-up allows us to confirm the pre-main sequence nature of several GPS and VVV Objects. Most objects in both samples show spectroscopic signatures that can be attributed to YSOs undergoing high states of accretion, such as veiling of photospheric features and CO emission, or show FUor-like spectra. We also find a large fraction of objects with 2.12 μm H2 emission that

  6. Active region flows

    NASA Technical Reports Server (NTRS)

    Foukal, Peter

    1987-01-01

    A wide range of observations has shown that active region phenomena in the photospheric, chromospheric and coronal temperature regimes are dynamical in nature. At the photosphere, recent observations of full line profiles place an upper limit of about + or - 20/msec on any downflows at supergranule cell edges. Observations of the full Stokes 5 profiles in the network show no evidence for downflows in magnetic flux tubes. In the area of chromospheric dynamics, several models were put forward recently to reproduce the observed behavior of spicules. However, it is pointed out that these adiabatic models do not include the powerful radiative dissipation which tend to damp out the large amplitude disturbances that produce the spicular acceleration in the models. In the corona, loop flows along field lines clearly transport mass and energy at rates important for the dynamics of these structures. However, advances in understanding the heating and mass balance of the loop structures seem to require new kinds of observations. Some results are presented using a remote sensing diagnostic of the intensity and orientation of macroscopic plasma electric fields predicted by models of reconnective heating and also wave heating.

  7. A search for Wolf-Rayet stars in active star forming regions of low mass galaxies - GR8, NGC 2366, IC 2574, and NGC 1569

    NASA Astrophysics Data System (ADS)

    Drissen, Laurent; Roy, Jean-Rene; Moffat, Anthony F. J.

    1993-10-01

    We report the detection, via narrow-band 4686 A filter imagery, of possible new Wolf-Rayet stars in the most massive giant H II regions of the irregular galaxies NGC 2366 and IC 2574. One stellar knot in the post-starburst galaxy NGC 1569 also appears to contain a weak excess of light at 4686 A. A similar search yielded negative results in the very low mass galaxy GR8. The strongest 4686 A excess is located close to the secondary eastern knot in the core of NGC 2366-I (NGC 2363). If this excess is of stellar origin, about five Wolf-Rayet stars of the luminous late-type can account for the excess emission. Nebular emission wraps around this cluster in the form of a shell. The putative Wolf-Rayet stars appear to be close to the center of the large expanding H II bubble discovered by Roy et al. (1991). A possible nebular origin of the 4686 A excess is also discussed.

  8. Elementary bipoles of active regions and ephemeral active regions

    NASA Technical Reports Server (NTRS)

    Martin, Sara F.

    1990-01-01

    The general properties of elementary bipoles (EBs), the class of moving magnetic features identified by Frazier (1972) as building blocks of new solar active regions, are described, and variations in their characteristics are illustrated with extensive videomagnetograms obtained at Big Bear Solar Observatory during 1984-1989. Consideration is given to ephemeral active regions consisting of EBs with only one positive and one negative pole, multiple-pole ephemeral regions, reversed-polarity EBs, interactions among EBs and adjacent magnetic features, and the EBs of small and medium active regions. The detection of EBs prior to the appearance of arch filaments confirms the relationship found by Frazier.

  9. Regional Activities Division. Papers.

    ERIC Educational Resources Information Center

    International Federation of Library Associations, The Hague (Netherlands).

    Papers on library network activities in Canada, the Third World, Japan, Malaysia, Brazil, and Sweden which were presented at the 1982 International Federation of Library Associations (IFLA) conference include: (1) "Canada: A Voluntary and Flexible Network," a review by Guy Sylvestre of the political, social, and economic structures…

  10. Regional Activities Division. Papers.

    ERIC Educational Resources Information Center

    International Federation of Library Associations, The Hague (Netherlands).

    Papers on library network activities in Canada, the Third World, Japan, Malaysia, Brazil, and Sweden which were presented at the 1982 International Federation of Library Associations (IFLA) conference include: (1) "Canada: A Voluntary and Flexible Network," a review by Guy Sylvestre of the political, social, and economic structures…

  11. Unexpected fireworks! Active region 808

    NASA Astrophysics Data System (ADS)

    Roberts, Harry

    2005-12-01

    The activity in 2005 September of the large sunspot group 10808 is discussed. This was the return of active region 10798 of the previous month. That such activity on the Sun continued despite the proximity of Solar Minimum adds to the excitement and interest of these regions. Observations in hydrogen alpha light enable detailed phenomenon to be followed both on and off the Sun's disc.

  12. Silicon on insulator with active buried regions

    DOEpatents

    McCarthy, Anthony M.

    1996-01-01

    A method for forming patterned buried components, such as collectors, sources and drains, in silicon-on-insulator (SOI) devices. The method is carried out by epitaxially growing a suitable sequence of single or multiple etch stop layers ending with a thin silicon layer on a silicon substrate, masking the silicon such that the desired pattern is exposed, introducing dopant and activating in the thin silicon layer to form doped regions. Then, bonding the silicon layer to an insulator substrate, and removing the silicon substrate. The method additionally involves forming electrical contact regions in the thin silicon layer for the buried collectors.

  13. Silicon on insulator with active buried regions

    DOEpatents

    McCarthy, Anthony M.

    1998-06-02

    A method for forming patterned buried components, such as collectors, sources and drains, in silicon-on-insulator (SOI) devices. The method is carried out by epitaxially growing a suitable sequence of single or multiple etch stop layers ending with a thin silicon layer on a silicon substrate, masking the silicon such that the desired pattern is exposed, introducing dopant and activating in the thin silicon layer to form doped regions. Then, bonding the silicon layer to an insulator substrate, and removing the silicon substrate. The method additionally involves forming electrical contact regions in the thin silicon layer for the buried collectors.

  14. Silicon on insulator with active buried regions

    DOEpatents

    McCarthy, A.M.

    1996-01-30

    A method is disclosed for forming patterned buried components, such as collectors, sources and drains, in silicon-on-insulator (SOI) devices. The method is carried out by epitaxially growing a suitable sequence of single or multiple etch stop layers ending with a thin silicon layer on a silicon substrate, masking the silicon such that the desired pattern is exposed, introducing dopant and activating in the thin silicon layer to form doped regions. Then, bonding the silicon layer to an insulator substrate, and removing the silicon substrate. The method additionally involves forming electrical contact regions in the thin silicon layer for the buried collectors. 10 figs.

  15. Silicon on insulator with active buried regions

    DOEpatents

    McCarthy, A.M.

    1998-06-02

    A method is disclosed for forming patterned buried components, such as collectors, sources and drains, in silicon-on-insulator (SOI) devices. The method is carried out by epitaxially growing a suitable sequence of single or multiple etch stop layers ending with a thin silicon layer on a silicon substrate, masking the silicon such that the desired pattern is exposed, introducing dopant and activating in the thin silicon layer to form doped regions. Then, bonding the silicon layer to an insulator substrate, and removing the silicon substrate. The method additionally involves forming electrical contact regions in the thin silicon layer for the buried collectors. 10 figs.

  16. Evolution of active region outflows throughout an active region lifetime

    NASA Astrophysics Data System (ADS)

    Zangrilli, L.; Poletto, G.

    2016-10-01

    Context. We have shown previously that SOHO/UVCS data allow us to detect active region (AR) outflows at coronal altitudes higher than those reached by other instrumentation. These outflows are thought to be a component of the slow solar wind. Aims: Our purpose is to study the evolution of the outflows in the intermediate corona from AR 8100, from the time the AR first forms until it dissolves, after several transits at the solar limb. Methods: Data acquired by SOHO/UVCS at the time of the AR limb transits, at medium latitudes and at altitudes ranging from 1.5 to 2.3 R⊙, were used to infer the physical properties of the outflows through the AR evolution. To this end, we applied the Doppler dimming technique to UVCS spectra. These spectra include the H i Lyα line and the O vi doublet lines at 1031.9 and 1037.6 Å. Results: Plasma speeds and electron densities of the outflows were inferred over several rotations of the Sun. AR outflows are present in the newly born AR and persist throughout the entire AR life. Moreover, we found two types of outflows at different latitudes, both possibly originating in the same negative polarity area of the AR. We also analyzed the behavior of the Si xii 520 Å line along the UVCS slit in an attempt to reveal changes in the Si abundance when different regions are traversed. Although we found some evidence for a Si enrichment in the AR outflows, alternative interpretations are also plausible. Conclusions: Our results demonstrate that outflows from ARs are detectable in the intermediate corona throughout the whole AR lifetime. This confirms that outflows contribute to the slow wind.

  17. Active Region Release Two CMEs

    NASA Image and Video Library

    Solar material can be seen blowing off the sun in this video captured by NASA’s Solar Dynamics Observatory (SDO) on the night of Feb. 5, 2013. This active region on the sun sent out two coronal ...

  18. Region 8 NPDES Lagoon General Permit Notice of Intent Form

    EPA Pesticide Factsheets

    Adobe Acrobat fillable form of the Notice of Intent for Coverage under the EPA Region 8 Lagoon General Permit for Wastewater Systems located in Indian Country in Colorado, Montana, North Dakota, South Dakota, Utah and Wyoming.

  19. Heavily Obscured Star-Forming Regions in the LVL Galaxies

    NASA Astrophysics Data System (ADS)

    Dale, Daniel A.; Aller, K.; Staudaher, S.

    2009-01-01

    We use data from the Spitzer Local Volume Legacy to study the infrared and optical properties of star forming regions in galaxies on 300pc scales. Our main goal is to determine the fraction of heavily-obscured star-forming regions. Here we study 908 regions within 55 galaxies. The median attenuation in Hα is 0.69 mag, and only a small fraction is highly obscured (Aα> 2). There is very little variation in the median attenuation over scales of 200pc to 1000pc.

  20. Hydrocarbons near the Cores of Massive Star-Forming Regions

    NASA Astrophysics Data System (ADS)

    Jiang, Xue-Jian

    2015-08-01

    Chemical models suggest that the reduced abundance of the abundant molecular species C2H can be the signpost of the heated molecular gas in the ˜104 AU vicinity around embedded high-mass stars. High angular resolution observations of C2H and other simple hydrocanbons therefore may offer valuable diagnose of embedded star-forming activities. With the aid of single dish (Delingha, CSO, JCMT) and interferometric (SMA and CARMA) observations of C2H, C3H, HC3N, etc., and mm continuum emission towards a few OB cluster-forming regions AFGL 490, ON 1, W33 Main, and G10.6-0.4, which cover a broad range of bolometric luminosity (˜103-106 L⊙). We found that on large scales, the C2H line emission traces the dense molecular gas envelope. However, for all observed sources, the C2H emission peaks are offset by several times 104 AU from the 1.1 mm continuum emission peaks, at which the most luminous stars are located. The C2H hyperfine lines and the 1.1 mm continuum emission show that the C2H column density (and abundances) around the continuum peaks is lower than those in the ambient gas envelope. Our results support the theoretical prediction for centrally embedded ˜103-106 L⊙ OB star-forming cores, while future higher resolution observations, as well as comparison with elaborate chemical models are required to examine the behavior of hydrocarbons around the localized sites of high-mass star-formation.

  1. Proton Form Factors Measurements in the Time-Like Region

    SciTech Connect

    Anulli, F.; /Frascati

    2007-10-22

    I present an overview of the measurement of the proton form factors in the time-like region. BABAR has recently measured with great accuracy the e{sup +}e{sup -} {yields} p{bar p} reaction from production threshold up to an energy of {approx} 4.5 GeV, finding evidence for a ratio of the electric to magnetic form factor greater than unity, contrary to expectation. In agreement with previous measurements, BABAR confirmed the steep rise of the magnetic form factor close to the p{bar p} mass threshold, suggesting the possible presence of an under-threshold N{bar N} vector state. These and other open questions related to the nucleon form factors both in the time-like and space-like region, wait for more data with different experimental techniques to be possibly solved.

  2. SDO Sees Active Region Outbursts

    NASA Image and Video Library

    This close up video by NASA’s Solar Dynamics Observatory shows an active region near the right-hand edge of the sun’s disk, which erupted with at least a dozen minor events over a 30-hour period fr...

  3. Algodystrophy: complex regional pain syndrome and incomplete forms

    PubMed Central

    Giannotti, Stefano; Bottai, Vanna; Dell’Osso, Giacomo; Bugelli, Giulia; Celli, Fabio; Cazzella, Niki; Guido, Giulio

    2016-01-01

    Summary The algodystrophy, also known as complex regional pain syndrome (CRPS), is a painful disease characterized by erythema, edema, functional impairment, sensory and vasomotor disturbance. The diagnosis of CRPS is based solely on clinical signs and symptoms, and for exclusion compared to other forms of chronic pain. There is not a specific diagnostic procedure; careful clinical evaluation and additional test should lead to an accurate diagnosis. There are similar forms of chronic pain known as bone marrow edema syndrome, in which is absent the history of trauma or triggering events and the skin dystrophic changes and vasomotor alterations. These incomplete forms are self-limited, and surgical treatment is generally not needed. It is still controversial, if these forms represent a distinct self-limiting entity or an incomplete variant of CRPS. In painful unexplained conditions such as frozen shoulder, post-operative stiff shoulder or painful knee prosthesis, the algodystrophy, especially in its incomplete forms, could represent the cause. PMID:27252736

  4. Astronomers Discover New Star-Forming Regions in Milky Way

    NASA Astrophysics Data System (ADS)

    2010-05-01

    Astronomers studying the Milky Way have discovered a large number of previously-unknown regions where massive stars are being formed. Their discovery provides important new information about the structure of our home Galaxy and promises to yield new clues about the chemical composition of the Galaxy. "We can clearly relate the locations of these star-forming sites to the overall structure of the Galaxy. Further studies will allow us to better understand the process of star formation and to compare the chemical composition of such sites at widely different distances from the Galaxy's center," said Thomas Bania, of Boston University. Bania worked with Loren Anderson of the Astrophysical Laboratory of Marseille in France, Dana Balser of the National Radio Astronomy Observatory (NRAO), and Robert Rood of the University of Virginia. The scientists presented their findings to the American Astronomical Society's meeting in Miami, Florida. The star-forming regions the astronomers sought, called H II regions, are sites where hydrogen atoms are ionized, or stripped of their electrons, by the intense radiation of the massive, young stars. To find these regions hidden from visible-light detection by the Milky Way's gas and dust, the researchers used infrared and radio telescopes. "We found our targets by using the results of infrared surveys done with NASA's Spitzer Space Telescope and of surveys done with the National Science Foundation's (NSF) Very Large Array (VLA) radio telescope," Anderson said. "Objects that appear bright in both the Spitzer and VLA images we studied are good candidates for H II regions," he explained. The astronomers then used the NSF's giant Robert C. Byrd Green Bank Telescope (GBT) in West Virginia, an extremely sensitive radio telescope. With the GBT, they were able to detect specific radio frequencies emitted by electrons as they recombined with protons to form hydrogen. This evidence of recombination confirmed that the regions contained ionized

  5. Concerning ``A new form of optical activity''

    NASA Astrophysics Data System (ADS)

    Harris, Robert A.; McClain, Wm. M.

    1992-07-01

    We show that the "… new form of natural optical activity" of Hecht and Nafie is a special case of scattering phenomena predicted by a very general theorem. In addition, the "…new form…" is closely related to its well known elastic cousin.

  6. The 17 GHz active region number

    SciTech Connect

    Selhorst, C. L.; Pacini, A. A.; Costa, J. E. R.; Giménez de Castro, C. G.; Valio, A.; Shibasaki, K.

    2014-08-01

    We report the statistics of the number of active regions (NAR) observed at 17 GHz with the Nobeyama Radioheliograph between 1992, near the maximum of cycle 22, and 2013, which also includes the maximum of cycle 24, and we compare with other activity indexes. We find that NAR minima are shorter than those of the sunspot number (SSN) and radio flux at 10.7 cm (F10.7). This shorter NAR minima could reflect the presence of active regions generated by faint magnetic fields or spotless regions, which were a considerable fraction of the counted active regions. The ratio between the solar radio indexes F10.7/NAR shows a similar reduction during the two minima analyzed, which contrasts with the increase of the ratio of both radio indexes in relation to the SSN during the minimum of cycle 23-24. These results indicate that the radio indexes are more sensitive to weaker magnetic fields than those necessary to form sunspots, of the order of 1500 G. The analysis of the monthly averages of the active region brightness temperatures shows that its long-term variation mimics the solar cycle; however, due to the gyro-resonance emission, a great number of intense spikes are observed in the maximum temperature study. The decrease in the number of these spikes is also evident during the current cycle 24, a consequence of the sunspot magnetic field weakening in the last few years.

  7. Decay of Solar Active Regions

    NASA Technical Reports Server (NTRS)

    Hathaway, David H.; Choudhary, Debi Prasad

    2005-01-01

    We examine the record of sunspot group areas observed over a period of 100 years to determine the rate of decay of solar active regions. We exclude observations of groups when they are more than 60deg in longitude from the central meridian and only include data when at least three days of observations are available following the date of maximum area for a spot group's disk passage. This leaves data for some 24,000 observations of active region decay. We find that the decay rate is a constant 20 microHem/day for spots smaller than about 200 microHem (about the size of a supergranule). This decay rate increases linearly to about 90 microHem/day for spots with areas of 1000 microHem. We find no evidence for significant variations in active region decay from one solar cycle to another. However, we do find that the decay rate is slower at lower latitudes. This gives a slower decay rate during the declining phase of sunspot cycles.

  8. Decay of Solar Active Regions

    NASA Technical Reports Server (NTRS)

    Hathaway, David H.; Choudhary, Debi Prasad

    2005-01-01

    We examine the record of sunspot group areas observed over a period of 100 years to determine the rate of decay of solar active regions. We exclude observations of groups when they are more than 60deg in longitude from the central meridian and only include data when at least three days of observations are available following the date of maximum area for a spot group's disk passage. This leaves data for some 24,000 observations of active region decay. We find that the decay rate is a constant 20 microHem/day for spots smaller than about 200 microHem (about the size of a supergranule). This decay rate increases linearly to about 90 microHem/day for spots with areas of 1000 microHem. We find no evidence for significant variations in active region decay from one solar cycle to another. However, we do find that the decay rate is slower at lower latitudes. This gives a slower decay rate during the declining phase of sunspot cycles.

  9. Attention to form or surface properties modulates different regions of human occipitotemporal cortex.

    PubMed

    Cant, Jonathan S; Goodale, Melvyn A

    2007-03-01

    We carried out 2 functional magnetic resonance imaging experiments to investigate the cortical mechanisms underlying the contribution of form and surface properties to object recognition. In experiment 1, participants performed same-different judgments in separate blocks of trials on pairs of unfamiliar "nonsense" objects on the basis of their form, surface properties (i.e., both color and texture), or orientation. Attention to form activated the lateral occipital (LO) area, whereas attention to surface properties activated the collateral sulcus (CoS) and the inferior occipital gyrus (IOG). In experiment 2, participants were required to make same-different judgments on the basis of texture, color, or form. Again attention to form activated area LO, whereas attention to texture activated regions in the IOG and the CoS, as well as regions in the lingual sulcus and the inferior temporal sulcus. Within these last 4 regions, activation associated with texture was higher than activation associated with color. No color-specific cortical areas were identified in these regions, although parts of V1 and the cuneus yielded higher activation for color as opposed to texture. These results suggest that there are separate form and surface-property pathways in extrastriate cortex. The extraction of information about an object's color seems to occur relatively early in visual analysis as compared with the extraction of surface texture, perhaps because the latter requires more complex computations.

  10. Dynamical processes in star forming regions: feedback and turbulence generation

    NASA Astrophysics Data System (ADS)

    Bally, John

    The efficiency of star formation may be determined by feedback of energy and momentum from young stars. In massive star forming regions, feedback is dominated by massive star winds, soft-UV, and ionising radiation, and at late times by supernova explosions. Dynamical interactions between stars in compact groups can also make a significant contribution. As they age, the impacts of massive stars can influence star formation in adjacent regions at distances of tens to hundreds of parsecs, either by striping away the reservoirs from which stars form, or by compressing clouds to the point of gravitational instability. In regions which give birth only to intermediate and low mass stars, locally generated protostellar outflows and soft-UV, combined with the geometrically diluted impacts of relatively distant massive stars play varying roles in feedback and self-regulation. When only low mass stars are created in isolated regions or in environments shielded from the influence of massive stars, protostellar outflows and the chaotic interactions of small-N non-hierarchical groups remain the only viable agents for the self-regulation of star formation. I review the results of complete surveys of molecular clouds in the Perseus and Orion star forming regions intended to measure the impacts of protostellar outflows on cloud structure and motions. The decay of turbulent motions, self-gravity, and forcing by distant sources of energy, momentum, and radiation appear to dominate cloud structure and motions on large scales. However, protostellar outflows and localized radiation sources play increasingly important roles on scales smaller than a few parsecs. The interactions of large-scale and local forcing with dissipation may lead to low star formation efficiency and the birth of transient star clusters containing tens to hundreds of mostly low to intermediate mass stars. Observations show that even in massive OB associations, this may be the most common mode of star formation.

  11. The IRAS 08589-4714 star-forming region

    NASA Astrophysics Data System (ADS)

    Saldaño, H. P.; Vasquez, J.; Cappa, C. E.; Gómez, M.; Duronea, N.; Rubio, M.

    2017-04-01

    We present an analysis of the IRAS 08589-4714 star-forming region. This region harbors candidate young stellar objects identified in the WISE and Herschel images using color index criteria and spectral energy distributions (SEDs). The SEDs of some of the infrared sources and the 70 μm radial intensity profile of the brightest source are modeled using the DUSTY code. For these objects, we estimate the main parameters, which suggest that they are very young, massive and luminous objects at early stages of the formation process. We use the emission distribution in the infrared at 70 and 160 μm to estimate the dust temperature gradient. This suggests that the nearby massive starforming region RCW 38, located at ≈10 pc from the IRAS source position, may be contributing to the photodissociation of the molecular gas and to the heating of the interstellar dust in the environs of the IRAS source.

  12. Solar active region display system

    NASA Astrophysics Data System (ADS)

    Golightly, M.; Raben, V.; Weyland, M.

    2003-04-01

    The Solar Active Region Display System (SARDS) is a client-server application that automatically collects a wide range of solar data and displays it in a format easy for users to assimilate and interpret. Users can rapidly identify active regions of interest or concern from color-coded indicators that visually summarize each region's size, magnetic configuration, recent growth history, and recent flare and CME production. The active region information can be overlaid onto solar maps, multiple solar images, and solar difference images in orthographic, Mercator or cylindrical equidistant projections. Near real-time graphs display the GOES soft and hard x-ray flux, flare events, and daily F10.7 value as a function of time; color-coded indicators show current trends in soft x-ray flux, flare temperature, daily F10.7 flux, and x-ray flare occurrence. Through a separate window up to 4 real-time or static graphs can simultaneously display values of KP, AP, daily F10.7 flux, GOES soft and hard x-ray flux, GOES >10 and >100 MeV proton flux, and Thule neutron monitor count rate. Climatologic displays use color-valued cells to show F10.7 and AP values as a function of Carrington/Bartel's rotation sequences - this format allows users to detect recurrent patterns in solar and geomagnetic activity as well as variations in activity levels over multiple solar cycles. Users can customize many of the display and graph features; all displays can be printed or copied to the system's clipboard for "pasting" into other applications. The system obtains and stores space weather data and images from sources such as the NOAA Space Environment Center, NOAA National Geophysical Data Center, the joint ESA/NASA SOHO spacecraft, and the Kitt Peak National Solar Observatory, and can be extended to include other data series and image sources. Data and images retrieved from the system's database are converted to XML and transported from a central server using HTTP and SOAP protocols, allowing

  13. Pluto's elongated dark regions formed by the Charon-forming giant impact

    NASA Astrophysics Data System (ADS)

    Genda, Hidenori; Sekine, Yusuhito; Kamata, Shunichi; Funatsu, Taro

    2017-04-01

    The New Horizons spacecraft has found elongated dark areas in the equatorial region of Pluto, which were informally called "the Whale" or Cthulhu Region (Stern et al. 2015). Here we examine the possibility that the dark areas on Pluto were formed by thermal alterations and polymerization of interstellar volatiles caused by a Charon-forming giant impact. Pluto is one of the largest Kuiper belt objects, which is highly likely to contain various interstellar volatiles, including aldehyde and ammonia. The previous study (Cordy et al. 2011) shows that these interstellar volatiles are thermally polymerized in solutions at high temperatures, forming complex insoluble organic solids. Given the satellite-to-planet mass ratio, the Pluto-Charon system is suggested to be of a giant impact origin (Canup 2005). Impact-induced heating on Pluto could have converted these volatile into complex organic matter in solution near the surface, which may explain the presence of dark areas in the equatorial region of Pluto. Here, we produce complex organic matter for various temperatures by thermal polymerization of formaldehyde and ammonia in solutions. By measuring the UV-VIS absorption spectra of the produced organic matter, we found that the color of the solution changes to be dark if the temerature is above 50 degree C for months or more. This duration corresponds to the cooling timescale of a water pond with 500-km thickness. By using SPH code (Genda et al. 2015), we carried out many simulations of a giant impact, and we found that a molten hot pond with > 500-km thickness is formed around the equatorial region of Pluto by a Charon-forming giant impact, if the water/rock mixing mass ratio is less than 1 or if the pre-impact interior temperature is 150 K. Both the dark equatorial region and a Charon-sized moon are formed when the pre-impact Pluto is undifferentiated. To keep a rock-rich Pluto undifferentiated at time of the giant impact, Pluto may have been formed >100 Myrs after CAIs

  14. VLBA Helps Build New Picture of Star-Forming Regions

    NASA Astrophysics Data System (ADS)

    2007-01-01

    New, high-precision distance measurements by the National Science Foundation's Very Long Baseline Array (VLBA) radio telescope are providing a major advance for astronomers trying to understand how stars form. "A large improvement in measuring the distance to a young, still-forming star means a large improvement in measuring characteristics such as its mass and intrinsic brightness," said Laurent Loinard, of the National University of Mexico (UNAM). Loinard, Amy Mioduszewski of the National Radio Astronomy Observatory, UNAM graduate student Rosa Torres and UNAM professor Luis Rodriguez presented their findings to the American Astronomical Society's meeting in Seattle, Washington. Parallax Diagram Trigonometric Parallax method determines distance to star by measuring its slight shift in apparent position as seen from opposite ends of Earth's orbit. CREDIT: Bill Saxton, NRAO/AUI/NSF Image and Animation Files Parallax Diagram (above image, JPEG, 153K) Animation of apparant motion on sky of young star T Tauri S (MPEG, 891K) Still Frame from above animation (JPEG, 14K) B&W Plot of T Tauri S Parallax motion (JPEG, 51K) "Most of what we know about the processes of star formation has come from studying young stars in a few, relatively nearby regions," Loinard said. "However, estimates of the distance to these regions have been imprecise. That imprecision has limited the ability of real-world observations to improve theoretical models for star formation," he added. The new VLBA distance measurements are great improvements over earlier estimates. For example, earlier work placed a famous young stellar system in the constellation Taurus between 423 and 489 light-years from Earth. The new VLBA measurements narrow the range to 418-422 light-years. "Our observations brought the error in this measurement down from 66 light-years to four," Mioduszewski said. The new VLBA observations also refined the distance estimate to another star-forming region in the constellation Ophiuchus

  15. Planar H2O masers in star-forming regions

    NASA Technical Reports Server (NTRS)

    Elitzur, Moshe; Hollenbach, David J.; Mckee, Christopher F.

    1992-01-01

    The paper examines the planar geometry of shocked material, which is the key property in enabling the high brightness temperatures of H2O masers in star-forming regions. The brightness temperature, beaming angle, and the maser spot size are determined for thin, saturated planar masers under the assumption that the velocity change across the maser due to ordered motions is small compared with the thermal or microturbulent line width. For a given set of physical parameters, the brightness temperature is essentially fully determined by the length of the velocity-coherent region in the shocked plane along the line of sight. Effective aspect ratios (about 5-50) are found that are in agreement with values previously inferred from observed brightness temperatures.

  16. Planar H2O masers in star-forming regions

    NASA Technical Reports Server (NTRS)

    Elitzur, Moshe; Hollenbach, David J.; Mckee, Christopher F.

    1992-01-01

    The paper examines the planar geometry of shocked material, which is the key property in enabling the high brightness temperatures of H2O masers in star-forming regions. The brightness temperature, beaming angle, and the maser spot size are determined for thin, saturated planar masers under the assumption that the velocity change across the maser due to ordered motions is small compared with the thermal or microturbulent line width. For a given set of physical parameters, the brightness temperature is essentially fully determined by the length of the velocity-coherent region in the shocked plane along the line of sight. Effective aspect ratios (about 5-50) are found that are in agreement with values previously inferred from observed brightness temperatures.

  17. A STRUCTURAL ANALYSIS OF STAR-FORMING REGION AFGL 490

    SciTech Connect

    Masiunas, L. C.; Gutermuth, R. A.; Pipher, J. L.; Megeath, S. T.; Myers, P. C.; Kirk, H. M.; Fazio, G. G.; Allen, L. E.

    2012-06-20

    We present Spitzer IRAC and MIPS observations of the star-forming region containing intermediate-mass young stellar object (YSO) AFGL 490. We supplement these data with near-IR Two Micron All Sky Survey photometry and with deep Simultaneous Quad Infrared Imaging Device observations off the central high-extinction region. We have more than doubled the known membership of this region to 57 Class I and 303 Class II YSOs via the combined 1-24 {mu}m photometric catalog derived from these data. We construct and analyze the minimum spanning tree of their projected positions, isolating one locally overdense cluster core containing 219 YSOs (60.8% of the region's members). We find this cluster core to be larger yet less dense than similarly analyzed clusters. Although the structure of this cluster core appears irregular, we demonstrate that the parsec-scale surface densities of both YSOs and gas are correlated with a power-law slope of 2.8, as found for other similarly analyzed nearby molecular clouds. We also explore the mass segregation implications of AFGL 490's offset from the center of its core, finding that it has no apparent preferential central position relative to the low-mass members.

  18. The Gas to Dust Ratio in Three Star Forming Regions

    NASA Astrophysics Data System (ADS)

    Lv, Z. P.; Jiang, B. W.; Li, J.

    2017-03-01

    Gas to Dust Ratio (GDR) is the mass ratio of interstellar gas to dust. It is widely adopted that gas to dust mass ratio in our Galaxy has a value of about 100-150. We choose three typical star forming regions to study gas to dust ratio: the Orion molecular cloud -- a massive star forming region, the Taurus molecular cloud -- a low-mass star forming region, and the Polaris molecular cloud -- little or no star forming region. The mass of gas only takes into account the neutral gas because the amount of ionized gas is very small in molecular clouds, i.e. only atomic and molecular hydrogen. The column density of hydrogen is taken from the high-resolution, high-sensitivity all-sky survey EBHIS (Effelsberg-Bonn HI survey). The CO J=1→0 line is used to trace the molecular hydrogen, since the spectral lines of molecular hydrogen which can be detected are rare. The intensity of CO J=1→0 line is taken from the Planck all-sky survey. The mass of dust is traced by interstellar extinction based on the 2MASS (Two Micron All Sky Survey) photometric database in the direction of anti-Galactic center. Adopting a constant conversion coefficient from the integrated intensity of CO line to the column density of molecular hydrogen, X_{CO}=2.0×10^{20} cm^{-2}\\cdot (K \\cdot km/s)^{-1}, the gas to dust ratio N(H)/A_{V} is calculated, which is 25×10^{20}, 38×10^{20}, and 55×10^{20} cm^{-2}\\cdot mag^{-1} for Orion, Taurus, and Polaris molecular clouds, respectively. These values are significantly higher than previously obtained for the average situation of the Galaxy. Adopting the interstellar dust model with the ratio of total to selective extinction at V R_{V}=3.1 by WD01, the derived gas to dust mass ratio is 160, 243, and 354 for the Orion, Taurus, and Polaris molecular clouds, respectively, which is apparently higher than 100-150 for the diffuse interstellar medium. On the other hand, the high N(H)/A_{V} value may be explained by the growth of dust in molecular clouds because

  19. Molecular line tracers of high-mass star forming regions

    NASA Astrophysics Data System (ADS)

    Nagy, Zsofia

    2013-09-01

    High-mass stars influence their environment in different ways including feedback via their far-UV radiation and mechanical feedback via shocks and stellar winds. The penetration of FUV photons into molecular clouds creates Photon Dominated Regions (PDRs) with different chemical layers where the mainly ionized medium changes into mainly molecular. Different chemical layers in PDRs are traced by different species observable at sub-mm and far-infrared wavelengths. In this thesis we present results from two molecular line surveys. One of them is the James Clerk Maxwell Telescope (JCMT) Spectral Legacy Survey (SLS) toward the luminous (>10^7 L_Sun), massive (~10^6 M_Sun), and distant (11.4 kpc) star-forming region W49A. The SLS images a 2x2 arcminute field around W49A in the 330-373 GHz frequency range. The detected molecular lines reveal a complex chemistry and the importance of FUV-irradiation and shocks in the heating and chemistry of the region. The other line survey presented in this thesis is part of the HEXOS (Herschel observations of EXtra-Ordinary Sources) key program using the Herschel Space Observatory and is toward the nearby (~420 pc) prototypical edge-on Orion Bar PDR and the dense molecular condensation Orion S. Reactive ions, such as CH+, SH+, and CO+, detected as a part of this line survey trace the warm (~500-1000 K) surface region of PDRs. Spectroscopic data from the HIFI and PACS instruments of Herschel give constraints on the chemistry and excitation of reactive ions in these regions.

  20. Looking Closely at "Medusa": Star Forming Regions in NGC 4194

    NASA Technical Reports Server (NTRS)

    Weistrop, D.; Eggers, D.; Nelson, C. H.; Kaiser, M. E.

    2004-01-01

    The "Medusa" (NGC 4194, Mrk 201) is a blue compact galaxy, with strong far infrared and radio emission. Ground-based observations exhibit a distorted image with a tidal tail and regions of strong star formation. A population of massive O and early B stars is evident from the IUE spectra HST survey of Seyfert and starburst galaxies notes NCG 4194 is an HII galaxy with lumpy HII regions and knots. The central starburst is apparently produced by a galaxy merger. As part of an investigation of star formation in interacting galaxies, we have obtained ultraviolet and visible images of the central regions of NGC 4194 with the Space Telescope Imaging Spectrograph on HST. Imaging was obtained in two ultraviolet (FUV-MAMA+F25QTZ, NUV-MAMA+F25CN182) and one visible (CCD+F28X50LP) band. Individual star forming knots (at HST resolution) have been identified. We present sized and luminosities for the individual knots, and the knot luminosity function. We compare our data to current starburst models to constrain stellar ages and populations. Knot characteristics as a function of location in the galaxy will also be discussed.

  1. Looking Closely at "Medusa": Star Forming Regions in NGC 4194

    NASA Technical Reports Server (NTRS)

    Weistrop, D.; Eggers, D.; Nelson, C. H.; Kaiser, M. E.

    2004-01-01

    The "Medusa" (NGC 4194, Mrk 201) is a blue compact galaxy, with strong far infrared and radio emission. Ground-based observations exhibit a distorted image with a tidal tail and regions of strong star formation. A population of massive O and early B stars is evident from the IUE spectra HST survey of Seyfert and starburst galaxies notes NCG 4194 is an HII galaxy with lumpy HII regions and knots. The central starburst is apparently produced by a galaxy merger. As part of an investigation of star formation in interacting galaxies, we have obtained ultraviolet and visible images of the central regions of NGC 4194 with the Space Telescope Imaging Spectrograph on HST. Imaging was obtained in two ultraviolet (FUV-MAMA+F25QTZ, NUV-MAMA+F25CN182) and one visible (CCD+F28X50LP) band. Individual star forming knots (at HST resolution) have been identified. We present sized and luminosities for the individual knots, and the knot luminosity function. We compare our data to current starburst models to constrain stellar ages and populations. Knot characteristics as a function of location in the galaxy will also be discussed.

  2. Solar active region magnetic complexity

    NASA Astrophysics Data System (ADS)

    Nikbakhsh, Shabnam; Tanskanen, Eija; Hackman, Thomas

    2017-04-01

    We have studied the Mount Wilson Classification of solar Active Regions (ARs) for the period from 1996 to 2015. Sunspots are visual indicators of ARs where the solar magnetic field is disturbed. Major manifestations of solar magnetic activity, such as solar flares and Coronal Mass Ejections (CMEs), are associated with solar ARs. There has been so many attempts to classify solar ARs based on their magnetic complexity as a measure of their acitivity. For this study we applied the Mount Wilson Classification which groups ARs in terms of their magnetic complexity from the least complex alpha to the most complex one beta-gamma-delta. We compared the magnetic complexity data to two sets of sunspot number: 1- International Sunspot Number (ISSN) 2- NOAA sunspot number We have been found that the number of more complex structures reach its maximum two years after solar maximum. We also compared the result to our identified geomagnetic storm list. The results showed the more complex ARs are responsible for the strongest geomagnetic storms.

  3. Technique for inferring sizes of stellar-active regions

    SciTech Connect

    Dobson-Hockey, A.K.; Radick, R.R.

    1986-01-01

    Inspection of spectroheliograms showing large, well-developed active regions generally show the sunspots to lead the associated plage, in the sense of the solar rotation. Measurements have been made from spectroheliograms of spot-plage offsets and compared with nearly contemporaneous integrated disk observations. Larger active regions generally show larger spot leads; however, information regarding active-region sizes and spot-plage offsets is not readily obtainable form stellar-type observations of the Sun.

  4. VLBA Changes Picture of Famous Star-Forming Region

    NASA Astrophysics Data System (ADS)

    2007-10-01

    Using the supersharp radio "vision" of the National Science Foundation's Very Long Baseline Array (VLBA), astronomers have made the most precise measurement ever of the distance to a famous star-forming region. The measurement -- to the heavily studied Orion Nebula -- changes scientists' understanding of the characteristics of the young stars in the region. Parallax Diagram Trigonometric Parallax method determines distance to star by measuring its slight shift in apparent position as seen from opposite ends of Earth's orbit. CREDIT: Bill Saxton, NRAO/AUI/NSF Star Track Apparent track of star GMR A in the Orion Nebula Cluster, showing shift caused by Earth's orbital motion and star's movement in space. CREDIT: Sandstrom et al., NRAO/AUI/NSF Click on Images for Larger Files "This measurement is four times more precise than previous distance estimates. Because our measurement reduces the distance to this region, it tells us that the stars there are less bright than thought before, and changes the estimates of their ages," said Geoff Bower, an astronomer at the University of California at Berkeley. Bower, along with Karin Sandstrom, J.E.G. Peek, Alberto Bolatto and Richard Plambeck, all of Berkeley, published their findings in the October 10 edition of the Astrophysical Journal. The scientists determined the distance to a star called GMR A, one of a cluster of stars in the Orion Nebula, by measuring the slight shift in the star's apparent position in the sky caused by the Earth's motion around the Sun. Observing the star when the Earth is on opposite sides of its annual orbit allows astronomers to measure the angle of this small shift and thus provides a direct trigonometric calculation of its distance. "By using this technique, called parallax, we get a direct measurement that does not depend on various assumptions that are required to use less-direct methods," Bower said. "Only a telescope with the remarkable ability to see fine detail that is provided by the VLBA is

  5. VLA 7-mm Observations of Massive Star-forming Regions

    NASA Astrophysics Data System (ADS)

    Linz, Hendrik; Hofner, Peter; Araya, Esteban; Stecklum, Bringfried

    2003-07-01

    The early stages during the formation of massive stars are deeply enshrouded due to the presence of dense and dusty natal material. This prevents observations in the optical and often also in the near-infrared. The emission of the star-forming regions peaks in the far-infrared and sub-mm regime, but at these wavelengths, single-dish observations are restricted in spatial resolution and can give only upper limits on the energetics of the objects of interest. Interferometry at mm wavelengths is one appropriate technique to overcome these limitations. We have started an extensive programme to observe pre-selected massive star-forming regions. Our tool is the VLA and its 7-mm receiver system. The VLA can be operated in several antenna configurations delivering resolutions from 1.5 arcsec down to 0.05 arcsec, which is superior to other current mm-interferometers. Sub-arcsec resolution is strongly needed to disentangle the often crowded regions of high-mass star formation and to clearly separate our objects of interest from the adjacent ultracompact HII regions. At 7 mm we are on the save ground of the Rayleigh-Jeans limit even for emission of cold dust (a fact that is not always true for observations at smaller wavelengths). Almost all circumstellar density configurations are optically thin at 7 mm, thus, the observations will trace the total dust content. However, at 7 mm also the free-free emission from ionised gas (caused by the UV emission of the young massive stars) can contribute to the observed signal. Therefore, we have to identify and remove these "parasitic" constituents by extrapolating interferometric data obtained at cm-wavelengths. The targets are either taken from the list of Molinari (Molinari et al. 2000, A&A, 355, 617) or are well-known massive star-forming complexes, for which we have already acquired additional data at other wavelengths. We have started with observations at lower and medium resolution (1.5 - 0.5 arcsec) to distinguish candidates for

  6. Abundances of hydrogen sulfide in star-forming regions

    NASA Technical Reports Server (NTRS)

    Minh, Y. C.; Ziurys, L. M.; Irvine, W. M.; Mcgonagle, D.

    1991-01-01

    Interstellar H2S and its isotopic variant H2(S-34) have been observed toward several star-forming regions via their 1(10)-1(01) transitions at 2 mm, using the FCRAO telescope. In sources where both isotopic species were observed, column densities of about 10 to the 16th/sq cm were measured. Column density lower limits of about 10 to the 14th/sq cm for H2S were found for other sources, where only the main isotopic line was observed. The fractional abundances of H2S relative to molecular hydrogen appear to be enhanced by at least an order of magnitude relative to quiescent cloud values (about 10 to the -9th) for many of the observed sources.

  7. Abundances of hydrogen sulfide in star-forming regions

    NASA Technical Reports Server (NTRS)

    Minh, Y. C.; Ziurys, L. M.; Irvine, W. M.; Mcgonagle, D.

    1991-01-01

    Interstellar H2S and its isotopic variant H2(S-34) have been observed toward several star-forming regions via their 1(10)-1(01) transitions at 2 mm, using the FCRAO telescope. In sources where both isotopic species were observed, column densities of about 10 to the 16th/sq cm were measured. Column density lower limits of about 10 to the 14th/sq cm for H2S were found for other sources, where only the main isotopic line was observed. The fractional abundances of H2S relative to molecular hydrogen appear to be enhanced by at least an order of magnitude relative to quiescent cloud values (about 10 to the -9th) for many of the observed sources.

  8. Chemical Herschel Surveys of Star Forming Regions (chess)

    NASA Astrophysics Data System (ADS)

    Emprechtinger, Martin

    2011-06-01

    CHESS is an unbiased line survey of low-, intermediate-, and high-mass star forming regions at different stages of their evolution. The eight sources in the CHESS program are observed with the HIFI instrument on board of the Herschel Space Telescope, which provides a high spectral resolution (R˜ 10^6) and covers a frequency range from 480 to 1910 GHz. The objective of CHESS is to study the chemical composition and physical conditions in star forming regions and their variation with mass and evolutionary stage. To date about 50% of the program have been completed. One of the eight objects in the CHESS program is the hot core NGC 6334 I. With an envelope mass of 200 M_⊙ and temperatures 100 K, NGC 6334 I is very line rich. In this object emission lines of more than 40 species have been identified, including first detections of H_2Cl^+ (Lis et al. 2010) and H_2O^+ (Ossenkopf et al. 2010). Furthermore, several lines of ortho and para water and ammonia have been detected, allowing to determine the ortho/para ratio of these crucial species. In addition many hydrides (HF, CH) and hydride ions (SH^+, OH^+, CH^+) have been found. In the low mass protostar IRAS 16293-2422, another source of our sample, several deuterated species, including the first detection of ND (Bacmann et al. 2010), were found. The data allowed also the first determination of the ortho/para ratio of D_2H^+ (>2.6) (Vastel et al. 2010). In this talk I will give a summary of the conducted observation and highlight the most important results.

  9. HUBBLE'S PANORAMIC PORTRAIT OF A VAST STAR-FORMING REGION

    NASA Technical Reports Server (NTRS)

    2002-01-01

    NASA's Hubble Space Telescope has snapped a panoramic portrait of a vast, sculpted landscape of gas and dust where thousands of stars are being born. This fertile star-forming region, called the 30 Doradus Nebula, has a sparkling stellar centerpiece: the most spectacular cluster of massive stars in our cosmic neighborhood of about 25 galaxies. The mosaic picture shows that ultraviolet radiation and high-speed material unleashed by the stars in the cluster, called R136 [the large blue blob left of center], are weaving a tapestry of creation and destruction, triggering the collapse of looming gas and dust clouds and forming pillar-like structures that are incubators for nascent stars. The photo offers an unprecedented, detailed view of the entire inner region of 30 Doradus, measuring 200 light-years wide by 150 light-years high. The nebula resides in the Large Magellanic Cloud (a satellite galaxy of the Milky Way), 170,000 light-years from Earth. Nebulas like 30 Doradus are the 'signposts' of recent star birth. High-energy ultraviolet radiation from the young, hot, massive stars in R136 causes the surrounding gaseous material to glow. Previous Hubble telescope observations showed that R136 contains several dozen of the most massive stars known, each about 100 times the mass of the Sun and about 10 times as hot. These stellar behemoths all formed at the same time about 2 million years ago. The stars in R136 are producing intense 'stellar winds' (streams of material traveling at several million miles an hour), which are wreaking havoc on the gas and dust in the surrounding neighborhood. The winds are pushing the gas away from the cluster and compressing the inner regions of the surrounding gas and dust clouds [the pinkish material]. The intense pressure is triggering the collapse of parts of the clouds, producing a new generation of star formation around the central cluster. The new stellar nursery is about 30 to 50 light-years from R136. Most of the stars in the

  10. HUBBLE'S PANORAMIC PORTRAIT OF A VAST STAR-FORMING REGION

    NASA Technical Reports Server (NTRS)

    2002-01-01

    NASA's Hubble Space Telescope has snapped a panoramic portrait of a vast, sculpted landscape of gas and dust where thousands of stars are being born. This fertile star-forming region, called the 30 Doradus Nebula, has a sparkling stellar centerpiece: the most spectacular cluster of massive stars in our cosmic neighborhood of about 25 galaxies. The mosaic picture shows that ultraviolet radiation and high-speed material unleashed by the stars in the cluster, called R136 [the large blue blob left of center], are weaving a tapestry of creation and destruction, triggering the collapse of looming gas and dust clouds and forming pillar-like structures that are incubators for nascent stars. The photo offers an unprecedented, detailed view of the entire inner region of 30 Doradus, measuring 200 light-years wide by 150 light-years high. The nebula resides in the Large Magellanic Cloud (a satellite galaxy of the Milky Way), 170,000 light-years from Earth. Nebulas like 30 Doradus are the 'signposts' of recent star birth. High-energy ultraviolet radiation from the young, hot, massive stars in R136 causes the surrounding gaseous material to glow. Previous Hubble telescope observations showed that R136 contains several dozen of the most massive stars known, each about 100 times the mass of the Sun and about 10 times as hot. These stellar behemoths all formed at the same time about 2 million years ago. The stars in R136 are producing intense 'stellar winds' (streams of material traveling at several million miles an hour), which are wreaking havoc on the gas and dust in the surrounding neighborhood. The winds are pushing the gas away from the cluster and compressing the inner regions of the surrounding gas and dust clouds [the pinkish material]. The intense pressure is triggering the collapse of parts of the clouds, producing a new generation of star formation around the central cluster. The new stellar nursery is about 30 to 50 light-years from R136. Most of the stars in the

  11. Magnetic fields in star-forming regions - Observations

    NASA Technical Reports Server (NTRS)

    Heiles, Carl; Goodman, Alyssa A.; Mckee, Christopher F.; Zweibel, Ellen G.

    1993-01-01

    We review the observational aspects of magnetic fields in dense, star-forming regions. First we discuss ways to observe the field. These include direct methods, which consist of the measurement of both linear and circular polarization of spectral line and continuum radiation; and indirect methods, consisting of the angular distribution of H2O masers on the sky and the measurement of ambipolar diffusion. Next we discuss selected observational results, focusing on detailed discussions of a small number of points rather than a generalized discussion that covers the waterfront. We discuss the Orion/BN-KL region in detail, both on the small and large scales. Next we discuss the derivation of the complete magnetic vector, including both the systematic and fluctuating component, from a large sample of Zeeman and linear polarization measurements for the L204 dark cloud. We examine the virial theorem as it applies to dark clouds in general and one dark cloud, Barnard 1, in particular. We critically discuss the numerous claims for alignment of cloud structural features with the plane-of-the-sky component of the magnetic field, and find that many of these have not been definitively established.

  12. Magnetic fields in star-forming regions - Observations

    NASA Technical Reports Server (NTRS)

    Heiles, Carl; Goodman, Alyssa A.; Mckee, Christopher F.; Zweibel, Ellen G.

    1993-01-01

    We review the observational aspects of magnetic fields in dense, star-forming regions. First we discuss ways to observe the field. These include direct methods, which consist of the measurement of both linear and circular polarization of spectral line and continuum radiation; and indirect methods, consisting of the angular distribution of H2O masers on the sky and the measurement of ambipolar diffusion. Next we discuss selected observational results, focusing on detailed discussions of a small number of points rather than a generalized discussion that covers the waterfront. We discuss the Orion/BN-KL region in detail, both on the small and large scales. Next we discuss the derivation of the complete magnetic vector, including both the systematic and fluctuating component, from a large sample of Zeeman and linear polarization measurements for the L204 dark cloud. We examine the virial theorem as it applies to dark clouds in general and one dark cloud, Barnard 1, in particular. We critically discuss the numerous claims for alignment of cloud structural features with the plane-of-the-sky component of the magnetic field, and find that many of these have not been definitively established.

  13. On the distance to the Ophiuchus star-forming region

    NASA Astrophysics Data System (ADS)

    Mamajek, E. E.

    2008-01-01

    The Ophiuchus molecular cloud complex has produced in Lynds 1688 the richest known embedded cluster within ˜300 pc of the Sun. Unfortunately, distance estimates to the Oph complex vary by nearly ˜40% (˜120-165 pc). Here I calculate a new independent distance estimate of 135 ± 8 pc to this benchmark star-forming region based on Hipparcos trigonometric parallaxes to stars illuminating reflection nebulosity in close proximity to Lynds 1688. Combining this value with recent distance estimates from reddening studies suggests a consensus distance of 139 ± 6 pc (4% error), situating it within ˜11 pc of the centroid of the ˜5 Myr old Upper Sco OB subgroup of Sco OB2 (145 pc). The velocity vectors for Oph and Upper Sco are statistically indistinguishable within ˜1 km s-1 in each vector component. Both Oph and Upper Sco have negligible motion (<1 km s-1) in the Galactic vertical direction with respect to the Local Standard of Rest, which is inconsistent with the young stellar groups having formed via the high velocity cloud impact scenario.

  14. Locating star-forming regions in quasar host galaxies

    NASA Astrophysics Data System (ADS)

    Young, J. E.; Eracleous, M.; Shemmer, O.; Netzer, H.; Gronwall, C.; Lutz, Dieter; Ciardullo, R.; Sturm, Eckhard

    2014-02-01

    We present a study of the morphology and intensity of star formation in the host galaxies of eight Palomar-Green quasars using observations with the Hubble Space Telescope. Our observations are motivated by recent evidence for a close relationship between black hole growth and the stellar mass evolution in its host galaxy. We use narrow-band [O II]λ3727, Hβ, [O III]λ5007 and Paα images, taken with the Wide Field Planetary Camera 2 and NICMOS instruments, to map the morphology of line-emitting regions, and, after extinction corrections, diagnose the excitation mechanism and infer star-formation rates. Significant challenges in this type of work are the separation of the quasar light from the stellar continuum and the quasar-excited gas from the star-forming regions. To this end, we present a novel technique for image decomposition and subtraction of quasar light. Our primary result is the detection of extended line-emitting regions with sizes ranging from 0.5 to 5 kpc and distributed symmetrically around the nucleus, powered primarily by star formation. We determine star-formation rates of the order of a few tens of M⊙ yr-1. The host galaxies of our target quasars have stellar masses of the order of 1011 M⊙ and specific star-formation rates on a par with those of M82 and luminous infrared galaxies. As such they fall at the upper envelope or just above the star-formation mass sequence in the specific star formation versus stellar mass diagram. We see a clear trend of increasing star-formation rate with quasar luminosity, reinforcing the link between the growth of the stellar mass of the host and the black hole mass found by other authors.

  15. Modelling of Deuterium Chemistry in Star-Forming Regions

    NASA Astrophysics Data System (ADS)

    Roberts, Helen

    2005-08-01

    Several new multiply deuterated species have been detected over the past three years, including ND3 (van der Tak et al. 2002; Lis et al. 2002), CHD2OH, CD3OH (Parise et al. 2002, 2004), D2S (Vastel et al. 2003), HD2+ (Vastel et al. 2004) and D2CS (Marcelino et al. 2005). In addition, mono-deuterated species have been observed with abundances >10% of their un-deuterated analogues (e.g. CH2DOH observed by Parise et al. 2002; NH2D observed by Saito et al. 2000 and Hatchell 2003). These are remarkable results, given that the underlying abundance of deuterium in the local interstellar medium (ISM) is ˜10-5 times lower than that of hydrogen (Linsky 1998; Sonneborn et al. 2000).Such large enhancements in the abundances of deuterium-bearing molecules can either be due to gas-phase or to grain-surface fractionation. Grain-surface reactions are undoubtedly important in producing saturated species such as methanol, water, ammonia, and hydrogen sulphide. Water ice is observed to be abundant and ubiquitous throughout the ISM, and enhanced abundances of gas-phase NH3, CH3OH, H2CO and H2S (among others) are observed in warmer regions around protostars where grain mantles have evaporated.Recent observational and theoretical evidence suggests that the deuterium fractionation in star-forming regions is set by gas-phase and grain-surface reactions during the cold, dense pre-protostellar phase. For species which form on grain surfaces via H atom addition to CO, N, O and S, the deuterium fractionation on grains comes from the relative amounts of atomic D and H which are accreting from the gas. The observations of deuterated methanol and D2S require that the gas-phase atomic D/H ratio at the time the molecules formed was ≥ 0.1.This paper presents results from chemical models of the prestellar core phase of star formation, showing how this high atomic D/H ratio can be produced, and discusses how models can also be used to look at deuterium fractionation in the protostellar stages of

  16. Emission measure distribution for diffuse regions in solar active regions

    SciTech Connect

    Subramanian, Srividya; Tripathi, Durgesh; Klimchuk, James A.; Mason, Helen E.

    2014-11-01

    Our knowledge of the diffuse emission that encompasses active regions is very limited. In this paper we investigate two off-limb active regions, namely, AR 10939 and AR 10961, to probe the underlying heating mechanisms. For this purpose, we have used spectral observations from Hinode/EIS and employed the emission measure (EM) technique to obtain the thermal structure of these diffuse regions. Our results show that the characteristic EM distributions of the diffuse emission regions peak at log T = 6.25 and the coolward slopes are in the range 1.4-3.3. This suggests that both low- as well as high-frequency nanoflare heating events are at work. Our results provide additional constraints on the properties of these diffuse emission regions and their contribution to the background/foreground when active region cores are observed on-disk.

  17. Feature-oriented regional modeling and simulations (FORMS) for the western South Atlantic: Southeastern Brazil region

    NASA Astrophysics Data System (ADS)

    Calado, L.; Gangopadhyay, A.; da Silveira, I. C. A.

    The multi-scale synoptic circulation system in the southeastern Brazil (SEBRA) region is presented using a feature-oriented approach. Prevalent synoptic circulation structures, or "features," are identified from previous observational studies. These features include the southward-flowing Brazil Current (BC), the eddies off Cabo São Tomé (CST - 22°S) and off Cabo Frio (CF - 23°S), and the upwelling region off CF and CST. Their synoptic water-mass ( T- S) structures are characterized and parameterized to develop temperature-salinity ( T- S) feature models. Following [Gangopadhyay, A., Robinson, A.R., Haley, P.J., Leslie, W.J., Lozano, C.J., Bisagni, J., Yu, Z., 2003. Feature-oriented regional modeling and simulation (forms) in the gulf of maine and georges bank. Cont. Shelf Res. 23 (3-4), 317-353] methodology, a synoptic initialization scheme for feature-oriented regional modeling and simulation (FORMS) of the circulation in this region is then developed. First, the temperature and salinity feature-model profiles are placed on a regional circulation template and objectively analyzed with available background climatology in the deep region. These initialization fields are then used for dynamical simulations via the Princeton Ocean Model (POM). A few first applications of this methodology are presented in this paper. These include the BC meandering, the BC-eddy interaction and the meander-eddy-upwelling system (MEUS) simulations. Preliminary validation results include realistic wave-growth and eddy formation and sustained upwelling. Our future plan includes the application of these feature models with satellite, in-situ data and advanced data-assimilation schemes for nowcasting and forecasting the SEBRA region.

  18. THE DISK POPULATION OF THE TAURUS STAR-FORMING REGION

    SciTech Connect

    Luhman, K. L.; Allen, P. R.; Espaillat, C.; Hartmann, L.; Calvet, N.

    2010-01-01

    We have analyzed nearly all images of the Taurus star-forming region at 3.6, 4.5, 5.8, 8.0, and 24 {mu}m that were obtained during the cryogenic mission of the Spitzer Space Telescope (46 deg{sup 2}) and have measured photometry for all known members of the region that are within these data, corresponding to 348 sources, or 99% of the known stellar population. By combining these measurements with previous observations with the Spitzer Infrared Spectrograph and other facilities, we have classified the members of Taurus according to whether they show evidence of circumstellar disks and envelopes (classes I, II, and III). Through these classifications, we find that the disk fraction in Taurus, N(II)/N(II+III), is {approx}75% for solar-mass stars and declines to {approx}45% for low-mass stars and brown dwarfs (0.01-0.3 M {sub sun}). This dependence on stellar mass is similar to that measured for Chamaeleon I, although the disk fraction in Taurus is slightly higher overall, probably because of its younger age (1 Myr versus 2-3 Myr). In comparison, the disk fraction for solar-mass stars is much lower ({approx}20%) in IC 348 and {sigma} Ori, which are denser than Taurus and Chamaeleon I and are roughly coeval with the latter. These data indicate that disk lifetimes for solar-mass stars are longer in star-forming regions that have lower stellar densities. Through an analysis of multiple epochs of Spitzer photometry that are available for {approx}200 Taurus members, we find that stars with disks exhibit significantly greater mid-infrared (mid-IR) variability than diskless stars, which agrees with the results of similar variability measurements for a smaller sample of stars in Chamaeleon I. The variability fraction for stars with disks is higher in Taurus than in Chamaeleon I, indicating that the IR variability of disks decreases with age. Finally, we have used our data in Taurus to refine the observational criteria for primordial, evolved, and transitional disks. The ratio

  19. Preferential Pathway for Glycine Formation in Star-Forming Regions

    NASA Astrophysics Data System (ADS)

    Pilling, S.; Boechat-Roberty, H. M.; Baptista, L.; Santos A. C., F.

    Interstellar clouds, similar to that from which the solar system was formed, contain many organic molecules including aldehydes, acids, ketones, and sugars Ehrenfreund & Charnley (2000). Those organic compounds have important functions in terrestrial biochemistry and could also have been important in prebiotic synthesis. The simplest amino acid, glycine (NH2CH2COOH), was recently detected in the hot molecular cores Sgr B2(N-LMH), Orion KL, and W51 e1/e2 Kuan et al. (2003). The formic acid (HCOOH) and acetic acid(CH3COOH) have also been detected in those regions Liu et al. (2002), Remijan et al. (2004). The goal of this work is to study experimentally photoionization and photodissociation processes of glycine precursor molecules, acetic acid and formic acid to elucidate a possible preferentially in the glycine synthesis between ice and gas phase. The measurements were taken at the Brazilian Synchrotron Light Laboratory (LNLS), employing soft X-ray photons from a toroidal grating monochromator TGM) beamline (100 - 310 eV). The experimental set up consists of a high vacuum chamber with a Time-Of-Flight Mass Spectrometer (TOF-MS). Mass spectra were obtained using PhotoElectron PhotoIon Coincidence (PEPICO) technique. Kinetic energy distributions and abundances for each ionic fragment have been obtained from the analysis of the corresponding peak shapes in the mass spectra. Dissociative and non-dissociative photoionization cross sections for both molecules were also determined Boechat-Roberty, Pilling & Santos (2005). Due to the high photodissociation cross section of formic acid it is possible that in PDRs regions, just after molecules evaporation from the grains surface, it is almost destructed by soft X-rays, justifying the observed low abundance of HCOOH in gaseous phase Ehrenfreund et al. (2001). Acetic acid have shown to be more stable to the ionizing field, and its main outcomes from dissociation process were the reactive ionic fragments COOH+ and CH3CO+. To

  20. Testing Grain Surface Chemistry in Star Forming Regions

    NASA Astrophysics Data System (ADS)

    Keane, Jacqueline; Boogert, Adwin

    2008-03-01

    The key chemical reactions that produce the first generation ice mantles in dense molecular clouds are still poorly known. Within cold, dense clouds, species formed in the gas and on the grain surfaces will stick to the grains and form icy mantles. However, during star-formation, materials in the general cloud medium are subjected to numerous chemical and physical processes that are driven mostly by thermal and energetic radiation. The comparison between background stars and protostars is a proven excellent tool for this purpose. By comparing observed interstellar solid state abundances with models of grain surface chemistry it is possible to elucidate the efficiency and hence relevancy of a number of chemical reactions, in particular the CO_2 formation pathways. In part because of Spitzer, significant progress has been made towards understanding the various effects of these radiation processes on the ices around a large sample of high- and low-mass protostars. First results suggest that two different CO2 formation pathways play a role in these harsh environments. Though which reaction initially dominated the chemistry is unknown due to the numerous physical processes. Unfortunately, only a small sample of background field stars have been observed, most notably Taurus. In Taurus, only one reaction pathway appears to be efficient in quiescent regions, but this result is sample limited. We propose to take low resolution spectra from 5 to 22 microns along the line of sight toward 31 field stars behind the LDN 673 molecular cloud. Differences in near-IR ice chemistry have already been observed and we will use these mid-infrared data to provide more stringent constraints on chemical models of grain surface chemistry. With this sample it is possible to address fundamental questions in astrochemistry: what are the dominant grain surface chemistry pathways? What is the composition of the first generation ice mantles in molecular clouds?

  1. CME Productivity of Active Regions.

    NASA Astrophysics Data System (ADS)

    Liu, L.; Wang, Y.; Wang, J.; Shen, C.; Ye, P.; Zhang, Q.; Liu, R.; Wang, S.

    2015-12-01

    Solar active regions (ARs) are the major sources of two kinds of the most violent solar eruptions, namely flares and coronal mass ejections (CMEs). Although they are believed to be two phenomena in the same eruptive process, the productivity of them could be quiet different for various ARs. Why is an AR productive? And why is a flare-rich AR CME-poor? To answer these questions, we compared the recent super flare-rich but CME-poor AR 12192, with other four ARs; two were productive in both flares and CMEs and the other two were inert to produce any M-class or intenser flares or CMEs. By investigating the photospheric parameters based on the SDO/HMI vector magnetogram, we find the three productive ARs have larger magnetic flux, current and free magnetic energy than the inert ARs. Furthermore, the two ARs productive in both flares and CMEs contain higher current helicity, concentrating along both sides of the flaring neutral lines, indicating the presence of a seed magnetic structure( that is highly sheared or twisted) of a CME; they also have higher decay index in the low corona, showing weak constraint. The results suggest that productive ARs are always large and have strong current system and sufficient free energy to power flares, and more importantly whether or not a flare is accompanied by a CME is seemingly related to (1) if there is significant sheared or twisted core field serving as the seed of the CME and (2) if the constraint of the overlying arcades is weak enough. Moreover, some productive ARs may frequently produce more than one CME. How does this happen? We do a statistical investigation of waiting times of quasi-homologous CMEs ( CME ssuccessive originating from the same ARs within short intervals) from super ARs in solar cycle 23 to answer this question. The waiting times of quasi-homologous CMEs have a two-component distribution with a separation at about 18 hours, the first component peaks at 7 hours. The correlation analysis among CME waiting times

  2. Water in star- and planet-forming regions.

    PubMed

    Bergin, Edwin A; van Dishoeck, Ewine F

    2012-06-13

    In this paper, we discuss the astronomical search for water vapour in order to understand the disposition of water in all its phases throughout the processes of star and planet formation. Our ability to detect and study water vapour has recently received a tremendous boost with the successful launch and operation of the Herschel Space Observatory. Herschel spectroscopic detections of numerous transitions in a variety of astronomical objects, along with previous work by other space-based observatories, will be threaded throughout this paper. In particular, we present observations of water tracing the earliest stage of star birth where it is predominantly frozen as ice. When a star is born, the local energy release by radiation liberates ices in its surrounding envelope and powers energetic outflows that appear to be water factories. In these regions, water plays an important role in the gas physics. Finally, we end with an exploration of water in planet-forming discs surrounding young stars. The availability of accurate molecular data (frequencies, collisional rate coefficients and chemical reaction rates) is crucial to analyse the observations at each of these steps.

  3. Combining regional expertise to form a bereavement support alliance.

    PubMed

    Friedrichs, Judy B; Kobler, Kathie; Roose, Rosmarie E; Meyer, Charlotte; Schmitz, Nancy; Kavanaugh, Karen

    2014-01-01

    Providing compassionate bereavement care for families experiencing perinatal loss is a standard of care in most healthcare organizations. In this article, we describe the development of The Alliance of Perinatal Bereavement Support Facilitators, begun over 25 years ago in Chicago by staff who identified the need to reach out to colleagues at other area institutions for advice and support in this work. This collaboration created a regional support network that has resulted in a long-lasting, active, sustainable organization of excellence focused on enhancing practice, education, and perinatal bereavement care. Alliance activities center around four main areas: education, networking/support, policy, and recognizing outstanding service to families. By continuing to draw upon the collective talent, wisdom, and expertise of its members, The Alliance still serves grieving families and provides mentoring for future interdisciplinary team members engaged in this work. The path taken to build this organization can be used by professionals in other specialties who are looking to create their own alliance infrastructure based on mutual benefit and interest.

  4. Kinked Loop Stretching Between Two Active Regions

    NASA Image and Video Library

    2017-07-25

    Numerous arches of magnetic field lines danced and swayed above a large active region over about a 30-hour period (July 17-18, 2017). We can also see the magnetic field lines from the large active region reached out and connected with a smaller active region. Those linked lines then strengthened (become brighter), but soon began to develop a kink in them and rather swiftly faded from view. All of this activity is driven by strong magnetic forces associated with the active regions. The images were taken in a wavelength of extreme ultraviolet light. https://photojournal.jpl.nasa.gov/catalog/PIA21838

  5. Nanoflare Properties throughout Active Regions: Comparing SDO/AIA Observations with Modeled Active Region Light Curves

    NASA Astrophysics Data System (ADS)

    Viall, Nicholeen; Klimchuk, J.

    2012-05-01

    Coronal plasma in active regions is typically measured to be at temperatures near 1-3 MK. Is the majority of the coronal plasma in hydrostatic equilibrium, maintained at these temperatures through a form of quasi-steady heating, or is this simply a measure of the average temperature of widely varying, impulsively heated coronal plasma? Addressing this question is complicated by the fact that the corona is optically thin: many thousands of flux tubes which are heated completely independently are contributing to the total emission along a given line of sight. There is a large body of work focused on the heating of isolated features - coronal loops - which are impulsively heated, however it is the diffuse emission between loops which often comprises the majority of active region emission. Therefore in this study we move beyond isolated features and analyze all of the emission in an entire active region from all contributing flux tubes. We investigate light curves systematically using SDO/AIA observations. We also model the active region corona as a line-of-sight integration of many thousands of completely independently heated flux tubes. The emission from these flux tubes may be time dependent, quasi-steady, or a mix of both, depending on the cadence of heat release. We demonstrate that despite the superposition of randomly heated flux tubes, different distributions of nanoflare cadences produce distinct signatures in light curves observed with multi-wavelength and high time cadence data, such as those from SDO/AIA. We conclude that the majority of the active region plasma is not maintained in hydrostatic equilibrium, rather it is undergoing dynamic heating and cooling cycles. The observed emission is consistent with heating through impulsive nanoflares, whose energy is a function of location within the active region. This research was supported by an appointment to the NASA Postdoctoral Program at GSFC/NASA.

  6. Nanoflare Properties throughout Active Regions: Comparing SDO/AIA Observations with Modeled Active Region Light Curves

    NASA Technical Reports Server (NTRS)

    Viall, Nicholeen

    2012-01-01

    Coronal plasma in active regions is typically measured to be at temperatures near 1-3 MK. Is the majority of the coronal plasma in hydrostatic equilibrium, maintained at these temperatures through a form of quasi-steady heating, or is this simply a measure of the average temperature of widely varying, impulsively heated coronal plasma? Addressing this question is complicated by the fact that the corona is optically thin: many thousands of flux tubes which are heated completely independently are contributing to the total emission along a given line of sight. There is a large body of work focused on the heating of isolated features - coronal loops - which are impulsively heated, however it is the diffuse emission between loops which often comprises the majority of active region emission. Therefore in this study we move beyond isolated features and analyze all of the emission in an entire active region from all contributing flux tubes. We investigate light curves systematically using SDO/AIA observations. We also model the active region corona as a line-of-sight integration of many thousands of completely independently heated flux tubes. The emission from these flux tubes may be time dependent, quasi-steady, or a mix of both, depending on the cadence of heat release. We demonstrate that despite the superposition of randomly heated flux tubes, different distributions of nanoflare cadences produce distinct signatures in light curves observed with multi-wavelength and high time cadence data, such as those from SDO/AIA. We conclude that the majority of the active region plasma is not maintained in hydrostatic equilibrium, rather it is undergoing dynamic heating and cooling cycles. The observed emission is consistent with heating through impulsive nanoflares, whose energy is a function of location within the active region.

  7. Physical properties of star-forming regions across the Galaxy

    NASA Astrophysics Data System (ADS)

    Dunham, Miranda Kay

    2010-12-01

    The Bolocam Galactic Plane Survey (BGPS) has surveyed the northern Galactic plane at 1.1 mm and detected 8,358 sources. The BGPS catalog is large enough to characterize the properties of massive star formation in a statistically significant way. In this dissertation, I have conducted a survey of NH2 lines toward 771 BGPS sources located throughout the Galactic plane. The NH2 and 1.1 mm continuum observations together have allowed for complete characterization of the physical properties of these sources. I detected the NH2(1,1) line toward 408 BGPS sources in the inner Galaxy, allowing for determination of their kinematic distances. At distances less than roughly 1 kpc, the BGPS detects predominately cores which will form a single star or small multiple system, while at distances between 1 and 7 kpc the BGPS detects predominately clumps which will form entire stellar clusters. At distances greater than 7 kpc, the BGPS detects the large scale clouds which contain clumps and cores. I have correlated the BGPS catalog with mid-IR catalogs of massive young stellar objects (MYSOs), and found that 49% of the BGPS sources contain signs of active star formation. The masses, densities, H2 and NH2 column densities, gas kinetic temperatures, and NH2 velocity dispersions are higher in BGPS sources with associated mid-IR sources. I have also studied the physical properties of the BGPS sources as a function of Galactocentric radius, R[subscript Gal]. I find that the mean radius and mass decrease with increasing R[subscript Gal] but peak within the 5 kpc molecular ring where the gas kinetic temperature reaches a minimum. The fraction of BGPS sources with associated mid-IR sources decreases by 10% within the molecular ring. I postulate that these trends can be explained by an ambient gas density which decreases with R[subscript Gal], but peaks within the molecular ring. Similarly, the NH2 column density and abundance decrease by almost an order! of magnitude from the inner to outer

  8. Intermediate-Mass Star-Forming Regions: What are the Most Massive Stars Formed?

    NASA Astrophysics Data System (ADS)

    Kobulnicky, Chip; Vargas, Carlos; Kerton, Charles; Arvidsson, Kim

    2010-08-01

    High-mass star formation cannot be viewed as simply a scaled-up version of the paradigm for low-mass star formation. The high-mass regime (M> 10 Msun) appears to require significant differences in cloud fragmentation, accretion, radiation, turbulence, and overall molecular density compared to the low-mass regime. We have identified a sample of intermediate-mass star-forming regions (IM SFRs) hosting embedded clusters that straddle the boundary of these two regimes and can be used to understand the factors that govern the transition between these extremes. Most notable among these factors is the possibility of a critical cloud mass column density that appears to divide high-mass SFRs from IM SFRs. Yet, the very nature of IM SFRs and their stellar content are almost completely unknown, primarily because of the previous difficulty in identifying such objects. We propose HK band spectroscopy of the brightest stellar sources near nine IM SFRs to identify probable members, confirm the IM nature of the most massive stars, and characterize their evolutionary state. Three nights with FLAMINGOS on the 4 m (or equivalent IR spectrograph) will suffice to obtain classification spectra and several spectral diagnostics sensitive to accretion for at least 8-10 stars per object.

  9. Active compounds release from semisolid dosage forms.

    PubMed

    Olejnik, Anna; Goscianska, Joanna; Nowak, Izabela

    2012-11-01

    The aim of this paper is to review all the aspects of the in vitro release testing (IVRT) from semisolid dosage forms. Although none of the official dissolution methods has been specified for use with semisolid dosage forms, their utility for assessing release rates of drugs from semisolid dosage forms has become a topic of considerable interest. One can expect to overcome such complexity in the future, when the official "Topical and Transdermal Drug Products-Product Performance Tests" will be published in an issue of the Pharmacopeial Forum. Many factors such as type of the dissolution medium, membrane, temperature, and speed have an influence on the mechanism and kinetics of the release testing from gels, creams, and ointments; therefore, those parameters have been widely discussed. Copyright © 2012 Wiley Periodicals, Inc.

  10. 76 FR 61725 - Agency Information Collection Activities: Case Submission Form, Case Assistance Form; (Form DHS...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-05

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF HOMELAND...-7001), Online Ombudsman Form DHS-7001 AGENCY: Office of the Citizenship and Immigration Service...- 7001)'' The name of the system has changed from ``Virtual Ombudsman System'' to ``Online Ombudsman Form...

  11. The Main Sequence of Explosive Solar Active Regions: Comparison of Emerging and Mature Active Regions

    NASA Technical Reports Server (NTRS)

    Falconer, David; Moore, Ron

    2011-01-01

    For mature active regions, an active region s magnetic flux content determines the maximum free energy the active region can have. Most Large flares and CMEs occur in active regions that are near their free-energy limit. Active-region flare power radiated in the GOES 1-8 band increases steeply as the free-energy limit is approached. We infer that the free-energy limit is set by the rate of release of an active region s free magnetic energy by flares, CMEs and coronal heating balancing the maximum rate the Sun can put free energy into the active region s magnetic field. This balance of maximum power results in explosive active regions residing in a "mainsequence" in active-region (flux content, free energy content) phase space, which sequence is analogous to the main sequence of hydrogen-burning stars in (mass, luminosity) phase space.

  12. The Twist Limit for Bipolar Active Regions

    NASA Technical Reports Server (NTRS)

    Moore, Ron; Falconer, David; Gary, Allen

    2008-01-01

    We present new evidence that further supports the standard idea that active regions are emerged magnetic-flux-rope omega loops. When the axial magnetic twist of a cylindrical flux rope exceeds a critical amount, the flux rope becomes unstable to kinking, and the excess axial twist is converted into writhe twist by the kinking. This suggests that, if active regions are emerged omega loops, then (1) no active region should have magnetic twist much above the limit set by kinking, (2) active regions having twist near the limit should often arise from kinked omega loops, and (3) since active regions having large delta sunspots are outstandingly twisted, these arise from kinked omega loops and should have twist near the limit for kinking. From each of 36 vector magnetograms of bipolar active regions, we have measured (1) the total flux of the vertical field above 100 G, (2) the area covered by this flux, and (3) the net electric current that arches over the polarity inversion line. These three quantities yield an estimate of the axial magnetic twist in a simple model cylindrical flux rope that corresponds to the top of the active region s hypothetical omega loop prior to emergence. In all 36 cases, the estimated twist is below the critical limit for kinking. The 11 most twisted active regions (1) have estimated twist within a factor of approx.3 of the limit, and (2) include all of our 6 active regions having large delta sunspots. Thus, our observed twist limit for bipolar active regions is in good accord with active regions being emerged omega loops.

  13. The Twist Limit for Bipolar Active Regions

    NASA Technical Reports Server (NTRS)

    Moore, Ron; Falconer, David; Gary, Allen

    2008-01-01

    We present new evidence that further supports the standard idea that active regions are emerged magnetic-flux-rope omega loops. When the axial magnetic twist of a cylindrical flux rope exceeds a critical amount, the flux rope becomes unstable to kinking, and the excess axial twist is converted into writhe twist by the kinking. This suggests that, if active regions are emerged omega loops, then (1) no active region should have magnetic twist much above the limit set by kinking, (2) active regions having twist near the limit should often arise from kinked omega loops, and (3) since active regions having large delta sunspots are outstandingly twisted, these arise from kinked omega loops and should have twist near the limit for kinking. From each of 36 vector magnetograms of bipolar active regions, we have measured (1) the total flux of the vertical field above 100 G, (2) the area covered by this flux, and (3) the net electric current that arches over the polarity inversion line. These three quantities yield an estimate of the axial magnetic twist in a simple model cylindrical flux rope that corresponds to the top of the active region s hypothetical omega loop prior to emergence. In all 36 cases, the estimated twist is below the critical limit for kinking. The 11 most twisted active regions (1) have estimated twist within a factor of approx.3 of the limit, and (2) include all of our 6 active regions having large delta sunspots. Thus, our observed twist limit for bipolar active regions is in good accord with active regions being emerged omega loops.

  14. Region 6 Targeted Brownfields Assessment Form and Consent for Access to Property

    EPA Pesticide Factsheets

    To request Region 6 to perform a Targeted Brownfields Assessment, complete and submit the Region 6 Targeted Brownfields Assessment Form. To grant the EPA access to your property, complete and submit the Consent to Access to Property form.

  15. Molecular cloud/HII region interfaces in the star forming region NGC 6357.

    NASA Astrophysics Data System (ADS)

    Massi, F.; Brand, J.; Felli, M.

    1997-04-01

    We have performed ^12^CO(1-0), ^12^CO(2-1), ^13^CO(1-0), ^13^CO(2-1), C^18^O(1-0), C^18^O(2-1), HCO^+^(1-0) and H^13^CO^+^(1-0) observations towards two selected areas in the star forming complex NGC 6357 with angular resolutions from 21" to 55". In particular, we have mapped the molecular gas around the two HII regions G353.1+0.6 and G353.2+0.9 in the ^12^CO(1-0) and ^13^CO(1-0) transitions with a resolution of ~43". This improves on the coarser ^12^CO(1-0) observations previously carried out by others. We have also studied the physical properties of gas along strips through the molecular cloud/HII region interfaces. For G353.1+0.6, the observations confirm that an ionization front is eroding a warm, dense molecular cloud located to the north of the optical nebula. The molecular gas appears fragmented on a scale size >0.5pc and not all the components are related to the HII region. There is evidence of a density increase near the front and indications of temperature gradients toward the exciting stars. This is further suggested by the presence of ^12^CO(1-0) self-absorption produced by a cooler external layer. The isotopic ratio X(^13^CO)/X(C^18^O) decreases from the inner part of the clouds towards the front, contrary to what is theoretically predicted and observed in many other regions. This may be due to excitation or optical depths effects. An evolutionary scenario is proposed where the exciting stars form at the edge of a molecular cloud. The morphology of G353.2+0.9 is rather different from what previously believed. Only a weak "bar" of molecular material was found to the south of the sharp ionization front observed optically and in the radio-continuum, and most of the molecular emission arises from regions behind or to the north of the HII region. This indicates that we are viewing a late stage "blister" configuration face-on. This region is fragmented on a scale size >0.5pc, and a warm, dense and compact molecular fragment coincides with the elephant trunk

  16. Neural network with formed dynamics of activity

    SciTech Connect

    Dunin-Barkovskii, V.L.; Osovets, N.B.

    1995-03-01

    The problem of developing a neural network with a given pattern of the state sequence is considered. A neural network structure and an algorithm, of forming its bond matrix which lead to an approximate but robust solution of the problem are proposed and discussed. Limiting characteristics of the serviceability of the proposed structure are studied. Various methods of visualizing dynamic processes in a neural network are compared. Possible applications of the results obtained for interpretation of neurophysiological data and in neuroinformatics systems are discussed.

  17. Depth of origin of solar active regions

    NASA Technical Reports Server (NTRS)

    Parker, E. N.

    1984-01-01

    Observations show that the individual bipolar magnetic regions on the sun remain confined during their decay phase, with much of the magnetic field pulling back under the surface, in reverse of the earlier emergence. This suggests that the magnetic field is held on a short rein by subsurface forces, for otherwise the region would decay entirely by dispersing across the face of the sun. With the simple assumption that the fields at the surface are controlled from well-defined anchor points at a depth h, it is possible to relate the length l of the bipolar region at the surface to the depth h, with h about equal to l. The observed dimensions l about equal to 100,000 km for normal active regions, and l about equal to 10,000 km for the ephemeral active regions, indicate comparable depths of origin. More detailed observational studies of the active regions may be expected to shed further light on the problem.

  18. Star forming regions in gas-rich SO galaxies

    NASA Technical Reports Server (NTRS)

    Pogge, Richard W.; Eskridge, Paul B.

    1987-01-01

    The first results of an H alpha imaging survey of HI rich SO galaxies, which were searched for HII regions and other sources of emission, are presented. The charge coupled device H alpha interference filter images were made of 16 galaxies. Eight of these galaxies show evidence for on-going star formation, one has nuclear emission but no HII regions, and the remaining seven have no emissions detected within well defined upper limits. With the exception of one notably peculiar galaxy in which the emission from HII regions appears pervasive, the HII regions are either organized into inner-disk rings or randomly distributed throughout the disk. A few of these galaxies are found to be clearly not SO's; or peculiar objects atypical of the SO class. Using simple models star formation rates (SFRs) and gas depletion times from the observed H alpha fluxes were estimated. In general, the derived SFRs are much lower than those found in isolated field spiral galaxies and the corresponding gas depletion time scales are also longer.

  19. Orion B: Anatomy of a star-forming region

    NASA Astrophysics Data System (ADS)

    Barnes, Peter John

    The compact H II region/molecular cloud Orion B was observed with the Very Large Array (VLA) in the radio continuum and OH absorption line at a frequency of 1667 MHz, in the near-infrared continuum and H2 emission line at a wavelength of 2 micrometers, and in several millimeter wavelength molecular transitions (of HCO+, SO, 13-HCN, and HC(15)N) with the Hat Creek Array. The VLA continuum map has an integrated flux density of 59 + or - 2 Jy, and it is estimated that the total flux density is 63 + or - 4 Jy at this frequency. In OH absorption maps, the eastern loop (EL) shows up near the velocity of the Zeeman-split OH in such a way as to suggest expansion, and a high optical depth cloud appears in the north central part of the nebula at the velocity of the main OH absorption. The infrared source IRS 2, with a strong stellar wind and a location within the EL, is deduced to be the cause of this loop. The IR observations reveal many new sources which together may supply the missing ionizing flux for the nebula. The ionizing front (IF) is traced by the H2 line emission. In the dense molecular core the HCO+ line maps show a centrally located broad line region with an elliptical velocity distribution, a long, quiescent, NS-oriented ridge, an EW ridge which exactly abuts the IF of the adjacent H II region, and a possible one-sided high density outflow to the south with an origin apparently not near any of the IR sources mentioned. These observations support and expand the previously proposed model of the H II region. An improved model and a suggested history for the H II region and the first detailed model for the molecular core are presented.

  20. Ice Forming Regions during Evolution of the Solar Nebula

    NASA Technical Reports Server (NTRS)

    Davis, Sanford S.

    2005-01-01

    The condensation/sublimation front using a two dimensional model of the evolving solar system is investigated based on combined viscous and radiative heating. The snow line is shown to be a two-branched curve reflecting the competing effects of solar heating in the photosphere and internal heating at the center plane. The evolution of the icy region is described from a limited region early in the disk evolution to final positions near 1 AU. The snow line evolution predicted using two surface density models, a Hayashi minimum mass power law and an analytical solution of the nebula evolution equation. Possible effects of this dynamic motion on disk chemistry and organic molecule formation is also described.

  1. Ice Forming Regions during Evolution of the Solar Nebula

    NASA Technical Reports Server (NTRS)

    Davis, Sanford S.

    2005-01-01

    The condensation/sublimation front using a two dimensional model of the evolving solar system is investigated based on combined viscous and radiative heating. The snow line is shown to be a two-branched curve reflecting the competing effects of solar heating in the photosphere and internal heating at the center plane. The evolution of the icy region is described from a limited region early in the disk evolution to final positions near 1 AU. The snow line evolution predicted using two surface density models, a Hayashi minimum mass power law and an analytical solution of the nebula evolution equation. Possible effects of this dynamic motion on disk chemistry and organic molecule formation is also described.

  2. Suppression of Active-Region CME Production by the Presence of Other Active Regions

    NASA Technical Reports Server (NTRS)

    Falconer, David; Moore, Ron; Barghouty, Abdulnasser; Khazanov, Igor

    2009-01-01

    From the SOHO mission s data base of MDI full-disk magnetograms spanning solar cycle 23, we have obtained a set of 40,000 magnetograms of 1,300 active regions, tracking each active region across the 30 degree central solar disk. Each active region magnetogram is cropped from the full-disk magnetogram by an automated code. The cadence is 96 minutes. From each active-region magnetogram, we have measured two whole-active-region magnetic quantities: (1) the magnetic size of the active region (the active region s total magnetic flux), and (2) a gauge of the active region s free magnetic energy (part of the free energy is released in the production of a flare and/or CME eruption). From NOAA Flare/CME catalogs, we have obtained the event (Flare/CME/SEP event) production history of each active region. Using all these data, we find that for each type of eruptive event, an active region s expected rate of event production increases as a power law of our gauge of active-region free magnetic energy. We have also found that, among active regions having nearly the same free energy, the rate of the CME production is less when there are many other active regions on the disk than when there are few or none, but there is no significant discernible suppression of the rate of flare production. This indicates that the presence of other active regions somehow tends to inhibit an active region s flare-producing magnetic explosions from becoming CMEs, contrary to the expectation from the breakout model for the production of CMEs.

  3. A new star-forming region in Canis Major

    NASA Astrophysics Data System (ADS)

    Magakian, T. Yu.; Movsessian, T. A.; Bally, J.

    2016-07-01

    A new southern star-formation region, located at an estimated distance of ˜1.5 kpc in the Lynds 1664 dark cloud in Canis Major, is described. Lynds 1664 contains several compact star clusters, small stellar groups and young stars associated with reflection nebulae. Narrow-band H α and [S II] images obtained with the 4-m telescope at the Cerro Tololo Inter-American Observatory reveal more than 20 new Herbig-Haro objects associated with several protostellar outflows.

  4. New far infrared images of bright, nearby, star-forming regions

    NASA Technical Reports Server (NTRS)

    Harper, D. AL, Jr.; Cole, David M.; Dowell, C. Darren; Lees, Joanna F.; Lowenstein, Robert F.

    1995-01-01

    Broadband imaging in the far infrared is a vital tool for understanding how young stars form, evolve, and interact with their environment. As the sensitivity and size of detector arrays has increased, a richer and more detailed picture has emerged of the nearest and brightest regions of active star formation. We present data on M 17, M 42, and S 106 taken recently on the Kuiper Airborne Observatory with the Yerkes Observatory 60-channel far infrared camera, which has pixel sizes of 17 in. at 60 microns, 27 in. at 100 microns, and 45 in. at 160 and 200 microns. In addition to providing a clearer view of the complex central cores of the regions, the images reveal new details of the structure and heating of ionization fronts and photodissociation zones where radiation form luminous stars interacts with adjacent molecular clouds.

  5. New far infrared images of bright, nearby, star-forming regions

    NASA Technical Reports Server (NTRS)

    Harper, D. AL, Jr.; Cole, David M.; Dowell, C. Darren; Lees, Joanna F.; Lowenstein, Robert F.

    1995-01-01

    Broadband imaging in the far infrared is a vital tool for understanding how young stars form, evolve, and interact with their environment. As the sensitivity and size of detector arrays has increased, a richer and more detailed picture has emerged of the nearest and brightest regions of active star formation. We present data on M 17, M 42, and S 106 taken recently on the Kuiper Airborne Observatory with the Yerkes Observatory 60-channel far infrared camera, which has pixel sizes of 17 in. at 60 microns, 27 in. at 100 microns, and 45 in. at 160 and 200 microns. In addition to providing a clearer view of the complex central cores of the regions, the images reveal new details of the structure and heating of ionization fronts and photodissociation zones where radiation form luminous stars interacts with adjacent molecular clouds.

  6. Gas Evolution in the Planet-Forming Region of Disks

    NASA Astrophysics Data System (ADS)

    Pascucci, Ilaria

    2010-11-01

    The timescale over which gas-rich disks disperse profoundly affects not only the formation of giant planets but also the habitability of terrestrial planets. In this contributed talk we presented new atomic and molecular diagnostics that can be used to trace the dispersal of gas at disk radii where planets form. We also showed the first observational evidence for photoevaporation driven by the central star and discussed the efficiency of this disk dispersal mechanism.

  7. Active Region Emergence and Remote Flares

    NASA Astrophysics Data System (ADS)

    Fu, Yixing; Welsch, Brian T.

    2016-02-01

    We study the effect of new emerging solar active regions on the large-scale magnetic environment of existing regions. We first present a theoretical approach to quantify the "interaction energy" between new and pre-existing regions as the difference between i) the summed magnetic energies of their individual potential fields and ii) the energy of their superposed potential fields. We expect that this interaction energy can, depending upon the relative arrangements of newly emerged and pre-existing magnetic flux, indicate the existence of "topological" free magnetic energy in the global coronal field that is independent of any "internal" free magnetic energy due to coronal electric currents flowing within the newly emerged and pre-existing flux systems. We then examine the interaction energy in two well-studied cases of flux emergence, but find that the predicted energetic perturbation is relatively small compared to energies released in large solar flares. Next, we present an observational study of the influence of the emergence of new active regions on flare statistics in pre-existing active regions, using NOAA's Solar Region Summary and GOES flare databases. As part of an effort to precisely determine the emergence time of active regions in a large event sample, we find that emergence in about half of these regions exhibits a two-stage behavior, with an initial gradual phase followed by a more rapid phase. Regarding flaring, we find that the emergence of new regions is associated with a significant increase in the occurrence rate of X- and M-class flares in pre-existing regions. This effect tends to be more significant when pre-existing and new emerging active regions are closer. Given the relative weakness of the interaction energy, this effect suggests that perturbations in the large-scale magnetic field, such as topology changes invoked in the "breakout" model of coronal mass ejections, might play a significant role in the occurrence of some flares.

  8. NUCLEAR ACTIVITY IS MORE PREVALENT IN STAR-FORMING GALAXIES

    SciTech Connect

    Rosario, D. J.; Lutz, D.; Berta, S.; Popesso, P.; Genzel, R.; Saintonge, A.; Tacconi, L.; Wuyts, S. E-mail: lutz@mpe.mpg.de E-mail: popesso@mpe.mpg.de E-mail: amelie@mpe.mpg.de E-mail: swuyts@mpe.mpg.de; and others

    2013-07-01

    We explore the question of whether low and moderate luminosity active galactic nuclei (AGNs) are preferentially found in galaxies that are undergoing a transition from active star formation (SF) to quiescence. This notion has been suggested by studies of the UV-optical colors of AGN hosts, which find them to be common among galaxies in the so-called Green Valley, a region of galaxy color space believed to be composed mostly of galaxies undergoing SF quenching. Combining the deepest current X-ray and Herschel/PACS far-infrared (FIR) observations of the two Chandra Deep Fields with redshifts, stellar masses, and rest-frame photometry derived from the extensive and uniform multi-wavelength data in these fields, we compare the rest-frame U - V color distributions and star formation rate distributions of AGNs and carefully constructed samples of inactive control galaxies. The UV-to-optical colors of AGNs are consistent with equally massive inactive galaxies at redshifts out to z {approx} 2, but we show that such colors are poor tracers of SF. While the FIR distributions of both star-forming AGNs and star-forming inactive galaxies are statistically similar, we show that AGNs are preferentially found in star-forming host galaxies, or, in other words, AGNs are less likely to be found in weakly star-forming or quenched galaxies. We postulate that, among X-ray-selected AGNs of low and moderate accretion luminosities, the supply of cold gas primarily determines the accretion rate distribution of the nuclear black holes.

  9. Hinode Captures Images of Solar Active Region

    NASA Image and Video Library

    In these images, Hinode's Solar Optical Telescope (SOT) zoomed in on AR 11263 on August 4, 2011, five days before the active region produced the largest flare of this cycle, an X6.9. We show images...

  10. Abundant cyanopolyynes as a probe of infall in the Serpens South cluster-forming region

    NASA Astrophysics Data System (ADS)

    Friesen, R. K.; Medeiros, L.; Schnee, S.; Bourke, T. L.; di Francesco, J.; Gutermuth, R.; Myers, P. C.

    2013-12-01

    We have detected bright HC7N J = 21 - 20 emission towards multiple locations in the Serpens South cluster-forming region using the K-Band Focal Plane Array at the Robert C. Byrd Green Bank Telescope. HC7N is seen primarily towards cold filamentary structures that have yet to form stars, largely avoiding the dense gas associated with small protostellar groups and the main central cluster of Serpens South. Where detected, the HC7N abundances are similar to those found in other nearby star-forming regions. Towards some HC7N `clumps', we find consistent variations in the line centroids relative to NH3 (1,1) emission, as well as systematic increases in the HC7N non-thermal line widths, which we argue reveal infall motions on to dense filaments within Serpens South with minimum mass accretion rates of M ˜ 2-5 M⊙ Myr-1. The relative abundance of NH3 to HC7N suggests that the HC7N is tracing gas that has been at densities n ˜ 104 cm-3 for time-scales t ≲ 1-2 × 105 yr. Since HC7N emission peaks are rarely co-located with those of either NH3 or continuum, it is likely that Serpens South is not particularly remarkable in its abundance of HC7N, but instead the serendipitous mapping of HC7N simultaneously with NH3 has allowed us to detect HC7N at low abundances in regions where it otherwise may not have been looked for. This result extends the known star-forming regions containing significant HC7N emission from typically quiescent regions, like the Taurus molecular cloud, to more complex, active environments.

  11. Flare Size Distributions and Active Region Types

    NASA Astrophysics Data System (ADS)

    Bai, Taeil

    2007-05-01

    Size distributions of solar flares measured by various size indicators follow a power law with a negative index of about 1.8. On the basis of general appearance of power-law distributions, Lu and his collegues proposed an avalenche model. According to this model, the power-law index should be independent of active region size, but the cutoff size above which the size distribution steepens rapidly is expected to depend on the active region size. I have analyzed the size distribution of flares, using GOES soft X-ray observations for 2004 and 2005. For flares observed by GOES during these years, their locations are almost completely identified even for C-class flares. This enable us to study the dependence of size distribution on active region type. Comparing the power-law portion of size distributions below the high-end cutoff, I have found that the size distribution index depends on active region type. Flares from prolific active regions exhibit a flatter distribution, while flares from non-prolific active regions exhibit a steeper distribution. I plan to discuss a plausible mechanism for such behavior.

  12. Cosmic-Ray Injection from Star-Forming Regions.

    PubMed

    Carlson, Eric; Profumo, Stefano; Linden, Tim

    2016-09-09

    At present, all physical models of diffuse Galactic γ-ray emission assume that the distribution of cosmic-ray sources traces the observed populations of either OB stars, pulsars, or supernova remnants. However, since H_{2}-rich regions host significant star formation and numerous supernova remnants, the morphology of observed H_{2} gas (as traced by CO line surveys) should also provide a physically motivated, high-resolution tracer for cosmic-ray injection. We assess the impact of utilizing H_{2} as a tracer for cosmic-ray injection on models of diffuse Galactic γ-ray emission. We employ state-of-the-art 3D particle diffusion and gas density models, along with a physical model for the star-formation rate based on global Schmidt laws. Allowing a fraction, f_{H_{2}}, of cosmic-ray sources to trace the observed H_{2} density, we find that a theoretically well-motivated value f_{H_{2}}∼0.20-0.25 (i) provides a significantly better global fit to the diffuse Galactic γ-ray sky and (ii) highly suppresses the intensity of the residual γ-ray emission from the Galactic center region. Specifically, in models utilizing our best global fit values of f_{H_{2}}∼0.20-0.25, the spectrum of the galactic center γ-ray excess is drastically affected, and the morphology of the excess becomes inconsistent with predictions for dark matter annihilation.

  13. Cosmic-Ray Injection from Star-Forming Regions

    NASA Astrophysics Data System (ADS)

    Carlson, Eric; Profumo, Stefano; Linden, Tim

    2016-09-01

    At present, all physical models of diffuse Galactic γ -ray emission assume that the distribution of cosmic-ray sources traces the observed populations of either OB stars, pulsars, or supernova remnants. However, since H2 -rich regions host significant star formation and numerous supernova remnants, the morphology of observed H2 gas (as traced by CO line surveys) should also provide a physically motivated, high-resolution tracer for cosmic-ray injection. We assess the impact of utilizing H2 as a tracer for cosmic-ray injection on models of diffuse Galactic γ -ray emission. We employ state-of-the-art 3D particle diffusion and gas density models, along with a physical model for the star-formation rate based on global Schmidt laws. Allowing a fraction, fH2,of cosmic-ray sources to trace the observed H2 density, we find that a theoretically well-motivated value fH 2˜0.20 - 0.25 (i) provides a significantly better global fit to the diffuse Galactic γ -ray sky and (ii) highly suppresses the intensity of the residual γ -ray emission from the Galactic center region. Specifically, in models utilizing our best global fit values of fH2˜0.20 - 0.25 , the spectrum of the galactic center γ -ray excess is drastically affected, and the morphology of the excess becomes inconsistent with predictions for dark matter annihilation.

  14. Software Displays Data on Active Regions of the Sun

    NASA Technical Reports Server (NTRS)

    Golightly, Mike; Weyland, Mark; Raben, Vern

    2011-01-01

    The Solar Active Region Display System is a computer program that generates, in near real time, a graphical display of parameters indicative of the spatial and temporal variations of activity on the Sun. These parameters include histories and distributions of solar flares, active region growth, coronal mass ejections, size, and magnetic configuration. By presenting solar-activity data in graphical form, this program accelerates, facilitates, and partly automates what had previously been a time-consuming mental process of interpretation of solar-activity data presented in tabular and textual formats. Intended for original use in predicting space weather in order to minimize the exposure of astronauts to ionizing radiation, the program might also be useful on Earth for predicting solar-wind-induced ionospheric effects, electric currents, and potentials that could affect radio-communication systems, navigation systems, pipelines, and long electric-power lines. Raw data for the display are obtained automatically from the Space Environment Center (SEC) of the National Oceanic and Atmospheric Administration (NOAA). Other data must be obtained from the NOAA SEC by verbal communication and entered manually. The Solar Active Region Display System automatically accounts for the latitude dependence of the rate of rotation of the Sun, by use of a mathematical model that is corrected with NOAA SEC active-region position data once every 24 hours. The display includes the date, time, and an image of the Sun in H light overlaid with latitude and longitude coordinate lines, dots that mark locations of active regions identified by NOAA, identifying numbers assigned by NOAA to such regions, and solar-region visual summary (SRVS) indicators associated with some of the active regions. Each SRVS indicator is a small pie chart containing five equal sectors, each of which is color-coded to provide a semiquantitative indication of the degree of hazard posed by one aspect of the activity at

  15. Antioxidative activity of bound-form phenolics in potato peel.

    PubMed

    Nara, Kazuhiro; Miyoshi, Takayuki; Honma, Tamaki; Koga, Hidenori

    2006-06-01

    Free and bound-form phenolics were isolated from potato (cv. Toyoshiro) flesh and peel. The free and bound-form phenolics in the peel showed high DPPH radical scavenging activity, while those in the flesh showed low activity. The total amount of chlorogenic acid and caffeic acid in the free-form phenolics from the peel was highly correlated with the DPPH radical scavenging activity. Ferulic acid was identified as the active radical scavenging compound in the bound-form phenolics from the peel. The potato peel may therefore offer an effective source of an antioxidative.

  16. Infrared and optical studies of the Chamaeleon II and Lupus low-mass star forming regions .

    NASA Astrophysics Data System (ADS)

    Spezzi, L.; Alcalá, J. M.; Chapman, N.; Covino, E.; Evans, N. J., II; Frasca, A.; Gandolfi, D.; Huard, T. L.; Oliveira, I.; Jørgensen, J. K.; Merín, B.; Stapelfeldt, K. R.

    The Spitzer Legacy survey ``From Molecular Cores to Planet-forming Disks'' \\citep[c2d][]{Eva03} provided infrared observations of sources that span the evolutionary sequence from molecular cores to proto-planetary disks, encompassing a wide range of star-forming environments. These overall observations allowed to study crucial steps in the formation of stars and planets with unprecedented sensitivity. We present some results from the Spitzer observations and complementary data in the low-mass star forming regions in Chamaeleon II and Lupus. We focus, in particular, on the star-formation history and activity of these clouds, the low-mass end of their IMF and the envelope/disk properties of their young populations.

  17. Distances, Kinematics, And Structure Of Nearby Star-Forming Regions

    NASA Astrophysics Data System (ADS)

    Kounkel, Marina

    2017-08-01

    In this thesis I present an analysis of the structure and kinematics of the Orion Molecular Cloud Complex in an effort to better characterize the dynamical state of the closest region of the ongoing massive star formation and to provide a baseline for comparison of the upcoming results from the Gaia space telescope. In order to achieve this goal, I measured stellar parallax and proper motions, using very large baseline radio interferometry of non-thermally-emitting sources.. Based on these observations I measured the average distance in Orion A molecular cloud of 388±5 pc toward the Orion Nebula Cluster (ONC), 428±10 pc toward the southern portion of L1641, as well as the distance in Orion B of 388±10 pc toward NGC 2068, and roughly ˜420 pc toward NGC 2024. These are the first direct distance measurements with < 5% uncertainty to the regions within the Orion Complex outside of the ONC. Little can be said about the proper motions due to the sparcity of the sample size; however, I identified a number of binary systems and fitted their orbital motion, which allows for the direct measurement of the masses of the individual components. I also identified three stars that have been ejected from the ONC due to the gravitational interactions with its most massive stars.I complemented the parallax and proper motion measurements with the observations of radial velocities (RV) of the stars toward the Orion Complex, probing the histories of both dynamic evolution and star formation in the region. I found that in the Orion A cloud and in NGC 2024 there exists an asymmetry between the stellar RVs and those of the molecular gas, with a small fraction of the stars stars being preferentially blueshifted relative to the gas. Several possible explanations for this have been proposed, although presently there is not yet a definitive solution. I also analyzed the multiplicity fraction of the spectroscopic binaries in the ONC, and found that it is largely consistent to what is

  18. The Physics of Molecular Shocks in Star-Forming Regions

    NASA Technical Reports Server (NTRS)

    Hollenbach, David; Cuzzi, Jeffrey (Technical Monitor)

    1996-01-01

    Molecular shocks are produced by the impact of the supersonic infall of gas and dust onto protostars and by the interaction of the supersonic outflow from the protostar with the circumstellar material. Infalling gas creates an accretion shock around the circumstellar disk which emits a unique infrared spectrum and which processes the interstellar dust as it enters the disk. The winds and jets from protostars also impact the disk, the infalling material, and the ambient molecular cloud core creating shocks whose spectrum and morphology diagnose the mass loss processes of the protostar and the orientation and structure of the star forming system. We discuss the physics of these shocks, the model spectra derived from theoretical models, and comparisons with observations of H2O masers, H2 emission, as well as other shocks tracers. We show the strong effect of magnetic fields on molecular shock structure, and elucidate the chemical changes induced by the shock heating and compression.

  19. Observations of Ices in Star-Forming Regions

    NASA Technical Reports Server (NTRS)

    Tielens, Alexander G. G. M.; Cuzzi, Jeffrey (Technical Monitor)

    1996-01-01

    Ground-based, air-borne, and space-based infrared spectra of protostars show prominent absorption features at 3.08, 3.54, 4.23, 4.67, 4.9, 6.0, 6.85, and 7.6 micrometers. These features are due to simple molecules such as H2O, CH3OH, CO2, CO, OCS, and CH4 in accreted icy grain mantles. These studies have revealed the presence of several independent ice components, often along the same line of sight. The observations and proposed identifications will be reviewed with the emphasis on recent results from ISO and on the organic inventory of interstellar ices. These molecular grain mantles are thought to form by accretion and reaction of gas phase species on a grain surface. Observed abundances will be compared with theoretical calculations and the important grain surface routes will be delineated. The importance of the 'diffusion' limit will be emphasized.

  20. Complex Network for Solar Active Regions

    NASA Astrophysics Data System (ADS)

    Daei, Farhad; Safari, Hossein; Dadashi, Neda

    2017-08-01

    In this paper we developed a complex network of solar active regions (ARs) to study various local and global properties of the network. The values of the Hurst exponent (0.8-0.9) were evaluated by both the detrended fluctuation analysis and the rescaled range analysis applied on the time series of the AR numbers. The findings suggest that ARs can be considered as a system of self-organized criticality (SOC). We constructed a growing network based on locations, occurrence times, and the lifetimes of 4227 ARs recorded from 1999 January 1 to 2017 April 14. The behavior of the clustering coefficient shows that the AR network is not a random network. The logarithmic behavior of the length scale has the characteristics of a so-called small-world network. It is found that the probability distribution of the node degrees for undirected networks follows the power law with exponents of about 3.7-4.2. This indicates the scale-free nature of the AR network. The scale-free and small-world properties of the AR network confirm that the system of ARs forms a system of SOC. Our results show that the occurrence probability of flares (classified by GOES class C> 5, M, and X flares) in the position of the AR network hubs takes values greater than that obtained for other nodes.

  1. Formation of active region and quiescent prominence magnetic field configurations

    NASA Technical Reports Server (NTRS)

    An, C.-H.; Bao, J. J.; Wu, S. T.

    1986-01-01

    To investigate the formation of prominences, researchers studied chromospheric mass injection into an overlying coronal dipole magnetic field using a 2-D ideal magnetohydrodynamic (MHD) numerical model. Researchers propose that active region prominences are formed by chromospheric plasmas injected directly into the overlying coronal magnetic field and that quiescent prominences are formed by plasmas evaporated at the interface between spicules and corona. Hence, for the simulation of an active region prominence magnetic field we inject the mass from one side, but use a symmetric mass injection to form a quiescent prominence field configuration. Researchers try to find optimum conditions for the formation of Kippenhahn-Schuluter(K-S)type field configuration for stable support of the injection plasmas. They find that the formation of K-S type field configuration by mass injection requires a delicate balance between injection velocity, density, and overlying magnetic fields. These results may explain why a prominence does not form on every neutral line.

  2. Energy Flow Continuity in Solar Active Regions

    NASA Technical Reports Server (NTRS)

    Schatten, K. H.

    1984-01-01

    The models for sunspots are combined into an active region model with consideration for the energy flow beneath active regions. An apparent average energy balance exists between the sunspot deficit and the facular excess, i.e., no 11 year variations in solar luminosity associated with the activity centers. This is seen as a consequence of the upper convection zone's inability to store these significant amounts of energy for periods greatly in excess of weeks. This view is supported by observed active region behavior and detailed numerical modelling. Increases in facular and spot brightness are nearly commensurate, with the faculae outlasting the spots on time scales of the order of weeks to a couple of months. Foukal finds the radiation (deficit from a sunspot blocking model) recovers slowly on a timescale of approximately 83 days.

  3. Polar Field Reversals and Active Region Decay

    NASA Astrophysics Data System (ADS)

    Petrie, Gordon; Ettinger, Sophie

    2015-07-01

    We study the relationship between polar field reversals and decayed active region magnetic flux. Photospheric active region flux is dispersed by differential rotation and turbulent diffusion, and is transported poleward by meridional flows and diffusion. We summarize the published evidence from observation and modeling of the influence of meridional flow variations and decaying active region flux's spatial distribution, such as the Joy's law tilt angle. Using NSO Kitt Peak synoptic magnetograms covering cycles 21-24, we investigate in detail the relationship between the transport of decayed active region flux to high latitudes and changes in the polar field strength, including reversals in the magnetic polarity at the poles. By means of stack plots of low- and high-latitude slices of the synoptic magnetograms, the dispersal of flux from low to high latitudes is tracked, and the timing of this dispersal is compared to the polar field changes. In the most abrupt cases of polar field reversal, a few activity complexes (systems of active regions) are identified as the main cause. The poleward transport of large quantities of decayed trailing-polarity flux from these complexes is found to correlate well in time with the abrupt polar field changes. In each case, significant latitudinal displacements were found between the positive and negative flux centroids of the complexes, consistent with Joy's law bipole tilt with trailing-polarity flux located poleward of leading-polarity flux. The activity complexes of the cycle 21 and 22 maxima were larger and longer-lived than those of the cycle 23 and 24 maxima, and the poleward surges were stronger and more unipolar and the polar field changes larger and faster. The cycle 21 and 22 polar reversals were dominated by only a few long-lived complexes whereas the cycle 23 and 24 reversals were the cumulative effects of more numerous, shorter-lived regions. We conclude that sizes and lifetimes of activity complexes are key to

  4. Polar Field Reversals and Active Region Decay

    NASA Astrophysics Data System (ADS)

    Petrie, Gordon; Ettinger, Sophie

    2017-09-01

    We study the relationship between polar field reversals and decayed active region magnetic flux. Photospheric active region flux is dispersed by differential rotation and turbulent diffusion, and is transported poleward by meridional flows and diffusion. We summarize the published evidence from observation and modeling of the influence of meridional flow variations and decaying active region flux's spatial distribution, such as the Joy's law tilt angle. Using NSO Kitt Peak synoptic magnetograms covering cycles 21-24, we investigate in detail the relationship between the transport of decayed active region flux to high latitudes and changes in the polar field strength, including reversals in the magnetic polarity at the poles. By means of stack plots of low- and high-latitude slices of the synoptic magnetograms, the dispersal of flux from low to high latitudes is tracked, and the timing of this dispersal is compared to the polar field changes. In the most abrupt cases of polar field reversal, a few activity complexes (systems of active regions) are identified as the main cause. The poleward transport of large quantities of decayed trailing-polarity flux from these complexes is found to correlate well in time with the abrupt polar field changes. In each case, significant latitudinal displacements were found between the positive and negative flux centroids of the complexes, consistent with Joy's law bipole tilt with trailing-polarity flux located poleward of leading-polarity flux. The activity complexes of the cycle 21 and 22 maxima were larger and longer-lived than those of the cycle 23 and 24 maxima, and the poleward surges were stronger and more unipolar and the polar field changes larger and faster. The cycle 21 and 22 polar reversals were dominated by only a few long-lived complexes whereas the cycle 23 and 24 reversals were the cumulative effects of more numerous, shorter-lived regions. We conclude that sizes and lifetimes of activity complexes are key to

  5. The Smad3 linker region contains a transcriptional activation domain.

    PubMed

    Wang, Guannan; Long, Jianyin; Matsuura, Isao; He, Dongming; Liu, Fang

    2005-02-15

    Transforming growth factor-beta (TGF-beta)/Smads regulate a wide variety of biological responses through transcriptional regulation of target genes. Smad3 plays a key role in TGF-beta/Smad-mediated transcriptional responses. Here, we show that the proline-rich linker region of Smad3 contains a transcriptional activation domain. When the linker region is fused to a heterologous DNA-binding domain, it activates transcription. We show that the linker region physically interacts with p300. The adenovirus E1a protein, which binds to p300, inhibits the transcriptional activity of the linker region, and overexpression of p300 can rescue the linker-mediated transcriptional activation. In contrast, an adenovirus E1a mutant, which cannot bind to p300, does not inhibit the linker-mediated transcription. The native Smad3 protein lacking the linker region is unable to mediate TGF-beta transcriptional activation responses, although it can be phosphorylated by the TGF-beta receptor at the C-terminal tail and has a significantly increased ability to form a heteromeric complex with Smad4. We show further that the linker region and the C-terminal domain of Smad3 synergize for transcriptional activation in the presence of TGF-beta. Thus our findings uncover an important function of the Smad3 linker region in Smad-mediated transcriptional control.

  6. Pu-238 fuel form activities, January 1-31, 1982

    SciTech Connect

    Not Available

    1982-03-01

    This monthly report for /sup 238/Pu fuel form activities has two main sections: SRP-PuFF facility and SRL fuel form activities. The program status, budget information, and milestone schedules are discussed in each main section. The Work Breakdown Structure (WBS) for this program is shown. Only one monthly report per year is processed for EDB.

  7. Growth and Decay of Solar Active Regions

    NASA Astrophysics Data System (ADS)

    Dobias, J. J.; Chapman, G. A.; Cookson, A. M.; Preminger, D. G.; Walton, S. R.

    2002-05-01

    We report here on a study of growth and decay rates of sunspot and facular areas of solar active regions. The data used in this project come from an ongoing program of daily photometric observations of the sun with the Cartesian Full Disk Telescope No. 1 (CFDT1) at the San Fernando Observatory (SFO). Sunspot regions are determined from images taken with a red filter centered at 672.3 nm with a bandpass of 9.7 nm, while images taken with a Ca II K line filter, centered at 393.4 nm and with a bandpass of only 1nm, are used to find facular areas. Before any areas can be found on any observed images, they have to be calibrated then flattened by removing limb darkening thus producing contrast images. Sunspot areas are then determined from any pixel with contrast of -8.5% or less, while any pixel on a K line contrast image with a contrast of +4.8%/μ or higher, where μ is the cosine of the heliocentric angle, is considered to be a facular pixel. To identify the areas as clearly as possible, studied active regions were usually observed on the sun with relatively low activity; that means that each region is either alone on the sun's disk or with only very few other active regions present. Furthermore, to obtain growth and decay patterns of the areas as reliably as possible, only such active regions must be chosen for which there is as complete observational coverage as possible. At the present time studies have been finished for only a few active regions, but analysis of several others is on going. Obtained results will be presented at the meeting. This work is supported by NSF grant ATM-9912132 and NASA grants NAG5-7191 and NAG5-7778.

  8. Tribal Minor NSR Synthetic Minor Limit Application Form in EPA's South Central Region

    EPA Pesticide Factsheets

    This Tribal Minor NSR application form should be used to notify the EPA Region 6 Tribal NSR Permitting Program of requested synthetic minor emission limits associated with a new source general application form.

  9. Tribal Minor NSR Synthetic Minor Limit Application Form in Region 8

    EPA Pesticide Factsheets

    This Tribal Minor NSR application form should be used to notify the EPA Region 8 Tribal NSR Permitting Program of requested synthetic minor emission limits associated with a new source general application form.

  10. The Magnetic Free Energy in Active Regions

    NASA Technical Reports Server (NTRS)

    Metcalf, Thomas R.; Mickey, Donald L.; LaBonte, Barry J.

    2001-01-01

    The magnetic field permeating the solar atmosphere governs much of the structure, morphology, brightness, and dynamics observed on the Sun. The magnetic field, especially in active regions, is thought to provide the power for energetic events in the solar corona, such as solar flares and Coronal Mass Ejections (CME) and is believed to energize the hot coronal plasma seen in extreme ultraviolet or X-rays. The question remains what specific aspect of the magnetic flux governs the observed variability. To directly understand the role of the magnetic field in energizing the solar corona, it is necessary to measure the free magnetic energy available in active regions. The grant now expiring has demonstrated a new and valuable technique for observing the magnetic free energy in active regions as a function of time.

  11. Fluxon Modeling of Active Region Evolution

    NASA Astrophysics Data System (ADS)

    Deforest, C. E.; Kankelborg, C. C.; Davey, A. R.; Rachmeler, L.

    2006-12-01

    We present current results and status on fluxon modeling of free energy buildup and release in active regions. Our publicly available code, FLUX, has the unique ability to track magnetic energy buildup with a truly constrained topology in evolving, nonlinear force-free conditions. Recent work includes validation of the model against Low &Lou force-free field solutions, initial evolution studies of idealized active regions, and inclusion of locally parameterized reconnection into the model. FLUX is uniquely able to simulate complete active regions in 3-D on a single workstation; we estimate that a parallelized fluxon model, together with computer vision code to ingest solar data, could run faster than real time on a cluster of \\textasciitilde 30 CPUs and hence provide a true predictive space weather model in the style of predictive simulations of terrestrial weather.

  12. Current Helicity of Emerging Active Regions

    NASA Astrophysics Data System (ADS)

    Pevtsov, A.

    2002-12-01

    We employ the SOHO MDI magnetograms and EIT images to study evolution of current helicity of solar active regions during early stages of their emergence. Using longitudinal magnetograms we compute linear force-free fields ∇ x B = α B and compare extrapolated field lines with bright coronal structures to constrain the value of α. At the beginning of emergence all studied regions have small α ~eq 0. As active region grows, α gradually increases and reaches a "plateau" within approximately one day of emergence. Using change in separation between negative and positive fluxes, we divide regions on "slow" and "rapid" emergence. Three regions show "slow" (> 1 day) emergence. For these regions α increases faster than the separation. In two "rapid" (< 1 day) emerging regions α grows slower that the separation. This observed evolution of current helicity is in agreement with Longcope and Welsch (2000) model of emergence of subphotospheric twisted flux rope into the corona. škip 0.5 truecm V. Maleev is NSO 2002 Summer Research Assistant from St. Petersburg State University, Russia

  13. Active Region Segmentation Based on Stokes Asymmetries

    NASA Astrophysics Data System (ADS)

    Choi, Jieun; Harker-Lundberg, B.

    2011-01-01

    During the Stokes inversion process, we would ideally use a distinct model for each structure in an active region which addresses the differences in the physical conditions of these regions. While the Milne-Eddington model of the atmosphere---a frequently-used ideal model that assumes all local thermodynamic equilibrium (LTE) conditions are satisfied---is a sufficient approximation for the description of the solar photosphere, we almost always observe deviations from this model. It is thus of interest to devise a method to systematically and accurately identify the active regions based on their spectra, such that we could use a more sophisticated model catered to each structure in an active region during the actual Stokes inversion process. We present a classification scheme for different active region structures using Stokes asymmetries and line core depths as discriminators. The data used for this investigation were obtained from the Synoptic Optical Long-term Investigations of the Sun (SOLIS) facility using the Vector Spectromagnetograph (VSM), observed in a 3 A bandpass around Fe I 6302.5 A, from March 27, 2008 to March 29, 2008. This work is carried out through the National Solar Observatory Research Experiences for Undergraduate (REU) site program, which is co-funded by the Department of Defense in partnership with the National Science Foundation REU Program. The National Solar Observatory is operated by the Association of Universities for Research in Astronomy, Inc. (AURA) under cooperative agreement with the National Science Foundation.

  14. DISTRIBUTION OF ELECTRIC CURRENTS IN SOLAR ACTIVE REGIONS

    SciTech Connect

    Török, T.; Titov, V. S.; Mikić, Z.; Leake, J. E.; Archontis, V.; Linton, M. G.; Dalmasse, K.; Aulanier, G.; Kliem, B.

    2014-02-10

    There has been a long-standing debate on the question of whether or not electric currents in solar active regions are neutralized. That is, whether or not the main (or direct) coronal currents connecting the active region polarities are surrounded by shielding (or return) currents of equal total value and opposite direction. Both theory and observations are not yet fully conclusive regarding this question, and numerical simulations have, surprisingly, barely been used to address it. Here we quantify the evolution of electric currents during the formation of a bipolar active region by considering a three-dimensional magnetohydrodynamic simulation of the emergence of a sub-photospheric, current-neutralized magnetic flux rope into the solar atmosphere. We find that a strong deviation from current neutralization develops simultaneously with the onset of significant flux emergence into the corona, accompanied by the development of substantial magnetic shear along the active region's polarity inversion line. After the region has formed and flux emergence has ceased, the strong magnetic fields in the region's center are connected solely by direct currents, and the total direct current is several times larger than the total return current. These results suggest that active regions, the main sources of coronal mass ejections and flares, are born with substantial net currents, in agreement with recent observations. Furthermore, they support eruption models that employ pre-eruption magnetic fields containing such currents.

  15. ON THE FORMATION OF ACTIVE REGIONS

    SciTech Connect

    Stein, Robert F.; Nordlund, Ake E-mail: aake@nbi.dk

    2012-07-01

    Magnetoconvection can produce an active region without an initial coherent flux tube. A simulation was performed where a uniform, untwisted, horizontal magnetic field of 1 kG strength was advected into the bottom of a computational domain 48 Mm wide by 20 Mm deep. The up and down convective motions produce a hierarchy of magnetic loops with a wide range of scales, with smaller loops riding 'piggy-back' in a serpentine fashion on larger loops. When a large loop approaches the surface, it produces a small active region with a compact leading spot and more diffuse following spots.

  16. Polar Field Reversals and Active Region Decay

    NASA Astrophysics Data System (ADS)

    Petrie, Gordon; Ettinger, Sophie

    2015-04-01

    We study the relationship between polar field reversals and decayed active region magnetic flux. Photospheric active region flux is dispersed by differential rotation and turbulent diffusion, and is transported poleward by meridional flows and diffusion. Using NSO Kitt Peak synoptic magnetograms, we investigate in detail the relationship between the transport of decayed active region flux to high latitudes and changes in the polar field strength, including reversals in the magnetic polarity at the poles. By means of stack plots of low- and high-latitude slices of the synoptic magnetograms, the dispersal of flux from low to high latitudes is tracked, and the timing of this dispersal is compared to the polar field changes. In the most abrupt cases of polar field reversal, a few activity complexes (systems of active regions) are identified as the main cause. The poleward transport of large quantities of decayed lagging-polarity flux from these complexes is found to correlate well in time with the abrupt polar field changes. In each case, significant latitudinal displacements were found between the positive and negative flux centroids of the complexes, consistent with Joy's law bipole tilt with lagging-polarity flux located poleward of leading-polarity flux. This work is carried out through the National Solar Observatory Summer Research Assistantship (SRA) Program. The National Solar Observatory is operated by the Association of Universities for Research in Astronomy, Inc. (AURA) under cooperative agreement with the National Science Foundation.

  17. Complex organic molecules toward low-mass and high-mass star forming regions

    NASA Astrophysics Data System (ADS)

    Favre, C.; Ceccarelli, C.; Lefloch, B.; Bergin, E.; Carvajal, M.; Brouillet, N.; Despois, D.; Jørgensen, J.; Kleiner, I.

    2016-12-01

    One of the most important questions in molecular astrophysics is how, when, and where complex organic molecules, COMs (≥ 6 atoms) are formed. In the Interstellar-Earth connection context, could this have a bearing on the origin of life on Earth? Formation mechanisms of COMs, which include potentially prebiotic molecules, are still debated and may include grain-mantle and/or gas-phase chemistry. Understanding the mechanisms that lead to the interstellar molecular complexification, along with the involved physicochemical processes, is mandatory to answer the above questions. In that context, active researches are ongoing in theory, laboratory experiment, chemical modeling and observations. Thanks to recent progress in radioastronomy instrumentation for both single-dish and millimeter array (e.g. Herschel, NOEMA, ALMA), new results have been obtained. I will review some notable results on the detection of COMs, including prebiotic molecules, towards star forming regions.

  18. Millimetre spectral line mapping observations towards four massive star-forming H II regions

    NASA Astrophysics Data System (ADS)

    Li, Shanghuo; Wang, Junzhi; Zhang, Zhi-Yu; Fang, Min; Li, Juan; Zhang, Jiangshui; Fan, Junhui; Zhu, Qingfeng; Li, Fei

    2017-04-01

    We present spectral line mapping observations towards four massive star-forming regions - Cepheus A, DR21S, S76E and G34.26+0.15 - with the IRAM 30-m telescope at the 2 and 3 mm bands. In total, 396 spectral lines from 51 molecules, one helium recombination line, 10 hydrogen recombination lines and 16 unidentified lines were detected in these four sources. An emission line of nitrosyl cyanide (ONCN, 140, 14-130, 13) was detected in G34.26+0.15, as the first detection in massive star-forming regions. We found that c-C3H2 and NH2D show enhancement in shocked regions, as suggested by the evidence of SiO and/or SO emission. The column density and rotational temperature of CH3CN were estimated with the rotational diagram method for all four sources. Isotope abundance ratios of 12C/13C were derived using HC3N and its 13C isotopologue, which were around 40 in all four massive star-forming regions and slightly lower than the local interstellar value (∼65). The 14N/15N and 16O/18O abundance ratios in these sources were also derived using the double isotopic method, which were slightly lower than in the local interstellar medium. Except for Cep A, the 33S/34S ratios in the other three targets were derived, which were similar to that in the local interstellar medium. The column density ratios of N(DCN)/N(HCN) and N(DCO+)/N(HCO+) in these sources were more than two orders of magnitude higher than the elemental [D]/[H] ratio, which is 1.5 × 10-5. Our results show that the later stage sources, G34.26+0.15 in particular, present more molecular species than earlier stage sources. Evidence of shock activity is seen in all stages studied.

  19. AFS dynamics in a short-lived active region

    NASA Astrophysics Data System (ADS)

    Zuccarello, F.; Battiato, V.; Contarino, L.; Romano, P.; Spadaro, D.; Vlahos, L.

    2005-11-01

    In the framework of the study on active region emergence, we report the results obtained from the analysis of the short-lived (7 days) active region NOAA 10407. The data used were acquired during an observational campaign carried out with the THEMIS telescope in IPM mode in July 2003, coordinated with other ground- and space-based instruments (INAF-OACT, DOT, BBSO, MDI/SOHO, EIT/SOHO, TRACE). We determined the morphological and magnetic evolution of NOAA 10407, as well as the velocity fields associated with its magnetic structures. Within the limits imposed by the spatial and temporal resolution of the images analyzed, the first evidence of the active region formation is initially observed in the transition region and lower corona, and later on (i.e. after about 7 h) in the inner layers, as found in a previous analysis concerning a long-lived, recurrent active region. The results also indicate that the AFS formed in the active region shows typical upward motion at the AFS's tops and downward motion at the footpoints. The velocity values relevant to the upward motions decrease over the evolution of the region, similarly to the case of the recurrent active region, while we notice an increasing trend in the downflow velocity during the early phases of the time interval analyzed by THEMIS. On the other hand, the AFS preceding legs show a higher downflow than the following ones, a result in contrast with that found in the long-lived active region. The chromospheric area overhanging the sunspot umbra shows an upward motion of ˜ 2 km s-1, while that above the pores shows a downward motion of ~4 km s-1.

  20. Solar Eruptions Initiated in Sigmoidal Active Regions

    NASA Astrophysics Data System (ADS)

    Savcheva, Antonia

    2016-07-01

    active regions that have been shown to possess high probability for eruption. They present a direct evidence of the existence of flux ropes in the corona prior to the impulsive phase of eruptions. In order to gain insight into their eruptive behavior and how they get destabilized we need to know their 3D magnetic field structure. First, we review some recent observations and modeling of sigmoidal active regions as the primary hosts of solar eruptions, which can also be used as useful laboratories for studying these phenomena. Then, we concentrate on the analysis of observations and highly data-constrained non-linear force-free field (NLFFF) models over the lifetime of several sigmoidal active regions, where we have captured their magnetic field structure around the times of major flares. We present the topology analysis of a couple of sigmoidal regions pointing us to the probable sites of reconnection. A scenario for eruption is put forward by this analysis. We demonstrate the use of this topology analysis to reconcile the observed eruption features with the standard flare model. Finally, we show a glimpse of how such a NLFFF model of an erupting region can be used to initiate a CME in a global MHD code in an unprecedented realistic manner. Such simulations can show the effects of solar transients on the near-Earth environment and solar system space weather.

  1. Thoughts on the development of active regional public health systems.

    PubMed

    Reis, Ademar Arthur Chioro Dos; Sóter, Ana Paula Menezes; Furtado, Lumena Almeida Castro; Pereira, Silvana Souza da Silva

    2017-04-01

    Decentralization and regionalization are strategic themes for reforms in the health system. This paper analyzes the complex process of health regionalization being developed in Brazil. This paper identifies that the normative framework from the Brazilian National Health System, SUS has made advances with respect to its institutionalization and overcoming the initial centrality involved in municipalization. This has strengthened the development of regionalization and the intergovernmental agreement on health but the evidence points to the need to promote a revision. Based on document analysis, literature review and the views given by the authors involved in management in SUS as well as generating radically different views, the challenges for the construction of a regionalization that is active, is debated. We also discuss: its relations with planning and the dimensioning of service networks, the production of active care networks and shared management spaces, the inter-federative agreements and regional regulations, the capacity to coordinate regional systems and financing and the impact of the political dimension and electoral cycles. Regionalization (and SUS itself) is an open book, therefore ways and possibilities on how to maintain an active form of regionalization can be recommended.

  2. Variation in the egg cell forming region of Gyrodactylus kobayashii Hukuda, 1940 (Monogenea:Gyrodactylidae).

    PubMed

    Jones, M K; Ernst, I; Whittington, I D

    1997-05-01

    The egg cell forming region of Gyrodactylus kobayashii from goldfish (Carassius auratus) is a thin nucleated cytoplasmic layer surrounding the developing egg cell (= oocyte). The cytoplasm contains numerous elougate membranes. As parasites age, the egg cell forming region becomes electron lucent. The apical membrane of the egg cell forming region becomes disrupted in places. A basal matrix is indistinct in new-born and young worms, becoming more evident as worms grow older. Numerous pits (= basal pits) are found along the basal plasma membrane of worms with a mature male system. These pits appear to be stable components of the membrane and resemble hemidesmosomes. Basal pits were co-incident with sperm in the egg cell forming region in 3 of 5 worms examined. The function of the basal pits of G. kobayashii could not be determined. It is postulated, however, that they either assist sperm to traverse the egg cell forming region to fertilize the egg cell or stabilize the egg cell forming region against damage by sperm traversing this layer. The egg cell forming region encloses a large egg cell and 1 or more smaller differentiating egg cells. The ripening egg cell has a large nucleus and extensive cytoplasm. The cell has a thickened membrane. Large vacuoles and invaginations at the periphery of the egg cell appear to engulf cytoplasm of the egg cell forming region.

  3. Earthquake Activity in the North Greenland Region

    NASA Astrophysics Data System (ADS)

    Larsen, Tine B.; Dahl-Jensen, Trine; Voss, Peter H.

    2017-04-01

    Many local and regional earthquakes are recorded on a daily basis in northern Greenland. The majority of the earthquakes originate at the Arctic plate boundary between the Eurasian and the North American plates. Particularly active regions away from the plate boundary are found in NE Greenland and in northern Baffin Bay. The seismograph coverage in the region is sparse with the main seismograph stations located at the military outpost, Stations Nord (NOR), the weather station outpost Danmarkshavn (DAG), Thule Airbase (TULEG), and the former ice core drilling camp (NEEM) in the middle of the Greenland ice sheet. Furthermore, data is available from Alert (ALE), Resolute (RES), and other seismographs in northern Canada as well as from a temporary deployment of BroadBand seismographs along the north coast of Greenland from 2004 to 2007. The recorded earthquakes range in magnitude from less than 2 to a 4.8 event, the largest in NE Greenland, and a 5.7 event, the largest recorded in northern Baffin Bay. The larger events are recorded widely in the region allowing for focal mechanisms to be calculated. Only a few existing focal mechanisms for the region can be found in the ISC bulletin. Two in NE Greenland representing primarily normal faulting and one in Baffin Bay resulting from reverse faulting. New calculations of focal mechanisms for the region will be presented as well as improved hypocenters resulting from analysis involving temporary stations and regional stations that are not included in routine processing.

  4. Pu-238 fuel form activities, June 1-30, 1980

    SciTech Connect

    Not Available

    1980-07-18

    This monthly report for Pu-238 Fuel Form Activities has two main sections: SRP-PuFF Pu-238 Fuel Form Production Processes and SRL Pu-238 Fuel Form Research and Development. The program status, budget information, and milestone information are discussed in each main section. The Work Breakdown Structures (WBS) for this program is outlined. Only one monthly report per year is processed for EDB.

  5. New Forms of Student Activism: Lobbying, Trusteeing, and Collective Bargaining.

    ERIC Educational Resources Information Center

    Beeler, Kent D.

    1979-01-01

    This article focuses on three new forms of student activism: lobbying, trusteeing, and collective bargaining. Related aspects of student involvement in the political, legal, and consumer areas are discussed briefly. (Author)

  6. Neogene-Quaternary Volcanic forms in the Carpathian-Pannonian Region: a review

    NASA Astrophysics Data System (ADS)

    Lexa, Jaroslav; Seghedi, Ioan; Németh, Karoly; Szakács, Alexandru; Koneĉny, Vlastimil; Pécskay, Zoltan; Fülöp, Alexandrina; Kovacs, Marinel

    2010-09-01

    Neogene to Quaternary volcanic/magmatic activity in the Carpathian-Pannonian Region (CPR) occurred between 21 and 0.1 Ma with a distinct migration in time from west to east. It shows a diverse compositional variation in response to a complex interplay of subduction with rollback, back-arc extension, collision, slab break-off, delamination, strike-slip tectonics and microplate rotations, as well as in response to further evolution of magmas in the crustal environment by processes of differentiation, crustal contamination, anatexis and magma mixing. Since most of the primary volcanic forms have been affected by erosion, especially in areas of post-volcanic uplift, based on the level of erosion we distinguish: (1) areas eroded to the basement level, where paleovolcanic reconstruction is not possible; (2) deeply eroded volcanic forms with secondary morphology and possible paleovolcanic reconstruction; (3) eroded volcanic forms with remnants of original morphology preserved; and (4) the least eroded volcanic forms with original morphology quite well preserved. The large variety of volcanic forms present in the area can be grouped in a) monogenetic volcanoes and b) polygenetic volcanoes and their subsurface/intrusive counterparts that belong to various rock series found in the CPR such as calc-alkaline magmatic rock-types (felsic, intermediate and mafic varieties) and alkalic types including K-alkalic, shoshonitic, ultrapotassic and Na-alkalic. The following volcanic/subvolcanic forms have been identified: (i) domes, shield volcanoes, effusive cones, pyroclastic cones, stratovolcanoes and calderas with associated intrusive bodies for intermediate and basic calclkaline volcanism; (ii) domes, calderas and ignimbrite/ash-flow fields for felsic calc-alkaline volcanism and (iii) dome flows, shield volcanoes, maars, tuffcone/tuff-rings, scoria-cones with or without related lava flow/field and their erosional or subsurface forms (necks/ plugs, dykes, shallow intrusions

  7. Magnetic helicity in emerging solar active regions

    SciTech Connect

    Liu, Y.; Hoeksema, J. T.; Bobra, M.; Hayashi, K.; Sun, X.; Schuck, P. W.

    2014-04-10

    Using vector magnetic field data from the Helioseismic and Magnetic Imager instrument aboard the Solar Dynamics Observatory, we study magnetic helicity injection into the corona in emerging active regions (ARs) and examine the hemispheric helicity rule. In every region studied, photospheric shearing motion contributes most of the helicity accumulated in the corona. In a sample of 28 emerging ARs, 17 follow the hemisphere rule (61% ± 18% at a 95% confidence interval). Magnetic helicity and twist in 25 ARs (89% ± 11%) have the same sign. The maximum magnetic twist, which depends on the size of an AR, is inferred in a sample of 23 emerging ARs with a bipolar magnetic field configuration.

  8. Active region evolution in the chromosphere and transtition region

    NASA Technical Reports Server (NTRS)

    Shine, R. A.; Schrijver, C. J.

    1988-01-01

    Images in the C IV 1548 A and the Si II 1526 S lines taken with the ultraviolet spectrometer polarimeter (UVSP) instrument on board the Solar Maximum Mission (SMM) satellite were combined into movies showing the evolution of active regions and the neighboring supergranulation over several days. The data sets generally consist of 240 by 240 arc second rasters with 3 arc second pixels taken one per orbit (about every 90 minutes). The images are projected on a latitude/longitude grid to remove the forshortening as the region rotates across the solar disk and further processed to remove jitter and gain variations. Movies were made with and without differential rotation. Although there are occasional missing orbits, these series do not suffer from the long nighttime gaps that occur in observations taken at a single groundbased observatory and are excellent for studying changes on time scales of several hours. The longest sequence processed to date runs from 20 Oct. 1980 to 25 Oct. 1980. This was taken during an SMM flare buildup study on AR 2744. Several shorter sequences taken in 1980 and 1984 will also be shown. The results will be presented on a video disk which can be interactively controlled to view the movies.

  9. Acoustic Oscillation Properties of Active Region 12193

    NASA Astrophysics Data System (ADS)

    Monsue, Teresa; Pesnell, William D.; Hill, Frank

    2017-08-01

    Solar flares are dynamic objects occurring randomly and yet unannounced in nature. In order to find an efficient detection method, we require a greater breadth of knowledge of the system. One path to such a method is to observe the solar atmosphere in a region around a flare in different wavelengths of light and acoustic frequency bands. This provides information from different altitudes in the solar atmosphere and allows us to study the temporal evolution of each altitude through the flaring event. A more complete understanding of the time evolution may lead to yet undiscovered precursors of the flare. In this project, we study Active Region 12192 using acoustic observations near an X3 flare occurring on October 24, 2014 at 21:41UT. Our wavelet analysis utilizes time series data to create Fourier power spectra of individual pixels spatially resolved around the flare region, to study the frequency bands. In order to study the power distribution in regions around the flare and to search for any correlation we apply several methods. One method we partition sub-regions in our main flaring region and take a survey of the oscillations for each frequency band within power maps. Another method we average the FFT to take measurements within the p-modes (2-4 mHz) and chromospheric (4-6 mHz) frequencies. The application of these methods should be able to get us closer to tracking waveforms within power maps.

  10. Supergranule Diffusion and Active Region Decay

    NASA Technical Reports Server (NTRS)

    Hathaway, David H.; Choudhary, Debi Prasad

    2004-01-01

    Models of the Sun's magnetic dynamo include turbulent diffusion to parameterize the effects of convective motions on the evolution of the Sun's magnetic field. Supergranules are known to dominate the evolution of the surface magnetic field structure as evidenced by the structure of both the active and quiet magnetic network. However, estimates for the dif hivity attributed to su perymules differ by an order of magnitude from about 100 km sup2/s to more than 1000 km sup2/s. We examine this question of the e i v i t y using three merent approaches. 1) We study the decay of more than 30,000 active regions by determining the rate of change in the sunspot area of each active region from day-to-day. 2) We study the decay of a single isolated active region near the time of solar minimum by examining the magnetic field evolution over five solar rotations fiom SOHOMDI magnetograms obtained at 96-minute intervals. 3) We study the characteristics of supergranules that influence the estimates of their diffusive properties - flow speeds and lifetimes as functions of size - fiom SOHO/MDI Dopplergrams.

  11. Supergranule Diffusion and Active Region Decay

    NASA Technical Reports Server (NTRS)

    Hathaway, David H.; Choudhary, Debi Prasad

    2004-01-01

    Models of the Sun's magnetic dynamo include turbulent diffusion to parameterize the effects of convective motions on the evolution of the Sun's magnetic field. Supergranules are known to dominate the evolution of the surface magnetic field structure as evidenced by the structure of both the active and quiet magnetic network. However, estimates for the dif hivity attributed to su perymules differ by an order of magnitude from about 100 km sup2/s to more than 1000 km sup2/s. We examine this question of the e i v i t y using three merent approaches. 1) We study the decay of more than 30,000 active regions by determining the rate of change in the sunspot area of each active region from day-to-day. 2) We study the decay of a single isolated active region near the time of solar minimum by examining the magnetic field evolution over five solar rotations fiom SOHOMDI magnetograms obtained at 96-minute intervals. 3) We study the characteristics of supergranules that influence the estimates of their diffusive properties - flow speeds and lifetimes as functions of size - fiom SOHO/MDI Dopplergrams.

  12. Form-Focused Discovery Activities in English Classes

    ERIC Educational Resources Information Center

    Ogeyik, Muhlise Cosgun

    2011-01-01

    Form-focused discovery activities allow language learners to grasp various aspects of a target language by contributing implicit knowledge by using discovered explicit knowledge. Moreover, such activities can assist learners to perceive and discover the features of their language input. In foreign language teaching environments, they can be used…

  13. Form-Focused Discovery Activities in English Classes

    ERIC Educational Resources Information Center

    Ogeyik, Muhlise Cosgun

    2011-01-01

    Form-focused discovery activities allow language learners to grasp various aspects of a target language by contributing implicit knowledge by using discovered explicit knowledge. Moreover, such activities can assist learners to perceive and discover the features of their language input. In foreign language teaching environments, they can be used…

  14. Stars and Star Clusters: A Look at Intermediate-Mass Star-Forming Regions

    NASA Astrophysics Data System (ADS)

    Lundquist, Michael J.; Kobulnicky, Henry A.; Lau, Ryan M.

    2017-01-01

    Star-forming regions hosting intermediate-mass stars straddle the boundary separating the the low- and high-mass regimes. These intermediate-mass star-forming regions can be used to probe this transition from low- to high-mass star formation. Our team has assembled an all-sky catalog of 616 candidate intermediate-mass star forming regions (IMSFRs) selected by IRAS colors and refined by visual inspection of WISE imagery. We present here two outer-Galaxy star-forming regions, IRAS22451+6154 and IRAS23448+6010, that despite having similar IRAS colors and mid-infrared morphologies, have vastly different stellar content. We combine Gemini and IRTF NIR spectroscopy with WIYN and SOFIA imaging for a thorough look at the stellar content of these two regions.

  15. Patterns of helicity in solar active regions

    NASA Technical Reports Server (NTRS)

    Pevtsov, Alexei A.; Canfield, Richard C.; Metcalf, Thomas R.

    1994-01-01

    Using 46 vector magnetograms from the Stokes Polarimeter of Mees Solar Observatory (MSO), we studied patterns of local helicity in three diverse solar active regions. From these magnetograms we computed maps of the local helicity parameter alpha = J(sub z)/B(sub z). Although such maps are noisy, we found patterns at the level approximately 2 to 3 sigma(sub J(sub z)), which repeat in successive magnetograms for up to several days. Typically, the alpha maps of any given active region contain identifiable patches with both positive and negative values of alpha. Even within a single sunspot complex, several such alpha patches can often be seen. We followed 68 alpha patches that could be identified on at least two successive alpha maps. We found that the persistence fraction of such patches decrease exponentially, with a characteristic time approximately 27 hr.

  16. Helicity Evolution in Emerging Active Regions

    NASA Astrophysics Data System (ADS)

    Pevtsov, Alexei A.; Maleev, Vasily M.; Longcope, Dana W.

    2003-08-01

    We study the evolution of twist and magnetic helicity in the coronal fields of active regions as they emerge. We use multiday sequences of Solar and Heliospheric Observatory Michelson Doppler Interferometer magnetograms to characterize the region's emergence. We quantify the overall twist in the coronal field, α, by matching a linear force-free field to bright coronal structures in EUV images. At the beginning of emergence, all regions studied have α~=0. As the active region grows, α increases and reaches a plateau within approximately 1 day of emergence. The inferred helicity transport rate is larger than differential rotation could produce. Following the 2000 work of Longcope & Welsch, we develop a model for the injection of helicity into the corona by the emergence of a twisted flux tube. This model predicts a ramp-up period of approximately 1 day. The observed time history α(t) is fitted by this model assuming reasonable values for the subphotospheric Alfvén speed. The implication is that helicity is carried by twisted flux tubes rising from the convection zone and transported across the photosphere by spinning of the poles driven by magnetic torque.

  17. Two New SiO Maser Sources in High-Mass Star-forming Regions

    NASA Astrophysics Data System (ADS)

    Cho, Se-Hyung; Yun, Youngjoo; Kim, Jaeheon; Liu, Tie; Kim, Kee-Tae; Choi, Minho

    2016-08-01

    Silicon monoxide (SiO) masers are rare in star-forming regions, with the exception of five known SiO maser sources. However, we detected two new SiO maser sources from infrared-loud clumps of the high-mass star-forming regions G19.61-0.23 and G75.78+0.34. High angular resolution observations toward G19.61-0.23 suggest that the deeply embedded young stellar object (YSO) of SMA1 is powering the SiO masers. In addition, the SiO v = 1, J = 1 \\to 0 line shows four spike features, while the v = 2 maser shows combined features of one spike and broad wing components, implying energetic activities of the YSO of SMA1 in the G19.61-0.23 hot molecular core. The SiO v = 0, J = 2 \\to 1 emission shows bipolar outflows in the NE-SW direction with respect to the center of the SiO maser source. A high angular resolution map of the SiO v = 1, J = 2 \\to 1 maser in G75.78+0.34 shows that the SiO maser is associated with the CORE source at the earliest stage of high-mass star formation. Therefore, the newly detected SiO masers and their associated outflows will provide good probes for investigating this early high-mass star formation.

  18. Activated carbon fibers and engineered forms from renewable resources

    DOEpatents

    Baker, Frederick S.

    2010-06-01

    A method of producing activated carbon fibers (ACFs) includes the steps of providing a natural carbonaceous precursor fiber material, blending the carbonaceous precursor material with a chemical activation agent to form chemical agent-impregnated precursor fibers, spinning the chemical agent-impregnated precursor material into fibers, and thermally treating the chemical agent-impregnated precursor fibers. The carbonaceous precursor material is both carbonized and activated to form ACFs in a single step. The method produces ACFs exclusive of a step to isolate an intermediate carbon fiber.

  19. Activated carbon fibers and engineered forms from renewable resources

    DOEpatents

    Baker, Frederick S

    2013-02-19

    A method of producing activated carbon fibers (ACFs) includes the steps of providing a natural carbonaceous precursor fiber material, blending the carbonaceous precursor material with a chemical activation agent to form chemical agent-impregnated precursor fibers, spinning the chemical agent-impregnated precursor material into fibers, and thermally treating the chemical agent-impregnated precursor fibers. The carbonaceous precursor material is both carbonized and activated to form ACFs in a single step. The method produces ACFs exclusive of a step to isolate an intermediate carbon fiber.

  20. Magnetic Energy Storage in Coronal Active Regions

    NASA Astrophysics Data System (ADS)

    Wolfson, Richard; Drake, C.; Kennedy, M.

    2011-05-01

    We consider magnetic energy storage in a force-free coronal model that simulates an active region by superposing a strong, localized magnetic bipole on a global background dipole. As we found earlier for dipolar and quadrupolar boundary conditions, our solutions develop detached flux ropes, whose energy can exceed that of the corresponding open field; this excess energy is available to power eruptive events such as coronal mass ejections. Our earlier work, and that of others on related magnetic configurations, has generally yielded excess energies of at most approximately 25 percent of the corresponding potential-field energy. Our new active-region models greatly exceed that value, with stressed force-free fields whose energy excess above the open-field state can be well over 100 percent of the energy stored in the associated potential field. Moving the model active region poleward increases the maximum value of this excess stored energy. This work is funded by NSF grant AGS0940503 to Middlebury College.

  1. Proper Motion Of Emerging Active Regions

    NASA Astrophysics Data System (ADS)

    Tian, Lirong

    2009-05-01

    Observational and modeling results indicate that typically the leading magnetic field of bipolar active regions is often spatially more compact, while more dispersed and fragmented in following polarity. Tian & Alexander (2009, ApJ, 695) studied 15 emerging active regions and find that magnetic helicity flux injected into the corona by the leading polarity is generally several times larger than that injected by the following polarity. They argue that the asymmetry of the magnetic helicity should be responsible for the asymmetry of the magnetic morphology. This argument is supported by two resent model results that magnetic flux tubes with higher degree of twist (and therefor greater magnetic tension) have higher rates of emergence (Murray & Hood 2008, A&A, 479; Cheung et al. 2008, ApJ, 687). These results are consistent because the proper motion (related to the emergence) of the leading polarity was found to be faster than that of the following polarity (van Driel-Gesztelyi & Petrovay 1990, Solar Phys., 126). In this paper, we will reinvestigate the proper motion of leading and following polarities of the emerging active regions, and study possible relationship between the proper motion and magnetic helicity.

  2. The complex high-mass star-forming region IRAS 15507-5359

    NASA Astrophysics Data System (ADS)

    Persi, P.; Tapia, M.; Roth, M.; Elia, D.; López-Vázquez, J. A.

    2016-06-01

    The far-infrared IRAS 15507-5359 source is known to be a medium-mass star-forming region associated with a compact H II region and a near-infrared embedded cluster. We present a survey of infrared-calibrated images ranging from 1.2 to 500 μm obtained with the Baade telescope at Las Campanas Observatory, and the Herschel space telescope with additional archive Spitzer data. We confirm the distance to the complex to be 5.0 kpc. Three Herschel far-infrared sources are found, I, II, III, identified with dense cores at different evolutionary stages. One (III) is a starless infrared dark cloud showing, near its edge, two infrared reflection nebulae (R1) and (R2) with dispersed young stellar populations, including a knot of shocked H2 line emission. Both show considerable polycyclic aromatic hydrocarbon emission. Core II has associated a radio H II region and a deeply embedded one-million-year-old cluster (Cl 1) that contains more than 45 young stellar objects, reddened by at least 20 visual magnitudes. About 20 per cent of them show considerable infrared excess emission. Core I appears void of a near-infrared population, and coincides with a long emission bar that resembles a photodissociation front. We determine the properties of the two most luminous Class I sources in the region by fitting models of young stars with accreting discs and envelopes to their 1-500 μm spectral energy distributions. This is another example of a medium-mass region with at least three well-defined active centres of star formation separated by about 1 pc and at different evolutionary stages.

  3. Activated microglia do not form functional gap junctions in vivo.

    PubMed

    Wasseff, Sameh K; Scherer, Steven S

    2014-04-15

    We investigated whether microglia form gap junctions with themselves, or with astrocytes, oligodendrocytes, or neurons in vivo in normal mouse brains, and in pathological conditions that induce microglial activation - brain injury and a model of Alzheimer's disease. Although microglia are in close physical proximity to glia and neurons, they do not form functional gap junctions under these pathological conditions. Copyright © 2014 Elsevier B.V. All rights reserved.

  4. 78 FR 10600 - Proposed Information Collection; Comment Request; Southeast Region Logbook Family of Forms

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-14

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration Proposed Information Collection; Comment Request; Southeast Region Logbook Family of Forms AGENCY: National Oceanic and Atmospheric Administration (NOAA)....

  5. Doppler Shifts in Active Region Moss Using SOHO/SUMER

    NASA Astrophysics Data System (ADS)

    Winebarger, Amy; Tripathi, Durgesh; Mason, Helen E.; Del Zanna, Giulio

    2013-04-01

    The velocity of the plasma at the footpoint of hot loops in active region cores can be used to discriminate between different heating frequencies. Velocities on the order of a few kilometers per second would indicate low-frequency heating on sub-resolution strands, while velocities close to zero would indicate high-frequency (steady) heating. To discriminate between these two values requires accurate velocity measurements; previous velocity measurements suffer from large uncertainties, mainly due to the lack of an absolute wavelength reference scale. In this paper, we determine the velocity in the loop footpoints using observations from Solar Ultraviolet Measurements of Emitted Radiation (SUMER) on Solar and Heliospheric Observatory. We use neutral spectral lines to determine the wavelength scale of the observations with an uncertainty in the absolute velocity of <3.5 km s-1 and co-aligned Transition Region and Coronal Explorer (TRACE) images to identify footpoint regions. We studied three different active regions and found average redshifts in the Ne VIII 770 Å emission line (formed at 6 × 105 K) of 5.17 ± 5.37 km s-1 and average redshifts in the C IV 1548 and 1550 Å emission lines (formed at 1 × 105 K) of 13.94 ± 4.93 km s-1 and 14.91 ± 6.09 km s-1, respectively. We find no correlation between the brightness in the spectral line and the measured velocity, nor do we find correlation between the Ne VIII and C IV velocities measured co-spatially and co-temporally. SUMER scanned two of the active regions twice; in those active regions we find positive correlation between the co-spatial velocities measured during the first and second scans. These results provide definitive and quantitative measurements for comparisons with simulations of different coronal heating mechanisms.

  6. The Role of Grain Surface Reactions in the Chemistry of Star Forming Regions

    NASA Technical Reports Server (NTRS)

    Kress, M. E.; Tielens, A. G. G. M.; Roberge, W. G.

    1998-01-01

    The importance of reactions at the surfaces of dust grains has long been recognized to be one of the two main chemical processes that form molecules in cold, dark interstellar clouds where simple, saturated (fully-hydrogenated) molecules such as H2 water, methanol, H2CO, H2S, ammonia and CH4 are present in quantities far too high to be consistent with their extremely low gas phase formation rates. In cold dark regions of interstellar space, dust grains provide a substrate onto which gas-phase species can accrete and react. Grains provide a "third body" or a sink for the energy released in the exothermic reactions that form chemical bonds. In essence, the surfaces of dust grains open up alternative reaction pathways to form observed molecules whose abundances cannot be explained with gas-phase chemistry alone. This concept is taken one step further in this work: instead of merely acting as a substrate onto which radicals and molecules may physically adsorb, some grains may actively participate in the reaction itself, forming chemical bonds with the accreting species. Until recently, surface chemical reactions had not been thought to be important in warm circumstellar media because adspecies rapidly desorb from grains at very low temperatures; thus, the residence times of molecules and radicals on the surface of grains at all but the lowest temperatures are far too short to allow these reactions to occur. However, if the adspecies could adsorb more strongly, via a true chemical bond with surfaces of some dust grains, then grain surface reactions will play an important role in warm circumstellar regions as well. In this work, the surface-catalyzed reaction CO + 3 H2 yields CH4 + H2O is studied in the context that it may be very effective at converting the inorganic molecule CO into the simplest organic compound, methane. H2 and CO are the most abundant molecules in space, and the reaction converting them to methane, while kinetically inhibited in the gas phase under

  7. The Connection Between Galaxy Environment and the Luminosity Function Slopes of Star-Forming Regions

    NASA Astrophysics Data System (ADS)

    Cook, David O.; Dale, Daniel A.; Lee, Janice C.; Thilker, David A.; Calzetti, Daniela; Kennicutt, Robert

    2016-06-01

    We present the first study of GALEX far ultra-violet (FUV) luminosity functions of individual star-forming regions within a sample of 258 nearby galaxies spanning a large range in total stellar mass and star formation properties. We identify ~65,000 star-forming regions (i.e., FUV sources), measure each galaxy's luminosity function, and characterize the relationships between the luminosity function slope (α) and several global galaxy properties. A final sample of \

  8. Solar irradiance variations due to active regions

    SciTech Connect

    Oster, L.; Schatten, K.H.; Sofia, S.

    1982-05-15

    We have been able to reproduce the variations of the solar irradiance observed by ACRIM to an accuracy of better than +- 0.4 W m/sup -2/, assuming that during the 6 month observation period in 1980 the solar luminosity was constant. The improvement over previous attempts is primarily due to the inclusion of faculae. The reproduction scheme uses simple geometrical data on spot and facula areas, and conventional parameters for the respective fluxes and angular dependencies. The quality of reproduction is not very sensitive to most of the details of these parameters; nevertheless, there conventional parameters cannot be very different from their actual values in the solar atmosphere. It is interesting that the time average of the integrated excess emission (over directions) of the faculae cancels out the integrated deficit produced by the spots, within an accuracy of about 10%. If this behavior were maintained over longer periods of time, say, on the order of an activity cycle, active regions could be viewed as a kind of lighthouse where the energy deficit near the normal direction, associated with the spots, is primarily reemitted close to the tangential directions by the faculae. The currently available data suggest that energy ''storage'' associated with the redirection of flux near active regions on the Sun is comparable to the lifetime of the faculae.

  9. Observations of an active region filament

    NASA Astrophysics Data System (ADS)

    Zong, W. G.; Tang, Y. H.; Fang, C.; Xu, A. A.

    An active region filament was well observed on September 4, 2002 with THEMIS at the Teide observatory and SOHO/MDI. The full Stokes parameters of the filament were obtained in Hα and FeI 6302 Å lines. Using the data, we have studied the fine structure of the filament and obtained the parameters at the barb endpoints, including intensity, velocity and longitudinal magnetic field. Our results indicate: (a) the Doppler velocities are quiet different at barb endpoints; (b) the longitudinal magnetic fields at the barb endpoints are very weak; (c) there is a strong magnetic field structure under the filament spine.

  10. Solar Coronal Jets in Active Regions

    NASA Astrophysics Data System (ADS)

    Sterling, A. C.; Moore, R. L.; Martinez, F.; Falconer, D. A.

    2016-12-01

    Solar coronal jets are common in both coronal holes and in active regions. Recently, Sterling et al. (2015, Nature 523, 437), using data from Hinode/XRT and SDO/AIA, found that coronal jets originating in polar coronal holes result from the eruption of small-scale filaments (minifilaments). The jet bright point (JBP) seen in X-rays and hotter EUV channels off to one side of the base of the jet's spire develops at the location where the minifilament erupts, consistent with the JBPs being miniature versions of typical solar flares that occur in the wake of large-scale filament eruptions. Here we consider whether active region coronal jets also result from the same minifilament-eruption mechanism, or whether they instead result from a different process, such as emerging flux. Here we present observations of NOAA active region 12259, over 13-20 Jan 2015, using observations from Hinode/XRT, and from SDO/AIA and HMI. We focused on 13 standout jets that we identified from an initial survey of the XRT X-ray images, and we found many more jets in the AIA data set, which have higher cadence and more continuous coverage than our XRT data. All 13 jets originated from identifiable magnetic neutral lines; we further found magnetic flux cancelation to be occurring at essentially all of these neutral lines. At least 6 of those 13 jets were homologous, developing with similar morphology from nearly the same location, and in fact there were many more jets in the homologous sequence apparent in the higher-fidelity AIA data. Each of these homologous jets was consistent with minifilament-like ejections at the start of the jets. Other jets displayed a variety of morphologies, at least some of which were consistent with minifilament eruptions. For other jets however we have not yet clearly deciphered the driving mechanism. Our overall conclusions are similar to those of our earlier study of active region jets (Sterling et al. 2016, ApJ, 821, 100), where we found: some jets clearly to

  11. The evolution of active region loop plasma

    NASA Technical Reports Server (NTRS)

    Krall, K. R.; Antiochos, S. K.

    1980-01-01

    The adjustment of coronal active-region loops to changes in their heating rate is investigated numerically. The one-dimensional hydrodynamic equations are solved subject to boundary conditions in which heat flux-induced mass exchange between coronal and chromospheric components is allowed. The calculated evolution of physical parameters suggests that (1) mass supplied during chromospheric evaporation is much more effective in moderating coronal temperature excursions than when downward heat flux is dissipated by a static chromosphere, and (2) the method by which the chromosphere responds to changing coronal conditions can significantly influence coronal readjustment time scales. Observations are cited which illustrate the range of possible fluctuations in the heating rates.

  12. 76 FR 17839 - Proposed Information Collection; Comment Request; Northeast Region Permit Family of Forms

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-31

    ...--Permit Transfer, Notification Harvest Activity-- Aquaculture Live Rock, Request for Octocoral or... Form, South Atlantic Golden Crab Vessel Form, Colombian Treaty Vessel Form, Aquaculture Live Rock Site... minutes; Aquaculture Live Rock Site Evaluation Report, 45 minutes; Rock Shrimp Vessel Operator Permit Card...

  13. Pore-forming activity of clostridial binary toxins.

    PubMed

    Knapp, O; Benz, R; Popoff, M R

    2016-03-01

    Clostridial binary toxins (Clostridium perfringens Iota toxin, Clostridium difficile transferase, Clostridium spiroforme toxin, Clostridium botulinum C2 toxin) as Bacillus binary toxins, including Bacillus anthracis toxins consist of two independent proteins, one being the binding component which mediates the internalization into cell of the intracellularly active component. Clostridial binary toxins induce actin cytoskeleton disorganization through mono-ADP-ribosylation of globular actin and are responsible for enteric diseases. Clostridial and Bacillus binary toxins share structurally and functionally related binding components which recognize specific cell receptors, oligomerize, form pores in endocytic vesicle membrane, and mediate the transport of the enzymatic component into the cytosol. Binding components retain the global structure of pore-forming toxins (PFTs) from the cholesterol-dependent cytotoxin family such as perfringolysin. However, their pore-forming activity notably that of clostridial binding components is more related to that of heptameric PFT family including aerolysin and C. perfringens epsilon toxin. This review focuses upon pore-forming activity of clostridial binary toxins compared to other related PFTs. This article is part of a Special Issue entitled: Pore-Forming Toxins edited by Mauro Dalla Serra and Franco Gambale. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. Pederson Current Dissipation In Emerging Active Regions

    NASA Astrophysics Data System (ADS)

    Leake, James E.; Linton, M. G.

    2011-05-01

    Pederson current dissipation in emerging active regions. Certain regions of the solar atmosphere, such as the photosphere and chromosphere, as well as prominences, contain a significant amount of neutral atoms, and a complete description of the plasma requires including the effects of partial ionization. In the chromosphere the dissipation of Pederson currents is important for the evolution of emerging magnetic fields. Due to the relatively high number density in the chromosphere, the ion-neutral collision time-scale is much smaller than timescales associated with flux emergence. Hence we use a single-fluid approach to model the partially ionized plasma. Looking at both the emergence of large-scale sub-surface structures, and the emergence and reconnection of undulatory fields, we investigate the effect of Pederson current dissipation on the state of the emerging field, on magnetic reconnection and on dissipative heating of the atmosphere. Specifically we examine the effect of motions across fieldlines in the partially ionized regions, and how this can increase the free energy supplied to the corona by flux emergence. We also look at reconnection associated with flux emergence in the partially ionized atmosphere, and how this can account for observed small-scale brightenings (Ellerman Bombs).

  15. The role of energetic processing on solid-phase chemistry in star forming regions

    NASA Astrophysics Data System (ADS)

    Palumbo, M. E.; Urso, R. G.; Kaňuchová, Z.; Scirè, C.; Accolla, M.; Baratta, G. A.; Strazzulla, G.

    2016-05-01

    It is generally accepted that complex molecules observed in star forming regions are formed in the solid phase on icy grain mantles and are released to the gas-phase after desorption of icy mantles. Most of our knowledge on the physical and chemical properties of ices in star forming regions is based on the comparison between observations and laboratory experiments performed at low temperature (10-100 K). Here we present some recent laboratory experiments which show the formation of (complex) molecular species after ion bombardment of simple ices.

  16. HEROES Observations of a Quiescent Active Region

    NASA Astrophysics Data System (ADS)

    Shih, A. Y.; Christe, S.; Gaskin, J.; Wilson-Hodge, C.

    2014-12-01

    Hard X-ray (HXR) observations of solar flares reveal the signatures of energetic electrons, and HXR images with high dynamic range and high sensitivity can distinguish between where electrons are accelerated and where they stop. Even in the non-flaring corona, high-sensitivity HXR measurements may be able to detect the presence of electron acceleration. The High Energy Replicated Optics to Explore the Sun (HEROES) balloon mission added the capability of solar observations to an existing astrophysics balloon payload, HERO, which used grazing-incidence optics for direct HXR imaging. HEROES measures HXR emission from ~20 to ~75 keV with an angular resolution of 33" HPD. HEROES launched on 2013 September 21 from Fort Sumner, New Mexico, and had a successful one-day flight. We present the detailed analysis of the 7-hour observation of AR 11850, which sets new upper limits on the HXR emission from a quiescent active region, with corresponding constraints on the numbers of tens of keV energetic electrons present. Using the imaging capability of HEROES, HXR upper limits are also obtained for the quiet Sun surrounding the active region. We also discuss what can be achieved with new and improved HXR instrumentation on balloons.

  17. Active Region Loop Models and Observations

    NASA Astrophysics Data System (ADS)

    Landi, E.; Landini, M.

    2004-01-01

    The analysis of broad band images from EIT and TRACE and spectra from SUMER and CDS have triggered a heated debate on 1) whether the loops are isothermal for most of their length 2) whether they are multithermal across their section and 3) what is the shape of their heating function. Our work describes a detailed comparison between SOHO-CDS observations of an active region loop with a standard RTV-like loop model developed assuming a temperature-independent heating function in the energy balance equation and a variable loop cross-section. Observations of an active region loop recorded by CDS have been analyzed. Additional data from EIT MDI and Yohkoh-SXT have been considered. Electron density temperature and pressure along the selected loop structure have been measured by means of line ratio techniques and an emission measure analysis. Comparison with CDS data has shown that 1) the RTV-like model is not able to reproduce the observations 2) the loop is isothermal along most of its length 3) the loop is isothermal across its section.

  18. Young open clusters in the Galactic star forming region NGC 6357

    NASA Astrophysics Data System (ADS)

    Massi, F.; Giannetti, A.; Di Carlo, E.; Brand, J.; Beltrán, M. T.; Marconi, G.

    2015-01-01

    Context. NGC 6357 is an active star forming region with very young massive open clusters. These clusters contain some of the most massive stars in the Galaxy and strongly interact with nearby giant molecular clouds. Aims: We study the young stellar populations of the region and of the open cluster Pismis 24, focusing on their relationship with the nearby giant molecular clouds. We seek evidence of triggered star formation "propagating" from the clusters. Methods: We used new deep JHKs photometry, along with unpublished deep Spitzer/IRAC mid-infrared photometry, complemented with optical HST/WFPC2 high spatial resolution photometry and X-ray Chandra observations, to constrain age, initial mass function, and star formation modes in progress. We carefully examine and discuss all sources of bias (saturation, confusion, different sensitivities, extinction). Results: NGC 6357 hosts three large young stellar clusters, of which Pismis 24 is the most prominent. We found that Pismis 24 is a very young (~1-3 Myr) open cluster with a Salpeter-like initial mass function and a few thousand members. A comparison between optical and infrared photometry indicates that the fraction of members with a near-infrared excess (i.e., with a circumstellar disk) is in the range 0.3-0.6, consistent with its photometrically derived age. We also find that Pismis 24 is likely subdivided into a few different subclusters, one of which contains almost all the massive members. There are indications of current star formation triggered by these massive stars, but clear age trends could not be derived (although the fraction of stars with a near-infrared excess does increase towards the Hii region associated with the cluster). The gas out of which Pismis 24 formed must have been distributed in dense clumps within a cloud of less dense gas ~1 pc in radius. Conclusions: Our findings provide some new insight into how young stellar populations and massive stars emerge, and evolve in the first few Myr after

  19. Photometric and spectroscopic studies of star-forming regions within Wolf-Rayet galaxies

    NASA Astrophysics Data System (ADS)

    Karthick, M. Chrisphin; López-Sánchez, Ángel R.; Sahu, D. K.; Sanwal, B. B.; Bisht, Shuchi

    2014-03-01

    We present a study of the properties of star-forming regions within a sample of seven Wolf-Rayet (WR) galaxies. We analyse their morphologies, colours, star-formation rates (SFRs), metallicities and stellar populations, combining broad-band and narrow-band photometry with low-resolution optical spectroscopy. The UBVRI observations were made with the 2-m HCT (Himalayan Chandra Telescope) and 1-m ARIES telescope. The spectroscopic data were obtained using the Hanle Faint Object Spectrograph Camera (HFOSC) mounted on the 2-m HCT. The observed galaxies are NGC 1140, IRAS 07164+5301, NGC 3738, UM 311, NGC 6764, NGC 4861 and NGC 3003. The optical spectra were used to search for the faint WR features, to confirm that the ionization of the gas is caused by the massive stars, and to quantify the oxygen abundance of each galaxy using several independent empirical calibrations. We detected broad features originating in WR stars in NGC 1140 and 4861 and used them to derive the massive star populations. For these two galaxies we also derived the oxygen abundance using a direct estimation of the electron temperature of the ionized gas. The N/O ratio in NGC 4861 is ˜0.25-0.35 dex higher than expected, which may be a consequence of the chemical pollution by N-rich material released by WR stars. Using our Hα images we identified tens of star-forming regions within these galaxies, for which we derived the SFR. Our Hα-based SFR usually agrees with the SFR computed using the far-infrared and the radio-continuum flux. For all regions we found that the most recent star-formation event is 3-6 Myr old. We used the optical broad-band colours in combination with Starburst99 models to estimate the internal reddening and the age of the dominant underlying stellar population within all these regions. Knots in NGC 3738, 6764 and 3003 generally show the presence of an important old (400-1000 Myr) stellar population. However, the optical colours are not able to detect stars older than 20

  20. The Lifetimes of Phases in High-mass Star-forming Regions

    NASA Astrophysics Data System (ADS)

    Battersby, Cara; Bally, John; Svoboda, Brian

    2017-02-01

    High-mass stars form within star clusters from dense, molecular regions (DMRs), but is the process of cluster formation slow and hydrostatic or quick and dynamic? We link the physical properties of high-mass star-forming regions with their evolutionary stage in a systematic way, using Herschel and Spitzer data. In order to produce a robust estimate of the relative lifetimes of these regions, we compare the fraction of DMRs above a column density associated with high-mass star formation, N(H2) > 0.4–2.5 × 1022 cm‑2, in the “starless” (no signature of stars ≳10 {M}ȯ forming) and star-forming phases in a 2° × 2° region of the Galactic Plane centered at ℓ = 30°. Of regions capable of forming high-mass stars on ∼1 pc scales, the starless (or embedded beyond detection) phase occupies about 60%–70% of the DMR lifetime, and the star-forming phase occupies about 30%–40%. These relative lifetimes are robust over a wide range of thresholds. We outline a method by which relative lifetimes can be anchored to absolute lifetimes from large-scale surveys of methanol masers and UCHII regions. A simplistic application of this method estimates the absolute lifetime of the starless phase to be 0.2–1.7 Myr (about 0.6–4.1 fiducial cloud free-fall times) and the star-forming phase to be 0.1–0.7 Myr (about 0.4–2.4 free-fall times), but these are highly uncertain. This work uniquely investigates the star-forming nature of high column density gas pixel by pixel, and our results demonstrate that the majority of high column density gas is in a starless or embedded phase.

  1. Functional Specificity of the Visual Word Form Area: General Activation for Words and Symbols but Specific Network Activation for Words

    ERIC Educational Resources Information Center

    Reinke, Karen; Fernandes, Myra; Schwindt, Graeme; O'Craven, Kathleen; Grady, Cheryl L.

    2008-01-01

    The functional specificity of the brain region known as the Visual Word Form Area (VWFA) was examined using fMRI. We explored whether this area serves a general role in processing symbolic stimuli, rather than being selective for the processing of words. Brain activity was measured during a visual 1-back task to English words, meaningful symbols…

  2. Functional Specificity of the Visual Word Form Area: General Activation for Words and Symbols but Specific Network Activation for Words

    ERIC Educational Resources Information Center

    Reinke, Karen; Fernandes, Myra; Schwindt, Graeme; O'Craven, Kathleen; Grady, Cheryl L.

    2008-01-01

    The functional specificity of the brain region known as the Visual Word Form Area (VWFA) was examined using fMRI. We explored whether this area serves a general role in processing symbolic stimuli, rather than being selective for the processing of words. Brain activity was measured during a visual 1-back task to English words, meaningful symbols…

  3. X-ray emission from T Tauri stars in the Lupus 3 star-forming region

    NASA Astrophysics Data System (ADS)

    Gondoin, P.

    2006-08-01

    Aims.In this paper, I present analysis results of an {XMM-Newton} observation of the Lupus 3 region that contains a high proportion of young low mass (M < 0.3 M⊙) T Tauri stars in the Lupus star-forming complex. Methods: .The detection of X-ray sources in 0.5 to 4.5 keV images of the Lupus 3 core was performed using the standard source detection method of the {XMM-Newton} Science Analysis Software. The detected sources were correlated with a list of Herbig-Haro objects and Hα emission stars that contains mainly classical T Tauri stars, with a catalogue of weak-line T Tauri Stars and with a recent list of new low-mass members of the Lupus 3 dark cloud found in a visible-light spectroscopic survey at the center of the Lupus 3 star-forming core. The light curves and spectra of the brightest X-ray sources with known T Tauri star counterparts were analysed. Results: .One hundred and two X-ray sources were detected in the 30´ diameter field-of-view of the EPIC cameras, of which 25 have visible or near-IR counterparts that are known as pre-main sequence stars. Their X-ray luminosity ranges from 3 × 1028 to 3 × 1030 erg s-1. Two of these objects with mass estimates lower than 0.075 M⊙ have an X-ray luminosity of about 4-7 × 1028 erg s-1, comparable with that of flaring young brown dwarfs. A linear correlation is found between the X-ray luminosity and the mass or volume of the stars that is qualitatively expected from some models of distributed turbulent dynamos. The EPIC spectra of the X-ray brightest sources can be fitted using optically thin plasma emission models with two components at temperatures in the ranges 3-9 × 106 K and 1-50 × 107 K, respectively. The large emission measure of hot plasma may be caused by disruptions of magnetic fields associated with an intense flaring activity, while the X-ray emission from the "cool" plasma components may result from solar-type active regions. The emission measures of the plasma components are of the order of 1052

  4. Liposomal forms of rhenium cluster compounds: enhancement of biological activity.

    PubMed

    Shtemenko, Natalia I; Zabitskaya, Elena D; Berzenina, Oksana V; Yegorova, Dina E; Shtemenko, Alexander V

    2008-08-01

    Liposomal formulations of dinuclear cluster rhenium (Re) compounds were used in biochemical trials. Interaction of liposomal forms of some Re compounds with red blood cells in experiments in vitro showed strong cell-stabilizing properties. In the models of tumor growth and hemolytic anemia in vivo, liposomal forms had better therapeutic effects in comparison with their solutions. The process of formation of liposomes of cluster Re compounds with different organic ligands was investigated by the method of electronic absorption spectra and mechanism of their interactions with lipids is proposed. Encapsulation of cluster Re compounds to lipid coating may have activation significance for the quadruple Re-Re bond.

  5. Active Region Transient Brightenings : EIT Versus SXT

    NASA Astrophysics Data System (ADS)

    Berghmans, D.; McKenzie, D.; Clette, F.

    1999-10-01

    On May 13, 1998, the Extreme-Ultraviolet Imaging Telescope (EIT, on board SOHO) has produced a unique image sequence operating in 'shutterless mode' (SOHO JOP 80). In JOP 80, EIT is the leading instrument, followed by several space born instruments (SXT, TRACE, MDI, CDS, SUMER), as well as two observatories on the ground (in La Palma and Sac Peak). The target of the campaign was a relatively small but rapidly evolving active region (AR 8218). For the EIT contribution, a 15 s cadence was achieved in the Fe XII bandpass at 195 deg by leaving EIT's shutter open for 1 hour and operating the CCD in frame transfer mode. We have started the analysis of the huge data set, by making an inventory of the transients observed in the EIT image sequence. These transients range from a B3.5 flare producing a large plasma flow along pre-existing loops, to smaller EUV brightenings of active region loops. In addition, a new class of weaker footpoint brightenings was discovered that produce wave-like disturbances propagating along quasi-open field lines (see the presentation by Eva Robbrecht at this workshop). In this paper we take the opportunity provided by JOP 80, to investigate the correspondence of the transient brightenings observed by EIT in this active region, with the ARTB previously observed by SXT and studied by Shimizu (1992). Within the simultaneous high cadence SOHO JOP 80 image sequences, both EIT and SXT accummulated a few tens of brightening events. At the time of the writing of this abstract, we can say that most of the SXT events have indeed 1 or more EIT counterparts. Typically the SXT events are somewhat bigger than the EIT events where the latter are ussualy located toward the point of origin of the SXT events. Whereas a few brightenings exist in one dataset without any trace in the other dataset (in both directions), we have additionally for a few brightenings in the SXT data, a corresponding EIT darkening as if the plasma is suddenly heated and dissappears from

  6. Crystal Structure of an Active Form of Human MMP-1

    PubMed Central

    Iyer, Shalini; Visse, Robert; Nagase, Hideaki; Acharya, K. Ravi

    2006-01-01

    The extracellular matrix is a dynamic environment that constantly undergoes remodelling and degradation during vital physiological processes such as angiogenesis, wound healing, and development. Unbalanced extracellular matrix breakdown is associated with many diseases such as arthritis, cancer and fibrosis. Interstitial collagen is degraded by matrix metalloproteinases with collagenolytic activity by MMP-1, MMP-8 and MMP-13, collectively known as the collagenases. Matrix metalloproteinase 1 (MMP-1) plays a pivotal role in degradation of interstitial collagen types I, II, and III. Here, we report the crystal structure of the active form of human MMP-1 at 2.67 Å resolution. This is the first MMP-1 structure that is free of inhibitor and a water molecule essential for peptide hydrolysis is observed coordinated with the active site zinc. Comparing this structure with the human proMMP-1 shows significant structural differences, mainly in the relative orientation of the hemopexin domain, between the pro form and active form of the human enzyme. PMID:16890240

  7. NEAR-INFRARED CIRCULAR POLARIZATION SURVEY IN STAR-FORMING REGIONS: CORRELATIONS AND TRENDS

    SciTech Connect

    Kwon, Jungmi; Tamura, Motohide; Hough, James H.; Lucas, Phil W.; Kusakabe, Nobuhiko; Kandori, Ryo; Nagata, Tetsuya; Nakajima, Yasushi; Nagayama, Takahiro

    2014-11-01

    We have conducted a systematic near-infrared circular polarization (CP) survey in star-forming regions, covering high-mass, intermediate-mass, and low-mass young stellar objects. All the observations were made using the SIRPOL imaging polarimeter on the Infrared Survey Facility 1.4 m telescope at the South African Astronomical Observatory. We present the polarization properties of 10 sub-regions in 6 star-forming regions. The polarization patterns, extents, and maximum degrees of linear and circular polarizations are used to determine the prevalence and origin of CP in the star-forming regions. Our results show that the CP pattern is quadrupolar in general, the CP regions are extensive, up to 0.65 pc, the CP degrees are high, up to 20%, and the CP degrees decrease systematically from high- to low-mass young stellar objects. The results are consistent with dichroic extinction mechanisms generating the high degrees of CP in star-forming regions.

  8. Distribution of water in the G327.3-0.6 massive star-forming region

    NASA Astrophysics Data System (ADS)

    Leurini, S.; Herpin, F.; van der Tak, F.; Wyrowski, F.; Herczeg, G. J.; van Dishoeck, E. F.

    2017-06-01

    Aims: Following our past study of the distribution of warm gas in the G327.3-0.6 massive star-forming region, we aim here at characterizing the large-scale distribution of water in this active region of massive star formation made of individual objects in different evolutionary phases. We investigate possible variations of the water abundance as a function of evolution. Methods: We present Herschel/PACS (4'× 4') continuum maps at 89 and179 μm encompassing the whole region (Hii region and the infrared dark cloud, IRDC) and an APEX/SABOCA (2'× 2') map at 350 μm of the IRDC. New spectral Herschel/HIFI maps toward the IRDC region covering the low-energy water lines at 987 and 1113 GHz (and their H218O counterparts) are also presented and combined with HIFI pointed observations toward the G327 hot core region. We infer the physical properties of the gas through optical depth analysis and radiative transfer modeling of the HIFI lines. Results: The distribution of the continuum emission at 89 and 179 μm follows the thermal continuum emission observed at longer wavelengths, with a peak at the position of the hot core and a secondary peak in the Hii region, and an arch-like layer of hot gas west of this Hii region. The same morphology is observed in the p-H2O 111-000 line, in absorption toward all submillimeter dust condensations. Optical depths of approximately 80 and 15 are estimated and correspond to column densities of 1015 and 2 × 1014 cm-2, respectively, for the hot core and IRDC position. These values indicate an abundance of water relative to H2 of 3 × 10-8 toward the hot core, while the abundance of water does not change along the IRDC with values close to some 10-8. Infall (over at least 20″) is detected toward the hot core position with a rate of 1-1.3 × 10-2M⊙ /yr, high enough to overcome the radiation pressure that is due to the stellar luminosity. The source structure of the hot core region appears complex, with a cold outer gas envelope in

  9. Dynamics and evolution of emerging active regions .

    NASA Astrophysics Data System (ADS)

    Battiato, V.; Billotta, S.; Contarino, L.; Romano, P.; Spadaro, D.; Zuccarello, F.

    In the framework of the study on active region emergence, we report the results obtained from the analysis of two ARs (NOAA 10050 and NOAA 10407), characterized by different lifetimes: recurrent the former and short-lived (7 days) the latter. The data used were acquired during two observational campaigns carried out at THEMIS telescope in IPM mode, coordinated with other instruments (IOACT, DOT, BBSO, MDI/SOHO, EIT/SOHO, TRACE). The results obtained have provided indications on the atmospheric layers where the first manifestations of the emerging AR are evidenced, on the rate of emergence of magnetic flux, on the upward velocity of AFS, on asymmetries in downward motions in the AFS legs.

  10. FIP bias in a sigmoidal active region

    NASA Astrophysics Data System (ADS)

    Baker, D.; Brooks, D. H.; Démoulin, P.; van Driel-Gesztelyi, Lidia; Green, L. M.; Steed, K.; Carlyle, J.

    2014-01-01

    We investigate first ionization potential (FIP) bias levels in an anemone active region (AR) - coronal hole (CH) complex using an abundance map derived from Hinode/EIS spectra. The detailed, spatially resolved abundance map has a large field of view covering 359'' × 485''. Plasma with high FIP bias, or coronal abundances, is concentrated at the footpoints of the AR loops whereas the surrounding CH has a low FIP bias, ~1, i.e. photospheric abundances. A channel of low FIP bias is located along the AR's main polarity inversion line containing a filament where ongoing flux cancellation is observed, indicating a bald patch magnetic topology characteristic of a sigmoid/flux rope configuration.

  11. EUV Observations of Active Region Dynamics

    NASA Astrophysics Data System (ADS)

    Deluca, E. E.; Cirtain, J. W.; del Zanna, G.; Mason, H. E.; Martens, P. C.; Schmelz, J.; Golub, L.

    2005-05-01

    Data collected during SoHO JOP 146, in collaboration with TRACE, is used to investigate the physical characteristics of coronal active region loops as a function of time and position along and across loop structures. These data include TRACE images in all three EUV passbands, and simultaneous CDS spectroscopic observations. Preliminary measurements of the loop temperature both along the loop half-length and loop cross-section are presented as a function of time. We will show the temperature and density profiles of several structures as a function of position, show changes in temperature and density with time and characterize the coronal background emission. Questions raised by these results will be greatly advanced with the high resolution spectra available from the EIS on Solar-B.

  12. Canonical nucleosome organization at promoters forms during genome activation.

    PubMed

    Zhang, Yong; Vastenhouw, Nadine L; Feng, Jianxing; Fu, Kai; Wang, Chenfei; Ge, Ying; Pauli, Andrea; van Hummelen, Paul; Schier, Alexander F; Liu, X Shirley

    2014-02-01

    The organization of nucleosomes influences transcriptional activity by controlling accessibility of DNA binding proteins to the genome. Genome-wide nucleosome binding profiles have identified a canonical nucleosome organization at gene promoters, where arrays of well-positioned nucleosomes emanate from nucleosome-depleted regions. The mechanisms of formation and the function of canonical promoter nucleosome organization remain unclear. Here we analyze the genome-wide location of nucleosomes during zebrafish embryogenesis and show that well-positioned nucleosome arrays appear on thousands of promoters during the activation of the zygotic genome. The formation of canonical promoter nucleosome organization is independent of DNA sequence preference, transcriptional elongation, and robust RNA polymerase II (Pol II) binding. Instead, canonical promoter nucleosome organization correlates with the presence of histone H3 lysine 4 trimethylation (H3K4me3) and affects future transcriptional activation. These findings reveal that genome activation is central to the organization of nucleosome arrays during early embryogenesis.

  13. Active region helicity evolution and related coronal mass ejection activity.

    NASA Astrophysics Data System (ADS)

    Green, L.; Mandrini, C.; van Driel-Gesztelyi, L.; Demoulin, P.

    The computation of magnetic helicity has become increasingly important in the studies of solar activity. Observations of helical structures in the solar atmosphere, and their subsequent ejection into the interplanetary medium, have resulted in considerable interest to find the link between the amount of helicity in the coronal magnetic field and the origin of coronal mass ejections (CMEs). This is reinforced by theory which shows magnetic helicity to be a well preserved quantity (Berger, 1984), and so with a continued injection into the corona an endless accumulation will occur. CMEs therefore provide a natural method to remove helicity from the corona. Recent works (DeVore, 2000, Chae, 2001, Chae et al., 2001, Demoulin et al., 2002, Green et al., 2002) have endeavoured to find the source of helicity in the corona to explain the observed CME activity in specific cases. The main candidates being differential rotation, shear motions or a transfer of helicity from below the photosphere into the corona. In order to establish a confident relation between CMEs and helicity, these works needs to be expanded to include CME source regions with different characteristics. A study of a very different active region will be presented and the relationship between helicity content and CME activity will be discussed in the framework of the previous studies.

  14. VizieR Online Data Catalog: Parallaxes of high mass star forming regions (Reid+, 2014)

    NASA Astrophysics Data System (ADS)

    Reid, M. J.; Menten, K. M.; Brunthaler, A.; Zheng, X. W.; Dame, T. M.; Xu, Y.; Wu, Y.; Zhang, B.; Sanna, A.; Sato, M.; Hachisuka, K.; Choi, Y. K.; Immer, K.; Moscadelli, L.; Rygl, K. L. J.; Bartkiewicz, A.

    2016-04-01

    Table1 lists the parallaxes and proper motions of 103 regions of high-mass star formation measured with Very Long Baseline Interferometry (VLBI) techniques, using the National Radio Astronomy Observatory's Very Long Baseline Array (VLBA), the Japanese VLBI Exploration of Radio Astrometry (VERA; http://veraserver.mtk.nao.ac.jp) project, and the European VLBI Network (EVN). We have include three red supergiants (NML Cyg, S Per, VY CMa) as indicative of high-mass star forming regions. (2 data files).

  15. a Census of Medium-Mass Star-Forming Regions Within 1 KPC

    NASA Astrophysics Data System (ADS)

    Barnes, Peter J.; Myers, Philip C.; Burton, Michael G.

    We have used 13CO to associate kinematic distances for a sample of prospective medium-mass star-forming regions in the southern Milky Way. This complements the equivalent northern survey already completed and we present a valuable new source list for galactic star formation studies comprising dozens of previously unrecognised such regions. We also present preliminary results of maps of C18O CS and/or NH3 emission from these sources and analysis of these sources' spectral energy distributions.

  16. VizieR Online Data Catalog: Star forming regions sulphur ICFs (Dors+, 2016)

    NASA Astrophysics Data System (ADS)

    Dors, O. L.; Perez-Montero, E.; Hagele, G. F.; Cardaci, M. V.; Krabbe, A. C.

    2016-10-01

    We compiled from the literature emission-line intensities of HII regions and star-forming galaxies obtained in the optical and infrared spectral ranges. These measurements were used to obtain sulphur and oxygen ionic abundances in order to verify if our photoionization models are representative of real HIi regions, to check if the theoretical ICFs are compatible with the ones derived directly from observations and investigating the S/O-O/H relation. (5 data files).

  17. THE EVOLUTION OF DARK CANOPIES AROUND ACTIVE REGIONS

    SciTech Connect

    Wang, Y.-M.; Robbrecht, E.; Muglach, K. E-mail: eva.robbrecht@oma.be

    2011-05-20

    As observed in spectral lines originating from the chromosphere, transition region, and low corona, active regions are surrounded by an extensive 'circumfacular' area which is darker than the quiet Sun. We examine the properties of these dark moat- or canopy-like areas using Fe IX 17.1 nm images and line-of-sight magnetograms from the Solar Dynamics Observatory. The 17.1 nm canopies consist of fibrils (horizontal fields containing extreme-ultraviolet-absorbing chromospheric material) clumped into featherlike structures. The dark fibrils initially form a quasiradial or vortical pattern as the low-lying field lines fanning out from the emerging active region connect to surrounding network and intranetwork elements of opposite polarity. The area occupied by the 17.1 nm fibrils expands as supergranular convection causes the active-region flux to spread into the background medium; the outer boundary of the dark canopy stabilizes where the diffusing flux encounters a unipolar region of opposite sign. The dark fibrils tend to accumulate in regions of weak longitudinal field and to become rooted in mixed-polarity flux. To explain the latter observation, we note that the low-lying fibrils are more likely to interact with small loops associated with weak, opposite-polarity flux elements in close proximity, than with high loops anchored inside strong unipolar network flux. As a result, the 17.1 nm fibrils gradually become concentrated around the large-scale polarity inversion lines (PILs), where most of the mixed-polarity flux is located. Systematic flux cancellation, assisted by rotational shearing, removes the field component transverse to the PIL and causes the fibrils to coalesce into long PIL-aligned filaments.

  18. STAR-FORMING REGION Sh 2-233IR. I. DEEP NEAR-INFRARED OBSERVATIONS TOWARD THE EMBEDDED STELLAR CLUSTERS

    SciTech Connect

    Yan, Chi-Hung; Wang, Shiang-Yu; Su, Yu-Nang; Minh, Y. C.; Ginsburg, Adam

    2010-09-01

    We observed the Sh 2-233IR (S233IR) region with better sensitivity in the near-infrared than in previous studies of this region. By applying statistical subtraction of the background stars, we identified member sources and derived the age and mass of three distinguishable sub-groups in this region: Sh 2-233IR NE, Sh 2-233IR SW, and the 'distributed stars' over the whole cloud. Star formation may occur sequentially with a relatively small age difference ({approx}0.2-0.3 Myr) between subclusters. We found that the slopes for the initial mass function ({Gamma} {approx} -0.5) of two subclusters are flatter than those of Salpeter, which suggests that more massive stars were preferentially formed in those clusters compared to other Galactic star-forming regions. These subclusters may not result from the overall collapse of the whole cloud, but have formed by triggering before the previous star formation activities disturbed the natal molecular cloud. Additionally, high star formation efficiency ({approx}>40%) of the subclusters may also suggest that stars form very efficiently in the center of the northeast.

  19. Substrate-emitting semiconductor laser with a trapezoidal active region

    SciTech Connect

    Dikareva, N V; Nekorkin, S M; Karzanova, M V; Zvonkov, B N; Aleshkin, V Ya; Dubinov, A A; Afonenko, A A

    2014-04-28

    Semiconductor lasers with a narrow (∼2°) directional pattern in the planes both parallel and perpendicular to the p–n junction are fabricated. To achieve a low radiation divergence in the p–n junction plane, the active region in this plane was designed in the form of a trapezium. The narrow directional pattern in the plane perpendicular to the p–n junction was ensured by the use of a leaky mode, through which more than 90% of laser power was coupled out. (lasers)

  20. Hinode Observations of an Eruption from a Sigmoidal Active Region

    NASA Astrophysics Data System (ADS)

    Green, L. M.; Wallace, A. J.; Kliem, B.

    2012-08-01

    We analyse the evolution of a bipolar active region which produces an eruption during its decay phase. The soft X-ray arcade develops high shear over a time span of two days and transitions to sigmoidal shortly before the eruption. We propose that the continuous sigmoidal soft X-ray threads indicate that a flux rope has formed which is lying low in the solar atmosphere with a bald patch separatrix surface topology. The formation of the flux rope is driven by the photospheric evolution which is dominated by fragmentation of the main polarities, motion due to supergranular flows and cancellation at the polarity inversion line.

  1. Emission Measure Distribution and Heating of Two Active Region Cores

    NASA Technical Reports Server (NTRS)

    Tripathi, Durgesh; Klimchuk, James A.; Mason, Helen E.

    2011-01-01

    Using data from the Extreme-ultraviolet Imaging Spectrometer aboard Hinode, we have studied the coronal plasma in the core of two active regions. Concentrating on the area between opposite polarity moss, we found emission measure distributions having an approximate power-law form EM/T(exp 2.4) from log T = 5.55 up to a peak at log T = 6.57. The observations are explained extremely well by a simple nanoflare model. However, in the absence of additional constraints, the observations could possibly also be explained by steady heating.

  2. Channel-Forming Activities in the Glycosomal Fraction from the Bloodstream Form of Trypanosoma brucei

    PubMed Central

    Miinalainen, Ilkka J.; Hiltunen, J. Kalervo; Michels, Paul A. M.; Antonenkov, Vasily D.

    2012-01-01

    Background Glycosomes are a specialized form of peroxisomes (microbodies) present in unicellular eukaryotes that belong to the Kinetoplastea order, such as Trypanosoma and Leishmania species, parasitic protists causing severe diseases of livestock and humans in subtropical and tropical countries. The organelles harbour most enzymes of the glycolytic pathway that is responsible for substrate-level ATP production in the cell. Glycolysis is essential for bloodstream-form Trypanosoma brucei and enzymes comprising this pathway have been validated as drug targets. Glycosomes are surrounded by a single membrane. How glycolytic metabolites are transported across the glycosomal membrane is unclear. Methods/Principal Findings We hypothesized that glycosomal membrane, similarly to membranes of yeast and mammalian peroxisomes, contains channel-forming proteins involved in the selective transfer of metabolites. To verify this prediction, we isolated a glycosomal fraction from bloodstream-form T.brucei and reconstituted solubilized membrane proteins into planar lipid bilayers. The electrophysiological characteristics of the channels were studied using multiple channel recording and single channel analysis. Three main channel-forming activities were detected with current amplitudes 70–80 pA, 20–25 pA, and 8–11 pA, respectively (holding potential +10 mV and 3.0 M KCl as an electrolyte). All channels were in fully open state in a range of voltages ±150 mV and showed no sub-conductance transitions. The channel with current amplitude 20–25 pA is anion-selective (PK+/PCl−∼0.31), while the other two types of channels are slightly selective for cations (PK+/PCl− ratios ∼1.15 and ∼1.27 for the high- and low-conductance channels, respectively). The anion-selective channel showed an intrinsic current rectification that may suggest a functional asymmetry of the channel's pore. Conclusions/Significance These results indicate that the membrane of glycosomes apparently

  3. Centrally formed acetaldehyde mediates ethanol-induced brain PKA activation.

    PubMed

    Tarragon, E; Baliño, P; Aragon, C M G

    2014-09-19

    Centrally formed acetaldehyde has proven to be responsible for several psychopharmacological effects induced by ethanol. In addition, it has been suggested that the cAMP-PKA signaling transduction pathway plays an important role in the modulation of several ethanol-induced behaviors. Therefore, we hypothesized that acetaldehyde might be ultimately responsible for the activation of this intracellular pathway. We used three pharmacological agents that modify acetaldehyde activity (α-lipoic acid, aminotriazole, and d-penicillamine) to study the role of this metabolite on EtOH-induced PKA activation in mice. Our results show that the injection of α-lipoic acid, aminotriazole and d-penicillamine prior to acute EtOH administration effectively blocks the PKA-enhanced response to EtOH in the brain. These results strongly support the hypothesis of a selective release of acetaldehyde-dependent Ca(2+) as the mechanism involved in the neurobehavioral effects elicited by EtOH.

  4. MHD simulation of mass injection - A mechanism for the formation of active region loops

    NASA Technical Reports Server (NTRS)

    Cheng, Chung-Chieh; Wu, S. T.

    1988-01-01

    A two-dimensional nonlinear MHD numerical code is used to simulate the formation and dynamic evolution of active regions loops subjected to mass injections at the footpoints. The UV and X-ray signatures of the plasmas are also calculated. It is found that it is possible to form loops in a low beta plasma that occurs in the solar active regions.

  5. Weak and Compact Radio Emission in Early High-Mass Star Forming Regions

    NASA Astrophysics Data System (ADS)

    Rosero Rueda, Viviana Andrea

    2017-04-01

    I present a high sensitivity radio continuum survey at 6 and 1.3 cm using the Karl. G. Jansky Very Large Array towards a sample of 58 high-mass star forming regions. The sample was chosen from clumps within infrared dark clouds, also known as cold molecular clumps (CMCs) with and without IR sources (CMC-IRs, CMCs, respectively) and hot molecular cores (HMCs), with no previous radio continuum detection at the 1 mJy level. Due to the remarkable improvement in the continuum sensitivity of the VLA, this survey achieved map rms levels of 3-10 ?Jy/beam at sub-arcsecond angular resolution. From this dataset I extracted 70 centimeter continuum sources that are associated with 1.2 mm dust clumps. Most sources are weak, compact, and are prime candidates for high-mass protostars. Detection rates of radio sources associated with the mm dust clumps for CMCs, CMC-IRs and HMCs are 6%, 53% and 100%, respectively. This result is consistent with increasing high-mass star formation activity from CMCs to HMCs. I calculated 5-25 GHz spectral indices using power law fits and obtain a median value of 0.5 (i.e., flux increasing with frequency), which is consistent with thermal emission from ionized jets. Moreover, these detected ionized jets towards high-mass stars are well correlated with jets formed towards lower masses, providing further evidence that ionized jets from any luminosity have a common origin. Ultimately, this set of detections will likely provide good candidates to enable new tests of high-mass star formation theories, in particular testing predictions of core accretion and competitive accretion models.

  6. Inner and outer star forming regions over the discs of spiral galaxies I. Sample characterization

    NASA Astrophysics Data System (ADS)

    Rodríguez-Baras, Marina; Díaz, A. I.; Rosales-Ortega, F. F.

    2017-03-01

    This project is aimed at understanding the dependence of star formation on the environment by analysing young stellar populations in two very different positions in disk galaxies: circumnuclear and outer disk giant regions. Integral field spectroscopy (IFS) provide an ideal means to achieve these goals providing simultaneous spatial and spectral resolution. Here we present the characterization of the work sample, composed by 671 outer regions and 725 inner regions from 263 isolated spirals galaxies observed by the CALIFA survey. The wide number of regions in both samples allows us to obtain statistically relevant results about the influence of metallicity, density and environment on star formation, and how it disseminates over the galaxy, to obtain evolutionary stories for the star-forming regions and to compare our results with models of massive star formation and galactic chemical evolution.

  7. Armenia as a Regional Centre for Astronomy for Development activities

    NASA Astrophysics Data System (ADS)

    Mickaelian, A.

    2015-03-01

    The Byurakan Astrophysical Observatory (BAO, Armenia, http://www.bao.am) are among the candidate IAU Regional Nodes for Astronomy for Development activities. It is one of the main astronomical centers of the former Soviet Union and the Middle East region. At present there are 48 qualified researchers at BAO, including six Doctors of Science and 30 PhDs. Five important observational instruments are installed at BAO, the larger ones being 2.6m Cassegrain (ZTA-2.6) and 1m Schmidt (the one that provided the famous Markarian survey). BAO is regarded as a national scientific-educational center, where a number of activities are being organized, such as: international conferences (4 IAU symposia and 1 IAU colloquium, JENAM-2007, etc.), small workshops and discussions, international summer schools (1987, 2006, 2008 and 2010), and Olympiads. BAO collaborates with scientists from many countries. The Armenian Astronomical Society (ArAS, http://www.aras.am/) is an NGO founded in 2001; it has 93 members and it is rather active in the organization of educational, amateur, popular, promotional and other matters. The Armenian Virtual Observatory (ArVO, http://www.aras.am/Arvo/arvo.htm) is one of the 17 national VO projects forming the International Virtual Observatories Alliance (IVOA) and is the only VO project in the region serving also for educational purposes. A number of activities are planned, such as management, coordination and evaluation of the IAU programs in the area of development and education, establishment of the new IAU endowed lectureship program and organization of seminars and public lectures, coordination and initiation of fundraising activities for astronomy development, organization of regional scientific symposia, conferences and workshops, support to Galileo Teacher Training Program (GTTP), production/publication of educational and promotional materials, etc.

  8. 76 FR 30738 - Agency Information Collection Activities: Form G-845 and Form G-845 Supplement, Revision of a...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-26

    ... SECURITY U.S. Citizenship and Immigration Services Agency Information Collection Activities: Form G-845 and Form G- 845 Supplement, Revision of a Currently Approved Information Collection; Comment Request ACTION: 30-Day Notice of Information Collection under Review: Form G- 845 and Form G-845 Supplement, Document...

  9. 76 FR 27077 - Agency Information Collection Activities: Form AR-11 and Form AR-11SR, Extension of an Existing...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-10

    ... SECURITY U.S. Citizenship and Immigration Services Agency Information Collection Activities: Form AR-11 and Form AR- 11SR, Extension of an Existing Information Collection; Comment Request ACTION: 60-Day Notice of Information Collection under Review: Form AR- 11 and Form AR-11SR, Alien's Change of Address Card...

  10. YOUNG STELLAR OBJECTS IN THE MASSIVE STAR-FORMING REGION W49

    SciTech Connect

    Saral, G.; Hora, J. L.; Willis, S. E.; Koenig, X. P.; Gutermuth, R. A.; Saygac, A. T.

    2015-11-01

    We present the initial results of our investigation of the star-forming complex W49, one of the youngest and most luminous massive star-forming regions in our Galaxy. We used Spitzer/Infrared Array Camera (IRAC) data to investigate massive star formation with the primary objective of locating a representative set of protostars and the clusters of young stars that are forming around them. We present our source catalog with the mosaics from the IRAC data. In this study we used a combination of IRAC, MIPS, Two Micron All Sky Survey, and UKIRT Deep Infrared Sky Survey (UKIDSS) data to identify and classify the young stellar objects (YSOs). We identified 232 Class 0/I YSOs, 907 Class II YSOs, and 74 transition disk candidate objects using color–color and color–magnitude diagrams. In addition, to understand the evolution of star formation in W49, we analyzed the distribution of YSOs in the region to identify clusters using a minimal spanning tree method. The fraction of YSOs that belong to clusters with ≥7 members is found to be 52% for a cutoff distance of 96″, and the ratio of Class II/I objects is 2.1. We compared the W49 region to the G305 and G333 star-forming regions and concluded that W49 has the richest population, with seven subclusters of YSOs.

  11. Region 9 Tribal Minor NSR: New Source General Application (Form NEW)

    EPA Pesticide Factsheets

    This form should be used to register New or Modified Minor Sources (except Oil and Gas Industry Sources until March 2, 2016) with proposed construction or modifications that are subject to minor NSR with the EPA Region 9 Tribal NSR Permitting Program.

  12. Looking for phase-space structures in star-forming regions: an MST-based methodology

    NASA Astrophysics Data System (ADS)

    Alfaro, Emilio J.; González, Marta

    2016-03-01

    We present a method for analysing the phase space of star-forming regions. In particular we are searching for clumpy structures in the 3D sub-space formed by two position coordinates and radial velocity. The aim of the method is the detection of kinematic segregated radial velocity groups, that is, radial velocity intervals whose associated stars are spatially concentrated. To this end we define a kinematic segregation index, tilde{Λ }(RV), based on the Minimum Spanning Tree graph algorithm, which is estimated for a set of radial velocity intervals in the region. When tilde{Λ }(RV) is significantly greater than 1 we consider that this bin represents a grouping in the phase space. We split a star-forming region into radial velocity bins and calculate the kinematic segregation index for each bin, and then we obtain the spectrum of kinematic groupings, which enables a quick visualization of the kinematic behaviour of the region under study. We carried out numerical models of different configurations in the sub-space of the phase space formed by the coordinates and the that various case studies illustrate. The analysis of the test cases demonstrates the potential of the new methodology for detecting different kind of groupings in phase space.

  13. WIDE-FIELD INFRARED SURVEY EXPLORER OBSERVATIONS OF THE EVOLUTION OF MASSIVE STAR-FORMING REGIONS

    SciTech Connect

    Koenig, X. P.; Leisawitz, D. T.; Benford, D. J.; Padgett, D. L.; Rebull, L. M.

    2012-01-10

    We present the results of a mid-infrared survey of 11 outer Galaxy massive star-forming regions and 3 open clusters with data from the Wide-field Infrared Survey Explorer (WISE). Using a newly developed photometric scheme to identify young stellar objects and exclude extragalactic contamination, we have studied the distribution of young stars within each region. These data tend to support the hypothesis that latter generations may be triggered by the interaction of winds and radiation from the first burst of massive star formation with the molecular cloud material leftover from that earlier generation of stars. We dub this process the 'fireworks hypothesis' since star formation by this mechanism would proceed rapidly and resemble a burst of fireworks. We have also analyzed small cutout WISE images of the structures around the edges of these massive star-forming regions. We observe large (1-3 pc size) pillar and trunk-like structures of diffuse emission nebulosity tracing excited polycyclic aromatic hydrocarbon molecules and small dust grains at the perimeter of the massive star-forming regions. These structures contain small clusters of emerging Class I and Class II sources, but some are forming only a single to a few new stars.

  14. Wide-Field Infrared Survey Explorer Observations of the Evolution of Massive Star-Forming Regions

    NASA Technical Reports Server (NTRS)

    Koenig, X. P.; Leisawitz, D. T.; Benford, D. J.; Rebull, L. M.; Padgett, D. L.; Asslef, R. J.

    2012-01-01

    We present the results of a mid-infrared survey of II outer Galaxy massive star-forming regions and 3 open clusters with data from the Wide-field Infrared Survey Explorer (WISE). Using a newly developed photometric scheme to identify young stellar objects and exclude extragalactic contamination, we have studied the distribution of young stars within each region. These data tend to support the hypothesis that latter generations may be triggered by the interaction of winds and radiation from the first burst of massive star formation with the molecular cloud material leftover from that earlier generation of stars. We dub this process the "fireworks hypothesis" since star formation by this mechanism would proceed rapidly and resemble a burst of fireworks. We have also analyzed small cutout WISE images of the structures around the edges of these massive star-forming regions. We observe large (1-3 pc size) pillar and trunk-like structures of diffuse emission nebulosity tracing excited polycyclic aromatic hydrocarbon molecules and small dust grains at the perimeter of the massive star-forming regions. These structures contain small clusters of emerging Class I and Class II sources, but some are forming only a single to a few new stars.

  15. Wide-Field Infrared Survey Explorer Observations of the Evolution of Massive Star-Forming Regions

    NASA Technical Reports Server (NTRS)

    Koenig, X. P.; Leisawitz, D. T.; Benford, D. J.; Rebull, L. M.; Padgett, D. L.; Assef, R. J.

    2011-01-01

    We present the results of a mid-infrared survey of 11 outer Galaxy massive star-forming regions and 3 open clusters with data from the Wide-field Infrared Survey Explorer (WISE). Using a newly developed photometric scheme to identify young stellar objects and exclude extragalactic contamination, we have studied the distribution of young stars within each region. These data tend to support the hypothesis that latter generations may be triggered by the interaction of winds and radiation from the first burst of massive star formation with the molecular cloud material leftover from that earlier generation of stars.We dub this process the "fireworks hypothesis" since star formation by this mechanism would proceed rapidly and resemble a burst of fireworks.We have also analyzed small cutout WISE images of the structures around the edges of these massive star-forming regions. We observe large (1-3 pc size) pillar and trunk-like structures of diffuse emission nebulosity tracing excited polycyclic aromatic hydrocarbon molecules and small dust grains at the perimeter of the massive star-forming regions. These structures contain small clusters of emerging Class I and Class II sources, but some are forming only a single to a few new stars.

  16. Wide-Field Infrared Survey Explorer Observations of the Evolution of Massive Star-Forming Regions

    NASA Technical Reports Server (NTRS)

    Koenig, X. P.; Leisawitz, D. T.; Benford, D. J.; Rebull, L. M.; Padgett, D. L.; Asslef, R. J.

    2012-01-01

    We present the results of a mid-infrared survey of II outer Galaxy massive star-forming regions and 3 open clusters with data from the Wide-field Infrared Survey Explorer (WISE). Using a newly developed photometric scheme to identify young stellar objects and exclude extragalactic contamination, we have studied the distribution of young stars within each region. These data tend to support the hypothesis that latter generations may be triggered by the interaction of winds and radiation from the first burst of massive star formation with the molecular cloud material leftover from that earlier generation of stars. We dub this process the "fireworks hypothesis" since star formation by this mechanism would proceed rapidly and resemble a burst of fireworks. We have also analyzed small cutout WISE images of the structures around the edges of these massive star-forming regions. We observe large (1-3 pc size) pillar and trunk-like structures of diffuse emission nebulosity tracing excited polycyclic aromatic hydrocarbon molecules and small dust grains at the perimeter of the massive star-forming regions. These structures contain small clusters of emerging Class I and Class II sources, but some are forming only a single to a few new stars.

  17. Wide-Field Infrared Survey Explorer Observations of the Evolution of Massive Star-Forming Regions

    NASA Technical Reports Server (NTRS)

    Koenig, X. P.; Leisawitz, D. T.; Benford, D. J.; Rebull, L. M.; Padgett, D. L.; Assef, R. J.

    2011-01-01

    We present the results of a mid-infrared survey of 11 outer Galaxy massive star-forming regions and 3 open clusters with data from the Wide-field Infrared Survey Explorer (WISE). Using a newly developed photometric scheme to identify young stellar objects and exclude extragalactic contamination, we have studied the distribution of young stars within each region. These data tend to support the hypothesis that latter generations may be triggered by the interaction of winds and radiation from the first burst of massive star formation with the molecular cloud material leftover from that earlier generation of stars.We dub this process the "fireworks hypothesis" since star formation by this mechanism would proceed rapidly and resemble a burst of fireworks.We have also analyzed small cutout WISE images of the structures around the edges of these massive star-forming regions. We observe large (1-3 pc size) pillar and trunk-like structures of diffuse emission nebulosity tracing excited polycyclic aromatic hydrocarbon molecules and small dust grains at the perimeter of the massive star-forming regions. These structures contain small clusters of emerging Class I and Class II sources, but some are forming only a single to a few new stars.

  18. The Life Cycle of Active Region Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Cheung, M. C. M.; van Driel-Gesztelyi, L.; Martínez Pillet, V.; Thompson, M. J.

    2017-09-01

    We present a contemporary view of how solar active region magnetic fields are understood to be generated, transported and dispersed. Empirical trends of active region properties that guide model development are discussed. Physical principles considered important for active region evolution are introduced and advances in modeling are reviewed.

  19. Mantle diapirism and the formation of newly formed basins and surrounding centrifugally vergence orogens in the Mediterranean and Caribbean regions

    NASA Astrophysics Data System (ADS)

    Goncharov, M. A.; Koronovskii, N. V.; Raznitsin, Yu. N.; Svalova, V. B.

    2015-11-01

    Mantle diapirism contributes considerably to the formation of newly formed basins and surrounding centrifugally vergence fold-thrust belts in the Mediterranean and Caribbean regions. Mantle diapirism results from density inversion in the geosphere of astenosphere+lithosphere geosystem. Such inversion has become a driving force in the background of increasing heat flow caused by the heat-resistant convergence of Africa and Eurasia (in the case of the Mediterranean region) and North and South Americas (Caribbean region) in the Cenozoic. Mantle diapirism is caused by unstable gravity in the periods of tectonomagmatic activations. The analytical solution of the problem yields the critical parameters coupling the mantle flow dynamics and surface relief evolution. The difference between the structures and evolutions for Mediterranean and Caribbean regions is the following. In the Mediterranean region, the mantle diapirism produces newly formed basins of intercontinental seas at the final stage of Africa-Eurasia convergence (in the Cenozoic). In the Caribbean region, intensive mantle diapirism first disjoined the North and South Americas in the Mesozoic, and then played the same role as in the Mediterranean for the convergence of these continents in the Cenozoic.

  20. Dynamics of emerging active region flux loops

    NASA Technical Reports Server (NTRS)

    Fan, Y.; Fisher, G. H.; Mcclymont, A. N.

    1994-01-01

    The buoyant rise of a magnetic flux loop arising from a single perturbed segment of a toroidal flux ring lying slightly beneath the base of the convection zone is studied by way of numerical simulations. We have considered flux loop evolution assuming both solid-body rotation, and differential rotation consistent with recent results from helioseismology. Our major results are presented, and we offer some speculations on the decay of active regions, based on the results of our studies. We speculate that as plasma in the tube attempts to establish hydrostatic equilibrium along the field lines after the flux emergence has taken place, the tube field strength at some intermediate depths below the surface becomes sufficiently small at the surface portions of the tube (which have cooled and undergone convective collapse) become dynamically disconnected from those portions near the base of the convection zone. The surface proportions of the emerged flux tubes are then transported by motions near the photosphere, such as supergranular convection and meridional flow.

  1. Spitzer Local Volume Legacy (LVL) Star-Forming Regions: Luminosity Functions

    NASA Astrophysics Data System (ADS)

    Cook, David O.; Dale, Daniel A.; Lee, Janice C.; LVL Team

    2015-01-01

    The conversion of gas into stars is one of the most fundamental processes in the universe, yet the effects of environmental conditions are poorly constrained. Observations of star-forming regions (young star clusters and HII regions) have shown evidence of a fractal pattern in their mass and luminosity distributions. The Mass Function (MF), and similarly the Luminosity Function (LF), of star-forming regions can be approximated as a power-law and is characterized by the power-law slope. A consistent slope of -2 has been observed across numerous galaxies, however, systematic deviations from this canonical slope have been measured across different environments. We present the LF slopes for 258 nearby galaxies in the Local Volume Legacy (LVL) sample utilizing tens of thousands of Hα- and FUV-selected sources. We test any relationships between LF slope and global galaxy properties to quantify the effect of environment on the star formation process. In addition, we combine the entire star-forming region sample in an attempt to characterize a previously proposed break in the HII region LF power-law at L˜38.6 erg/s.

  2. Mycelial forms of Pseudallescheria boydii present ectophosphatase activities.

    PubMed

    Kiffer-Moreira, Tina; Pinheiro, Ana Acacia S; Pinto, Márcia R; Esteves, Fabiano F; Souto-Padrón, Thais; Barreto-Bergter, Eliana; Meyer-Fernandes, José R

    2007-08-01

    Phosphatase activities were characterized in intact mycelial forms of Pseudallescheria boydii, which are able to hydrolyze the artificial substrate p-nitrophenylphosphate (p-NPP) to p-nitrophenol (p-NP) at a rate of 41.41+/-2.33 nmol p-NP per h per mg dry weight, linearly with increasing time and with increasing cell density. MgCl2, MnCl2 and ZnCl2 were able to increase the (p-NPP) hydrolysis while CdCl2 and CuCl2 inhibited it. The (p-NPP) hydrolysis was enhanced by increasing pH values (2.5-8.5) over an approximately 5-fold range. High sensitivity to specific inhibitors of alkaline and acid phosphatases suggests the presence of both acid and alkaline phosphatase activities on P. boydii mycelia surface. Cytochemical localization of the acid and alkaline phosphatase showed electron-dense cerium phosphate deposits on the cell wall, as visualized by electron microscopy. The product of p-NPP hydrolysis, inorganic phosphate (Pi), and different inhibitors for phosphatase activities inhibited p-NPP hydrolysis in a dose-dependent manner, but only the inhibition promoted by sodium orthovanadate and ammonium molybdate is irreversible. Intact mycelial forms of P. boydii are also able to hydrolyze phosphoaminoacids with different specificity.

  3. The growth of the central region by acquisition of counterrotating gas in star-forming galaxies.

    PubMed

    Chen, Yan-Mei; Shi, Yong; Tremonti, Christy A; Bershady, Matt; Merrifield, Michael; Emsellem, Eric; Jin, Yi-Fei; Huang, Song; Fu, Hai; Wake, David A; Bundy, Kevin; Stark, David; Lin, Lihwai; Argudo-Fernandez, Maria; Bergmann, Thaisa Storchi; Bizyaev, Dmitry; Brownstein, Joel; Bureau, Martin; Chisholm, John; Drory, Niv; Guo, Qi; Hao, Lei; Hu, Jian; Li, Cheng; Li, Ran; Lopes, Alexandre Roman; Pan, Kai-Ke; Riffel, Rogemar A; Thomas, Daniel; Wang, Lan; Westfall, Kyle; Yan, Ren-Bin

    2016-10-19

    Galaxies grow through both internal and external processes. In about 10% of nearby red galaxies with little star formation, gas and stars are counter-rotating, demonstrating the importance of external gas acquisition in these galaxies. However, systematic studies of such phenomena in blue, star-forming galaxies are rare, leaving uncertain the role of external gas acquisition in driving evolution of blue galaxies. Here, based on new measurements with integral field spectroscopy of a large representative galaxy sample, we find an appreciable fraction of counter-rotators among blue galaxies (9 out of 489 galaxies). The central regions of blue counter-rotators show younger stellar populations and more intense, ongoing star formation than their outer parts, indicating ongoing growth of the central regions. The result offers observational evidence that the acquisition of external gas in blue galaxies is possible; the interaction with pre-existing gas funnels the gas into nuclear regions (<1 kpc) to form new stars.

  4. Investigation flora and life form of plants in protected region Sarigol (North Khorasan Province, Iran).

    PubMed

    Nadaf, M; Mortazavi, S M

    2011-01-01

    Apart Flora, life form and chorotype of plants in protected region Sarigol was investigated in this study. It's located at the 57 degrees 47' to 57 degrees 76' Eastern latitude and 37 degrees 55' to 37 degrees 80' Northern longitude. A part plant of this area was collected in this region by classical method of regional floristic studies. The results of field investigation were identification of 78 plant species belong to 66 genera and 25 families. Lamiaceae, Poaceae, Fabaceae, Brassicaceae and Asteraceae were the most dominant families analysis of life form has shown proportion hemicryptophytes 39.74, followed by therophytes 21.79%, chamaephytes 19.23%, cryptophytes 11.53% and phanerophytes 7.69%. phytogeographical data has indicated that the most plants belong to the Irano-Turanian floral elements 75.64%.

  5. Photometric observations of the energetics of small solar active regions

    SciTech Connect

    Lawrence, J.K.; Chapman, G.A. )

    1990-10-01

    The energetics of small solar active regions was investigated using for the analysis the photometric solar images taken from July 29 to September 6, 1984 with the San Fernando Observatory's 28-cm vacuum telescope, vacuum spectroheliograph, and dual 512 element Reticon linear diode arrays. Ten small newly formed regions were observed, whose entire sunspot evolution apparently occurred within the observed disk crossing. Seven of these showed a net energy excess of a few times 10 to the 33th ergs during this time. These results are discussed in connection with the 0.1 percent decline in solar irradiance observed by the SMM/ACRIM and Nimbus 7/ERB radiometers between 1980 and 1986. 35 refs.

  6. A {sup 13}CO SURVEY OF INTERMEDIATE-MASS STAR-FORMING REGIONS

    SciTech Connect

    Lundquist, Michael J.; Kobulnicky, Henry A.; Kerton, Charles R.; Arvidsson, Kim

    2015-06-10

    We have conducted a {sup 13}CO survey of a sample of 128 infrared color-selected intermediate-mass star-forming region (IM SFR) candidates. We utilized the Onsala 20 m telescope to observe {sup 13}CO (1–0) toward 67 northern IM SFRs, used the 12 m Atacama Pathfinder Experiment telescope to observe {sup 13}CO (2–1) toward 22 southern IM SFRs, and incorporated an additional 39 sources from the Boston University Five College Radio Astronomy Observatory Galactic Ring Survey which observed {sup 13}CO (1–0). We detect {sup 13}CO (1–0) in 58 of the 67 northern sources and {sup 13}CO (2–1) in 20 of the 22 southern sources. The mean molecular column densities and {sup 13}CO linewidths in the inner Galaxy are higher by factors of 3.4 and 1.5, respectively, than the outer Galaxy. We attribute this difference to molecular clouds in the inner Galaxy being more massive and hosting star forming regions with higher luminosities on average than the outer Galaxy. IM SFRs have mean a molecular column density of 7.89 × 10{sup 21} cm{sup −2}, a factor of 3.1 lower than that for a sample of high-mass regions, and have a mean {sup 13}CO linewidth of 1.84 km s{sup −1}, a factor of 1.5 lower than that for high-mass regions. We demonstrate a correlation between {sup 13}CO linewidth and infrared luminosity as well as between molecular column density and infrared luminosity for the entire sample of intermediate-mass and high-mass regions. IM SFRs appear to form in distinctly lower-density environments with mean linewidths and beam-averaged column densities a factor of several lower than high-mass star-forming regions.

  7. 13C Isotopic Fractionation of HC3N in Star-forming Regions: Low-mass Star-forming Region L1527 and High-mass Star-forming Region G28.28-0.36

    NASA Astrophysics Data System (ADS)

    Taniguchi, Kotomi; Saito, Masao; Ozeki, Hiroyuki

    2016-10-01

    We observed the J = 9-8 and 10-9 rotational lines of three 13C isotopologues of HC3N in L1527 and G28.28-0.36, with the 45 m radio telescope of the Nobeyama Radio Observatory, in order to constrain the main formation mechanisms of HC3N in each source. The abundance ratios of the three 13C isotopologues of HC3N are found to be 0.9 (±0.2) : 1.00 : 1.29 (±0.19) (1σ), and 1.0 (±0.2) : 1.00 : 1.47 (±0.17) (1σ), for [H13CCCN : HC13CCN : HCC13CN] in L1527 and G28.28-0.36, respectively. We recognize, from a similar 13C isotopic fractionation pattern, that the abundances of H13CCCN and HC13CCN are comparable, and HCC13CN is more abundant than the others. Based on the results, we discuss the main formation pathway of HC3N. The 13C isotopic fractionation pattern derived from our observations can be explained by the neutral-neutral reaction between C2H2 and CN in both the low-mass (L1527) and high-mass (G28.28-0.36) star-forming regions.

  8. Tracing the potential planet-forming regions around seven pre-main-sequence stars

    NASA Astrophysics Data System (ADS)

    Schegerer, A. A.; Wolf, S.; Hummel, C. A.; Quanz, S. P.; Richichi, A.

    2009-07-01

    Aims: We investigate the nature of the innermost regions with radii of several AUs of seven circumstellar disks around pre-main-sequence stars, T Tauri stars in particular. Our object sample contains disks apparently at various stages of their evolution. Both single stars and spatially resolved binaries are considered. In particular, we search for inner disk gaps as proposed for several young stellar objects (YSOs). When analyzing the underlying dust population in the atmosphere of circumstellar disks, the shape of the 10 μm feature should additionally be investigated. Methods: We performed interferometric observations in N band (8-13 μm) with the Mid-Infrared Interferometric Instrument (MIDI) at the Very Large Telescope Interferometer (VLTI) using baseline lengths of between 54 m and 127 m. The data analysis is based on radiative-transfer simulations using the Monte Carlo code MC3D by modeling simultaneously the spectral energy distribution (SED), N band spectra, and interferometric visibilities. Correlated and uncorrelated N band spectra are compared to investigate the radial distribution of the dust composition of the disk atmosphere. Results: Spatially resolved mid-infrared (MIR) emission was detected in all objects. For four objects (DR Tau, RU Lup, S CrA N, and S CrA S), the observed N band visibilities and corresponding SEDs could be simultaneously simulated using a parameterized active disk-model. For the more evolved objects of our sample, HD 72106 and HBC 639, a purely passive disk-model provides the closest fit. The visibilities inferred for the source RU Lup allow the presence of an inner disk gap. For the YSO GW Ori, one of two visibility measurements could not be simulated by our modeling approach. All uncorrelated spectra reveal the 10 μm silicate emission feature. In contrast to this, some correlated spectra of the observations of the more evolved objects do not show this feature, indicating a lack of small silicates in the inner versus the outer

  9. Auditory selective attention to speech modulates activity in the visual word form area.

    PubMed

    Yoncheva, Yuliya N; Zevin, Jason D; Maurer, Urs; McCandliss, Bruce D

    2010-03-01

    Selective attention to speech versus nonspeech signals in complex auditory input could produce top-down modulation of cortical regions previously linked to perception of spoken, and even visual, words. To isolate such top-down attentional effects, we contrasted 2 equally challenging active listening tasks, performed on the same complex auditory stimuli (words overlaid with a series of 3 tones). Instructions required selectively attending to either the speech signals (in service of rhyme judgment) or the melodic signals (tone-triplet matching). Selective attention to speech, relative to attention to melody, was associated with blood oxygenation level-dependent (BOLD) increases during functional magnetic resonance imaging (fMRI) in left inferior frontal gyrus, temporal regions, and the visual word form area (VWFA). Further investigation of the activity in visual regions revealed overall deactivation relative to baseline rest for both attention conditions. Topographic analysis demonstrated that while attending to melody drove deactivation equivalently across all fusiform regions of interest examined, attending to speech produced a regionally specific modulation: deactivation of all fusiform regions, except the VWFA. Results indicate that selective attention to speech can topographically tune extrastriate cortex, leading to increased activity in VWFA relative to surrounding regions, in line with the well-established connectivity between areas related to spoken and visual word perception in skilled readers.

  10. Magnetic field measurements in and above a limb active region

    NASA Astrophysics Data System (ADS)

    Philip, Judge

    2013-07-01

    We analyze spectropolarimetric data of a limb active region (NOAA 11302) obtained on September 22nd 2011 using the Facility Infrared Spectrometer (FIRS) at the Dunn Solar Telescope (DST). Stokes profiles including lines of Si I 1028.7 nm and He I 1083 nm were obtained in three scans over a 45"x75" area. Simultaneous narrow band Ca II K and G-band intensity data were acquired with a cadence of 5s at the DST. The He I data show not only typical active region polarization signatures, but also signatures in plumes -- cool post flare loops -- which extend many Mm into the corona across the visible limb. The plumes have remarkably uniform brightness, and the plume plasma is significantly Doppler shifted as it drains from the corona. Using carefully constructed observing and calibration sequences and applying Principal Component Analysis to remove instrumental artifacts, we achieved a polarization sensitivity approaching 0.02%. With this sensitivity we attempt to diagnose the vector magnetic fields and plasma properties of chromospheric and cool coronal material in and above NOAA 11302. Inversions using various radiative transfer models in the HAZEL code are remarkably consistent with the idea that plume spectra are formed in a simple, slab-like geometry, but that the ``disk'' spectra are formed under more traditional models (Milne-Eddington). The inverted magnetic data of He I lines are compared with photospheric inversions of DST Si I and Fe I data from the Solar Dynamics Observatory.

  11. Zeeman Effect in Sulfur Monoxide: a Probe to Observe Magnetic Fields in Star Forming Regions?

    NASA Astrophysics Data System (ADS)

    Cazzoli, Gabriele; Lattanzi, Valerio; Coriani, Sonia; Gauss, Jürgen; Codella, Claudio; Ramos, Andrés Asensio; Cernicharo, Jose; Puzzarini, Cristina

    2017-06-01

    Magnetic fields play a fundamental role in star formation processes and the best method to evaluate their intensity is is to measure the Zeeman effect of atomic and molecular lines. However, a direct measurement of the Zeeman spectral pattern from interstellar molecular species is challenging due to the high sensitivity and high spectral resolution required. So far, the Zeeman effect has been detected unambiguously in star forming regions for very few non-masing species, such as OH and CN. We decided to investigate the ability of sulfur monoxide (SO), which is one of the most abundant species in star forming regions, for probing the intensity of magnetic fields via Zeeman effect. The Zeeman effect for several rotational transitions of SO in the (sub-)mm spectral regions has been investigated by using a frequency-modulated, computer-controlled spectrometer, and by applying a magnetic field parallel to the radiation source. To support the experimental determination of the g factors of SO, a systematic quantum-chemical investigation of these parameters for both SO and O_2 has been carried out. An effective experimental-computational strategy for providing accurate g factors as well as for identifying the rotational transitions showing the strongest Zeeman effect has been presented. Our investigation supports SO as a good candidate for probing magnetic fields in high-density star forming regions.

  12. Phase-space structures and stellar populations in the star-forming region NGC 2264

    NASA Astrophysics Data System (ADS)

    González, Marta; Alfaro, Emilio J.

    2017-02-01

    In this work, we analyse the structure of a subspace of the phase space of the star-forming region NGC 2264 using the spectrum of kinematic groupings (SKG). We show that the SKG can be used to process a collection of star data to find substructure at different scales. We have found structure associated with the NGC 2264 region and also with the background area. In the NGC 2264 region, a hierarchical analysis shows substructure compatible with that found in previous specific studies of the area but with an objective, compact methodology that allows us to homogeneously compare the structure of different clusters and star-forming regions. Moreover, this structure is compatible with the different ages of the main NGC 2264 star-forming populations. The structure found in the field can be roughly associated with giant stars far in the background, dynamically decoupled from NGC 2264, which could be related either with the Outer Arm or Monoceros Ring. The results in this paper confirm the relationship between structure in the radial velocity phase-space subspace and different kinds of populations, defined by other variables not necessarily analysed with the SKG, such as age or distance, showing the importance of detecting phase-space substructure in order to trace stellar populations in the broadest sense of the word.

  13. A Comparative Observational Study of YSO Classification in Four Small Star-forming H ii Regions

    NASA Astrophysics Data System (ADS)

    Kang, Sung-Ju; Kerton, C. R.; Choi, Minho; Kang, Miju

    2017-08-01

    We have developed a new young stellar object (YSO) identification and classification technique using mid-infrared Wide-field Infrared Survey Explorer (WISE) data. We compare this new technique with previous WISE YSO detection and classification methods that used either infrared colors or spectral energy distribution slopes. In this study, we also use the new technique to detect and examine the YSO population associated with four small H ii regions: KR 7, KR 81, KR 120, and KR 140. The relatively simple structure of these regions allows us to effectively use both spatial and temporal constraints to identify YSOs that are potential products of triggered star formation. We are also able to identify regions of active star formation around these H ii regions that are clearly not influenced by the H ii region expansion, and thus demonstrate that star formation is on-going on megayear timescales in some of these molecular clouds.

  14. The Limit of Free Magnetic Energy in Active Regions

    NASA Technical Reports Server (NTRS)

    Moore, Ron; Falconer, David; Sterling, Alphonse

    2012-01-01

    By measuring from active-region magnetograms a proxy of the free energy in the active region fs magnetic field, it has been found previously that (1) there is an abrupt upper limit to the free energy the field can hold that increases with the amount of magnetic field in the active region, the active region fs magnetic flux content, and (2) the free energy is usually near its limit when the field explodes in a CME/flare eruption. That is, explosive active regions are concentrated in a main-sequence path bordering the free-energy ]limit line in (flux content, free-energy proxy) phase space. Here, from measurement of Marshall Space Flight Center vector magnetograms, we find the magnetic condition that underlies the free ]energy limit and the accompanying main sequence of explosive active regions. Using a suitable free ]energy proxy measured from vector magnetograms of 44 active regions, we find that (1) in active regions at and near their free ]energy limit, the ratio of magnetic-shear free energy to the non ]free magnetic energy the potential field would have is approximately 1 in the core field, the field rooted along the neutral line, and (2) this ratio is progressively less in active regions progressively farther below their free ]energy limit. This shows that most active regions in which this core-field energy ratio is much less than 1 cannot be triggered to explode; as this ratio approaches 1, most active regions become capable of exploding; and when this ratio is 1 or greater, most active regions are compelled to explode. From these results we surmise the magnetic condition that determines the free ]energy limit is the ratio of the free magnetic energy to the non-free energy the active region fs field would have were it completely relaxed to its potential ]field configuration, and that this ratio is approximately 1 at the free-energy limit and in the main sequence of explosive active regions.

  15. FORMATION OF CORONAL HOLES ON THE ASHES OF ACTIVE REGIONS

    SciTech Connect

    Karachik, Nina V.; Pevtsov, Alexei A.; Abramenko, Valentyna I. E-mail: apevtsov@nso.ed

    2010-05-10

    We investigate the formation of isolated non-polar coronal holes (CHs) on the remnants of decaying active regions (ARs) at the minimum/early ascending phase of sunspot activity. We follow the evolution of four bipolar ARs and measure several parameters of their magnetic fields including total flux, imbalance, and compactness. As regions decay, their leading and following polarities exhibit different dissipation rates: loose polarity tends to dissipate faster than compact polarity. As a consequence, we see a gradual increase in flux imbalance inside a dissipating bipolar region, and later a formation of a CH in place of more compact magnetic flux. Out of four cases studied in detail, two CHs had formed at the following polarity of the decaying bipolar AR, and two CHs had developed in place of the leading polarity field. All four CHs contain a significant fraction of magnetic field of their corresponding AR. Using potential field extrapolation, we show that the magnetic field lines of these CHs were closed on the polar CH at the North, which at the time of the events was in imbalance with the polar CH at the South. This topology suggests that the observed phenomenon may play an important role in transformation of toroidal magnetic field to poloidal field, which is a key step in transitioning from an old solar cycle to a new one. The timing of this observed transition may indicate the end of solar cycle 23 and the beginning of cycle 24.

  16. Cosmic ion irradiation and UV photolysis of solids in star forming regions .

    NASA Astrophysics Data System (ADS)

    Palumbo, M. E.; Baratta, G. A.; Spinella, F.

    The presence of icy grain mantles along the line of sight of star forming regions is clearly evidenced by infrared observations. Due to the presence of the protostar and of cosmic radiation, ices suffer from ion bombardment, UV photolysis and thermal annealing. Most of our knowledge on the physical and chemical properties of ices is based on the comparison between observations and laboratory experiments performed at low temperature (10-80 K). Experimental results show that after ion irradiation and UV photolysis the chemical composition and the structure of the sample is modified. Both more volatile and less volatile species are formed and if a C-bearing species is present in the original sample a refractory residue is formed. Eventually thermal annealing causes the sublimation of icy mantles. Thus molecules are released to the gas phase which could be enriched by species formed in the solid phase. Here we will discuss some recent laboratory experiments relevant to the knowledge of the physico-chemical properties of ices in star forming regions.

  17. Mass Segregation in Star-Forming Regions on Multi-Spatial Scales

    NASA Astrophysics Data System (ADS)

    Kuhn, Michael A.; MYStIX Collaboration

    2017-06-01

    The MYStIX study of 20 nearby star-forming regions reveals diversity in stellar mass segregation. We use the two-point correlation function to statistically test for mass segregation on different spatial scales. Some regions have segregated OB stars, while others do not, and in others segregation exists down to 1.5 solar-mass stars. Mass segregation can occur on scales of 0.1 pc to scales of 1 pc. And, a few cases (notably NGC 1893) exhibit inverse mass segregation. We find no observational evidence for increasing mass segregation with cluster age. Theoretical implications are discussed.

  18. Star Formation Rate Indicators in Different Scales: from Star Forming Regions to Galaxies

    NASA Astrophysics Data System (ADS)

    Hei Law, Ka; Gordon, K.

    2011-01-01

    Do Star Formation Rate (SFR) indicators derived from galaxies work in star forming regions, or vice versa? We explore the behavior and effectiveness of various single- and multi-band SFR indicators across different scales. Our sample spans over 4 orders of magnitudes in total infrared luminosity and covers a wide range of spatial scale - from individual regions in nearby galaxies such as those in SMC, LMC, M33 and M31, to whole galaxies, including galaxies from the Spitzer Local Volume Legacy Survey (LVL; Dale et al. 2009), the Spitzer Infrared Nearby Galaxies Survey (SINGS; Kennicutt et al. 2003), and starburst galaxies from Engelbracht et al. 2008.

  19. The comparison of physical properties derived from gas and dust in a massive star-forming region

    SciTech Connect

    Battersby, Cara; Bally, John; Ginsburg, Adam; Darling, Jeremy; Dunham, Miranda; Longmore, Steve

    2014-05-10

    We explore the relationship between gas and dust in a massive star-forming region by comparing the physical properties derived from each. We compare the temperatures and column densities in a massive star-forming Infrared Dark Cloud (G32.02+0.05), which shows a range of evolutionary states, from quiescent to active. The gas properties were derived using radiative transfer modeling of the (1,1), (2,2), and (4,4) transitions of NH{sub 3} on the Karl G. Jansky Very Large Array, while the dust temperatures and column densities were calculated using cirrus-subtracted, modified blackbody fits to Herschel data. We compare the derived column densities to calculate an NH{sub 3} abundance, χ{sub NH{sub 3}} = 4.6 × 10{sup –8}. In the coldest star-forming region, we find that the measured dust temperatures are lower than the measured gas temperatures (mean and standard deviations T {sub dust,} {sub avg} ∼ 11.6 ± 0.2 K versus T {sub gas,} {sub avg} ∼ 15.2 ± 1.5 K), which may indicate that the gas and dust are not well-coupled in the youngest regions (∼0.5 Myr) or that these observations probe a regime where the dust and/or gas temperature measurements are unreliable. Finally, we calculate millimeter fluxes based on the temperatures and column densities derived from NH{sub 3}, which suggest that millimeter dust continuum observations of massive star-forming regions, such as the Bolocam Galactic Plane Survey or ATLASGAL, can probe hot cores, cold cores, and the dense gas lanes from which they form, and are generally not dominated by the hottest core.

  20. Doppler wavelength shifts of ultraviolet spectral lines in solar active regions

    NASA Technical Reports Server (NTRS)

    Feldman, U.; Doschek, G. A.; Cohen, L.

    1982-01-01

    Doppler shifts are measured for solar UV emission lines formed in the lower transition region of active regions. Doppler shifts in different regions at the same solar location, variations of Doppler shift with position of an active region on the disk, and variations of Doppler shift with time at the same solar location in the same active region were studied. Observations were made with the NRL slit spectrograph on Skylab. Excluding flare and flare-related phenomena, only redshifts are found whose magnitudes correspond to downflow velocities between about 4 and 17 km/s. Shifts are largest for lines formed between about 50,000 and 100,000 K, and are distinctly less for lines formed above 100,000 K. The shifts persist out to the limb, but not above it. There is no obvious change in redshift for lines measured at the same solar location over time intervals of about 20 minutes.

  1. Active region upflows. I. Multi-instrument observations

    NASA Astrophysics Data System (ADS)

    Vanninathan, K.; Madjarska, M. S.; Galsgaard, K.; Huang, Z.; Doyle, J. G.

    2015-12-01

    responsible for the formation of the upflow region. High cadence Hα observations are used to study the chromosphere at the footpoints of the upflow region. We find no significant jet-like (spicule/rapid blue excursion) activity to account for several hours/days of plasma upflow. The jet-like activity in this region is not continuous and blueward asymmetries are a bare minimum. Using an image enhancement technique for imaging and spectral data, we show that the coronal structures seen in the AIA 193 Å channel are comparable to the EIS Fe xii images, while images in the AIA 171 Å channel reveal additional loops that are a result of contribution from cooler emission to this channel. Conclusions: Our results suggest that at chromospheric heights there are no signatures that support the possible contribution of spicules to active region upflows. We suggest that magnetic flux diffusion is responsible for the formation of the coronal upflows. The existence of two velocity components possibly indicates the presence of two different flows, which are produced by two different physical mechanisms, e.g. magnetic reconnection and pressure-driven jets. Movies associated to Figs. A.1-A.3 are available in electronic form at http://www.aanda.org

  2. Experimental study on interface region of two-dimensional Si layers by forming gas annealing

    NASA Astrophysics Data System (ADS)

    Mizuno, Tomohisa; Suzuki, Yuhya; Kikuchi, Reika; Suzuki, Ayaka; Inoue, Ryohsuke; Yamanaka, Masahiro; Yokoyama, Miki; Nagamine, Yoshiki; Aoki, Takashi; Maeda, Tatsuro

    2016-04-01

    We experimentally studied the SiO2/Si and Si/buried oxide (BOX) interface regions of a two-dimensional (2D) Si layer, by forming gas annealing (FGA). A photoluminescence (PL) result measured at various lattice temperature, T L, values shows that the PL intensity I PL of the 2D-Si layer rapidly increases and then saturates with increasing FGA temperature, T A, and time, t A. I PL also increases with decreasing T L. A one-dimensional (1D) Schroedinger equation simulator indicates that some of the electrons in the 2D-Si layer generated by a PL excitation laser are quantum-mechanically transmitted into Si interface regions. Actually, we experimentally confirmed that the PL spectra of the 2D-Si layer can be fitted by the PL emission from two regions with different PL peak photon energy values, E PH, which consist of a typical 2D-Si and the interface regions of both the surface SiO2/Si and Si/BOX. Thus, this forming gas dependence is probably attributable to the improved lifetime τ of electrons in the surface interface region, because the Si surface is terminated by H atoms. Moreover, the E PH of the interface region is higher than that of the 2D-Si layer, because of the graded increased bandgap in the interface regions. However, the E PH of 2D-Si is independent of both T A and T L, and this T L independence does not agree with that of a 3D-Si layer. Consequently, we experimentally verified the larger impact of the Si interface on the performance of 2D-Si layer.

  3. Ultraluminous X-Ray Source Correlations with Star-Forming Regions

    NASA Astrophysics Data System (ADS)

    Swartz, Douglas A.; Tennant, Allyn F.; Soria, Roberto

    2009-09-01

    Maps of low-inclination nearby galaxies in Sloan Digitized Sky Survey u - g, g - r, and r - i colors are used to determine whether ultraluminous X-ray sources (ULXs) are predominantly associated with star-forming regions of their host galaxies. An empirical selection criterion is derived from colors of H II regions in M 81 and M 101 that differentiates between the young, blue stellar component and the older disk and bulge population. This criterion is applied to a sample of 58 galaxies of Hubble type S0 and later and verified through an application of Fisher's linear discriminant analysis. It is found that 60% (49%) of ULXs in optically bright environments are within regions blueward of their host galaxy's H II regions compared to only 27% (0%) of a control sample according to the empirical (Fisher) criterion. This is an excess of 3σ above the 32% (27%) expected if the ULXs were randomly distributed within their galactic hosts. This indicates a ULX preference for young, lsim10 Myr, OB associations. However, none of the ULX environments have the morphology and optical brightness suggestive of a massive young super-star cluster though several are in extended or crowded star-forming (blue) environments that may contain clusters unresolved by Sloan imaging. Ten of the 12 ULX candidates with estimated X-ray luminosities in excess of 3 × 1039 erg s-1 are equally divided among the group of ULX environments redward of H II regions and the group of optically faint regions. This likely indicates that the brightest ULXs turn on at a time somewhat later than typical of H II regions; say 10-20 Myr after star formation has ended. This would be consistent with the onset of an accretion phase as the donor star ascends the giant branch if the donor is an lsim20 M sun star.

  4. ULTRALUMINOUS X-RAY SOURCE CORRELATIONS WITH STAR-FORMING REGIONS

    SciTech Connect

    Swartz, Douglas A.; Tennant, Allyn F.; Soria, Roberto

    2009-09-20

    Maps of low-inclination nearby galaxies in Sloan Digitized Sky Survey u - g, g - r, and r - i colors are used to determine whether ultraluminous X-ray sources (ULXs) are predominantly associated with star-forming regions of their host galaxies. An empirical selection criterion is derived from colors of H II regions in M 81 and M 101 that differentiates between the young, blue stellar component and the older disk and bulge population. This criterion is applied to a sample of 58 galaxies of Hubble type S0 and later and verified through an application of Fisher's linear discriminant analysis. It is found that 60% (49%) of ULXs in optically bright environments are within regions blueward of their host galaxy's H II regions compared to only 27% (0%) of a control sample according to the empirical (Fisher) criterion. This is an excess of 3sigma above the 32% (27%) expected if the ULXs were randomly distributed within their galactic hosts. This indicates a ULX preference for young, {approx}<10 Myr, OB associations. However, none of the ULX environments have the morphology and optical brightness suggestive of a massive young super-star cluster though several are in extended or crowded star-forming (blue) environments that may contain clusters unresolved by Sloan imaging. Ten of the 12 ULX candidates with estimated X-ray luminosities in excess of 3 x 10{sup 39} erg s{sup -1} are equally divided among the group of ULX environments redward of H II regions and the group of optically faint regions. This likely indicates that the brightest ULXs turn on at a time somewhat later than typical of H II regions; say 10-20 Myr after star formation has ended. This would be consistent with the onset of an accretion phase as the donor star ascends the giant branch if the donor is an {approx}<20 M{sub sun} star.

  5. Statistical Analysis of Acoustic Wave Parameters Near Solar Active Regions

    NASA Astrophysics Data System (ADS)

    Rabello-Soares, M. Cristina; Bogart, Richard S.; Scherrer, Philip H.

    2016-08-01

    In order to quantify the influence of magnetic fields on acoustic mode parameters and flows in and around active regions, we analyze the differences in the parameters in magnetically quiet regions nearby an active region (which we call “nearby regions”), compared with those of quiet regions at the same disk locations for which there are no neighboring active regions. We also compare the mode parameters in active regions with those in comparably located quiet regions. Our analysis is based on ring-diagram analysis of all active regions observed by the Helioseismic and Magnetic Imager (HMI) during almost five years. We find that the frequency at which the mode amplitude changes from attenuation to amplification in the quiet nearby regions is around 4.2 mHz, in contrast to the active regions, for which it is about 5.1 mHz. This amplitude enhacement (the “acoustic halo effect”) is as large as that observed in the active regions, and has a very weak dependence on the wave propagation direction. The mode energy difference in nearby regions also changes from a deficit to an excess at around 4.2 mHz, but averages to zero over all modes. The frequency difference in nearby regions increases with increasing frequency until a point at which the frequency shifts turn over sharply, as in active regions. However, this turnover occurs around 4.9 mHz, which is significantly below the acoustic cutoff frequency. Inverting the horizontal flow parameters in the direction of the neigboring active regions, we find flows that are consistent with a model of the thermal energy flow being blocked directly below the active region.

  6. Multiplicity study of young pre-main sequence stars in the Lupus star-forming Region

    NASA Astrophysics Data System (ADS)

    Vogt, Nikolaus; Mugrauer, Markus; Schmidt, Tobias O. B.; Neuhaeuser, Ralph; Ginski, Christian

    2013-07-01

    We have conducted a high contrast imaging search for (sub)stellar companions among 63 young pre-main sequence stars in the Lupus star forming region, using the adaptive optics imager NACO at UT4 of the ESO Paranal observatory. We detected faint co-moving companions around our targets at angular separations between about 0.1 up to several arc seconds (binaries and triple systems). Some of these companions are in the sub stellar mass regime, according to their apparent near infrared photometry at the distance of the Lupus star forming region (about 140pc). We give a progress report to our long-term project, still in execution with the follow-up spectroscopy of detected substellar companion-candidates, and present some first results.

  7. PARALLAXES OF STAR-FORMING REGIONS IN THE OUTER SPIRAL ARM OF THE MILKY WAY

    SciTech Connect

    Hachisuka, K.; Choi, Y. K.; Reid, M. J.; Dame, T. M.; Brunthaler, A.; Menten, K. M.; Sanna, A.

    2015-02-10

    We report parallaxes and proper motions of three water maser sources in high-mass star-forming regions in the Outer Spiral Arm of the Milky Way. The observations were conducted with the Very Long Baseline Array as part of Bar and Spiral Structure Legacy Survey and double the number of such measurements in the literature. The Outer Arm has a pitch angle of 14.°9 ± 2.°7 and a Galactocentric distance of 14.1 ± 0.6 kpc toward the Galactic anticenter. The average motion of these sources toward the Galactic center is 10.7 ± 2.1 km s{sup –1} and we see no sign of a significant fall in the rotation curve out to 15 kpc from the Galactic center. The three-dimensional locations of these star-forming regions are consistent with a Galactic warp of several hundred parsecs from the plane.

  8. 75 FR 16492 - Agency Information Collection Activities: Form G-28, and Form G-28I, Revision of an Existing...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-01

    ... SECURITY U.S. Citizenship and Immigration Services Agency Information Collection Activities: Form G-28, and Form G- 28I, Revision of an Existing Information Collection; Comment Request ACTION: 60-Day Notice of Information Collection under Review: Form G- 28, Notice of Entry of Appearance as Attorney or Accredited...

  9. VizieR Online Data Catalog: OH maser emission from star forming regions (Szymczak+, 2004)

    NASA Astrophysics Data System (ADS)

    Szymczak, M.; Gerard, E.

    2003-11-01

    High sensitivity observations of all four transitions of the ground state at 18cm of OH in both senses of circular polarization have been carried out with the Nancay radio telescope. The sample was a set of 100 star forming regions detected in a recent unbiased survey of 6668MHz methanol masers (Szymczak et al., 2002A&A...392..277S). OH maser emission was found in 55 objects of which 31 were not previously catalogued. (4 data files).

  10. The connection between galaxy environment and the luminosity function slopes of star-forming regions

    NASA Astrophysics Data System (ADS)

    Cook, David O.; Dale, Daniel A.; Lee, Janice C.; Thilker, David; Calzetti, Daniela; Kennicutt, Robert C.

    2016-11-01

    We present the first study of GALEX far-ultraviolet (FUV) luminosity functions of individual star-forming regions within a sample of 258 nearby galaxies spanning a large range in total stellar mass and star formation properties. We identify ˜65 000 star-forming regions (i.e. FUV sources), measure each galaxy's luminosity function, and characterize the relationships between the luminosity function slope (α) and several global galaxy properties. A final sample of 82 galaxies with reliable luminosity functions are used to define these relationships and represent the largest sample of galaxies with the largest range of galaxy properties used to study the connection between luminosity function properties and galaxy environment. We find that α correlates with global star formation properties, where galaxies with higher star formation rates and star formation rate densities (ΣSFR) tend to have flatter luminosity function slopes. In addition, we find that neither stochastic sampling of the luminosity function in galaxies with low-number statistics nor the effects of blending due to distance can fully account for these trends. We hypothesize that the flatter slopes in high ΣSFR galaxies is due to higher gas densities and higher star formation efficiencies which result in proportionally greater numbers of bright star-forming regions. Finally, we create a composite luminosity function composed of star-forming regions from many galaxies and find a break in the luminosity function at brighter luminosities. However, we find that this break is an artefact of varying detection limits for galaxies at different distances.

  11. The Non-Thermal Radio Jet in the NGC 2264 Star-Forming Region

    NASA Astrophysics Data System (ADS)

    Trejo, A.; Rodríguez, L. F.

    2008-06-01

    We investigated the non-thermal radio jet in the NGC 2264 star forming region. The jet was discovered by tet{t-re04}, and it has a non-thermal spectrum and high polarization. We made new observations with the VLA in 2006 and compared with 1995 archival data to search for proper motions and flux density variability. We only detect flux variability in the core. The general lack of variability and proper motions favors an extragalactic nature for this jet.

  12. VizieR Online Data Catalog: Star-forming regions deuteration (Gerner+, 2015)

    NASA Astrophysics Data System (ADS)

    Gerner, T.; Shirley, Y. L.; Beuther, H.; Semenov, D.; Linz, H.; Albertsson, T.; Henning, T.

    2015-10-01

    The sources were taken from Gerner et al. (2014, Cat. J/A+A/563/A97) and were initially selected from different source lists. The total sample contains 59 high-mass star-forming regions, consisting of 19 IRDCs and 20 HMPOs as well as 11 HMCs and 9 UCHIIs. The sources were selected from well-known source catalogs of the literature without specific selection criteria such as spherical symmetry. (3 data files).

  13. T Tauri Stars in Taurus-Auriga Star-Forming Region: Reliable Interstellar Extinction

    NASA Astrophysics Data System (ADS)

    Grankin, K. N.

    2017-07-01

    Long-term homogeneous photometry for 35 classical T Tauri stars (CTTS) in the Taurus-Auriga star-forming region (SFR) has been analyzed. The original method of interstellar absorption estimation on line of sight has been proposed, taking into account the effects that are caused by magnetospheric accretion, cold spots, and extended variable circumstellar extinction. Reliable values of the interstellar extinction for 35 CTTS have been determined.

  14. The Schmidt Law in Six Galactic Massive Star-forming Regions

    NASA Astrophysics Data System (ADS)

    Willis, S.; Guzman, A.; Marengo, M.; Smith, H. A.; Martínez-Galarza, J. R.; Allen, L.

    2015-08-01

    We present a census of young stars in five massive star-forming regions in the 4th Galactic quadrant, G305, G326-4, G326-6, G333 (RCW 106), and G351, and combine this census with an earlier census of young stars in NGC 6334. Each region was observed at J, H, and Ks with the NOAO Extremely Wide-Field Infrared Imager and combined with deep observations taken with the Infrared Array Camera (IRAC) on board the Spitzer Space Telescope at the wavelengths 3.6 and 4.5 μm. We derived a five band point-source catalog containing >200,000 infrared sources in each region. We have identified a total of 2871 YSO candidates, 363 Class I YSOs, and 2508 Class II YSOs. We mapped the column density of each cloud using observations from Herschel between 160 and 500 μm and near-infrared extinction maps in order to determine the average gas surface density above AV > 2. We study the surface density of the YSOs and the star-formation rate as a function of the column density within each cloud and compare them to the results for nearby star-forming regions. We find a range in power-law indices across the clouds, with the dispersion in the local relations in an individual cloud much lower than the average over the six clouds. We find the average over the six clouds to be {{{Σ }}}{SFR}∼ {{{Σ }}}{gas}2.15+/- 0.41 and power-law exponents ranging from 1.77 to 2.86, similar to the values derived within nearby star-forming regions, including Taurus and Orion. The large dispersion in the power-law relations between individual Milky Way molecular clouds reinforces the idea that there is not a direct universal connection between Σgas and a cloud's observed star-formation rate.

  15. Optically active surfaces formed by ion implantation and thermal treatment

    SciTech Connect

    Gea, L.A.; Boatner, L.A.; Evans, H.M.; Zuhr, R.

    1996-08-01

    Embedded VO{sub 2} precipitates have been formed in single-crystal sapphire by the ion co-implantation of vanadium and oxygen and subsequent thermal annealing. The embedded VO{sub 2} particles have been shown to exhibit an optical switching behavior that is comparable to that of continuous thin films. In this work, the mechanisms of formation of these optically active particles are investigated. It is shown that precipitation of the vanadium dioxide phase is favored when the thermal treatment is performed on an ion-damaged but still crystalline (rather than amorphized) Al{sub 2}O{sub 3} substrate. The best optical switching behavior is observed in this case, and this behavior is apparently correlated with a more-favorable dispersion of VO{sub 2} small particles inside the matrix.

  16. Young Stellar Populations in MYStIX Star-forming Regions: Candidate Protostars

    NASA Astrophysics Data System (ADS)

    Romine, Gregory; Feigelson, Eric D.; Getman, Konstantin V.; Kuhn, Michael A.; Povich, Matthew S.

    2016-12-01

    The Massive Young Star-Forming Complex in Infrared and X-ray (MYStIX) project provides a new census on stellar members of massive star-forming regions within 4 kpc. Here the MYStIX Infrared Excess catalog and Chandra-based X-ray photometric catalogs are mined to obtain high-quality samples of Class I protostars using criteria designed to reduce extragalactic and Galactic field star contamination. A total of 1109 MYStIX Candidate Protostars (MCPs) are found in 14 star-forming regions. Most are selected from protoplanetary disk infrared excess emission, but 20% are found from their ultrahard X-ray spectra from heavily absorbed magnetospheric flare emission. Two-thirds of the MCP sample is newly reported here. The resulting samples are strongly spatially associated with molecular cores and filaments on Herschel far-infrared maps. This spatial agreement and other evidence indicate that the MCP sample has high reliability with relatively few “false positives” from contaminating populations. But the limited sensitivity and sparse overlap among the infrared and X-ray subsamples indicate that the sample is very incomplete with many “false negatives.” Maps, tables, and source descriptions are provided to guide further study of star formation in these regions. In particular, the nature of ultrahard X-ray protostellar candidates without known infrared counterparts needs to be elucidated.

  17. The First Detections of the Key Prebiotic Molecule PO in Star-forming Regions

    NASA Astrophysics Data System (ADS)

    Rivilla, V. M.; Fontani, F.; Beltrán, M. T.; Vasyunin, A.; Caselli, P.; Martín-Pintado, J.; Cesaroni, R.

    2016-08-01

    Phosphorus is a crucial element in biochemistry, in particular the P-O bond, which is key in the formation of the backbone of deoxyribonucleic acid. So far, PO has only been detected toward the envelope of evolved stars, but never toward star-forming regions. We report the first detection of PO toward two massive star-forming regions, W51 e1/e2 and W3(OH), using data from the IRAM 30 m telescope. PN has also been detected toward the two regions. The abundance ratio PO/PN is 1.8 and 3 for W51 and W3(OH), respectively. Our chemical model indicates that the two molecules are chemically related and are formed via gas-phase ion-molecule and neutral-neutral reactions during cold collapse. The molecules freeze out onto grains at the end of the collapse and desorb during the warm-up phase once the temperature reaches ˜35 K. Similar abundances of the two species are expected during a period of ˜5 × 104 yr at the early stages of the warm-up phase, when the temperature is in the range 35-90 K. The observed molecular abundances of 10-10 are predicted by the model if a relatively high initial abundance of 5 × 10-9 of depleted phosphorus is assumed.

  18. FRB 121102 Is Coincident with a Star-forming Region in Its Host Galaxy

    NASA Astrophysics Data System (ADS)

    Bassa, C. G.; Tendulkar, S. P.; Adams, E. A. K.; Maddox, N.; Bogdanov, S.; Bower, G. C.; Burke-Spolaor, S.; Butler, B. J.; Chatterjee, S.; Cordes, J. M.; Hessels, J. W. T.; Kaspi, V. M.; Law, C. J.; Marcote, B.; Paragi, Z.; Ransom, S. M.; Scholz, P.; Spitler, L. G.; van Langevelde, H. J.

    2017-07-01

    We present optical, near-infrared, and mid-infrared imaging of the host galaxy of FRB 121102 with the Gemini North telescope, the Hubble Space Telescope, and the Spitzer Space Telescope. The FRB 121102 host galaxy is resolved, revealing a bright star-forming region located in the outskirts of the irregular, low-metallicity dwarf galaxy. The star-forming region has a half-light radius of 0.68 kpc (0\\buildrel{\\prime\\prime}\\over{.} 20), encompassing the projected location of the compact (< 0.7 pc), persistent radio source that is associated with FRB 121102. The half-light diameter of the dwarf galaxy is 5-7 kpc, and broadband spectral energy distribution fitting indicates that it has a total stellar mass of {M}\\star ˜ {10}8 {M}⊙ . The properties of the host galaxy of FRB 121102 are comparable to those of extreme emission line galaxies, also known as hosts to some hydrogen-poor superluminous supernovae and long-duration γ-ray bursts. The projected location of FRB 121102 within the star-forming region supports the proposed connection of FRBs with newly born neutron stars or magnetars.

  19. Machine Learning Models for Detection of Regions of High Model Form Uncertainty in RANS

    NASA Astrophysics Data System (ADS)

    Ling, Julia; Templeton, Jeremy

    2015-11-01

    Reynolds Averaged Navier Stokes (RANS) models are widely used because of their computational efficiency and ease-of-implementation. However, because they rely on inexact turbulence closures, they suffer from significant model form uncertainty in many flows. Many RANS models make use of the Boussinesq hypothesis, which assumes a non-negative, scalar eddy viscosity that provides a linear relation between the Reynolds stresses and the mean strain rate. In many flows of engineering relevance, this eddy viscosity assumption is violated, leading to inaccuracies in the RANS predictions. For example, in near wall regions, the Boussinesq hypothesis fails to capture the correct Reynolds stress anisotropy. In regions of flow curvature, the linear relation between Reynolds stresses and mean strain rate may be inaccurate. This model form uncertainty cannot be quantified by simply varying the model parameters, as it is rooted in the model structure itself. Machine learning models were developed to detect regions of high model form uncertainty. These machine learning models consisted of binary classifiers that predicted, on a point-by-point basis, whether or not key RANS assumptions were violated. These classifiers were trained and evaluated for their sensitivity, specificity, and generalizability on a database of canonical flows.

  20. The Stellar Content of Intermediate-Mass Star-Forming Regions.

    NASA Astrophysics Data System (ADS)

    Lundquist, Michael; Kobulnicky, H.; Alexander, M.; Vargas Alvarez, C.; Arvidsson, K.; Kerton, C.

    2012-01-01

    In an effort to understand the factors that govern the transition from low- to high-mass star formation, we report near-infrared imaging and spectroscopy of stars within a sample of intermediate-mass star-forming regions (IMSFRs). Some IMSFRs appear to contain compact <1 pc embedded clusters at an early evolutionary stage similar to compact HII regions, but lacking the massive ionizing central star(s). The IMSFRs have photodissociation regions with diameters 1 pc powered by the equivalent of an early B star, but because all sources lack radio free-free emission, they must host a collection of less massive stars. These spectroscopic observations using FLAMINGOS on the Kitt Peak 4 m telescope, coupled with 2MASS and UKIDSS infrared imaging, identify which candidate IMSFRs host probable stellar clusters and address the nature of their most massive stellar constituents.

  1. ON MAGNETIC ACTIVITY BAND OVERLAP, INTERACTION, AND THE FORMATION OF COMPLEX SOLAR ACTIVE REGIONS

    SciTech Connect

    McIntosh, Scott W.; Leamon, Robert J.

    2014-11-20

    Recent work has revealed a phenomenological picture of the how the ∼11 yr sunspot cycle of the Sun arises. The production and destruction of sunspots is a consequence of the latitudinal-temporal overlap and interaction of the toroidal magnetic flux systems that belong to the 22 yr magnetic activity cycle and are rooted deep in the Sun's convective interior. We present a conceptually simple extension of this work, presenting a hypothesis on how complex active regions can form as a direct consequence of the intra- and extra-hemispheric interaction taking place in the solar interior. Furthermore, during specific portions of the sunspot cycle, we anticipate that those complex active regions may be particularly susceptible to profoundly catastrophic breakdown, producing flares and coronal mass ejections of the most severe magnitude.

  2. Dynamical histories of the IC 348 and NGC 1333 star-forming regions in Perseus

    NASA Astrophysics Data System (ADS)

    Parker, Richard J.; Alves de Oliveira, Catarina

    2017-07-01

    We present analyses of the spatial distributions of stars in the young (1-3 Myr) star-forming regions IC 348 and NGC 1333 in the Perseus giant molecular cloud. We quantify the spatial structure using the Q-parameter and find that both IC 348 and NGC 1333 are smooth and centrally concentrated with Q-parameters of 0.98 and 0.89, respectively. Neither region exhibits mass segregation (Λ _MSR = 1.1^{+0.2}_{-0.3} for IC 348 and Λ _MSR = 1.2^{+0.4}_{-0.3} for NGC 1333, where ΛMSR ˜ 1 corresponds to no mass segregation) nor do the most massive stars reside in areas of enhanced stellar surface density compared to the average surface density, according to the ΣLDR method. We then constrain the dynamical histories and hence initial conditions of both regions by comparing the observed values to N-body simulations at appropriate ages. Stars in both regions likely formed with subvirial velocities that contributed to merging of substructure and the formation of smooth clusters. The initial stellar densities were no higher than ρ ˜ 100-500 M⊙ pc-3 for IC 348 and ρ ˜ 500-2000 M⊙ pc-3 for NGC 1333. These initial densities, in particular that of NGC 1333, are high enough to facilitate dynamical interactions that would likely affect ˜10 per cent of protoplanetary discs and binary stars.

  3. The Charon-forming giant impact as a source of Pluto's dark equatorial regions

    NASA Astrophysics Data System (ADS)

    Sekine, Yasuhito; Genda, Hidenori; Kamata, Shunichi; Funatsu, Taro

    2017-01-01

    Pluto exhibits complex regional diversity in its surface materials 1,2 . One of the most striking features is the dark reddish material, possibly organic matter, along Pluto's equator coexisting with the H2O-rich crust 2 . Little is known, however, about the surface process responsible for the dark equatorial regions. Here, we propose that Pluto's dark regions were formed through reactions in elongated pools of liquid water near the equator, generated by the giant impact that formed Charon 3-5 . Our laboratory experiments show that dark reddish organic matter, comparable to Pluto's dark materials, is produced through polymerization of simple organic compounds 6,7 that would have been present in proto-Pluto (for example, formaldehyde) by prolonged heating at temperatures ≥50 °C. Through hydrodynamic impact simulations, we demonstrate that an impactor, one-third the mass of Pluto, colliding with proto-Pluto—with an interior potential temperature of 150-200 K—could have generated both a Charon-sized satellite and high-temperature regions around Pluto's equator. We also propose that high-velocity giant impacts result in global or hemispherical darkening and reddening, suggesting that the colour variety of large Kuiper belt objects 8-12 could have been caused by frequent, stochastic giant impacts in a massive outer protoplanetary disk in the early Solar System 13-16 .

  4. THE PROTOPLANETARY DISKS IN THE NEARBY MASSIVE STAR-FORMING REGION CYGNUS OB2

    SciTech Connect

    Guarcello, M. G.; Drake, J. J.; Wright, N. J.; Hora, J. L.; Aldcroft, T.; Fruscione, A.; Kashyap, V. L.; Drew, J. E.; Gutermuth, R. A.; Naylor, T.; King, R.; Garcia-Alvarez, D.

    2013-08-20

    The formation of stars in massive clusters is one of the main modes of the star formation process. However, the study of massive star-forming regions is hampered by their typically large distances to the Sun. One exception to this is the massive star-forming region Cygnus OB2 in the Cygnus X region, at the distance of {approx}1400 pc. Cygnus OB2 hosts very rich populations of massive and low-mass stars, being the best target in our Galaxy to study the formation of stars, circumstellar disks, and planets in the presence of massive stars. In this paper, we combine a wide and deep set of photometric data, from the r band to 24 {mu}m, in order to select the disk-bearing population of stars in Cygnus OB2 and identify the class I, class II, and stars with transition and pre-transition disks. We selected 1843 sources with infrared excesses in an area of 1 Degree-Sign Multiplication-Sign 1 Degree-Sign centered on Cyg OB2 in several evolutionary stages: 8.4% class I, 13.1% flat-spectrum sources, 72.9% class II, 2.3% pre-transition disks, and 3.3% transition disks. The spatial distribution of these sources shows a central cluster surrounded by an annular overdensity and some clumps of recent star formation in the outer region. Several candidate subclusters are identified, both along the overdensity and in the rest of the association.

  5. Lipid droplets form from distinct regions of the cell in the fission yeast Schizosaccharomyces pombe

    DOE PAGES

    Meyers, Alex; del Rio, Zuania P.; Beaver, Rachael A.; ...

    2016-04-29

    Eukaryotic cells store cholesterol/sterol esters (SEs) and triacylglycerols (TAGs) in lipid droplets, which form from the contiguous endoplasmic reticulum (ER) network. However, it is not known if droplets preferentially form from certain regions of the ER over others. Here, we used fission yeast Schizosaccharomyces pombe cells where the nuclear and cortical/peripheral ER domains are distinguishable by light microscopy to show that SE-enriched lipid droplets form away from the nucleus at the cell tips, whereas TAG-enriched lipid droplets form around the nucleus. Sterols localize to the regions of the cells where droplets enriched in SEs are observed. TAG droplet formation aroundmore » the nucleus appears to be a strong function of diacylglycerol (DAG) homeostasis with Cpt1p, which coverts DAG into phosphatidylcholine and phosphatidylethanolamine localized exclusively to the nuclear ER. Also, Dgk1p, which converts DAG into phosphatidic acid localized strongly to the nuclear ER over the cortical/peripheral ER. We also show that TAG more readily translocates from the ER to lipid droplets than do SEs. Lastly, the results augment the standard lipid droplet formation model, which has SEs and TAGs flowing into the same nascent lipid droplet regardless of its biogenesis point in the cell.« less

  6. Lipid Droplets Form from Distinct Regions of the Cell in the Fission Yeast Schizosaccharomyces pombe.

    PubMed

    Meyers, Alex; Del Rio, Zuania P; Beaver, Rachael A; Morris, Ryan M; Weiskittel, Taylor M; Alshibli, Amany K; Mannik, Jaana; Morrell-Falvey, Jennifer; Dalhaimer, Paul

    2016-06-01

    Eukaryotic cells store cholesterol/sterol esters (SEs) and triacylglycerols (TAGs) in lipid droplets, which form from the contiguous endoplasmic reticulum (ER) network. However, it is not known if droplets preferentially form from certain regions of the ER over others. Here, we used fission yeast Schizosaccharomyces pombe cells where the nuclear and cortical/peripheral ER domains are distinguishable by light microscopy to show that SE-enriched lipid droplets form away from the nucleus at the cell tips, whereas TAG-enriched lipid droplets form around the nucleus. Sterols localize to the regions of the cells where droplets enriched in SEs are observed. TAG droplet formation around the nucleus appears to be a strong function of diacylglycerol (DAG) homeostasis with Cpt1p, which coverts DAG into phosphatidylcholine and phosphatidylethanolamine localized exclusively to the nuclear ER. Also, Dgk1p, which converts DAG into phosphatidic acid localized strongly to the nuclear ER over the cortical/peripheral ER. We also show that TAG more readily translocates from the ER to lipid droplets than do SEs. The results augment the standard lipid droplet formation model, which has SEs and TAGs flowing into the same nascent lipid droplet regardless of its biogenesis point in the cell.

  7. Radio and infrared study of the star-forming region IRAS 20286+4105

    NASA Astrophysics Data System (ADS)

    Ramachandran, Varsha; Das, S. R.; Tej, A.; Vig, S.; Ghosh, S. K.; Ojha, D. K.

    2017-03-01

    In this paper, we present a multiwavelength investigation of the star-forming complex IRAS 20286+4105, located in the Cygnus X region. Near-infrared K-band data are used to revisit the cluster/stellar group identified in previous studies. Radio continuum observations at 610 and 1280 MHz show the presence of a H II region possibly powered by a star of spectral type B0-B0.5. The cometary morphology of the ionized region is explained by invoking the bow-shock model, where the likely association with a nearby supernova remnant is also explored. A compact radio knot with a non-thermal spectral index is detected towards the centre of the cloud. Mid-infrared data from the Spitzer Legacy Survey of the Cygnus X region show the presence of six Class I young stellar objects inside the cloud. Thermal dust emission in this complex is modelled using Herschel far-infrared data to generate dust temperature and column density maps. Herschel images also show the presence of two clumps in this region, the masses of which are estimated to be ∼175 and 30 M⊙. The mass-radius relation and the surface density of the clumps mean that they do not qualify as massive star-forming sites. An overall picture of a runaway star ionizing the cloud and a triggered population of intermediate-mass, Class I sources located towards the cloud centre emerges from this multiwavelength study. Variation in the dust emissivity spectral index is shown to exist in this region and is seen to have an inverse relation with the dust temperature.

  8. The metal abundance of circumnuclear star-forming regions in early-type spirals. Spectrophotometric observations

    NASA Astrophysics Data System (ADS)

    Díaz, Ángeles I.; Terlevich, Elena; Castellanos, Marcelo; Hägele, Guillermo F.

    2007-11-01

    We have obtained long-slit observations in the optical and near-infrared of 12 circumnuclear HII regions [circumnuclear star-forming regions (CNSFR)] in the early-type spiral galaxies NGC2903, 3351 and 3504 with the aim of deriving their chemical abundances. Only for one of the regions, the [SIII] λ6312Å was detected providing, together with the nebular [SIII] lines at λλ9069, 9532Å, a value of the electron temperature of . A semi-empirical method for the derivation of abundances in the high metallicity regime is presented. We obtain abundances which are comparable to those found in high metallicity disc HII regions from direct measurements of electron temperatures and consistent with solar values within the errors. The region with the highest oxygen abundance is R3+R4 in NGC3504, 12 + log(O/H) = 8.85, about 1.5 solar if the solar oxygen abundance is set at the value derived by Asplund, Grevesse & Sauval, 12 + log(O/H)solar = 8.66 +/- 0.05. Region R7 in NGC3351 has the lowest oxygen abundance of the sample, about 0.6 times solar. In all the observed CNSFR the O/H abundance is dominated by the O+/H+ contribution, as is also the case for high metallicity disc HII regions. For our observed regions, however, also the S+/S2+ ratio is larger than one, contrary to what is found in high metallicity disc HII regions for which, in general, the sulphur abundances are dominated by S2+/H+. The derived N/O ratios are in average larger than those found in high metallicity disc HII regions and they do not seem to follow the trend of N/O versus O/H which marks the secondary behaviour of nitrogen. On the other hand, the S/O ratios span a very narrow range between 0.6 and 0.8 of the solar value. As compared to high metallicity disc HII regions, CNSFR show values of the O23 and the N2 parameters whose distributions are shifted to lower and higher values, respectively, hence, even though their derived oxygen and sulphur abundances are similar, higher values would in principle be

  9. First results from XILO: XMM-Newton Investigations in the Lambda Orionis star forming region

    NASA Astrophysics Data System (ADS)

    Stelzer, B.; Barrado y Navascues, D.; Huelamo, N.; Morales-Calderon, M.; Bayo, A.

    2010-11-01

    The λ Orionis star formation region (1-6 Myr, 400 pc) is a complex of star-forming clouds surrounded by a molecular ring with ~ 5° radius which was probably formed by a supernova explosion (Dolan & Mathieu 2002). For a complete picture of star formation, believed to be determined by the supernova blast, the large-scale distribution of the pre-main sequence population in λ Ori needs to be examined. We have embarked on a multi-wavelength study (XMM-Newton/X-ray, CFHT/optical, Spitzer/IR) of selected areas within this intriguing star-forming complex that enables us to identify young stars and brown dwarfs. Our study comprises various areas within the cloud complex as shown in Fig.1. This data set is among the most extended X-ray surveys carried out with XMM-Newton in a coherent star-forming environment. The XMM-Newton observations combined with optical and IR data reveal the low-mass stellar population down to ~ 0.4 M⊙. For this mass-limited sample, our preliminary analysis confirms the anomalously low disk-fraction of the central star cluster Coll 69, the Eastern extension of its low-mass population pointing towards B 35, and the concentration of young stars in front of B 35. The analysis of the ‘on-cloud field' of B 35 (white in the figure) will show if the cloud is currently forming stars. This will be crucial for determining the star-forming history in the whole λ Ori region.

  10. Monitoring rice farming activities in the Mekong Delta region

    NASA Astrophysics Data System (ADS)

    Nguyen, S. T.; Chen, C. F.; Chen, C. R.; Chiang, S. H.; Chang, L. Y.; Khin, L. V.

    2015-12-01

    . The results in forms of spatialtemporal and quantitative information of rice sowing and harvesting activities were vital for crop management, and the methods are thus suggested for rice crop monitoring in the study region and could be transferable to other regions for crop monitoring.

  11. Neutral and ionized hydrides in star-forming regions. Observations with Herschel/HIFI.

    PubMed

    Benz, Arnold O; Bruderer, Simon; van Dishoeck, Ewine F; Stäuber, Pascal; Wampfler, Susanne F

    2013-10-03

    The cosmic abundance of hydrides depends critically on high-energy UV, X-ray, and particle irradiation. Here we study hydrides in star-forming regions where irradiation by the young stellar object can be substantial, and density and temperature can be much enhanced over interstellar values. Lines of OH, CH, NH, and SH and their ions OH(+), CH(+), NH(+), SH(+), H2O(+), and H3O(+) were observed in star-forming regions by the HIFI spectrometer onboard the Herschel Space Observatory. Molecular column densities are derived from observed ground-state lines, models, or rotational diagrams. We report here on two prototypical high-mass regions, AFGL 2591 and W3 IRS5, and compare them to chemical calculations by making assumptions on the high-energy irradiation. A model assuming no ionizing protostellar emission is compared with (i) a model assuming strong protostellar X-ray emission and (ii) a two-dimensional (2D) model including emission in the far UV (FUV, 6-13.6 eV), irradiating the outflow walls that separate the outflowing gas and infalling envelope material. We confirm that the effect of FUV in two-dimensional models with enlarged irradiated surfaces is clearly noticeable. A molecule that is very sensitive to FUV irradiation is CH(+), enhanced in abundance by more than 5 orders of magnitude. The HIFI observations of CH(+) lines agree with the two-dimensional FUV model by Bruderer et al., which computes abundances, non-LTE excitation, and line radiative transfer.20 It is concluded that CH(+) is a good FUV tracer in star-forming regions. The effect of potential X-ray irradiation is not excluded but cannot be demonstrated by the present data.

  12. DIFFERENT EVOLUTIONARY STAGES IN THE MASSIVE STAR-FORMING REGION W3 MAIN COMPLEX

    SciTech Connect

    Wang Yuan; Jiang Zhibo; Beuther, Henrik; Bik, Arjan; Zhang Qizhou; Rodon, Javier A.; Fallscheer, Cassandra

    2012-08-01

    We observed three high-mass star-forming regions in the W3 high-mass star formation complex with the Submillimeter Array and IRAM 30 m telescope. These regions, i.e., W3 SMS1 (W3 IRS5), SMS2 (W3 IRS4) and SMS3, are in different evolutionary stages and are located within the same large-scale environment, which allows us to study rotation and outflows as well as chemical properties in an evolutionary sense. While we find multiple millimeter continuum sources toward all regions, these three subregions exhibit different dynamical and chemical properties, which indicate that they are in different evolutionary stages. Even within each subregion, massive cores of different ages are found, e.g., in SMS2, sub-sources from the most evolved ultracompact H II region to potential starless cores exist within 30,000 AU of each other. Outflows and rotational structures are found in SMS1 and SMS2. Evidence for interactions between the molecular cloud and the H II regions is found in the {sup 13}CO channel maps, which may indicate triggered star formation.

  13. Artificial Syntactic Violations Activate Broca's Region

    ERIC Educational Resources Information Center

    Petersson, Karl Magnus; Forkstam, Christian; Ingvar, Martin

    2004-01-01

    In the present study, using event-related functional magnetic resonance imaging, we investigated a group of participants on a grammaticality classification task after they had been exposed to well-formed consonant strings generated from an artificial regular grammar. We used an implicit acquisition paradigm in which the participants were exposed…

  14. Artificial Syntactic Violations Activate Broca's Region

    ERIC Educational Resources Information Center

    Petersson, Karl Magnus; Forkstam, Christian; Ingvar, Martin

    2004-01-01

    In the present study, using event-related functional magnetic resonance imaging, we investigated a group of participants on a grammaticality classification task after they had been exposed to well-formed consonant strings generated from an artificial regular grammar. We used an implicit acquisition paradigm in which the participants were exposed…

  15. THE EXPANSION OF ACTIVE REGIONS INTO THE EXTENDED SOLAR CORONA

    SciTech Connect

    Morgan, Huw; Jeska, Lauren; Leonard, Drew

    2013-06-01

    Advanced image processing of Large Angle and Spectrometric Coronagraph Experiment (LASCO) C2 observations reveals the expansion of the active region closed field into the extended corona. The nested closed-loop systems are large, with an apparent latitudinal extent of 50 Degree-Sign , and expanding to heights of at least 12 R{sub Sun }. The expansion speeds are {approx}10 km s{sup -1} in the AIA/SDO field of view, below {approx}20 km s{sup -1} at 2.3 R{sub Sun }, and accelerate linearly to {approx}60 km s{sup -1} at 5 R{sub Sun }. They appear with a frequency of one every {approx}3 hr over a time period of around three days. They are not coronal mass ejections (CMEs) since their gradual expansion is continuous and steady. They are also faint, with an upper limit of 3% of the brightness of background streamers. Extreme ultraviolet images reveal continuous birth and expansion of hot, bright loops from a new active region at the base of the system. The LASCO images show that the loops span a radial fan-like system of streamers, suggesting that they are not propagating within the main coronal streamer structure. The expanding loops brighten at low heights a few hours prior to a CME eruption, and the expansion process is temporarily halted as the closed field system is swept away. Closed magnetic structures from some active regions are not isolated from the extended corona and solar wind, but can expand to large heights in the form of quiescent expanding loops.

  16. Tracked Active Region Patches for MDI and HMI

    NASA Astrophysics Data System (ADS)

    Turmon, Michael; Hoeksema, J. Todd; Bobra, Monica

    2014-06-01

    We describe tracked active-region patch data products that have been developed for HMI (HMI Active Region Patches, or HARPs) and for MDI (MDI Tracked Active Region Patches, or MDI TARPs). Both data products consist of tracked magnetic features on the scale of solar active regions. The now-released HARP data product covers 2010-present (>2000 regions to date). Like the HARPs, the MDI TARP data set is a catalog of active regions (ARs), indexed by a region ID number, analogous to a NOAA AR number, and time. The TARPs contain 6170 regions spanning 72000 images taken over 1996-2010, and will be availablein the MDI resident archive (RA).MDI TARPs are computed based on the 96-minute synoptic magnetograms and intensitygrams. As with the related HARP data product, the approximate threshold for significance is 100G. Use of both image types together allows faculae and sunspots to be separated out as sub-classes of activity, in addition to identifying the overall active region that they are in. After being identified in single images, the magnetically-active patches are grouped and tracked from image to image. Merges among growing active regions, as well as faint active regions hovering at the threshold of detection, are handled automatically. Regions are tracked from their inception until they decay within view, or transit off the visible disk. For each active region and for each time, a bitmap image is stored containing the precise outline of the active region. Also, metadata such as areas and integrated fluxes are stored for each AR and for each time. Because there is a cross-calibration between the HMI and MDI magnetograms (Liu et al. 2012), it is straightforward to use the same classification and tracking rules for the HMI HARPs and the MDI TARPs. We show results demonstrating region correspondence, region boundary agreement, and agreement of flux metadata using the approximately 140 regions in the May 2010-October 2010 time period. We envision several uses for these data

  17. Material Supply and Magnetic Configuration of an Active Region Filament

    NASA Astrophysics Data System (ADS)

    Zou, P.; Fang, C.; Chen, P. F.; Yang, K.; Hao, Q.; Cao, Wenda

    2016-11-01

    It is important to study the fine structures of solar filaments with high-resolution observations, since it can help us understand the magnetic and thermal structures of the filaments and their dynamics. In this paper, we study a newly formed filament located inside the active region NOAA 11762, which was observed by the 1.6 m New Solar Telescope at Big Bear Solar Observatory from 16:40:19 UT to 17:07:58 UT on 2013 June 5. As revealed by the Hα filtergrams, cool material is seen to be injected into the filament spine with a speed of 5-10 km s-1. At the source of the injection, brightenings are identified in the chromosphere, which are accompanied by magnetic cancellation in the photosphere, implying the importance of magnetic reconnection in replenishing the filament with plasmas from the lower atmosphere. Counter-streamings are detected near one endpoint of the filament, with the plane-of-the-sky speed being 7-9 km s-1 in the Hα red-wing filtergrams and 9-25 km s-1 in the blue-wing filtergrams. The observations are indicative that this active region filament is supported by a sheared arcade without magnetic dips, and the counter-streamings are due to unidirectional flows with alternative directions, rather than due to the longitudinal oscillations of filament threads as in many other filaments.

  18. LOW-LATITUDE CORONAL HOLES, DECAYING ACTIVE REGIONS, AND GLOBAL CORONAL MAGNETIC STRUCTURE

    SciTech Connect

    Petrie, G. J. D.; Haislmaier, K. J.

    2013-10-01

    We study the relationship between decaying active-region magnetic fields, coronal holes, and the global coronal magnetic structure using Global Oscillations Network Group synoptic magnetograms, Solar TErrestrial RElations Observatory extreme-ultraviolet synoptic maps, and coronal potential-field source-surface models. We analyze 14 decaying regions and associated coronal holes occurring between early 2007 and late 2010, 4 from cycle 23 and 10 from cycle 24. We investigate the relationship between asymmetries in active regions' positive and negative magnetic intensities, asymmetric magnetic decay rates, flux imbalances, global field structure, and coronal hole formation. Whereas new emerging active regions caused changes in the large-scale coronal field, the coronal fields of the 14 decaying active regions only opened under the condition that the global coronal structure remained almost unchanged. This was because the dominant slowly varying, low-order multipoles prevented opposing-polarity fields from opening and the remnant active-region flux preserved the regions' low-order multipole moments long after the regions had decayed. Thus, the polarity of each coronal hole necessarily matched the polar field on the side of the streamer belt where the corresponding active region decayed. For magnetically isolated active regions initially located within the streamer belt, the more intense polarity generally survived to form the hole. For non-isolated regions, flux imbalance and topological asymmetry prompted the opposite to occur in some cases.

  19. Formation of ethylene glycol and other complex organic molecules in star-forming regions

    NASA Astrophysics Data System (ADS)

    Rivilla, V. M.; Beltrán, M. T.; Cesaroni, R.; Fontani, F.; Codella, C.; Zhang, Q.

    2017-02-01

    Context. The detection of complex organic molecules related with prebiotic chemistry in star-forming regions allows us to investigate how the basic building blocks of life are formed. Aims: Ethylene glycol (CH2OH)2 is the simplest sugar alcohol and the reduced alcohol of the simplest sugar glycoladehyde (CH2OHCHO). We study the molecular abundance and spatial distribution of (CH2OH)2, CH2OHCHO and other chemically related complex organic species (CH3OCHO, CH3OCH3, and C2H5OH) towards the chemically rich massive star-forming region G31.41+0.31. Methods: We analyzed multiple single-dish (Green Bank Telescope and IRAM 30 m) and interferometric (Submillimeter Array) spectra towards G31.41+0.31, covering a range of frequencies from 45 to 258 GHz. We fitted the observed spectra with a local thermodynamic equilibrium (LTE) synthetic spectra, and obtained excitation temperatures and column densities. We compared our findings in G31.41+0.31 with the results found in other environments, including low- and high-mass star-forming regions, quiescent clouds and comets. Results: We report for the first time the presence of the aGg' conformer of (CH2OH)2 towards G31.41+0.31, detecting more than 30 unblended lines. We also detected multiple transitions of other complex organic molecules such as CH2OHCHO, CH3OCHO, CH3OCH3, and C2H5OH. The high angular resolution images show that the (CH2OH)2 emission is very compact, peaking towards the maximum of the 1.3 mm continuum. These observations suggest that low abundance complex organic molecules, like (CH2OH)2 or CH2OHCHO, are good probes of the gas located closer to the forming stars. Our analysis confirms that (CH2OH)2 is more abundant than CH2OHCHO in G31.41+0.31, as previously observed in other interstellar regions. Comparing different star-forming regions we find evidence of an increase of the (CH2OH)2/CH2OHCHO abundance ratio with the luminosity of the source. The CH3OCH3/CH3OCHO and (CH2OH)2/C2H5OH ratios are nearly constant with

  20. The growth of the central region by acquisition of counterrotating gas in star-forming galaxies

    PubMed Central

    Chen, Yan-Mei; Shi, Yong; Tremonti, Christy A.; Bershady, Matt; Merrifield, Michael; Emsellem, Eric; Jin, Yi-Fei; Huang, Song; Fu, Hai; Wake, David A.; Bundy, Kevin; Stark, David; Lin, Lihwai; Argudo-Fernandez, Maria; Bergmann, Thaisa Storchi; Bizyaev, Dmitry; Brownstein, Joel; Bureau, Martin; Chisholm, John; Drory, Niv; Guo, Qi; Hao, Lei; Hu, Jian; Li, Cheng; Li, Ran; Lopes, Alexandre Roman; Pan, Kai-Ke; Riffel, Rogemar A.; Thomas, Daniel; Wang, Lan; Westfall, Kyle; Yan, Ren-Bin

    2016-01-01

    Galaxies grow through both internal and external processes. In about 10% of nearby red galaxies with little star formation, gas and stars are counter-rotating, demonstrating the importance of external gas acquisition in these galaxies. However, systematic studies of such phenomena in blue, star-forming galaxies are rare, leaving uncertain the role of external gas acquisition in driving evolution of blue galaxies. Here, based on new measurements with integral field spectroscopy of a large representative galaxy sample, we find an appreciable fraction of counter-rotators among blue galaxies (9 out of 489 galaxies). The central regions of blue counter-rotators show younger stellar populations and more intense, ongoing star formation than their outer parts, indicating ongoing growth of the central regions. The result offers observational evidence that the acquisition of external gas in blue galaxies is possible; the interaction with pre-existing gas funnels the gas into nuclear regions (<1 kpc) to form new stars. PMID:27759033

  1. TRIGONOMETRIC PARALLAXES OF MASSIVE STAR-FORMING REGIONS. IX. THE OUTER ARM IN THE FIRST QUADRANT

    SciTech Connect

    Sanna, A.; Menten, K. M.; Brunthaler, A.; Reid, M. J.; Dame, T. M.; Moscadelli, L.; Zheng, X. W.; Xu, Y.

    2012-01-20

    We report a trigonometric parallax measurement with the Very Long Baseline Array for the water maser in the distant high-mass star-forming region G75.30+1.32. This source has a heliocentric distance of 9.25{sup +0.45}{sub -0.40} kpc, which places it in the Outer arm in the first Galactic quadrant. It lies 200 pc above the Galactic plane and is associated with a substantial H I enhancement at the border of a large molecular cloud. At a Galactocentric radius of 10.7 kpc, G75.30+1.32 is in a region of the Galaxy where the disk is significantly warped toward the North Galactic Pole. While the star-forming region has an instantaneous Galactic orbit that is nearly circular, it displays a significant motion of 18 km s{sup -1} toward the Galactic plane. The present results, when combined with two previous maser studies in the Outer arm, yield a pitch angle of about 12 Degree-Sign for a large section of the arm extending from the first quadrant to the third.

  2. EVN maps of 5 cm line OH emission from star-forming regions

    NASA Astrophysics Data System (ADS)

    Desmurs, J.-F.; Baudry, A.; Graham, D. A.

    We have used three antennas of the EVN (Effelsberg, Medicina and Jodrell Bank) to observe in W3(OH) and in five other star-forming regions, simultaneously, and for the first time, the two main lines of the 2φ 3/2, J= 5/2 excited state of OH with right and left circularly polarized feeds. The data were correlated with the MkIII MPIfR correlator in Bonn and processed with the AIPS package at the Observatoire de Bordeaux. In W3(OH) we made cleaned maps of all individual channels for each line and polarization. These maps made with a 5×6.5 mas beam reveal complex kinematics and spatial structure with both extended emission and unresolved features. This fact and polarization properties demon-strate the masing nature of the emission. Maser features are identified by searching for emission over adjacent channels, and adjacent positions (within about one synthesized beam) in both polarizations after we had mapped and selected one channel as a phase reference. We have been able to identify OH Zeeman pairs and to estimate the magnetic field strength across W3(OH); the field varies from about 1 to 10 mG. At the time of this conference, three other star-forming regions (M17, ON1 and W51) show fringes while two other regions are still incompletely processed.

  3. GLOBAL DYNAMICS OF SUBSURFACE SOLAR ACTIVE REGIONS

    SciTech Connect

    Jouve, L.; Brun, A. S.

    2013-01-01

    We present three-dimensional numerical simulations of a magnetic loop evolving in either a convectively stable or unstable rotating shell. The magnetic loop is introduced into the shell in such a way that it is buoyant only in a certain portion in longitude, thus creating an {Omega}-loop. Due to the action of magnetic buoyancy, the loop rises and develops asymmetries between its leading and following legs, creating emerging bipolar regions whose characteristics are similar to those of observed spots at the solar surface. In particular, we self-consistently reproduce the creation of tongues around the spot polarities, which can be strongly affected by convection. We further emphasize the presence of ring-shaped magnetic structures around our simulated emerging regions, which we call 'magnetic necklace' and which were seen in a number of observations without being reported as of today. We show that those necklaces are markers of vorticity generation at the periphery and below the rising magnetic loop. We also find that the asymmetry between the two legs of the loop is crucially dependent on the initial magnetic field strength. The tilt angle of the emerging regions is also studied in the stable and unstable cases and seems to be affected both by the convective motions and the presence of a differential rotation in the convective cases.

  4. OBSERVING CORONAL NANOFLARES IN ACTIVE REGION MOSS

    SciTech Connect

    Testa, Paola; DeLuca, Ed; Golub, Leon; Korreck, Kelly; Weber, Mark; De Pontieu, Bart; Martinez-Sykora, Juan; Title, Alan; Hansteen, Viggo; Cirtain, Jonathan; Winebarger, Amy; Kobayashi, Ken; Kuzin, Sergey; Walsh, Robert; DeForest, Craig

    2013-06-10

    The High-resolution Coronal Imager (Hi-C) has provided Fe XII 193A images of the upper transition region moss at an unprecedented spatial ({approx}0.''3-0.''4) and temporal (5.5 s) resolution. The Hi-C observations show in some moss regions variability on timescales down to {approx}15 s, significantly shorter than the minute-scale variability typically found in previous observations of moss, therefore challenging the conclusion of moss being heated in a mostly steady manner. These rapid variability moss regions are located at the footpoints of bright hot coronal loops observed by the Solar Dynamics Observatory/Atmospheric Imaging Assembly in the 94 A channel, and by the Hinode/X-Ray Telescope. The configuration of these loops is highly dynamic, and suggestive of slipping reconnection. We interpret these events as signatures of heating events associated with reconnection occurring in the overlying hot coronal loops, i.e., coronal nanoflares. We estimate the order of magnitude of the energy in these events to be of at least a few 10{sup 23} erg, also supporting the nanoflare scenario. These Hi-C observations suggest that future observations at comparable high spatial and temporal resolution, with more extensive temperature coverage, are required to determine the exact characteristics of the heating mechanism(s).

  5. Homologous flares and the evolution of NOAA Active Region 2372

    NASA Technical Reports Server (NTRS)

    Strong, K. T.; Smith, J. B., Jr.; Mccabe, M. K.; Machado, M. E.; Saba, J. L. R.; Simnett, G. M.

    1984-01-01

    A detailed record of the evolution of NOAA Active Region 2372 has been compiled by the FBS Homology Study Group. It was one of the most prolific flare-producing regions observed by SMM. The flares occurred in distinct stages which corresponded to particular evolutionary phases in the development of the active region magnetic field. By comparison with a similar but less productive active region, it is found that the activity seems to be related to the magnetic complexity of the region and the amount of shear in the field. Further, the soft X-ray emission in the quiescent active region is related to its flare rate. Within the broader definition of homology adopted, there was a degree of homology between the events within each stage of evolution of AR2372.

  6. A Fractal Dimension Survey of Active Region Complexity

    NASA Technical Reports Server (NTRS)

    McAteer, R. T. James; Gallagher, Peter; Ireland, Jack

    2005-01-01

    A new approach to quantifying the magnetic complexity of active regions using a fractal dimension measure is presented. This fully-automated approach uses full disc MDI magnetograms of active regions from a large data set (2742 days of the SoHO mission; 9342 active regions) to compare the calculated fractal dimension to both Mount Wilson classification and flare rate. The main Mount Wilson classes exhibit no distinct fractal dimension distribution, suggesting a self-similar nature of all active regions. Solar flare productivity exhibits an increase in both the frequency and GOES X-ray magnitude of flares from regions with higher fractal dimensions. Specifically a lower threshold fractal dimension of 1.2 and 1.25 exists as a necessary, but not sufficient, requirement for an active region to produce M- and X-class flares respectively .

  7. Subsurface helicity of active regions 12192 and 10486

    NASA Astrophysics Data System (ADS)

    Komm, Rudolf; Tripathy, Sushant; Howe, Rachel; Hill, Frank

    2015-04-01

    The active region 10486 that produced the Halloween flares in 2003 initiated our interest in the kinetic helicity of subsurface flows associated with active regions. This lead to the realization that the helicity of subsurface flows is related to the flare activity of active regions. Eleven years later, a similarly enormous active region (12192) appeared on the solar surface. We plan to study the kinetic helicity of the subsurface flows associated with region 12192 and compare it to that of region 10486. For 10486, we have analyzed Dopplergrams obtained with the Michelson Doppler Imager (MDI) onboard the Solar and Heliospheric Observatory (SOHO) and the Global Oscillation Network Group (GONG) with a dense-pack ring-diagram analysis. For 12192, we have analyzed Dopplergrams from GONG and the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO). We will present the latest results.

  8. A Fractal Dimension Survey of Active Region Complexity

    NASA Technical Reports Server (NTRS)

    McAteer, R. T. James; Gallagher, Peter; Ireland, Jack

    2005-01-01

    A new approach to quantifying the magnetic complexity of active regions using a fractal dimension measure is presented. This fully-automated approach uses full disc MDI magnetograms of active regions from a large data set (2742 days of the SoHO mission; 9342 active regions) to compare the calculated fractal dimension to both Mount Wilson classification and flare rate. The main Mount Wilson classes exhibit no distinct fractal dimension distribution, suggesting a self-similar nature of all active regions. Solar flare productivity exhibits an increase in both the frequency and GOES X-ray magnitude of flares from regions with higher fractal dimensions. Specifically a lower threshold fractal dimension of 1.2 and 1.25 exists as a necessary, but not sufficient, requirement for an active region to produce M- and X-class flares respectively .

  9. Structure of the cleavage-activated prefusion form of the parainfluenza virus 5 fusion protein.

    PubMed

    Welch, Brett D; Liu, Yuanyuan; Kors, Christopher A; Leser, George P; Jardetzky, Theodore S; Lamb, Robert A

    2012-10-09

    The paramyxovirus parainfluenza virus 5 (PIV5) enters cells by fusion of the viral envelope with the plasma membrane through the concerted action of the fusion (F) protein and the receptor binding protein hemagglutinin-neuraminidase. The F protein folds initially to form a trimeric metastable prefusion form that is triggered to undergo large-scale irreversible conformational changes to form the trimeric postfusion conformation. It is thought that F refolding couples the energy released with membrane fusion. The F protein is synthesized as a precursor (F0) that must be cleaved by a host protease to form a biologically active molecule, F1,F2. Cleavage of F protein is a prerequisite for fusion and virus infectivity. Cleavage creates a new N terminus on F1 that contains a hydrophobic region, known as the FP, which intercalates target membranes during F protein refolding. The crystal structure of the soluble ectodomain of the uncleaved form of PIV5 F is known; here we report the crystal structure of the cleavage-activated prefusion form of PIV5 F. The structure shows minimal movement of the residues adjacent to the protease cleavage site. Most of the hydrophobic FP residues are buried in the uncleaved F protein, and only F103 at the newly created N terminus becomes more solvent-accessible after cleavage. The conformational freedom of the charged arginine residues that compose the protease recognition site increases on cleavage of F protein.

  10. Space-weather MDI Active Region Patches (SMARPs)

    NASA Astrophysics Data System (ADS)

    Bobra, Monica

    2017-08-01

    We are developing a new data product from the Michelson Doppler Imager (MDI) onboard the Solar and Heliospheric Observatory (SoHO) called Space-weather MDI Active Region Patches (SMARPs). The SMARP data series provide maps of the photospheric line-of-sight magnetic field in patches that encompass automatically tracked magnetic concentrations, or active regions, for their entire lifetime. These concentrations are automatically detected in the photospheric line-of-sight magnetic field data using a method described in Turmon et al. (2010) and, thus, are necessarily different from NOAA's definition of an active region. As such, these regions are assigned their own identification number, or SMARP number, which is also linked to a NOAA active region number should it exist. In addition, keywords in the SMARP data series include parameters that concisely characterize the magnetic field distribution. These parameters may be useful for active region event forecasting and for identifying regions of interest. These parameters are calculated per patch and are available on a 96 minute cadence.The SMARP data product is designed to provide seamless coverage with its counterpart, the Space-weather HMI Active Region Patches (SHARPs), described in Bobra et al. (2014). Together, the SMARP and SHARP data series provide continuous coverage of tracked active regions for two solar cycles from 1996 to the present day. The SMARP data series, which runs from April 1996 to October 2010, contains 9496 unique active regions tracked throughout their lifetime. The SHARP data series, which runs from May 2010 to the present day, contains (as of May 30, 2017) 3883 unique active regions tracked throughout their lifetime. In addition, the two series contain 118 unique active regions during the overlap period between May and October 2010. SMARP data will be available at jsoc.stanford.edu and the photospheric line-of-sight magnetic field maps will be available in either of two different coordinate

  11. Tectonic activity on Pluto after the Charon-forming impact

    NASA Astrophysics Data System (ADS)

    Barr, Amy C.; Collins, Geoffrey C.

    2015-01-01

    The Pluto-Charon system, likely formed from an impact, has reached the endpoint of its tidal evolution. During its evolution into the dual-synchronous state, the equilibrium tidal figures of Pluto and Charon would have also evolved as angular momentum was transferred from Pluto's spin to Charon's orbit. The rate of tidal evolution is controlled by Pluto's interior physical and thermal state. We examine three interior models for Pluto: an undifferentiated rock/ice mixture, differentiated with ice above rock, and differentiated with an ocean. For the undifferentiated case without an ocean, the Pluto-Charon binary does not evolve to its current state unless its internal temperature Ti > 200K , which would likely lead to strong tidal heating, melting, and differentiation. Without an ocean, Pluto's interior temperature must be higher than 240 K for Charon to evolve on a time scale less than the age of the Solar System. Further tidal heating would likely create an ocean. If New Horizons finds evidence of ancient tidally-driven tectonic activity on either body, the most likely explanation is that Pluto had an internal ocean during Charon's orbital evolution.

  12. Multi-wavelength, Multi-scale Observations of Outflows in Star-Forming Regions

    NASA Astrophysics Data System (ADS)

    Plunkett, Adele Laurie Dennis

    ratio of outflow energy to gravitational binding energy; further, if gas escapes from NGC 1333, then outflow energy and gravitational energy may become comparable within the next N ~ 0.5 Myr, possibly disrupting the cluster. Finally, we investigate the properties of a particular Class 0 molecular outflow in Serpens South, providing evidence for episodic outflow events and corresponding accretion at a very early stage. This remarkable outflow remains intact even within the active, central hub region of Serpens South.

  13. Gas kinematics in high-mass star-forming regions from the Perseus spiral arm

    NASA Astrophysics Data System (ADS)

    Kirsanova, M. S.; Sobolev, A. M.; Thomasson, M.

    2017-09-01

    We present results of a survey of 14 star-forming regions from the Perseus spiral armin CS (2-1) and 13CO (1-0) lines with the Onsala Space Observatory 20 m telescope. Maps of 10 sources in both lines are obtained. For the remaining sources a map in just one line or a single-point spectrum is obtained. On the basis of newly obtained and published observational data we consider the relation between velocities of the "quasi-thermal" CS (2-1) line and 6.7 GHz methanol maser line in 24 high-mass star-forming regions in the Perseus arm. We show that, surprisingly, velocity ranges of 6.7 GHz methanol maser emission are predominantly red-shifted with respect to corresponding CS (2-1) line velocity ranges in the Perseus arm. We suggest that the predominance of the "red-shifted masers" in the Perseus arm could be related to the alignment of gas flows caused by the large-scalemotions in the Galaxy. Large-scale galactic shock related to the spiral structure is supposed to affect the local kinematics of the star-forming regions. Part of the Perseus arm, between galactic longitudes from 85° to 124° , does not contain blue-shifted masers at all. Radial velocities of the sources are the greatest in this particular part of the arm, so the velocity difference is clearly pronounced. 13CO (1-0) and CS (2-1) velocity maps of G183.35-0.58 show gas velocity difference between the center and the periphery of the molecular clump up to 1.2 km s-1. Similar situation is likely to occur in G85.40-0.00. This can correspond to the case when the large-scale shock wave entrains the outer parts of a molecular clump in motion while the dense central clump is less affected by the shock.

  14. Deep VLA observations of nearby star forming regions I: Barnard 59 and Lupus 1

    NASA Astrophysics Data System (ADS)

    Dzib, S. A.; Loinard, L.; Medina, S.-N. X.; Rodríguez, L. F.; Mioduszewski, A. J.; Torres, R. M.

    2016-10-01

    Barnard 59 and Lupus 1 are two nearby star-forming regions visible from the southern hemisphere. In this manuscript, we present deep (σ˜15 μJy) radio observations (ν=6 GHz) of these regions, and report the detection of a total of 114 sources. Thirteen of these sources are associated with known young stellar objects, nine in Barnard 59 and four in Lupus 1. The properties of the radio emission (spectral index and, in some cases, polarization) suggest a thermal origin for most young stellar objects. Only for two sources (Sz 65 and Sz 67) are there indications for a possible non-thermal origin. The remaining radio detections do not have counterparts at other wavelengths, and the number of sources detected per unit solid angle is in agreement with extragalactic number counts, suggesting that they are extragalactic sources.

  15. A kinematic analysis of the Giant star-forming Region of N11

    NASA Astrophysics Data System (ADS)

    Torres-Flores, Sergio; Barbá, Rodolfo; Maíz Apellániz, Jesús; Rubio, Mónica; Bosch, Guillermo

    2015-02-01

    In this work we present high resolution spectroscopic data of the giant star-forming region of N11, obtained with the GIRAFFE instrument at the Very Large Telescope. By using this data set, we find that most of the Hα emission lines profiles in this complex can be fitted by a single Gaussian, however, multiple emission line profiles can be observed in the central region of N11. By adding all the spectra, we derive the integrated Hα profile of this complex, which displays a width (σ) of about 12 km s-1 (corrected by instrumental and thermal width). We find that a single Gaussian fit on the integrated Hα profile leaves remaining wings, which can be fitted by a secondary broad Gaussian component. In addition, we find high velocity features, which spatially correlate with soft diffuse X-ray emission.

  16. An accretion disks in the high-mass star forming region IRA 23151+5912

    NASA Astrophysics Data System (ADS)

    Migenes, Victor; Rodríguez-Esnard, T.; Trinidad, M. A.

    2014-01-01

    We present observations of radio continuum emission at 1.3 and 3.6 cm and H2O masers toward the high-mass star-forming regions IRA 23151+5912 carried out with the VLA-EVLA. We detected one continuum source at 1.3 cm and 13 water maser spots which are distributed in three groups aligned along the northeast-southwest direction. Our results suggest that the 1.3 cm emission is consistent with an HC HII region, probably with an embedded zero-age main sequence star of type B2. In particular, we find that this radio continuum source is probably associated with a circumstellar disk of about 68 AU, as traced by water masers. Furthermore, the masers of the second group are probably describing another circumstellar disk of about 86 AU, whose central protostar is still undetected. We discuss this results in the light of more recent high-resolution observations.

  17. Circular polarisation in star-forming regions: possible implications for homochirality.

    PubMed

    Hough, J H; Bailey, J A; Chrysostomou, A; Gledhill, T M; Lucas, P W; Tamura, M; Clark, S; Yates, J; Menard, F

    2001-01-01

    Our discovery of high degrees of circular polarisation in some star-forming regions provides an attractive mechanism for the origin of homochirality. The largest degrees of circular polarisation, so far observed at near-infrared wavelengths, are thought to arise from the scattering of stellar radiation from aligned dust grains and are calculated to extend down to UV wavelengths. The extent of the region where circularly polarised light (CPL) of a single handedness originates is very large, and it is likely that the whole of a planetary system would see a single handedness of CPL also. We present the observational data, models of the scattering that leads to the production of CPL, and a model for the origin of homochirality. We also discuss briefly future laboratory and space-based experiments.

  18. Dynamical Masses of Low-mass Stars in the Taurus and Ophiuchus Star-forming Regions

    NASA Astrophysics Data System (ADS)

    Simon, M.; Guilloteau, S.; Di Folco, E.; Dutrey, A.; Grosso, N.; Piétu, V.; Chapillon, E.; Prato, L.; Schaefer, G. H.; Rice, E.; Boehler, Y.

    2017-08-01

    We report new dynamical masses for five pre-main sequence (PMS) stars in the L1495 region of the Taurus star-forming region (SFR) and six in the L1688 region of the Ophiuchus SFR. Since these regions have VLBA parallaxes, these are absolute measurements of the stars’ masses and are independent of their effective temperatures and luminosities. Seven of the stars have masses < 0.6 {M}⊙ , thus providing data in a mass range with little data, and of these, six are measured to precision < 5 % . We find eight stars with masses in the range 0.09-1.1 {M}⊙ that agree well with the current generation of PMS evolutionary models. The ages of the stars we measured in the Taurus SFR are in the range 1-3 Myr, and < 1 Myr for those in L1688. We also measured the dynamical masses of 14 stars in the ALMA archival data for Akeson & Jensen’s Cycle 0 project on binaries in the Taurus SFR. We find that the masses of seven of the targets are so large that they cannot be reconciled with reported values of their luminosity and effective temperature. We suggest that these targets are themselves binaries or triples.

  19. A Catalog of Methanol Masers in Massive Star-forming Regions. III. The Molecular Outflow Sample

    NASA Astrophysics Data System (ADS)

    Gómez-Ruiz, A. I.; Kurtz, S. E.; Araya, E. D.; Hofner, P.; Loinard, L.

    2016-02-01

    We present an interferometric survey of the 44 GHz class I methanol maser transition toward a sample of 69 sources consisting of high-mass protostellar object (HMPO) candidates and ultracompact (UC) H ii regions. We found a 38% detection rate (16 of 42) in the HMPO candidates and a 54% detection rate (13 of 24) for the regions with ionized gas. This result indicates that class I methanol maser emission is more common toward the more evolved young stellar objects of our sample. Comparing with similar interferometric data sets, our observations show narrower linewidths, likely due to our higher spatial resolution. Based on a comparison between molecular outflow tracers and the maser positions, we find several cases where the masers appear to be located at the outflow interface with the surrounding core. Unlike previous surveys, we also find several cases where the masers appear to be located close to the base of the molecular outflow, although we cannot discard projection effects. This and other surveys of class I methanol masers not only suggest that these masers may trace shocks at different stages, but also that they may even trace shocks arising from a number of different phenomena occurring in star-forming regions: young/old outflows, cloud-cloud collisions, expanding H ii regions, among others.

  20. A CATALOG OF METHANOL MASERS IN MASSIVE STAR-FORMING REGIONS. III. THE MOLECULAR OUTFLOW SAMPLE

    SciTech Connect

    Gómez-Ruiz, A. I.; Kurtz, S. E.; Loinard, L.; Araya, E. D.; Hofner, P.

    2016-02-15

    We present an interferometric survey of the 44 GHz class I methanol maser transition toward a sample of 69 sources consisting of high-mass protostellar object (HMPO) candidates and ultracompact (UC) H ii regions. We found a 38% detection rate (16 of 42) in the HMPO candidates and a 54% detection rate (13 of 24) for the regions with ionized gas. This result indicates that class I methanol maser emission is more common toward the more evolved young stellar objects of our sample. Comparing with similar interferometric data sets, our observations show narrower linewidths, likely due to our higher spatial resolution. Based on a comparison between molecular outflow tracers and the maser positions, we find several cases where the masers appear to be located at the outflow interface with the surrounding core. Unlike previous surveys, we also find several cases where the masers appear to be located close to the base of the molecular outflow, although we cannot discard projection effects. This and other surveys of class I methanol masers not only suggest that these masers may trace shocks at different stages, but also that they may even trace shocks arising from a number of different phenomena occurring in star-forming regions: young/old outflows, cloud–cloud collisions, expanding H ii regions, among others.

  1. The electromagnetic form factors of the Λ in the timelike region

    NASA Astrophysics Data System (ADS)

    Haidenbauer, J.; Meißner, U.-G.

    2016-10-01

    The reaction e+e- → Λ bar Λ is investigated for energies close to the threshold. Specific emphasis is put on the role played by the interaction in the final Λ bar Λ system which is taken into account rigorously. For that interaction a variety of Λ bar Λ potential models is employed that have been constructed for the analysis of the reaction p bar p → Λ bar Λ in the past. The enhancement of the effective form factor for energies close to the Λ bar Λ threshold, seen in pertinent experiments, is reproduced. Predictions for the Λ electromagnetic form factors GM and GE in the timelike region and for spin-dependent observables such as spin-correlation parameters are presented.

  2. Desert Pavement Process and Form: Modes and Scales of Landscape Stability and Instability in Arid Regions

    NASA Astrophysics Data System (ADS)

    Wells, Stephen G.; McFadden, Leslie D.; McDonald, Eric V.; Eppes, Martha C.; Young, Michael H.; Wood, Yvonne A.

    2014-05-01

    Desert pavements are recognized in arid landscapes around the world, developing via diminution of constructional/depositional landform relief and creating a 1-2 stone thick armor over a "stone free" layer. Surface exposure dating demonstrates that clasts forming the desert pavements are maintained at the land surface over hundreds of thousands of years, as aeolian fines are deposited on the land surface, transported into the underlying parent material and incorporated into accretionary soil horizons (e.g., the stone free or vesicular [Av] horizon). This surface armor provides long-term stability over extensive regions of the landscape. Over shorter time periods and at the landform-element scale, dynamic surficial processes (i.e., weathering, runoff) continue to modify the pavement form. Clast size reduction in comparison to underlying parent material, along with armoring and packing of clasts in pavements contribute to their persistence, and studies of crack orientations in pavement clasts indicate physical weathering and diminution of particle size are driven by diurnal solar insolation. Over geologic time, cracks form and propagate from tensile stresses related to temporal and spatial gradients in temperature that evolve and rotate in alignment with the sun's rays. Observed multimodal nature of crack orientations appear related to seasonally varying, latitude-dependent temperature fields resulting from solar angle and weather conditions. Surface properties and their underlying soil profiles vary across pavement surfaces, forming a landscape mosaic and controlling surface hydrology, ecosystem function and the ultimate life-cycle of arid landscapes. In areas of well-developed pavements, surface infiltration and soluble salt concentrations indicate that saturated hydraulic conductivity of Av horizons decline on progressively older alluvial fan surfaces. Field observations and measurements from well-developed desert pavement surfaces landforms also yield

  3. The distribution of warm dust in the star forming region Cepheus A: Infrared constraints

    NASA Astrophysics Data System (ADS)

    Colome, Cecilia; Harvey, Paul M.

    We have obtained new, high angular resolution far-infrared (FIR) maps (at 50 and 100 microns) of the star forming region Cepheus A and polarimetric images (1.65 and 2.2 microns) of the reflection nebulosity, IRS6, associated with this young stellar object. Our results are consistent with current star formation theories: a young stellar object surrounded by an infalling envelope with a characteristic density distribution of nd(r) proportional to r-1.5, a circumstellar disk, and a cavity (Ri approx. 0.07 pc) in which nd is constant, created by the dispersal of the initial dust cloud by a strong stellar wind.

  4. Trigonometric parallaxes of star forming regions in the Perseus spiral arm

    SciTech Connect

    Choi, Y. K.; Brunthaler, A.; Menten, K. M.; Hachisuka, K.; Reid, M. J.; Dame, T. M.; Xu, Y. E-mail: ykchoi@kasi.re.kr

    2014-08-01

    We report trigonometric parallaxes and proper motions of water masers for 12 massive star forming regions in the Perseus spiral arm of the Milky Way as part of the Bar and Spiral Structure Legacy (BeSSel) Survey. Combining our results with 14 parallax measurements in the literature, we estimate a pitch angle of 9.°9 ± 1.°5 for a section of the Perseus arm. The three-dimensional Galactic peculiar motions of these sources indicate that on average they are moving toward the Galactic center and slower than the Galactic rotation.

  5. A Survey of Large Molecules of Biological Interest toward Selected High Mass Star Forming Regions

    NASA Technical Reports Server (NTRS)

    Remijan, A.; Shiao, Y.-S.; Friedel, D. N.; Meier, D. S.; Snyder, L. E.

    2004-01-01

    We have surveyed three high mass Galactic star forming regions for interstellar methanol (CH3OH), formic acid (HCOOH), acetic acid (CH3COOH), methyl formate (HCOOCH3), methyl cyanide (CH3CN), and ethyl cyanide (CH3CH2CN) with the BIMA Array. From our observations, we have detected two new sources of interstellar HCOOH toward the hot core regions G19.61-0.23 and W75N. We have also made the first detections of CH3CH2CN and HCOOCH3 toward G19.61-0.23. The relative HCOOH/HCOOCH3 abundance ratio toward G19.61-0.23 is 0.18 which is comparable to the abundance ratios found by Liu and colleagues toward Sgr B2(N-LMH), Orion and W51(approximately 0.10). We have made the first detection of HCOOCH3 toward W75N. The relative HCOOH/HCOOCH3 abundance ratio toward W75N is 0.26 which is more than twice as large as the abundance ratios found by Liu and colleagues. Furthermore, the hot core regions around W75N show a chemical differentiation between the O and N cores similar to what is seen toward the Orion Hot Core and Compact Ridge and W3(OH) and W3(H2O). It is also apparent from our observations that the high mass star forming region G45.47+0.05 does not contain any compact hot molecular core and as a consequence its chemistry may be similar to cold dark clouds. Finally, the formation of CH3COOH appears to favor HMCs with well mixed N and O, despite the fact that CH3COOH does not contain a N atom. If proved to be true, this is an important constraint on CH3COOH formation and possibly other structurally similar biomolecules.

  6. An all-sky sample of intermediate-mass star-forming regions

    SciTech Connect

    Lundquist, Michael J.; Kobulnicky, Henry A.; Alexander, Michael J.; Kerton, Charles R.; Arvidsson, Kim

    2014-04-01

    We present an all-sky sample of 984 candidate intermediate-mass Galactic star-forming regions that are color selected from the Infrared Astronomical Satellite (IRAS) Point Source Catalog and morphologically classify each object using mid-infrared Wide-field Infrared Survey Explorer (WISE) images. Of the 984 candidates, 616 are probable star-forming regions (62.6%), 128 are filamentary structures (13.0%), 39 are point-like objects of unknown nature (4.0%), and 201 are galaxies (20.4%). We conduct a study of four of these regions, IRAS 00259+5625, IRAS 00420+5530, IRAS 01080+5717, and IRAS 05380+2020, at Galactic latitudes |b| > 5° using optical spectroscopy from the Wyoming Infrared Observatory, along with near-infrared photometry from the Two-Micron All Sky Survey, to investigate their stellar content. New optical spectra, color-magnitude diagrams, and color-color diagrams reveal their extinctions, spectrophotometric distances, and the presence of small stellar clusters containing 20-78 M {sub ☉} of stars. These low-mass diffuse star clusters contain ∼65-250 stars for a typical initial mass function, including one or more mid-B stars as their most massive constituents. Using infrared spectral energy distributions we identify young stellar objects near each region and assign probable masses and evolutionary stages to the protostars. The total infrared luminosity lies in the range 190-960 L {sub ☉}, consistent with the sum of the luminosities of the individually identified young stellar objects.

  7. Cool and hot emission in a recurring active region jet

    NASA Astrophysics Data System (ADS)

    Mulay, Sargam M.; Zanna, Giulio Del; Mason, Helen

    2017-09-01

    Aims: We present a thorough investigation of the cool and hot temperature components in four recurring active region jets observed on July 10, 2015 using the Atmospheric Imaging Assembly (AIA), X-ray Telescope (XRT), and Interface Region Imaging Spectrograph (IRIS) instruments. Methods: A differential emission measure (DEM) analysis was performed on areas in the jet spire and footpoint regions by combining the IRIS spectra and the AIA observations. This procedure better constrains the low temperature DEM values by adding IRIS spectral lines. Plasma parameters, such as Doppler velocities, electron densities, nonthermal velocities and a filling factor were also derived from the IRIS spectra. Results: In the DEM analysis, significant cool emission was found in the spire and the footpoint regions. The hot emission was peaked at log T [K] = 5.6-5.9 and 6.5 respectively. The DEM curves show the presence of hot plasma (T = 3 MK) in the footpoint region. We confirmed this result by estimating the Fe XVIII emission from the AIA 94 Å channel which was formed at an effective temperature of log T [K] = 6.5. The average XRT temperatures were also found to be in agreement with log T [K] = 6.5. The emission measure (EM) was found to be three orders of magnitude higher in the AIA-IRIS DEM compared with that obtained using only AIA. The O IV (1399/1401 Å) electron densities were found to be 2.0×1010 cm-3 in the spire and 7.6 × 1010 cm-3 in the footpoint. Different threads along the spire show different plane-of-sky velocities both in the lower corona and transition region. Doppler velocities of 32 km s-1 (blueshifted) and 13 km s-1 (redshifted) were obtained in the spire and footpoint, respectively from the Si IV 1402.77 Å spectral line. Nonthermal velocities of 69 and 53 km s-1 were recorded in the spire and footpoint region, respectively. We obtained a filling factor of 0.1 in the spire at log T [K] = 5. Conclusions: The recurrent jet observations confirmed the presence of

  8. Water in Star-forming Regions with Herschel (WISH): recent results and trends

    NASA Astrophysics Data System (ADS)

    van Dishoeck, E. F.

    2012-03-01

    Water is a key molecule in the physics and chemistry of star- and planet-forming regions. In the `Water in Star-forming Regions with Herschel' (WISH) Key Program, we have obtained a comprehensive set of water data toward a large sample of well-characterized protostars, covering a wide range of masses and luminosities --from the lowest to the highest mass protostars--, as well as evolutionary stages --from pre-stellar cores to disks. Lines of both ortho- and para-H_2O and their isotopologues, as well as chemically related hydrides, are observed with the HIFI and PACS instruments. The data elucidate the physical processes responsible for the warm gas, probe dynamical processes associated with forming stars and planets (outflow, infall, expansion), test basic chemical processes and reveal the chemical evolution of water and the oxygen-reservoir into planet-forming disks. In this brief talk a few recent WISH highlights will be presented, including determinations of the water abundance in each of the different physical components (inner and outer envelope, outflow) and constraints on the ortho/para ratio. Special attention will be given to trends found across the sample, especially the similarity in profiles from low to high-mass protostars and the evolution of the gas-phase water abundance from prestellar cores to disks. More details can be found at http://www.strw.leidenuniv.nl/WISH, whereas overviews are given in van Dishoeck et al. (2011, PASP 123, 138), Kristensen & van Dishoeck (2011, Astronomische Nachrichten 332, 475) and Bergin & van Dishoeck (2012, Phil. Trans. Royal Soc. A).

  9. A multi-wavelength database of water vapor in planet-forming regions

    NASA Astrophysics Data System (ADS)

    Pontoppidan, Klaus

    The inner few astronomical units of gas-rich protoplanetary disk are environments characterized by a rich and active gaseous chemistry. Primitive material left over from the formation of our own Solar System has for a long time yielded tantalizing clues to a heterogenous nebula with intricate dynamical, thermal and chemical structure that ultimately led to a great diversity in the planets and planetesimals of the Solar System. The discovery of a rich chemistry in protoplanetary disks via a forest of strong 3-40 micron molecular emission lines (H2O, OH, CO2, HCN, C2H2,...) allows us for the first time to investigate chemical diversity in other planet-forming environmments (Salyk et al. 2008; Carr & Najita 2008). Further efforts, supported by the Origins program, has established that this molecular forest is seen in the disks surrounding most young solar- type stars (Pontoppidan et al. 2010). We propose a 3-year program to analyze our growing multi-wavelength database of observations of water, OH and organic molecules in the surfaces of protoplanetary disks. The database includes high (R~25,000-100,000) and medium resolution (R~600-3000) 3- 200 micron spectra from a wide range of facilities (Keck-NIRSPEC, VLT-CRIRES, Spitzer-IRS, VLT-VISIR, Gemini-Michelle and Herschel-PACS). Our previous efforts have focused on demonstrating feasibility for observing water and other molecules in planet-forming regions, building statistics to show that the molecular forest is ubiquitous in disks around low-mass and solar-type stars and taking the first steps in understanding the implied chemical abundances. Now, as the next logical step, we will combine multi- wavelength data from our unique multi-wavelength database to map the radial distribution of, in particular, water and its derivatives. 1) Â We will use both line profile information from the high-resolution spectra, as well as line strengths, from a combination of high and low temperature lines to constrain the radial

  10. A multi-wavelength database of water vapor in planet-forming regions

    NASA Astrophysics Data System (ADS)

    Pontoppidan, Klaus

    The inner few astronomical units of gas-rich protoplanetary disk are environments characterized by a rich and active gaseous chemistry. Primitive material left over from the formation of our own Solar System has for a long time yielded tantalizing clues to a heterogenous nebula with intricate dynamical, thermal and chemical structure that ultimately led to a great diversity in the planets and planetesimals of the Solar System. The discovery of a rich chemistry in protoplanetary disks via a forest of strong 3-40 micron molecular emission lines (H2O, OH, CO2, HCN, C2H2,...) allows us for the first time to investigate chemical diversity in other planet-forming environmments (Salyk et al. 2008; Carr & Najita 2008). Further efforts, supported by the Origins program, has established that this molecular forest is seen in the disks surrounding most young solar- type stars (Pontoppidan et al. 2010). We propose a 3-year program to analyze our growing multi-wavelength database of observations of water, OH and organic molecules in the surfaces of protoplanetary disks. The database includes high (R~25,000-100,000) and medium resolution (R~600-3000) 3- 200 micron spectra from a wide range of facilities (Keck-NIRSPEC, VLT-CRIRES, Spitzer-IRS, VLT-VISIR, Gemini-Michelle and Herschel-PACS). Our previous efforts have focused on demonstrating feasibility for observing water and other molecules in planet-forming regions, building statistics to show that the molecular forest is ubiquitous in disks around low-mass and solar-type stars and taking the first steps in understanding the implied chemical abundances. Now, as the next logical step, we will combine multi- wavelength data from our unique multi-wavelength database to map the radial distribution of, in particular, water and its derivatives. 1) We will use both line profile information from the high-resolution spectra, as well as line strengths, from a combination of high and low temperature lines to constrain the radial abundance

  11. The interrelationship of dune forming processes and the occurrence of wetlands and peatbogs in the Holy Cross Mountains Region

    NASA Astrophysics Data System (ADS)

    Jaskowski, B.

    2003-04-01

    Dunes of the Holy Cross Mts. Region were formed, like those in other regions of Poland, in the Late Vistulian and were transformed during the different Holocene periods. Numerous factors were influential in the distribution of dunes in the Holy Cross Mts. Region such as relief, drainage pattern, distribution and thickness of deposits susceptible to eolian processes, depth of groundwater level and density of plants. In a number places the phenomena of encroaching complexes dunes, eolian cover sands in river valleys and the damming up of riverflows were observed. In newly created water reservoirs and wetlands organic sediments were deposited. These phenomena crated a modification in drainage pattern. Detailed investigations have determined that the phenomena are related to neotectonic activity of a basement complex. Dunes encroachment in river valleys causing damming of flow happened to occur on lines runnig transverse to the tectonic elevations. In the light of radiocarbon dating the organic sediments of the water reservoirs and wetlands were formed in the Late Vistulian period.

  12. Remote sensing application to regional activities

    NASA Technical Reports Server (NTRS)

    Shahrokhi, F.; Jones, N. L.; Sharber, L. A.

    1976-01-01

    Two agencies within the State of Tennessee were identified whereby the transfer of aerospace technology, namely remote sensing, could be applied to their stated problem areas. Their stated problem areas are wetland and land classification and strip mining studies. In both studies, LANDSAT data was analyzed with the UTSI video-input analog/digital automatic analysis and classification facility. In the West Tennessee area three land-use classifications could be distinguished; cropland, wetland, and forest. In the East Tennessee study area, measurements were submitted to statistical tests which verified the significant differences due to natural terrain, stripped areas, various stages of reclamation, water, etc. Classifications for both studies were output in the form of maps of symbols and varying shades of gray.

  13. Reading cinnamon activates olfactory brain regions.

    PubMed

    González, Julio; Barros-Loscertales, Alfonso; Pulvermüller, Friedemann; Meseguer, Vanessa; Sanjuán, Ana; Belloch, Vicente; Avila, César

    2006-08-15

    Some words immediately and automatically remind us of odours, smells and scents, whereas other language items do not evoke such associations. This study investigated, for the first time, the abstract linking of linguistic and odour information using modern neuroimaging techniques (functional MRI). Subjects passively read odour-related words ('garlic', 'cinnamon', 'jasmine') and neutral language items. The odour-related terms elicited activation in the primary olfactory cortex, which include the piriform cortex and the amygdala. Our results suggest the activation of widely distributed cortical cell assemblies in the processing of olfactory words. These distributed neuron populations extend into language areas but also reach some parts of the olfactory system. These distributed neural systems may be the basis of the processing of language elements, their related conceptual and semantic information and the associated sensory information.

  14. In-depth survey of sunspot and active region catalogs

    NASA Astrophysics Data System (ADS)

    Lefèvre, Laure; Clette, Frédéric; Baranyi, Tunde

    2011-08-01

    When consulting detailed photospheric catalogs for solar activity studies spanning long time intervals, solar physicists face multiple limitations in the existing catalogs: finite or fragmented time coverage, limited time overlap between catalogs and even more importantly, a mismatch in contents and conventions. In view of a study of new sunspot-based activity indices, we have conducted a comprehensive survey of existing catalogs. In a first approach, we illustrate how the information from parallel catalogs can be merged to form a much more comprehensive record of sunspot groups. For this, we use the unique Debrecen Photoheliographic Data (DPD), which is already a composite of several ground observatories and SOHO data, and the USAF/Mount Wilson catalog from the Solar Optical Observing Network (SOON). We also describe our semi-interactive cross-identification method, which was needed to match the non-overlapping solar active region nomenclature, the most critical and subtle step when working with multiple catalogs. This effort, focused here first on the last two solar cycles, should lead to a better central database collecting all available sunspot group parameters to address future solar cycle studies beyond the traditional sunspot index time series Ri.

  15. Observations of actively forming lava tubes and associated structures, Hawaii.

    NASA Technical Reports Server (NTRS)

    Greeley, R.

    1971-01-01

    Fluid basalts were erupted in August, 1970, from a vent near Alae Crater and flowed southeast. Forming exclusively in pahoehoe basalt, tubes in general evolve from lava channels by crustal formation, although some tubes develop directly from the vent. The observation discussed shows that channel crusts and tube roofs form in several ways. Lava channels usually form along the axis of highest velocity within the flow and are often centered along older lava channels, stream beds, rifts, grabens, or fracture zones.

  16. Interstellar reddening from the HIPPARCOS and TYCHO catalogues. I. Distances to nearby molecular clouds and star forming regions

    NASA Astrophysics Data System (ADS)

    Knude, J.; Hog, E.

    1998-10-01

    The Hipparcos and Tycho Catalogues offer an interesting possibility to study the local distribution of interstellar reddening from the combination of data contained in the catalogues: Hipparcos parallaxes, Tycho B - V and spectral and luminosity classification compiled from the literature. Parallactic distances may be derived for known absorbing features such as local molecular clouds and for large scale features such as sheets dividing bubbles. The stellar luminosity classes V and III offer more than 30.000 lines of sight for study, mostly for negative declinations where most classifications are available. We present some examples of this approach to derive information on the local interstellar medium. First we estimate the distance to the Southern Coalsack. Secondly, distances to the four nearby southern star forming clouds in the Chamaeleon region, the Lupus region, Corona Australis and finally the rho Ophiuchi are estimated. We find that these clouds are at 150 (Cha), 100 pc (Lup), i.e. about 50 pc closer than previously estimated, and that a feature with E_{B - V} ~ 0.15 (or A_V ~ 0.5) appears at 50 pc in this region. A distance of 170 pc is found for CrA compared to the previous estimate of 129 pc, and finally 120 pc for rho Oph compared to the previous 160 pc, strictly speaking the 120 pc are only measured for extinction values typical for the off core region in rho Ophiuchus. These distance changes are of some importance since these four regions show different stages of the star forming activity, as judged from the relative distribution of Class 0 - Class III YSOs (young stellar objects) in the Lbol - Tbol diagram. Precise calibrations of the YSOs' bolometric luminosities, applied in the definition of the bsf parameter (bsf: bright star fraction), require accurate distances of their parental clouds unless they are based on individual distances of the pre main sequence stars/protostellar sources.

  17. Developing a Comprehensive Active Region Database for the IRIS Observatory

    NASA Astrophysics Data System (ADS)

    Ho, A. Q. A.; Schmit, D. J.

    2016-12-01

    The fleet of space-based solar observatories provides a plethora of data to allow further analysis of the dynamics of active regions. In order to compare different solar remote sensing datasets, we determine the spatial and temporal overlap of datasets from different sources. We aim to facilitate analysis by creating an interactive visual tool that aids the comparison of observations of active regions from numerous sources such as IRIS and SDO/HMI, among others, that aggregates important physical quantities from each dataset. The interface allows for the selection and filtering of several key factors, such as particular active regions (organized by NOAA number) and specific time frames, to help refine searches. In addition, the tool provides a clearly organized map detailing the movement of active regions over time. The tool is projected to have several important implications, such as the ability to perform comprehensive statistical studies regarding the evolution of active regions and their chromospheres.

  18. Candidate X-Ray-emitting OB Stars in MYStIX Massive Star-forming Regions

    NASA Astrophysics Data System (ADS)

    Povich, Matthew S.; Busk, Heather A.; Feigelson, Eric D.; Townsley, Leisa K.; Kuhn, Michael A.

    2017-03-01

    Massive O-type and early B-type (OB) stars in the nearby Galaxy remain incompletely cataloged due to high extinction, bright visible and infrared nebular emission in H ii regions, and high field star contamination. These difficulties are alleviated by restricting the search to stars with X-ray emission. Using the X-ray point sources from the Massive Young Star-forming Complex Study in Infrared and X-Rays (MYStIX) survey of OB-dominated regions, we identify 98 MYStIX candidate OB (MOBc) stars by fitting their 1-8 μm spectral energy distributions (SEDs) with reddened stellar atmosphere models. We identify 27 additional MOBc stars based on JHK S photometry of X-ray stars lacking SED fitting. These candidate OB stars indicate that the current census of stars earlier than B1, taken across the 18 MYStIX regions studied, is less than 50% complete. We also fit the SEDs of 239 previously published OB stars to measure interstellar extinction and bolometric luminosities, revealing six candidate massive binary systems and five candidate O-type (super)giants. As expected, candidate OB stars have systematically higher extinction than previously published OB stars. Notable results for individual regions include identification of the OB population of a recently discovered massive cluster in NGC 6357, an older OB association in the M17 complex, and new massive luminous O stars near the Trifid Nebula. In several relatively poorly studied regions (RCW 38, NGC 6334, NGC 6357, Trifid, and NGC 3576), the OB populations may increase by factors of ≳ 2.

  19. Circumstellar disks in the outer Galaxy: the star-forming region NGC 1893

    NASA Astrophysics Data System (ADS)

    Caramazza, M.; Micela, G.; Prisinzano, L.; Rebull, L.; Sciortino, S.; Stauffer, J. R.

    2008-09-01

    Context: It is still debated whether star formation process depends on environment. In particular it is yet unclear whether star formation in the outer Galaxy, where the environmental conditions are, theoretically, less conducive, occurs in the same way as in the inner Galaxy. Aims: We investigate the population of NGC 1893, a young cluster ( 3{-}4 Myr) in the outer part of the Galaxy (RG ≥ 11 kpc), to explore the effects of environmental conditions on star forming regions. Methods: We present infrared observations acquired using the IRAC camera onboard the Spitzer Space Telescope and analyze the color-color diagrams to establish the membership of stars with excesses. We also merge this information with that obtained from Chandra ACIS-I observations, to identify the Class III population. Results: We find that the cluster is very rich, with 242 PMS Classical T Tauri stars and 7 Class 0/I stars. We identify 110 Class III candidate cluster members in the ACIS-I field of view. We estimate a disk fraction for NGC 1893 of about 67%, similar to fractions calculated for nearby star forming regions of the same age. Conclusions: Although environmental conditions are unfavorable, star formation can clearly be very successful in the outer Galaxy, allowing creation of a very rich cluster like NGC 1893.

  20. Water vapour and hydrogen in the terrestrial-planet-forming region of a protoplanetary disk.

    PubMed

    Eisner, J A

    2007-05-31

    Planetary systems (ours included) formed in disks of dust and gas around young stars. Disks are an integral part of the star and planet formation process, and knowledge of the distribution and temperature of inner-disk material is crucial for understanding terrestrial planet formation, giant planet migration, and accretion onto the central star. Although the inner regions of protoplanetary disks in nearby star-forming regions subtend only a few nano-radians, near-infrared interferometry has recently enabled the spatial resolution of these terrestrial zones. Most observations have probed only dust, which typically dominates the near-infrared emission. Here I report spectrally dispersed near-infrared interferometric observations that probe the gas (which dominates the mass and dynamics of the inner disk), in addition to the dust, within one astronomical unit (1 au, the Sun-Earth distance) of the young star MWC 480. I resolve gas, including water vapour and atomic hydrogen, interior to the edge of the dust disk; this contrasts with results of previous spectrally dispersed interferometry observations. Interactions of this accreting gas with migrating planets may lead to short-period exoplanets like those detected around main-sequence stars. The observed water vapour is probably produced by the sublimation of migrating icy bodies, and provides a potential reservoir of water for terrestrial planets.

  1. Fluctuations and Shape of Cooperative Rearranging Regions in Glass-Forming Liquids

    NASA Astrophysics Data System (ADS)

    Biroli, Giulio; Cammarota, Chiara

    2017-01-01

    We develop a theory of amorphous interfaces in glass-forming liquids. We show that the statistical properties of these surfaces, which separate regions characterized by different amorphous arrangements of particles, coincide with the ones of domain walls in the random field Ising model. A major consequence of our results is that supercooled liquids are characterized by two different static lengths: the point-to-set ξPS , which is a measure of the spatial extent of cooperative rearranging regions, and the wandering length ξ⊥, which is related to the fluctuations of their shape. We find that ξ⊥ grows when approaching the glass transition but slower than ξPS. The wandering length increases as sc-1 /2, where sc is the configurational entropy. Our results strengthen the relationship with the random field Ising model found in recent works. They are in agreement with previous numerical studies of amorphous interfaces and provide a theoretical framework for explaining numerical and experimental findings on pinned particle systems and static lengths in glass-forming liquids.

  2. trans-Protease Activity and Structural Insights into the Active Form of the Alphavirus Capsid Protease

    PubMed Central

    Aggarwal, Megha; Dhindwal, Sonali; Kumar, Pravindra; Kuhn, Richard J.

    2014-01-01

    ABSTRACT The alphavirus capsid protein (CP) is a serine protease that possesses cis-proteolytic activity essential for its release from the nascent structural polyprotein. The released CP further participates in viral genome encapsidation and nucleocapsid core formation, followed by its attachment to glycoproteins and virus budding. Thus, protease activity of the alphavirus capsid is a potential antialphaviral target to arrest capsid release, maturation, and structural polyprotein processing. However, the discovery of capsid protease inhibitors has been hampered due to the lack of a suitable screening assay and of the crystal structure in its active form. Here, we report the development of a trans-proteolytic activity assay for Aura virus capsid protease (AVCP) based on fluorescence resonance energy transfer (FRET) for screening protease inhibitors. Kinetic parameters using fluorogenic peptide substrates were estimated, and the Km value was found to be 2.63 ± 0.62 μM while the kcat/Km value was 4.97 × 104 M−1 min−1. Also, the crystal structure of the trans-active form of AVCP has been determined to 1.81-Å resolution. Structural comparisons of the active form with the crystal structures of available substrate-bound mutant and inactive blocked forms of the capsid protease identify conformational changes in the active site, the oxyanion hole, and the substrate specificity pocket residues, which could be critical for rational drug design. IMPORTANCE The alphavirus capsid protease is an attractive antiviral therapeutic target. In this study, we have described the formerly unappreciated trans-proteolytic activity of the enzyme and for the first time have developed a FRET-based protease assay for screening capsid protease inhibitors. Our structural studies unveil the structural features of the trans-active protease, which has been previously proposed to exist in the natively unfolded form (M. Morillas, H. Eberl, F. H. Allain, R. Glockshuber, and E. Kuennemann, J

  3. Zeeman effect in sulfur monoxide. A tool to probe magnetic fields in star forming regions

    NASA Astrophysics Data System (ADS)

    Cazzoli, Gabriele; Lattanzi, Valerio; Coriani, Sonia; Gauss, Jürgen; Codella, Claudio; Ramos, Andrés Asensio; Cernicharo, José; Puzzarini, Cristina

    2017-09-01

    Context. Magnetic fields play a fundamental role in star formation processes and the best method to evaluate their intensity is to measure the Zeeman effect of atomic and molecular lines. However, a direct measurement of the Zeeman spectral pattern from interstellar molecular species is challenging due to the high sensitivity and high spectral resolution required. So far, the Zeeman effect has been detected unambiguously in star forming regions for very few non-masing species, such as OH and CN. Aims: We decided to investigate the suitability of sulfur monoxide (SO), which is one of the most abundant species in star forming regions, for probing the intensity of magnetic fields via the Zeeman effect. Methods: We investigated the Zeeman effect for several rotational transitions of SO in the (sub-)mm spectral regions by using a frequency-modulated, computer-controlled spectrometer, and by applying a magnetic field parallel to the radiation propagation (i.e., perpendicular to the oscillating magnetic field of the radiation). To support the experimental determination of the g factors of SO, a systematic quantum-chemical investigation of these parameters for both SO and O2 has been carried out. Results: An effective experimental-computational strategy for providing accurate g factors as well as for identifying the rotational transitions showing the strongest Zeeman effect has been presented. Revised g factors have been obtained from a large number of SO rotational transitions between 86 and 389 GHz. In particular, the rotational transitions showing the largest Zeeman shifts are: N,J = 2, 2 ← 1, 1 (86.1 GHz), N,J = 4, 3 ← 3, 2 (159.0 GHz), N,J = 1, 1 ← 0, 1 (286.3 GHz), N,J = 2, 2 ← 1, 2 (309.5 GHz), and N,J = 2, 1 ← 1, 0 (329.4 GHz). Our investigation supports SO as a good candidate for probing magnetic fields in high-density star forming regions. The complete list of measured Zeeman components is only available at the CDS via anonymous ftp to http

  4. The Essay: Theory and Pedagogy for an Active Form.

    ERIC Educational Resources Information Center

    Heilker, Paul

    Calling for a radical reexamination of the traditional foundation of composition instruction--the thesis/support form, this book argues that the essay, with its informality, conversational tone, meditative mood, and integration of form and content, is better suited to developmental, epistemological, ideological, and feminist rhetorical…

  5. VERY LARGE ARRAY OH ZEEMAN OBSERVATIONS OF THE STAR-FORMING REGION S88B

    SciTech Connect

    Sarma, A. P.; Eftimova, M.; Brogan, C. L.; Bourke, T. L.; Troland, T. H.

    2013-04-10

    We present observations of the Zeeman effect in OH thermal absorption main lines at 1665 and 1667 MHz taken with the Very Large Array toward the star-forming region S88B. The OH absorption profiles toward this source are complicated, and contain several blended components toward a number of positions. Almost all of the OH absorbing gas is located in the eastern parts of S88B, toward the compact continuum source S88B-2 and the eastern parts of the extended continuum source S88B-1. The ratio of 1665/1667 MHz OH line intensities indicates the gas is likely highly clumped, in agreement with other molecular emission line observations in the literature. S88-B appears to present a similar geometry to the well-known star-forming region M17, in that there is an edge-on eastward progression from ionized to molecular gas. The detected magnetic fields appear to mirror this eastward transition; we detected line-of-sight magnetic fields ranging from 90 to 400 {mu}G, with the lowest values of the field to the southwest of the S88B-1 continuum peak, and the highest values to its northeast. We used the detected fields to assess the importance of the magnetic field in S88B by a number of methods; we calculated the ratio of thermal to magnetic pressures, we calculated the critical field necessary to completely support the cloud against self-gravity and compared it to the observed field, and we calculated the ratio of mass to magnetic flux in terms of the critical value of this parameter. All these methods indicated that the magnetic field in S88B is dynamically significant, and should provide an important source of support against gravity. Moreover, the magnetic energy density is in approximate equipartition with the turbulent energy density, again pointing to the importance of the magnetic field in this region.

  6. NH3 Survey Observation of Massive Star-Forming Region W 43

    NASA Astrophysics Data System (ADS)

    Nishitani, Hiroyuki; Sorai, Kazuo; Habe, Asao; Hosaki, Keita; Watanabe, Yoshimasa; Ohishi, Yukie; Motogi, Kazuhito; Minamidani, Tetsuhiro; Fujimoto, Masayuki Y.

    2012-04-01

    We consider the properties of giant molecular cloud complexes in the star-forming region W 43 with a resolution of several pc scale, and discuss their relations to the evolutionary stages of massive star formation. We performed a NH3 (J , K) = (1, 1), (2, 2), and (3, 3) inversion-line survey with the Hokkaido University 11-m telescope. Among 51 observed positions, selected based on integrated intensity maps of 13CO (J = 1-0), these three emissions were detected from 21, 8, and 5 positions, respectively. The integrated intensity of the NH3 (J , K) = (1, 1) line was found to be proportional to the far-infrared luminosity, estimated from IRAS data. The rotation temperatures were deduced to be ˜ 15-20 K at eight observed positions. In addition, the upper limits were estimated for 13 positions, which include the relatively low temperatures below 14 K at two positions with a relatively high fractions of NH3 for 13CO and with a low far-infrared luminosity. We derived the ortho-to-para abundance ratio of NH3. From the population distribution between the ortho- and para-levels of NH3, we also derived temperatures of ˜ 6-12 K, which may be interpreted as the temperatures when NH3 molecules were formed. We discuss the relevance of the present results of our observations to the massive star-formation process and the current status of the W 43 region while taking into account previous observations of other indicators of massive star formation. It is shown that the complexes contain several regions in different evolutionary stages, or with the distinct characteristics of star formation within a timescales shorter than the lifetime of massive stars.

  7. Carbon gas in SMC low-metallicity star-forming regions

    NASA Astrophysics Data System (ADS)

    Requena-Torres, M. A.; Israel, F. P.; Okada, Y.; Güsten, R.; Stutzki, J.; Risacher, C.; Simon, R.; Zinnecker, H.

    2016-05-01

    This paper presents [ CII ], [ CI ] and CO emission line maps of the star-forming regions N 66, N 25+N 26, and N 88 in the metal-poor Local Group dwarf galaxy SMC. The spatial and velocity structure of the large HII region N 66 reveals an expanding ring of shocked molecular gas centered on the exciting star cluster NGC 346, whereas a more distant dense molecular cloud is being eroded by UV radiation from the same cluster. In the N 25+N 26 and N 88 maps, diffuse [ CII ] emission at a relatively low surface brightness extends well beyond the compact boundaries of the bright emission associated with the HII regions. In all regions, the distribution of this bright [ CII ] emission and the less prominent [ CI ] emission closely follows the outline of the CO complexes, but the intensity of the [ CII ] and [ CI ] emission is generally anticorrelated, which can be understood by the action of photodissociation and photoionization processes. Notwithstanding the overall similarity of CO and [ CII ] maps, the intensity ratio of these lines varies significantly, mostly due to changes in CO brightness. [ CII ] emission line profiles are up to 50% wider in velocity than corresponding CO profiles. A radiative transfer analysis shows that the [ CII ] line is the dominant tracer of (CO-dark) molecular hydrogen in the SMC. CO emission traces only a minor fraction of the total amount of gas. The similarity of the spatial distribution and line profile shape, and the dominance of molecular gas associated with [ CII ] rather than CO emission imply that in the low-metallicity environment of the SMC the small amount of dense molecular gas traced by CO is embedded in the much more extended molecular gas traced only by [ CII ] emission. The contribution from neutral atomic and ionized hydrogen zones is negligible in the star-forming regions observed. The reduced datacubes (FITS files) are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via

  8. Periodic auroral forms and geomagnetic field oscillations in the 1400 MLT region

    SciTech Connect

    Potemra, T.A. ); Vo, H.; Venkatesan, D.; Cogger, L.L. ); Erlandson, R.E.; Zanetti, L.J.; Bythrow, P.F.; Anderson, B.J. )

    1990-05-01

    The UV images obtained with the Viking satellite often show bright features which resemble beads or pearls aligned in the east-west direction between noon and 1800 MLT. Viking acquired a series of 25 UV images during a 28-min period on July 29, 1986, which showed a distinct series of periodic bright features in this region. Magnetic field and hot plasma measurements obtained by Viking confirm that the UV emissions are colocated with the field line projection of an upward-flowing region 1 Birkeland current and precipitating energetic ({approximately}200 eV) electrons. The magnetic field and electric field measurements show transverse oscillations with a nearly constant period of about 3.5 min from 67{degree} invariant latitude equatorward up to the location of the large-scale Birkeland current system near 76{degree} invariant latitude. The electric field oscillations lead the magnetic field oscillations by about a quarter-period. The authors interpret the observed oscillations as standing Alfven waves driven at a frequency near the local resonance frequency by a large-scale wave in the boundary layer. They propose that the energy flux of the precipitating low-energy electrons in this afternoon region is modulated by this boundary wave and produces the periodic UV emission features. The results of this study support the view that large-scale oscillations of magnetospheric boundaries, possibly associated with the Kelvin-Helmholtz instability, can modulate currents, particles, and auroral forms.

  9. Infrared polarization images of star-forming regions. I - The ubiquity of bipolar structure

    NASA Technical Reports Server (NTRS)

    Tamura, M.; Gatley, Ian; Joyce, R. R.; Ueno, M.; Suto, H.; Sekiguchi, M.

    1991-01-01

    The inefficiency of the stellar formation process leads rather generally to high residual dust densities, and so to the existence of infrared reflection nebulosity (IRN), in regions of star formation. Polarization images of several star-forming regions with mass outflows (GSS 30, S255, GL 5180, GL 2591, GGD 27, and NGC 7538) presented here: (1) establish the universality of bipolarity and of shell or cavity structure in the IRN consistent with that of CO outflow; (2) identify the source of the mass outflow in each case; (3) show that the opening angle near this central source is large; and (4) demonstrate several instances of multiple shells, probably arising from episodic mass loss. Astrometry of 2.2-micron sources with arcsecond accuracy identifies the illuminating source of each IRN uniquely with a compact H II region or a bright IR source. The polarization images provide strong evidence for large-scale dust toroids around each of these sources. The density and mass of these disks are estimated from the extinction through the disk.

  10. Geodynamics Studies in the active seismic regions in Egypt

    NASA Astrophysics Data System (ADS)

    Mohamed, A. S.

    2003-04-01

    The recent crustal movement studies have a great role for evaluating the geodynamics of the seismo-active areas in the country. The crustal deformations must be in mind where it connecting significantly with the human life and its resources. From the historical point of view and recent instrumental records, there are some seismo-active areas in Egypt, where some significant earthquakes gad been occurred in different places. The special tectonic features in Egypt, Cairo, Aswan, Red Sea, Sinia and Nile Delta regions are the territories of a high seismic risk, which have to be monitored by up-to date technologies. The investigations of the seismic events and interpretations led to evaluate the seismic hazard for disaster prevention and for the safety of the dense populated areas and the vital national projects as the High Dam. In addition to the monitoring of the seismic events, the most powerful technique of satellite geodesy GPS will be used where geodetic networks are covering such seismic-active areas, around Nasser Lake, gulf of Suez, Cairo, Sinai and the Nile Delta. The main goal of these studies are monitoring of the crustal deformations associated with the earthquake occurrence in these seismo-active areas in order to study its geodynamical behavior and reducing the earthquake losses. The results of these movements at all networks in Egypt represent the form of the dynamic models for the deformations occurred during the different epochs of measurements. The final compiled output from the seismological and geodetic analysis will threw lights upon the geodynamical regime of these seismo-active areas.

  11. Smoking Discriminately Changes the Serum Active and Non-Active Forms of Vitamin B12.

    PubMed

    Shekoohi, Niloofar; Javanbakht, Mohammad Hassan; Sohrabi, Marjan; Zarei, Mahnaz; Mohammadi, Hamed; Djalali, Mahmoud

    2017-06-01

    Smoking may modify the appetite, and consequently affect nutrient intake and serum micronutrients. The effect of smoking on vitamin B12 status has been considered in several studies. The research proposed that organic nitrites, nitro oxide, cyanides, and isocyanides of cigarette smoke interfere with vitamin B12 metabolism, and convert it to inactive forms. This research was carried out to determine the serum level of active and inactive forms of vitamin B12 in male smokers in comparison with male nonsmokers. This is a case-control study, in which the participants were 85 male smokers and 85 male nonsmokers. The serum levels of total and active form of vitamin B12 were measured. Dietary intake was recorded by a quantitative food frequency questionnaire and one-day 24-hour dietary recall method. Independent two sample T test was used to compare quantitative variables between the case and control groups. The serum level of total vitamin B12 was not significantly different between two groups, but serum level of active form of vitamin B12 in the smoking group was significantly lower than non-smoking group (P<0.001). This is one of the first studies that evaluated the serum level of active form of vitamin B12 in smokers in the Iranian community. The results of this study identified that serum level of total vitamin B12 might be not different between smoking and non-smoking people, but the function of this vitamin is disturbed in the body of smokers through the reduction of serum level of active form of vitamin B12.

  12. CO observations of the galactic star-forming region W58

    NASA Technical Reports Server (NTRS)

    Israel, F. P.

    1980-01-01

    Observations of (C-12)O and (C-13)O have been made in the direction of the strong galactic radio source W58, which contains the compact H II regions K3-50 and ON-3. An extended molecular cloud with dimensions of 55 x 40 pc is associated with the northern part of the H II region complex. The density of the molecular cloud increases from west to east; the molecular cloud is bounded on the east by a larger H I cloud. Present star-formation activity is taking place at the position of maximum molecular density, at what appears to be the interface of the H I cloud and the H II region complex. The velocity structure of the CO cloud and the compact H II regions are in agreement with the blister model. Radio continuum and H I line observations show indications of a shell structure in the southwest of W58. Present star formation in W58 may be caused by this expanding shell.

  13. CO observations of the galactic star-forming region W58

    NASA Technical Reports Server (NTRS)

    Israel, F. P.

    1980-01-01

    Observations of (C-12)O and (C-13)O have been made in the direction of the strong galactic radio source W58, which contains the compact H II regions K3-50 and ON-3. An extended molecular cloud with dimensions of 55 x 40 pc is associated with the northern part of the H II region complex. The density of the molecular cloud increases from west to east; the molecular cloud is bounded on the east by a larger H I cloud. Present star-formation activity is taking place at the position of maximum molecular density, at what appears to be the interface of the H I cloud and the H II region complex. The velocity structure of the CO cloud and the compact H II regions are in agreement with the blister model. Radio continuum and H I line observations show indications of a shell structure in the southwest of W58. Present star formation in W58 may be caused by this expanding shell.

  14. High angular resolution observations of star-forming regions with BETTII and SOFIA

    NASA Astrophysics Data System (ADS)

    Rizzo, Maxime; Rinehart, Stephen; Mundy, Lee G.; Benford, Dominic J.; Dhabal, Arnab; Fixsen, Dale J.; Leisawitz, David; Maher, Stephen F.; Mentzell, Eric; Silverberg, Robert F.; Staguhn, Johannes; Veach, Todd; Cardiff BETTII Team

    2016-01-01

    High angular resolution observations in the far-infrared are important to understand the star formation process in embedded star clusters where extinction is large and stars form in close proximity. The material taking part in the star forming process is heated by the young stars and emits primarily in the far-IR; hence observations of the far-IR dust emission yields vital information about the gravitational potential, the mass and energy distribution, and core/star formation process. Previous observatories, such as Herschel, Spitzer and WISE lack the angular resolution required to study these dense star forming cores and are further limited by saturation in bright cores.The Balloon Experimental Twin Telescope for Infrared Interferometry (BETTII) is pioneering the path to sub-arcsecond resolution at far-IR wavelengths. This thesis talk discusses the instrumental challenges in building BETTII, as well as results from our SOFIA survey to illustrate the potential of higher-angular resolution observations. The 8m-long two element interferometer is being tested at NASA GSFC and is scheduled for first flight in fall 2016. BETTII will provide 0.5 to 1 arcsecond spatial resolution and spectral resolving power of 10 to 100 between 30 and 90 microns, where most of the dust continuum emission peaks in local star forming regions. It will achieve spatially-resolved spectroscopy of bright, dense cores with unprecedented high definition. This talk focuses on the main challenges and solutions associated with building BETTII: thermal stability, attitude/pointing control, and path length stabilization. In each of these areas we look at the trade-off between design, control, and knowledge in order to achieve the best-possible instrumental capability and sensitivity.As a first step towards resolving cluster cores, we surveyed 10 nearby star-forming clusters with SOFIA FORCAST at 11, 19, 31 and 37 microns. The FORCAST instrument has the highest angular resolution currently available in

  15. 3D MHD Models of Active Region Loops

    NASA Technical Reports Server (NTRS)

    Ofman, Leon

    2004-01-01

    Present imaging and spectroscopic observations of active region loops allow to determine many physical parameters of the coronal loops, such as the density, temperature, velocity of flows in loops, and the magnetic field. However, due to projection effects many of these parameters remain ambiguous. Three dimensional imaging in EUV by the STEREO spacecraft will help to resolve the projection ambiguities, and the observations could be used to setup 3D MHD models of active region loops to study the dynamics and stability of active regions. Here the results of 3D MHD models of active region loops are presented, and the progress towards more realistic 3D MHD models of active regions. In particular the effects of impulsive events on the excitation of active region loop oscillations, and the generation, propagations and reflection of EIT waves are shown. It is shown how 3D MHD models together with 3D EUV observations can be used as a diagnostic tool for active region loop physical parameters, and to advance the science of the sources of solar coronal activity.

  16. Functional modulation of cardiac form through regionally confined cell shape changes.

    PubMed

    Auman, Heidi J; Coleman, Hope; Riley, Heather E; Olale, Felix; Tsai, Huai-Jen; Yelon, Deborah

    2007-03-01

    Developing organs acquire a specific three-dimensional form that ensures their normal function. Cardiac function, for example, depends upon properly shaped chambers that emerge from a primitive heart tube. The cellular mechanisms that control chamber shape are not yet understood. Here, we demonstrate that chamber morphology develops via changes in cell morphology, and we determine key regulatory influences on this process. Focusing on the development of the ventricular chamber in zebrafish, we show that cardiomyocyte cell shape changes underlie the formation of characteristic chamber curvatures. In particular, cardiomyocyte elongation occurs within a confined area that forms the ventricular outer curvature. Because cardiac contractility and blood flow begin before chambers emerge, cardiac function has the potential to influence chamber curvature formation. Employing zebrafish mutants with functional deficiencies, we find that blood flow and contractility independently regulate cell shape changes in the emerging ventricle. Reduction of circulation limits the extent of cardiomyocyte elongation; in contrast, disruption of sarcomere formation releases limitations on cardiomyocyte dimensions. Thus, the acquisition of normal cardiomyocyte morphology requires a balance between extrinsic and intrinsic physical forces. Together, these data establish regionally confined cell shape change as a cellular mechanism for chamber emergence and as a link in the relationship between form and function during organ morphogenesis.

  17. Functional Modulation of Cardiac Form through Regionally Confined Cell Shape Changes

    PubMed Central

    Auman, Heidi J; Coleman, Hope; Riley, Heather E; Olale, Felix; Tsai, Huai-Jen; Yelon, Deborah

    2007-01-01

    Developing organs acquire a specific three-dimensional form that ensures their normal function. Cardiac function, for example, depends upon properly shaped chambers that emerge from a primitive heart tube. The cellular mechanisms that control chamber shape are not yet understood. Here, we demonstrate that chamber morphology develops via changes in cell morphology, and we determine key regulatory influences on this process. Focusing on the development of the ventricular chamber in zebrafish, we show that cardiomyocyte cell shape changes underlie the formation of characteristic chamber curvatures. In particular, cardiomyocyte elongation occurs within a confined area that forms the ventricular outer curvature. Because cardiac contractility and blood flow begin before chambers emerge, cardiac function has the potential to influence chamber curvature formation. Employing zebrafish mutants with functional deficiencies, we find that blood flow and contractility independently regulate cell shape changes in the emerging ventricle. Reduction of circulation limits the extent of cardiomyocyte elongation; in contrast, disruption of sarcomere formation releases limitations on cardiomyocyte dimensions. Thus, the acquisition of normal cardiomyocyte morphology requires a balance between extrinsic and intrinsic physical forces. Together, these data establish regionally confined cell shape change as a cellular mechanism for chamber emergence and as a link in the relationship between form and function during organ morphogenesis. PMID:17311471

  18. Spectropolarimetry of an Active Region at the Photosphere and Chromosphere

    NASA Astrophysics Data System (ADS)

    Nagaraju, K.; Sankarasubramanian, K.; Rangarajan, K. E.

    2009-06-01

    Initial results on the simultaneous spectropolarimetric observations of an active region at the photosphere and chromosphere are presented. For this purpose, the Fe I line at λ6569 and the H I at λ6563 (H α) are used. Stratification of the line-of-sight (LOS) velocity and magnetic fields above an active region are discussed. The LOS magnetic field strengths are derived using the center-of-gravity (COG) method and the LOS velocity gradients are derived using the bisector technique. From this analysis it is found that both the velocity and magnetic gradients are larger in the umbral region above the sunspot compared to the penumbral region. And the magnetic field strength decreases much faster with height in the umbral region compared to the penumbral region. Upflows with larger LOS velocity gradients are located in the regions where stronger photospheric fields are observed.

  19. HIGH-RESOLUTION STUDY OF THE MASSIVE STAR-FORMING REGION IRAS 06061+2151

    SciTech Connect

    Trinidad, M. A.; RodrIguez, T.

    2010-12-15

    We present observations of 3.6 cm continuum and water maser emission toward the high-mass star-forming region IRAS 06061+2151 (AFGL 5182), made at {approx}0.''3 and {approx}0.''1 resolution, respectively, using the Very Large Array (VLA) in the A configuration. Continuum and maser emission are not detected toward the center of AFGL 5182. However, we detected two groups of continuum sources located {approx}12'' and {approx}3' to the west and northeast of AFGL 5182, respectively. The first group, labeled as the G188.79+1.03 complex, is composed of three continuum sources in a region of about 6'' x 10'', while the second group, associated with the source G188.77+1.07, is composed of at least two continuum sources in a region {approx}1'' in diameter. The physical parameters estimated, based on the morphology and the continuum emission, suggest that all the continuum sources in both groups are ultracompact H II regions, associated with ZAMS B-type stars. Water maser emission is only detected toward the compact source VLA N2, which is located in the G188.79+1.03 complex. Accuracy in the relative positions between the radio continuum source and the water masers is of the order of 15 mas. In addition, the observed spatial and kinematical distribution of the water maser features has remained stable for several years, and we confirm that they are tracing a bipolar outflow, where the best candidate of the source powering the water masers and the outflow is VLA 2N.

  20. DISK EVOLUTION IN THE THREE NEARBY STAR-FORMING REGIONS OF TAURUS, CHAMAELEON, AND OPHIUCHUS

    SciTech Connect

    Furlan, E.; Watson, Dan M.; McClure, M. K. E-mail: dmw@pas.rochester.ed

    2009-10-01

    We analyze samples of Spitzer Infrared Spectrograph spectra of T Tauri stars in the Ophiuchus, Taurus, and Chamaeleon I star-forming regions, whose median ages lie in the <1-2 Myr range. The median mid-infrared spectra of objects in these three regions are similar in shape, suggesting, on average, similar disk structures. When normalized to the same stellar luminosity, the medians follow each other closely, implying comparable mid-infrared excess emission from the circumstellar disks. We use the spectral index between 13 and 31 {mu}m and the equivalent width of the 10 {mu}m silicate emission feature to identify objects whose disk configuration departs from that of a continuous, optically thick accretion disk. Transitional disks, whose steep 13-31 {mu}m spectral slope and near-IR flux deficit reveal inner disk clearing, occur with about the same frequency of a few percent in all three regions. Objects with unusually large 10 {mu}m equivalent widths are more common (20%-30%); they could reveal the presence of disk gaps filled with optically thin dust. Based on their medians and fraction of evolved disks, T Tauri stars in Taurus and Chamaeleon I are very alike. Disk evolution sets in early, since already the youngest region, the Ophiuchus core (L1688), has more settled disks with larger grains. Our results indicate that protoplanetary disks show clear signs of dust evolution at an age of a few Myr, even as early as approx1 Myr, but age is not the only factor determining the degree of evolution during the first few million years of a disk's lifetime.

  1. Fragmentation in the massive star-forming region IRAS 19410+2336

    NASA Astrophysics Data System (ADS)

    Rodón, J. A.; Beuther, H.; Schilke, P.

    2012-09-01

    Context. The core mass functions (CMFs) of low-mass star-forming regions are found to resemble the shape of the initial mass function (IMF). A similar result is observed for the dust clumps in high-mass star-forming regions, although on spatial scales of clusters that do not resolve the substructure that is found in these massive clumps. The region IRAS 19410+2336 is one exception, having been observed on spatial scales on the order of ~2500 AU, which are sufficient to resolve the clump substructure into individual cores. Aims: We investigate the protostellar content of IRAS 19410+2336 at high spatial resolution at 1.4 mm, determining the temperature structure of the region and deriving its CMF. Methods: The massive star-forming region IRAS 19410+2336 was mapped with the PdBI (BCD configurations) at 1.4 mm and 3 mm in the continuum and several transitions of formaldehyde (H2CO) and methyl cyanide (CH3CN). The H2CO transitions were also observed with the IRAM 30 m Telescope. Results: We detect 26 continuum sources at 1.4 mm with a spatial resolution as low as ~2200 AU, several of them with counterparts at near- and mid-infrared wavelengths, distributed in two (proto)clusters. With the PdBI CH3CN and PdBI/IRAM 30 m H2CO emission, we derive the temperature structure of the region, ranging from 35 K to 90 K. Using these temperatures, we calculate the core masses of the detected sources, ranging from ~0.7 M⊙ to ~8 M⊙. These masses are strongly affected by the spatial filtering of the interferometer, which removes a common envelope with ~90% of the single-dish flux. Considering only the detected dense cores and accounting for binning effects as well as cumulative distributions, we derive a CMF, with a power-law index β = -2.3 ± 0.2. We resolve the Jeans length of the (proto)clusters by one order of magnitude, and only find a small velocity dispersion between the different subsources. Conclusions: Since we cannot unambiguously differentiate between protostellar and

  2. Self-similar fragmentation regulated by magnetic fields in a region forming massive stars.

    PubMed

    Li, Hua-bai; Yuen, Ka Ho; Otto, Frank; Leung, Po Kin; Sridharan, T K; Zhang, Qizhou; Liu, Hauyu; Tang, Ya-Wen; Qiu, Keping

    2015-04-23

    Most molecular clouds are filamentary or elongated. For those forming low-mass stars (<8 solar masses), the competition between self-gravity and turbulent pressure along the dynamically dominant intercloud magnetic field (10 to 100 parsecs) shapes the clouds to be elongated either perpendicularly or parallel to the fields. A recent study also suggested that on the scales of 0.1 to 0.01 parsecs, such fields are dynamically important within cloud cores forming massive stars (>8 solar masses). But whether the core field morphologies are inherited from the intercloud medium or governed by cloud turbulence is unknown, as is the effect of magnetic fields on cloud fragmentation at scales of 10 to 0.1 parsecs. Here we report magnetic-field maps inferred from polarimetric observations of NGC 6334, a region forming massive stars, on the 100 to 0.01 parsec scale. NGC 6334 hosts young star-forming sites where fields are not severely affected by stellar feedback, and their directions do not change much over the entire scale range. This means that the fields are dynamically important. The ordered fields lead to a self-similar gas fragmentation: at all scales, there exist elongated gas structures nearly perpendicular to the fields. Many gas elongations have density peaks near the ends, which symmetrically pinch the fields. The field strength is proportional to the 0.4th power of the density, which is an indication of anisotropic gas contractions along the field. We conclude that magnetic fields have a crucial role in the fragmentation of NGC 6334.

  3. Active Region Morphologies Selected From Near-side Helioseismic Data

    NASA Astrophysics Data System (ADS)

    MacDonald, Gordon Andrew; Henney, Carl; Diaz Alfaro, Manuel; Gonzalez Hernandez, Irene; Arge, Nick; Lindsey, Charles; McAteer, James

    2015-04-01

    We estimate the morphology of near-side active regions using near-side helioseismology. Active regions from two data sets, ADAPT synchronic maps and GONG near-side helioseismic maps, were matched and their morphologies compared. Our algorithm recognizes 382 helioseismic active regions between 2002 April 25 and 2005 December 31 and matches them to their corresponding magnetic active regions with 100% success. A magnetic active region occupies 30% of the area of its helioseismic signature. Recovered helioseismic tilt angles are in good agreement with magnetic tilt angles. Approximately 20% of helioseismic active regions can be decomposed into leading and trailing polarity. Leading polarity components show no discernible scaling relationship, but trailing magnetic polarity components occupy approximately 25% of the area of the trailing helioseismic component. A nearside phase-magnetic calibration is in close agreement with a previous far-side helioseismic calibration and provides confidence that these morphological relationships can be used with far-side helioseismic data. Including far-side active region morphology in synchronic maps will have implications for coronal magnetic topology predictions and solar wind forecasts.

  4. Active Region Morphologies Selected from Near-side Helioseismic Data

    NASA Astrophysics Data System (ADS)

    MacDonald, G. A.; Henney, C. J.; Díaz Alfaro, M.; González Hernández, I.; Arge, C. N.; Lindsey, C.; McAteer, R. T. J.

    2015-07-01

    We estimate the morphology of near-side active regions using near-side helioseismology. Active regions from two data sets, Air Force Data Assimilative Photospheric flux Transport synchronic maps and Global Oscillation Network Group near-side helioseismic maps, were matched and their morphologies compared. Our algorithm recognizes 382 helioseismic active regions between 2002 April 25 and 2005 December 31 and matches them to their corresponding magnetic active regions with 100% success. A magnetic active region occupies 30% of the area of its helioseismic signature. Recovered helioseismic tilt angles are in good agreement with magnetic tilt angles. Approximately 20% of helioseismic active regions can be decomposed into leading and trailing polarity. Leading polarity components show no discernible scaling relationship, but trailing magnetic polarity components occupy approximately 25% of the area of the trailing helioseismic component. A nearside phase-magnetic calibration is in close agreement with a previous far-side helioseismic calibration and provides confidence that these morphological relationships can be used with far-side helioseismic data. Including far-side active region morphology in synchronic maps will have implications for coronal magnetic topology predictions and solar wind forecasts.

  5. A Multi Wavelength Study of Active Region Development

    NASA Astrophysics Data System (ADS)

    Lara, A.; Gopalswamy, N.; Kundu, M. R.; Perez-Enriquez, R.; Koshiishi, H.; Enome, S.

    1996-05-01

    We report on a study of the evolution of several active regions during 1993 April 17-28 using data obtained at multiple wavelengths that probe various heights of the active region corona. We use simultaneous microwave (1.5 and 17 GHz) and Soft X-ray images obtained by the Very Large Array (VLA), the Nobeyama Radio Heliograph (NRH) and the Soft X-ray Telescope (SXT) on board the Yohkoh spacecraft. We also use photospheric magnetograms from Kitt Peak National Observatory to study the development of Solar Active Regions. We have followed the development of various observed parameters such as brightness temperature and polarization using radio images. The X-ray data were used to track the development of density and temperature of active regions. Using the fact that the quiet active region radiation is thermal and adopting proper emission mechanism at each frequency domain, we construct a consistent picture for the three dimensional structure of the active regions. Particular attention has been paid to the mode coupling observed at 17 GHz while the active regions crossed the solar disk.

  6. ACTIVE REGION MORPHOLOGIES SELECTED FROM NEAR-SIDE HELIOSEISMIC DATA

    SciTech Connect

    MacDonald, G. A.; McAteer, R. T. J.; Henney, C. J.; Arge, C. N.; Díaz Alfaro, M.; González Hernández, I.; Lindsey, C.

    2015-07-01

    We estimate the morphology of near-side active regions using near-side helioseismology. Active regions from two data sets, Air Force Data Assimilative Photospheric flux Transport synchronic maps and Global Oscillation Network Group near-side helioseismic maps, were matched and their morphologies compared. Our algorithm recognizes 382 helioseismic active regions between 2002 April 25 and 2005 December 31 and matches them to their corresponding magnetic active regions with 100% success. A magnetic active region occupies 30% of the area of its helioseismic signature. Recovered helioseismic tilt angles are in good agreement with magnetic tilt angles. Approximately 20% of helioseismic active regions can be decomposed into leading and trailing polarity. Leading polarity components show no discernible scaling relationship, but trailing magnetic polarity components occupy approximately 25% of the area of the trailing helioseismic component. A nearside phase-magnetic calibration is in close agreement with a previous far-side helioseismic calibration and provides confidence that these morphological relationships can be used with far-side helioseismic data. Including far-side active region morphology in synchronic maps will have implications for coronal magnetic topology predictions and solar wind forecasts.

  7. Observations of Cyanopolyynes toward Four High-mass Star-forming Regions Containing Hot Cores

    NASA Astrophysics Data System (ADS)

    Taniguchi, Kotomi; Saito, Masao; Hirota, Tomoya; Ozeki, Hiroyuki; Miyamoto, Yusuke; Kaneko, Hiroyuki; Minamidani, Tetsuhiro; Shimoikura, Tomomi; Nakamura, Fumitaka; Dobashi, Kazuhito

    2017-07-01

    We carried out line survey observations at the 26-30 GHz band toward the four high-mass star-forming regions containing hot cores, G10.30-0.15, G12.89+0.49, G16.86-2.16, and G28.28-0.36, with the Robert C. Byrd Green Bank Telescope. We have detected HC5N from all of the sources, and HC7N from the three sources, except for G10.30-0.15. We further conducted observations of HC5N at the 42-46 GHz and 82-103 GHz bands toward the three sources, G12.89+0.49, G16.86-2.16, and G28.28-0.36, with the Nobeyama 45 m radio telescope. The rotational lines of HC5N with the high-excitation energies ({E}{{u}}/k˜ 63{--}100 K), which are hardly excited in the cold dark clouds, have been detected from the three sources. The rotational temperatures of HC5N are found to be ˜13-20 K in the three sources. The detection of the lines with the high-excitation energies and the derived rotational temperatures indicate that HC5N exists in the warm gas within 0.07-0.1 pc radii around massive young stellar objects. The column densities of HC5N in the three sources are derived to be (˜2.0-2.8) × {10}13 cm-2. We compare the ratios between N(HC5N) the column density of HC5N and W(CH3OH) the integrated intensity of the thermal CH3OH emission line among the three high-mass star-forming regions. We found a possibility of the chemical differentiation in the three high-mass star-forming regions; G28.28-0.36 shows the largest N(HC5N)/W(CH3OH) ratio of > 8.0× {10}14 in units of (K km s-1)-1 cm-2, while G12.89+0.49 and G16.86-2.16 show the smaller values (˜ 2× {10}13).

  8. Chemical characterization of the early evolutionary phases of high-mass star-forming regions

    NASA Astrophysics Data System (ADS)

    Gerner, Thomas

    2014-10-01

    The formation of high-mass stars is a very complex process and up to date no comprehensive theory about it exists. This thesis studies the early stages of high-mass star-forming regions and employs astrochemistry as a tool to probe their different physical conditions. We split the evolutionary sequence into four observationally motivated stages that are based on a classification proposed in the literature. The sequence is characterized by an increase of the temperatures and densities that strongly influences the chemistry in the different stages. We observed a sample of 59 high-mass star-forming regions that cover the whole sequence and statistically characterized the chemical compositions of the different stages. We determined average column densities of 18 different molecular species and found generally increasing abundances with stage. We fitted them for each stage with a 1D model, such that the result of the best fit to the previous stage was used as new input for the following. This is a unique approach and allowed us to infer physical properties like the temperature and density structure and yielded a typical chemical lifetime for the high-mass star-formation process of 1e5 years. The 18 analyzed molecular species also included four deuterated molecules whose chemistry is particularly sensitive to thermal history and thus is a promising tool to infer chemical ages. We found decreasing trends of the D/H ratios with evolutionary stage for 3 of the 4 molecular species and that the D/H ratio depends more on the fraction of warm and cold gas than on the total amount of gas. That indicates different chemical pathways for the different molecules and confirms the potential use of deuterated species as chemical age indicators. In addition, we mapped a low-mass star forming region in order to study the cosmic ray ionization rate, which is an important parameter in chemical models. While in chemical models it is commonly fixed, we found that it ! strongly varies with

  9. Regional Observation of Seismic Activity in Baekdu Mountain

    NASA Astrophysics Data System (ADS)

    Kim, Geunyoung; Che, Il-Young; Shin, Jin-Soo; Chi, Heon-Cheol

    2015-04-01

    Seismic unrest in Baekdu Mountain area between North Korea and Northeast China region has called attention to geological research community in Northeast Asia due to her historical and cultural importance. Seismic bulletin shows level of seismic activity in the area is higher than that of Jilin Province of Northeast China. Local volcanic observation shows a symptom of magmatic unrest in period between 2002 and 2006. Regional seismic data have been used to analyze seismic activity of the area. The seismic activity could be differentiated from other seismic phenomena in the region by the analysis.

  10. Detections of 2 cm formaldehyde emissions towards Galactic star-forming regions with 6 cm counterpart

    NASA Astrophysics Data System (ADS)

    Chen, Xi; Shen, Zhi-Qiang; Li, Xiao-Qiong; Yang, Kai; Li, Juan; Wang, Jun-Zhi; Wu, Ya-Jun; Zhao, Rong-Bin; Wang, Jin-Qing; Dong, Jian; Jiang, Dong-Rong; Li, Bin

    2017-01-01

    We report the detections of H2CO emission at the 2 cm transition towards Galactic star-forming regions with known 6 cm counterpart using the Shanghai Tianma Radio Telescope (TMRT). One significant detection (in NGC7538) and two possible detections (in G23.01-0.41 and G29.96-0.02) were made. Comparing with previous observations, we found that there is a time lag of appearance of 2 cm and 6 cm emissions detected in NGC7538, contradicting with the prediction of radiative pumping via radio continuum radiation. Combinations of the variability of 6 cm masers in NGC7538 suggest that collisional pumping via high-velocity shocks could better explain the 6 cm H2CO maser emission. Under this scheme, excitation of the 2 cm maser may require a higher collision energy compared to the 6 cm transition.

  11. STATISTICAL ANALYSIS OF WATER MASERS IN STAR-FORMING REGIONS: CEPHEUS A AND W75 N

    SciTech Connect

    Uscanga, L.; Gomez, J. F.; Anglada, G.; Canto, J.; Curiel, S.; Torrelles, J. M.; Patel, N. A.; Raga, A. C. E-mail: jfg@iaa.e E-mail: scuriel@astroscu.unam.m E-mail: npatel@cfa.harvard.ed

    2010-05-20

    We have done a statistical analysis of Very Long Baseline Array (VLBA) data of water masers in the star-forming regions (SFRs) Cepheus A and W75 N, using correlation functions to study the spatial clustering and Doppler-velocity distribution of these masers. Two-point spatial correlation functions show a characteristic scale size for clusters of water maser spots {approx_lt}1 AU, similar to the values found in other SFRs. This suggests that the scale for water maser excitation tends to be {approx_lt}1 AU. Velocity correlation functions show power-law dependences with indices that can be explained by regular velocity fields, such as expansion and/or rotation. These velocity fields are similar to those indicated by the water maser proper-motion measurements; therefore, the velocity correlation functions appear to reveal the organized motion of water maser spots on scales larger than 1 AU.

  12. The distribution of warm dust in the star forming region Cepheus A: Infrared constraints

    NASA Technical Reports Server (NTRS)

    Colome, Cecilia; Harvey, Paul M.

    1995-01-01

    We have obtained new, high angular resolution far-infrared (FIR) maps (at 50 and 100 microns) of the star forming region Cepheus A and polarimetric images (1.65 and 2.2 microns) of the reflection nebulosity, IRS6, associated with this young stellar object. Our results are consistent with current star formation theories: a young stellar object surrounded by an infalling envelope with a characteristic density distribution of n(sub d)(r) proportional to r(exp -1.5), a circumstellar disk, and a cavity (R(sub i) approx. 0.07 pc) in which n(sub d) is constant, created by the dispersal of the initial dust cloud by a strong stellar wind.

  13. Deep Near-Infrared Surveys and Young Brown Dwarf Populations in Star-Forming Regions

    NASA Astrophysics Data System (ADS)

    Tamura, M.; Naoi, T.; Oasa, Y.; Nakajima, Y.; Nagashima, C.; Nagayama, T.; Baba, D.; Nagata, T.; Sato, S.; Kato, D.; Kurita, M.; Sugitani, K.; Itoh, Y.; Nakaya, H.; Pickles, A.

    2003-06-01

    We are currently conducting three kinds of IR surveys of star forming regions (SFRs) in order to seek for very low-mass young stellar populations. First is a deep JHKs-bands (simultaneous) survey with the SIRIUS camera on the IRSF 1.4m or the UH 2.2m telescopes. Second is a very deep JHKs survey with the CISCO IR camera on the Subaru 8.2m telescope. Third is a high resolution companion search around nearby YSOs with the CIAO adaptive optics coronagraph IR camera on the Subaru. In this contribution, we describe our SIRIUS camera and present preliminary results of the ongoing surveys with this new instrument.

  14. Detections of 2 cm formaldehyde emissions towards Galactic star-forming regions with 6 cm counterpart

    NASA Astrophysics Data System (ADS)

    Chen, Xi; Shen, Zhi-Qiang; Li, Xiao-Qiong; Yang, Kai; Li, Juan; Wang, Jun-Zhi; Wu, Ya-Jun; Zhao, Rong-Bin; Wang, Jin-Qing; Dong, Jian; Jiang, Dong-Rong; Li, Bin

    2017-04-01

    We report the detections of H2CO emission at the 2 cm transition towards Galactic star-forming regions with known 6 cm counterpart using the Shanghai Tianma Radio Telescope. One significant detection (in NGC 7538) and two possible detections (in G23.01-0.41 and G29.96-0.02) were made. Comparing with previous observations, we found that there is a time lag of appearance of 2 and 6 cm emissions detected in NGC 7538, contradicting with the prediction of radiative pumping via radio continuum radiation. Combinations of the variability of 6 cm masers in NGC 7538 suggest that collisional pumping via high-velocity shocks could better explain the 6 cm H2CO maser emission. Under this scheme, excitation of the 2 cm maser may require a higher collision energy compared to the 6 cm transition.

  15. Gold ore-forming fluids of the Tanami region, Northern Australia

    NASA Astrophysics Data System (ADS)

    Mernagh, Terrence P.; Wygralak, Andrew S.

    2007-01-01

    Fluid inclusion studies have been carried out on major gold deposits and prospects in the Tanami region to determine the compositions of the associated fluids and the processes responsible for gold mineralization. Pre-ore, milky quartz veins contain only two-phase aqueous inclusions with salinities ≤19 wt% NaCl eq. and homogenization temperatures that range from 110 to 410°C. In contrast, the ore-bearing veins typically contain low to moderate salinity (<14 wt% NaCl eq.), H2O + CO2 ± CH4 ± N2-bearing fluids. The CO2-bearing inclusions coexist with two-phase aqueous inclusions that exhibit a wider range of salinities (≤21 wt% NaCl eq.). Post-ore quartz and carbonate veins contain mainly two-phase aqueous inclusions, with a last generation of aqueous inclusions being very CaCl2-rich. Salinities range from 7 to 33 wt% NaCl eq. and homogenization temperatures vary from 62 to 312°C. Gold deposits in the Tanami region are hosted by carbonaceous or iron-rich sedimentary rocks and/or mafic rocks. They formed over a range of depths at temperatures from 200 to 430°C. The Groundrush deposit formed at the greatest temperatures and depths (260-430°C and ≤11 km), whereas deposits in the Tanami goldfield formed at the lowest temperatures (≥200°C) and at the shallowest depths (1.5-5.6 km). There is also evidence in the Tanami goldfield for late-stage isothermal mixing with higher salinity (≤21 wt% NaCl eq.) fluids at temperatures between 100 and 200°C. Other deposits (e.g., The Granites, Callie, and Coyote) formed at intermediate depths and at temperatures ranging from 240 to 360°C. All ore fluids contained CO2 ± N2 ± CH4, with the more deeply formed deposits being enriched in CH4 and higher level deposits being enriched in CO2. Fluids from deposits hosted mainly by sedimentary rocks generally contained appreciable quantities of N2. The one exception is the Tanami goldfield, where the quartz veins were dominated by aqueous inclusions with rare CO2-bearing

  16. A Study on the CO Isotopic Lines of the Star Forming Region AFGL 5157

    NASA Astrophysics Data System (ADS)

    Mao, Chun-hua; Yang, Ji; Lu, Deng-rong

    2014-01-01

    By the mapping observations simultaneously at the 12CO (J=1-0), 13CO (J=1-0), and C18O (J=1-0) lines on the area of 24’×24’ (12 pc×12 pc) of the star forming region AFGL 5157, we have obtained the distribution and averaged physical parameters for the respective 13CO and C18O cores of this molecu- lar cloud. At the edge of the molecular cloud, the isotopic abundance ratio is X [(13CO)/(C18O)] ≈ 10, close to the ratio of a giant molecular cloud. The viral masses of the 13CO and C18O cores are less than the masses of the molecu-lar cloud cores, so the molecular cloud cores are gravitationally unstable, and the C18O molecular cloud core is more easy to collapse. The column density distributions of the C18O molecular cloud core in the northeast and southwest directions are, respectively, 1.1 × 1023× z-0.43 and 4.6 × 1025× z-0.58, where z is the distance from the center of the molecular cloud core. The high velocity molecular outflow has been confirmed from our 12CO spectra, the mass loss rate of the outflow has been estimated, and the mass-velocity relation of the outflow is fitted by a power-law function of m ∝ v-1.8. The star formation rate of the 13CO molecular cloud core is as high as 23%, probably, under the influence of the reflection nebula NGC 1985, this region is forming medium and large mass stars or clusters.

  17. CHEMICAL SEGREGATION TOWARD MASSIVE HOT CORES: THE AFGL2591 STAR-FORMING REGION

    SciTech Connect

    Jimenez-Serra, I.; Zhang, Q.; Viti, S.; Martin-Pintado, J.; De Wit, W.-J. E-mail: qzhang@cfa.harvard.edu E-mail: jmartin@cab.inta-csic.es

    2012-07-01

    We present high angular resolution observations (0.''5 Multiplication-Sign 0.''3) carried out with the Submillimeter Array (SMA) toward the AFGL2591 high-mass star-forming region. Our SMA images reveal a clear chemical segregation within the AFGL2591 VLA 3 hot core, where different molecular species (Types I, II, and III) appear distributed in three concentric shells. This is the first time that such a chemical segregation is ever reported at linear scales {<=}3000 AU within a hot core. While Type I species (H{sub 2}S and {sup 13}CS) peak at the AFGL2591 VLA 3 protostar, Type II molecules (HC{sub 3}N, OCS, SO, and SO{sub 2}) show a double-peaked structure circumventing the continuum peak. Type III species, represented by CH{sub 3}OH, form a ring-like structure surrounding the continuum emission. The excitation temperatures of SO{sub 2}, HC{sub 3}N, and CH{sub 3}OH (185 {+-} 11 K, 150 {+-} 20 K, and 124 {+-} 12 K, respectively) show a temperature gradient within the AFGL2591 VLA 3 envelope, consistent with previous observations and modeling of the source. By combining the H{sub 2}S, SO{sub 2}, and CH{sub 3}OH images, representative of the three concentric shells, we find that the global kinematics of the molecular gas follow Keplerian-like rotation around a 40 M{sub Sun} star. The chemical segregation observed toward AFGL2591 VLA 3 is explained by the combination of molecular UV photodissociation and a high-temperature ({approx}1000 K) gas-phase chemistry within the low extinction innermost region in the AFGL2591 VLA 3 hot core.

  18. Chemical Evolution in High-mass Star-forming Regions: Results from the MALT90 Survey

    NASA Astrophysics Data System (ADS)

    Hoq, Sadia; Jackson, James M.; Foster, Jonathan B.; Sanhueza, Patricio; Guzmán, Andrés; Whitaker, J. Scott; Claysmith, Christopher; Rathborne, Jill M.; Vasyunina, Tatiana; Vasyunin, Anton

    2013-11-01

    The chemical changes of high-mass star-forming regions provide a potential method for classifying their evolutionary stages and, ultimately, ages. In this study, we search for correlations between molecular abundances and the evolutionary stages of dense molecular clumps associated with high-mass star formation. We use the molecular line maps from Year 1 of the Millimetre Astronomy Legacy Team 90 GHz (MALT90) Survey. The survey mapped several hundred individual star-forming clumps chosen from the ATLASGAL survey to span the complete range of evolution, from prestellar to protostellar to H II regions. The evolutionary stage of each clump is classified using the Spitzer GLIMPSE/MIPSGAL mid-IR surveys. Where possible, we determine the dust temperatures and H2 column densities for each clump from Herschel/Hi-GAL continuum data. From MALT90 data, we measure the integrated intensities of the N2H+, HCO+, HCN and HNC (1-0) lines, and derive the column densities and abundances of N2H+ and HCO+. The Herschel dust temperatures increase as a function of the IR-based Spitzer evolutionary classification scheme, with the youngest clumps being the coldest, which gives confidence that this classification method provides a reliable way to assign evolutionary stages to clumps. Both N2H+ and HCO+ abundances increase as a function of evolutionary stage, whereas the N2H+ (1-0) to HCO+ (1-0) integrated intensity ratios show no discernable trend. The HCN (1-0) to HNC(1-0) integrated intensity ratios show marginal evidence of an increase as the clumps evolve.

  19. High-velocity Line Forming Regions in the Type Ia Supernova 2009ig

    NASA Astrophysics Data System (ADS)

    Marion, G. H.; Vinko, Jozsef; Wheeler, J. Craig; Foley, Ryan J.; Hsiao, Eric Y.; Brown, Peter J.; Challis, Peter; Filippenko, Alexei V.; Garnavich, Peter; Kirshner, Robert P.; Landsman, Wayne B.; Parrent, Jerod T.; Pritchard, Tyler A.; Roming, Peter W. A.; Silverman, Jeffrey M.; Wang, Xiaofeng

    2013-11-01

    We report measurements and analysis of high-velocity (HVF) (>20,000 km s-1) and photospheric absorption features in a series of spectra of the Type Ia supernova (SN) 2009ig obtained between -14 days and +13 days with respect to the time of maximum B-band luminosity (B-max). We identify lines of Si II, Si III, S II, Ca II, and Fe II that produce both HVF and photospheric-velocity (PVF) absorption features. SN 2009ig is unusual for the large number of lines with detectable HVF in the spectra, but the light-curve parameters correspond to a slightly overluminous but unexceptional SN Ia (MB = -19.46 mag and Δm 15(B) = 0.90 mag). Similarly, the Si II λ6355 velocity at the time of B-max is greater than "normal" for an SN Ia, but it is not extreme (v Si = 13,400 km s-1). The -14 days and -13 days spectra clearly resolve HVF from Si II λ6355 as separate absorptions from a detached line forming region. At these very early phases, detached HVF are prevalent in all lines. From -12 days to -6 days, HVF and PVF are detected simultaneously, and the two line forming regions maintain a constant separation of about 8000 km s-1. After -6 days all absorption features are PVF. The observations of SN 2009ig provide a complete picture of the transition from HVF to PVF. Most SNe Ia show evidence for HVF from multiple lines in spectra obtained before -10 days, and we compare the spectra of SN 2009ig to observations of other SNe. We show that each of the unusual line profiles for Si II λ6355 found in early-time spectra of SNe Ia correlate to a specific phase in a common development sequence from HVF to PVF.

  20. CHEMICAL EVOLUTION IN HIGH-MASS STAR-FORMING REGIONS: RESULTS FROM THE MALT90 SURVEY

    SciTech Connect

    Hoq, Sadia; Jackson, James M.; Foster, Jonathan B.; Sanhueza, Patricio; Claysmith, Christopher; Guzmán, Andrés; Whitaker, J. Scott; Rathborne, Jill M.; Vasyunina, Tatiana; Vasyunin, Anton E-mail: jackson@bu.edu E-mail: claysmit@bu.edu E-mail: aguzmanf@cfa.harvard.edu E-mail: rathborne@csiro.au E-mail: aiv3f@virginia.edu

    2013-11-10

    The chemical changes of high-mass star-forming regions provide a potential method for classifying their evolutionary stages and, ultimately, ages. In this study, we search for correlations between molecular abundances and the evolutionary stages of dense molecular clumps associated with high-mass star formation. We use the molecular line maps from Year 1 of the Millimetre Astronomy Legacy Team 90 GHz (MALT90) Survey. The survey mapped several hundred individual star-forming clumps chosen from the ATLASGAL survey to span the complete range of evolution, from prestellar to protostellar to H II regions. The evolutionary stage of each clump is classified using the Spitzer GLIMPSE/MIPSGAL mid-IR surveys. Where possible, we determine the dust temperatures and H{sub 2} column densities for each clump from Herschel/Hi-GAL continuum data. From MALT90 data, we measure the integrated intensities of the N{sub 2}H{sup +}, HCO{sup +}, HCN and HNC (1-0) lines, and derive the column densities and abundances of N{sub 2}H{sup +} and HCO{sup +}. The Herschel dust temperatures increase as a function of the IR-based Spitzer evolutionary classification scheme, with the youngest clumps being the coldest, which gives confidence that this classification method provides a reliable way to assign evolutionary stages to clumps. Both N{sub 2}H{sup +} and HCO{sup +} abundances increase as a function of evolutionary stage, whereas the N{sub 2}H{sup +} (1-0) to HCO{sup +} (1-0) integrated intensity ratios show no discernable trend. The HCN (1-0) to HNC(1-0) integrated intensity ratios show marginal evidence of an increase as the clumps evolve.

  1. Extremely Bright Submillimeter Galaxies beyond the Lupus-I Star-forming Region

    NASA Astrophysics Data System (ADS)

    Tamura, Y.; Kawabe, R.; Shimajiri, Y.; Tsukagoshi, T.; Nakajima, Y.; Oasa, Y.; Wilner, D. J.; Chandler, C. J.; Saigo, K.; Tomida, K.; Yun, M. S.; Taniguchi, A.; Kohno, K.; Hatsukade, B.; Aretxaga, I.; Austermann, J. E.; Dickman, R.; Ezawa, H.; Goss, W. M.; Hayashi, M.; Hughes, D. H.; Hiramatsu, M.; Inutsuka, S.; Ogasawara, R.; Ohashi, N.; Oshima, T.; Scott, K. S.; Wilson, G. W.

    2015-08-01

    We report detections of two candidate distant submillimeter galaxies (SMGs), MM J154506.4-344318 and MM J154132.7-350320, which are discovered in the AzTEC/ASTE 1.1 mm survey toward the Lupus-I star-forming region. The two objects have 1.1 mm flux densities of 43.9 and 27.1 mJy, and have Herschel/SPIRE counterparts as well. The Submillimeter Array counterpart to the former SMG is identified at 890 μm and 1.3 mm. Photometric redshift estimates using all available data from the mid-infrared to the radio suggest that the redshifts of the two SMGs are {z}{photo}≃ 4-5 and 3, respectively. Near-infrared objects are found very close to the SMGs and they are consistent with low-z ellipticals, suggesting that the high apparent luminosities can be attributed to gravitational magnification. The cumulative number counts at {S}1.1{mm}≥slant 25 mJy, combined with the other two 1.1 mm brightest sources, are {0.70}-0.34+0.56 deg-2, which is consistent with a model prediction that accounts for flux magnification due to strong gravitational lensing. Unexpectedly, a z\\gt 3 SMG and a Galactic dense starless core (e.g., a first hydrostatic core) could be similar in the mid-infrared to millimeter spectral energy distributions and spatial structures at least at ≳ 1\\prime\\prime . This indicates that it is necessary to distinguish the two possibilities by means of broadband photometry from the optical to centimeter and spectroscopy to determine the redshift, when a compact object is identified toward Galactic star-forming regions.

  2. Active Gaming as a Form of Exercise to Induce Hypoalgesia.

    PubMed

    Carey, Christopher; Naugle, Keith E; Aqeel, Dania; Ohlman, Thomas; Naugle, Kelly M

    2017-08-01

    An acute bout of moderate-to-vigorous exercise temporarily reduces pain sensitivity in healthy adults. Recently, active gaming has been rising in popularity as a means of light-to-moderate exercise and may be particularly suitable for deconditioned individuals. Whether the physical activity elicited in active games can produce a hypoalgesic effect remains unknown. The purpose of this study was to determine whether active videogames can reduce pressure and heat pain sensitivity in healthy adults. We also evaluated the relationship between the physical activity elicited by the games and the magnitude of the hypoalgesic response. Twenty-one healthy adults played four different active games on separate days, including Microsoft(®) Kinect Xbox(®) One's Fighter Within and Sports Rival's Tennis, and Nintendo(®) Wii™ Sports' Boxing and Tennis. Heat pain thresholds on the forearm and pressure pain thresholds (PPTs) on the trapezius and forearm were assessed immediately before and after a 15-minute active gaming or control session. Minutes spent in sedentary time and moderate-to-vigorous physical activity (MVPA) during active gaming were measured with an accelerometer. The analyses revealed that PPTs at the forearm and trapezius significantly increased from pretest to posttest following Kinect Fighter Within. PPTs at the trapezius also significantly increased from pretest to posttest following Wii Boxing. The magnitude of the hypoalgesic response was significantly correlated with MVPA and sedentary time during gameplay. These results suggest that an active gaming session played at a moderate intensity is capable of temporarily reducing pain sensitivity.

  3. 76 FR 41279 - Agency Information Collection Activities; Form I-864, Form I-864A, Form I-864EZ, and Form I-864W...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-13

    ..., Affidavit of Support Under Section 213A of the Act; Form I-864W, Intending Immigrant's Affidavit of Support... by family-based and certain employment-based immigrants to have the petitioning relative execute...

  4. 75 FR 26782 - Agency Information Collection Activities: Form I-864, Form I-864A, Form I-864EZ, and Form I-864W...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-12

    ... Act; Form I-864W, Intending Immigrant's Affidavit of Support Exemption; OMB Control No. 1615-0075. The... immigrants to have the petitioning relative execute an Affidavit of Support on their behalf. (5) An...

  5. 75 FR 51093 - Agency Information Collection Activities: Form I-864, Form I-864A, Form I-864EZ, and Form I-864W...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-18

    ...-864 EZ, Affidavit of Support Under Section 213A of the Act; Form I-864W, Intending Immigrant's... immigrants to have the petitioning relative execute an Affidavit of Support on their behalf. (5) An...

  6. Interactive flare sites within an active region complex

    NASA Technical Reports Server (NTRS)

    Poletto, G.; Gary, G. A.; Machado, M. E.

    1993-01-01

    We examine here a set of images of an active region complex, acquired on June 24-25, 1980, by the Hard X-ray Imaging Spectrometer on SMM, with the purpose of establishing whether there was any interplay between the frequent activity observed at different sites in the activity center and, in such a case, how the interaction was established. By analyzing both quiet and active orbits we show that, as a rule, activity originating in one region triggers the other region's activity. However, we find little unambiguous evidence for the presence of large-scale interconnecting loops. A comparison of X-ray images with magnetic field observations suggested that we interpret the active region behavior in terms of the interaction between different loop systems, in a scenario quite analogous to the interacting bipole representation of individual flares. We conclude that active region interplay provides an easily observable case to study the time-dependent topology and the mechanisms for the spreading of activity in transient events over all energy scales.

  7. THE MASSIVE STAR-FORMING REGIONS OMNIBUS X-RAY CATALOG

    SciTech Connect

    Townsley, Leisa K.; Broos, Patrick S.; Feigelson, Eric D.; Getman, Konstantin V.; Kuhn, Michael A.; Garmire, Gordon P.; Bouwman, Jeroen; Povich, Matthew S.

    2014-07-01

    We present the Massive Star-forming Regions (MSFRs) Omnibus X-ray Catalog (MOXC), a compendium of X-ray point sources from Chandra/ACIS observations of a selection of MSFRs across the Galaxy, plus 30 Doradus in the Large Magellanic Cloud. MOXC consists of 20,623 X-ray point sources from 12 MSFRs with distances ranging from 1.7 kpc to 50 kpc. Additionally, we show the morphology of the unresolved X-ray emission that remains after the cataloged X-ray point sources are excised from the ACIS data, in the context of Spitzer and WISE observations that trace the bubbles, ionization fronts, and photon-dominated regions that characterize MSFRs. In previous work, we have found that this unresolved X-ray emission is dominated by hot plasma from massive star wind shocks. This diffuse X-ray emission is found in every MOXC MSFR, clearly demonstrating that massive star feedback (and the several-million-degree plasmas that it generates) is an integral component of MSFR physics.

  8. THE INTERPLAY OF TURBULENCE AND MAGNETIC FIELDS IN STAR-FORMING REGIONS: SIMULATIONS AND OBSERVATIONS

    SciTech Connect

    Kirk, Helen; Johnstone, Doug; Basu, Shantanu

    2009-07-10

    We analyze a suite of thin-sheet magnetohydrodynamical simulations based on the formulation of Basu, Ciolek, Dapp, and Wurster. These simulations allow us to examine the observational consequences to a star-forming region of varying the input level of turbulence (between thermal and a Mach number of 4) and the initial magnetic field strength corresponding to a range of mass to flux ratios between subcritical ({mu}{sub 0} = 0.5) and supercritical ({mu}{sub 0} = 10). The input turbulence is allowed to decay over the duration of the simulation. We compare the measured observable quantities with those found from surveying the Perseus molecular cloud. We find that only the most turbulent of simulations (high Mach number and weak magnetic field) have sufficient large-scale velocity dispersion (at {approx}1 pc) to match that observed across extinction regions in Perseus. Generally, the simulated core ({approx}0.02 pc) and line-of-sight velocity dispersions provide a decent match to observations. The motion between the simulated core and its local environment, however, is far too large in simulations with high large-scale velocity dispersion.

  9. Re-forming medical delivery systems: economic organization and dynamics of regional planning and managed competition.

    PubMed

    Perkins, B B

    1999-01-01

    This paper compares structural components of medical delivery in two major systemwide reform strategies in the United States. Commonly portrayed in terms of opposing ideologies of planning vs. market reform, regional organization and managed competition have promoted similar structural elements and geographic configurations. They both support growth of institution-based specialized teams and hospital consolidation. They both differentiate hospital care into vertically integrated levels, and develop regions as the key production and market area for organized delivery systems. System-wide management or regulation in each has tried to control allocation of resources, capital investment, and competition. Developed in the context of large-scale industrial production, these components have inherent economic dynamics and together they shape the market structure of medical care. The final section briefly considers the locus of power in the two reform approaches and the implication for choosing mechanisms of reform. It also notes that despite their rhetoric, the two strategies do not shape their services according to information about population benefit. The conclusion points out that the commonalities in structure and power demonstrate the dominance of economic organization in medical reform and contribute to the wide acceptance of this business form of organization as an international model.

  10. New eruptive variable in the massive star-forming region associated with IRAS 18507+0121

    NASA Astrophysics Data System (ADS)

    Nikoghosyan, E. H.; Azatyan, N. M.; Khachatryan, K. G.

    2017-07-01

    Aims: We report the discovery of a strong outburst of the embedded young stellar object (YSO) UKIDSS-J185318.36+012454.5, located in the star-forming region associated with IRAS 18507+0121 and the ultra-compact H II region GAL 034.4+00.23. Methods: Using archival photometric data and images, we determined the amplitude and the epoch of the outburst as well as the evolution stage and the basic parameters of the object. Results: According to the near- and mid-infrared colors and spectral energy distribution, we classify the object as an intermediate-mass YSO with Class 0/I evolution stage. The outburst apparently started between May 2003 and April 2004. The amplitude of the outburst is at least ΔKs = 5.0 mag. The summation of the photometric and spectral data does not allow classifying UKIDSS-J185318.36+012454.5 as an FU Orionis (FUor) or EX Orionis (EXor) object. We can consider it as an eruptive variable with mixed characteristics or as an MNor type object.

  11. VLBA Surveys of OH Masers in Star-forming Regions. I. Satellite Lines

    NASA Astrophysics Data System (ADS)

    Ruiz-Velasco, A. E.; Felli, D.; Migenes, V.; Wiggins, B. K.

    2016-05-01

    Using the Very Long Baseline Array we performed a high-resolution OH maser survey in Galactic star-forming regions (SFRs). We observed all the ground state spectral lines: the main lines at 1665 and 1667 MHz and the satellite lines at 1612 and 1720 MHz. Due to the exceptionality of finding satellite lines in SFRs, we will focus our discussion on those lines. In our sample of 41 OH maser sources, five (12%) showed the 1612 MHz line and ten (24%) showed the 1720 MHz line, with only one source showing both lines. We find that 1720 MHz emission is correlated with the presence of H ii regions, suggesting that this emission could be used to diagnose or trace high-mass star formation. We include an analysis of the possible mechanisms that could be causing this correlation as well as assessing the possible relationships between lines in our sample. In particular, the presence of magnetic fields seems to play an important role as we found Zeeman splitting in four of our sources (W75 N, W3(OH), W51 and NGC 7538). Our results have implications for current understanding of the formation of high-mass stars as well as on the masing processes present in SFRs.

  12. Dominant Form of Congenital Hyperinsulinism Maps to HK1 Region on 10q

    PubMed Central

    Pinney, Sara E.; Ganapathy, Karthik; Bradfield, Jonathan; Stokes, David; Sasson, Ariella; Mackiewicz, Katarzyna; Boodhansingh, Kara; Hughes, Nkecha; Becker, Susan; Givler, Stephanie; Macmullen, Courtney; Monos, Dimitrios; Ganguly, Arupa; Hakonarson, Hakon; Stanley, Charles A.

    2013-01-01

    Background/Aims In a family with congenital hyperinsulinism (HI), first described in the 1950s by MacQuarrie, we examined the genetic locus and clinical phenotype of a novel form of dominant HI. Methods We surveyed 25 affected individuals, 7 of whom participated in tests of insulin dysregulation (24-hour fasting, oral glucose and protein tolerance tests). To identify the disease locus and potential disease-associated mutations we performed linkage analysis, whole transcriptome sequencing, whole genome sequencing, gene capture, and next generation sequencing. Results Most affecteds were diagnosed with HI before age one and 40% presented with a seizure. All affecteds responded well to diazoxide. Affecteds failed to adequately suppress insulin secretion following oral glucose tolerance test or prolonged fasting; none had protein-sensitive hypoglycemia. Linkage analysis mapped the HI locus to Chr10q21–22, a region containing 48 genes. Three novel non-coding variants were found in hexokinase 1 (HK1) and one missense variant in the coding region of DNA2. Conclusion Dominant, diazoxide-responsive HI in this family maps to a novel locus on Chr10q21–22. HK1 is the more attractive disease gene candidate since a mutation interfering with the normal suppression of HK1 expression in beta-cells could readily explain the hypoglycemia phenotype of this pedigree. PMID:23859901

  13. H{sub 2}D{sup +} IN THE HIGH-MASS STAR-FORMING REGION CYGNUS X

    SciTech Connect

    Pillai, T.; Lis, D. C.; Caselli, P.; Kauffmann, J.; Zhang, Q.; Thompson, M. A.

    2012-06-01

    H{sub 2}D{sup +} is a primary ion that dominates the gas-phase chemistry of cold dense gas. Therefore, it is hailed as a unique tool in probing the earliest, prestellar phase of star formation. Observationally, its abundance and distribution is, however, just beginning to be understood in low-mass prestellar and cluster-forming cores. In high-mass star-forming regions, H{sub 2}D{sup +} has been detected only in two cores, and its spatial distribution remains unknown. Here, we present the first map of the ortho-H{sub 2}D{sup +} J{sub k{sup +},k{sup -}} = 1{sub 1,0} {yields} 1{sub 1,1} and N{sub 2}H{sup +} 4-3 transition in the DR21 filament of Cygnus X with the James Clerk Maxwell Telescope, and N{sub 2}D{sup +} 3-2 and dust continuum with the Submillimeter Array. We have discovered five very extended ({<=}34, 000 AU diameter) weak structures in H{sub 2}D{sup +} in the vicinity of, but distinctly offset from, embedded protostars. More surprisingly, the H{sub 2}D{sup +} peak is not associated with either a dust continuum or N{sub 2}D{sup +} peak. We have therefore uncovered extended massive cold dense gas that was undetected with previous molecular line and dust continuum surveys of the region. This work also shows that our picture of the structure of cores is too simplistic for cluster-forming cores and needs to be refined: neither dust continuum with existing capabilities nor emission in tracers like N{sub 2}D{sup +} can provide a complete census of the total prestellar gas in such regions. Sensitive H{sub 2}D{sup +} mapping of the entire DR21 filament is likely to discover more of such cold quiescent gas reservoirs in an otherwise active high-mass star-forming region.

  14. Nitric oxide in star-forming regions - Further evidence for interstellar N-O bonds

    NASA Technical Reports Server (NTRS)

    Ziurys, L. M.; Mcgonagle, D.; Minh, Y.; Irvine, W. M.

    1991-01-01

    Nitric oxide has been newly detected toward several star-forming clouds, including Orion-KL, Sgr B2(N), W33A, W51M, and DR21(OH) via its J = 3/2-1/2 transitions near 150 GHz, using the FCRAO 14 m telescope. Both lambda-doubling components of NO were observed toward all sources. Column densities derived for nitric oxide in these clouds are 10 to the 15th-10 to the 16th/sq cm, corresponding to fractional abundances of 0.5-1.0 x 10 to the -8th, relative to H2. Toward Orion-KL, the NO line profile suggests that the species arises primarily from hot, dense gas. Nitric oxide may arise from warm material toward the other clouds as well. Nitric oxide in star-forming regions could be synthesized by high-temperature reactions, although the observed abundances do not disagree with values predicted from low-temperature, ion-molecule chemistry by more than one order of magnitude.

  15. Nitric oxide in star-forming regions - Further evidence for interstellar N-O bonds

    NASA Technical Reports Server (NTRS)

    Ziurys, L. M.; Mcgonagle, D.; Minh, Y.; Irvine, W. M.

    1991-01-01

    Nitric oxide has been newly detected toward several star-forming clouds, including Orion-KL, Sgr B2(N), W33A, W51M, and DR21(OH) via its J = 3/2-1/2 transitions near 150 GHz, using the FCRAO 14 m telescope. Both lambda-doubling components of NO were observed toward all sources. Column densities derived for nitric oxide in these clouds are 10 to the 15th-10 to the 16th/sq cm, corresponding to fractional abundances of 0.5-1.0 x 10 to the -8th, relative to H2. Toward Orion-KL, the NO line profile suggests that the species arises primarily from hot, dense gas. Nitric oxide may arise from warm material toward the other clouds as well. Nitric oxide in star-forming regions could be synthesized by high-temperature reactions, although the observed abundances do not disagree with values predicted from low-temperature, ion-molecule chemistry by more than one order of magnitude.

  16. Nitric oxide in star-forming regions: further evidence for interstellar N-O bonds.

    PubMed

    Ziurys, L M; McGonagle, D; Minh, Y; Irvine, W M

    1991-06-01

    Nitric oxide has been newly detected towards several star-forming clouds, including Orion-KL, Sgr B2(N), W33A, W51M, and DR21(OH) via its J = 3/2 --> 1/2 transitions near 150 GHz, using the FCRAO 14 m telescope. Both lambda-doubling components of NO were observed towards all sources. Column densities derived for nitric oxide in these clouds are N approximately 10(15)-10(16) cm-2, corresponding to fractional abundances of f approximately 0.5-1.0 x 10(-8), relative to H2. Towards Orion-KL, the NO line profile suggests that the species arises primarily from hot, dense gas. Nitric oxide may arise from warm material toward the other clouds as well. Nitric oxide in star-forming regions could be synthesized by high-temperature reactions, although the observed abundances do not disagree with values predicted from low-temperature, ion-molecule chemistry by more than one order of magnitude. The abundance of NO, unlike other simple interstellar nitrogen compounds, does appear to be reproduced by chemical models, at least to a good approximation. Regardless of the nature of formation of NO, it appears to be a common constituent of warm, dense molecular clouds. N-O bonds may therefore be more prevalent than previously thought.

  17. B- and A-Type Stars in the Taurus-Auriga Star-Forming Region

    NASA Technical Reports Server (NTRS)

    Mooley, Kunal; Hillenbrand, Lynne; Rebull, Luisa; Padgett, Deborah; Knapp, Gillian

    2013-01-01

    We describe the results of a search for early-type stars associated with the Taurus-Auriga molecular cloud complex, a diffuse nearby star-forming region noted as lacking young stars of intermediate and high mass. We investigate several sets of possible O, B, and early A spectral class members. The first is a group of stars for which mid-infrared images show bright nebulae, all of which can be associated with stars of spectral-type B. The second group consists of early-type stars compiled from (1) literature listings in SIMBAD, (2) B stars with infrared excesses selected from the Spitzer Space Telescope survey of the Taurus cloud, (3) magnitude- and color-selected point sources from the Two Micron All Sky Survey, and (4) spectroscopically identified early-type stars from the Sloan Digital Sky Survey coverage of the Taurus region. We evaluated stars for membership in the Taurus-Auriga star formation region based on criteria involving: spectroscopic and parallactic distances, proper motions and radial velocities, and infrared excesses or line emission indicative of stellar youth. For selected objects, we also model the scattered and emitted radiation from reflection nebulosity and compare the results with the observed spectral energy distributions to further test the plausibility of physical association of the B stars with the Taurus cloud. This investigation newly identifies as probable Taurus members three B-type stars: HR 1445 (HD 28929), t Tau (HD 29763), 72 Tau (HD 28149), and two A-type stars: HD 31305 and HD 26212, thus doubling the number of stars A5 or earlier associated with the Taurus clouds. Several additional early-type sources including HD 29659 and HD 283815 meet some, but not all, of the membership criteria and therefore are plausible, though not secure, members.

  18. SPITZER INFRARED SPECTROGRAPH SURVEY OF YOUNG STARS IN THE CHAMAELEON I STAR-FORMING REGION

    SciTech Connect

    Manoj, P.; Kim, K. H.; Watson, Dan M.; Forrest, W. J.; Bohac, C.; Arnold, L. A.; Furlan, E.; McClure, M. K.; Calvet, N.; Luhman, K. L.; Espaillat, C.; Najita, J. R.; D'Alessio, P.; Adame, L.; Sargent, B. A.; Green, J. D.

    2011-03-15

    We present 5-36 {mu}m mid-infrared spectra of 82 young stars in the {approx}2 Myr old Chamaeleon I star-forming region, obtained with the Spitzer Infrared Spectrograph (IRS). We have classified these objects into various evolutionary classes based on their spectral energy distributions and the spectral features seen in the IRS spectra. We have analyzed the mid-IR spectra of Class II objects in Chamaeleon I in detail, in order to study the vertical and radial structure of the protoplanetary disks surrounding these stars. We find evidence for substantial dust settling in most protoplanetary disks in Chamaeleon I. We have identified several disks with altered radial structures in Chamaeleon I, among them transitional disk candidates which have holes or gaps in their disks. Analysis of the silicate emission features in the IRS spectra of Class II objects in Cha I shows that the dust grains in these disks have undergone significant processing (grain growth and crystallization). However, disks with radial holes/gaps appear to have relatively unprocessed grains. We further find the crystalline dust content in the inner ({approx}<1-2 AU) and the intermediate ({approx}<10 AU) regions of the protoplanetary disks to be tightly correlated. We also investigate the effects of accretion and stellar multiplicity on the disk structure and dust properties. Finally, we compare the observed properties of protoplanetary disks in Cha I with those in slightly younger Taurus and Ophiuchus regions and discuss the effects of disk evolution in the first 1-2 Myr.

  19. B- AND A-TYPE STARS IN THE TAURUS-AURIGA STAR-FORMING REGION

    SciTech Connect

    Mooley, Kunal; Hillenbrand, Lynne; Rebull, Luisa; Padgett, Deborah; Knapp, Gillian

    2013-07-10

    We describe the results of a search for early-type stars associated with the Taurus-Auriga molecular cloud complex, a diffuse nearby star-forming region noted as lacking young stars of intermediate and high mass. We investigate several sets of possible O, B, and early A spectral class members. The first is a group of stars for which mid-infrared images show bright nebulae, all of which can be associated with stars of spectral-type B. The second group consists of early-type stars compiled from (1) literature listings in SIMBAD, (2) B stars with infrared excesses selected from the Spitzer Space Telescope survey of the Taurus cloud, (3) magnitude- and color-selected point sources from the Two Micron All Sky Survey, and (4) spectroscopically identified early-type stars from the Sloan Digital Sky Survey coverage of the Taurus region. We evaluated stars for membership in the Taurus-Auriga star formation region based on criteria involving: spectroscopic and parallactic distances, proper motions and radial velocities, and infrared excesses or line emission indicative of stellar youth. For selected objects, we also model the scattered and emitted radiation from reflection nebulosity and compare the results with the observed spectral energy distributions to further test the plausibility of physical association of the B stars with the Taurus cloud. This investigation newly identifies as probable Taurus members three B-type stars: HR 1445 (HD 28929), {tau} Tau (HD 29763), 72 Tau (HD 28149), and two A-type stars: HD 31305 and HD 26212, thus doubling the number of stars A5 or earlier associated with the Taurus clouds. Several additional early-type sources including HD 29659 and HD 283815 meet some, but not all, of the membership criteria and therefore are plausible, though not secure, members.

  20. AN INFRARED/X-RAY SURVEY FOR NEW MEMBERS OF THE TAURUS STAR-FORMING REGION

    SciTech Connect

    Luhman, K. L.; Allen, P. R.; Mamajek, E. E.; Cruz, K. L.

    2009-09-20

    We present the results of a search for new members of the Taurus star-forming region using data from the Spitzer Space Telescope and the XMM-Newton Observatory. We have obtained optical and near-infrared spectra of 44 sources that exhibit red Spitzer colors that are indicative of stars with circumstellar disks and 51 candidate young stars that were identified by Scelsi and coworkers using XMM-Newton. We also performed spectroscopy on four possible companions to members of Taurus that were reported by Kraus and Hillenbrand. Through these spectra, we have demonstrated the youth and membership of 41 sources, 10 of which were independently confirmed as young stars by Scelsi and coworkers. Five of the new Taurus members are likely to be brown dwarfs based on their late spectral types (>M6). One of the brown dwarfs has a spectral type of L0, making it the first known L-type member of Taurus and the least massive known member of the region (M {approx} 4-7 M{sub Jup}). Another brown dwarf exhibits a flat infrared spectral energy distribution, which indicates that it could be in the protostellar class I stage (star+disk+envelope). Upon inspection of archival images from various observatories, we find that one of the new young stars has a large edge-on disk (r = 2.''5 = 350 AU). The scattered light from this disk has undergone significant variability on a timescale of days in optical images from the Canada-France-Hawaii Telescope. Using the updated census of Taurus, we have measured the initial mass function for the fields observed by XMM-Newton. The resulting mass function is similar to previous ones that we have reported for Taurus, showing a surplus of stars at spectral types of K7-M1 (0.6-0.8 M{sub sun}) relative to other nearby star-forming regions, such as IC 348, Chamaeleon I, and the Orion Nebula Cluster.

  1. Phosphorylated Nuclear Receptor CAR Forms a Homodimer To Repress Its Constitutive Activity for Ligand Activation.

    PubMed

    Shizu, Ryota; Osabe, Makoto; Perera, Lalith; Moore, Rick; Sueyoshi, Tatsuya; Negishi, Masahiko

    2017-05-15

    The nuclear receptor CAR (NR1I3) regulates hepatic drug and energy metabolism as well as cell fate. Its activation can be a critical factor in drug-induced toxicity and the development of diseases, including diabetes and tumors. CAR inactivates its constitutive activity by phosphorylation at threonine 38. Utilizing receptor for protein kinase 1 (RACK1) as the regulatory subunit, protein phosphatase 2A (PP2A) dephosphorylates threonine 38 to activate CAR. Here we demonstrate that CAR undergoes homodimer-monomer conversion to regulate this dephosphorylation. By coexpression of two differently tagged CAR proteins in Huh-7 cells, mouse primary hepatocytes, and mouse livers, coimmunoprecipitation and two-dimensional gel electrophoresis revealed that CAR can form a homodimer in a configuration in which the PP2A/RACK1 binding site is buried within its dimer interface. Epidermal growth factor (EGF) was found to stimulate CAR homodimerization, thus constraining CAR in its inactive form. The agonistic ligand CITCO binds directly to the CAR homodimer and dissociates phosphorylated CAR into its monomers, exposing the PP2A/RACK1 binding site for dephosphorylation. Phenobarbital, which is not a CAR ligand, binds the EGF receptor, reversing the EGF signal to monomerize CAR for its indirect activation. Thus, the homodimer-monomer conversion is the underlying molecular mechanism that regulates CAR activation, by placing phosphorylated threonine 38 as the common target for both direct and indirect activation of CAR. Copyright © 2017 American Society for Microbiology.

  2. Prediction of Active-Region CME Productivity from Magnetograms

    NASA Technical Reports Server (NTRS)

    Falconer, D. A.; Moore, R. L.; Gary, G. A.

    2004-01-01

    We report results of an expanded evaluation of whole-active-region magnetic measures as predictors of active-region coronal mass ejection (CME) productivity. Previously, in a sample of 17 vector magnetograms of 12 bipolar active regions observed by the Marshall Space Flight Center (MSFC) vector magnetograph, from each magnetogram we extracted a measure of the size of the active region (the active region s total magnetic flux a) and four measures of the nonpotentiality of the active region: the strong-shear length L(sub SS), the strong-gradient length L(sub SG), the net vertical electric current I(sub N), and the net-current magnetic twist parameter alpha (sub IN). This sample size allowed us to show that each of the four nonpotentiality measures was statistically significantly correlated with active-region CME productivity in time windows of a few days centered on the day of the magnetogram. We have now added a fifth measure of active-region nonpotentiality (the best-constant-alpha magnetic twist parameter (alpha sub BC)), and have expanded the sample to 36 MSFC vector magnetograms of 31 bipolar active regions. This larger sample allows us to demonstrate statistically significant correlations of each of the five nonpotentiality measures with future CME productivity, in time windows of a few days starting from the day of the magnetogram. The two magnetic twist parameters (alpha (sub 1N) and alpha (sub BC)) are normalized measures of an active region s nonpotentially in that they do not depend directly on the size of the active region, while the other three nonpotentiality measures (L(sub SS), L(sub SG), and I(sub N)) are non-normalized measures in that they do depend directly on active-region size. We find (1) Each of the five nonpotentiality measures is statistically significantly correlated (correlation confidence level greater than 95%) with future CME productivity and has a CME prediction success rate of approximately 80%. (2) None of the nonpotentiality

  3. Field distribution of magnetograms from simulations of active region formation

    NASA Astrophysics Data System (ADS)

    Dacie, S.; van Driel-Gesztelyi, L.; Démoulin, P.; Linton, M. G.; Leake, J. E.; MacTaggart, D.; Cheung, M. C. M.

    2017-10-01

    Context. The evolution of the photospheric magnetic field distributions (probability densities) has previously been derived for a set of active regions. Photospheric field distributions are a consequence of physical processes that are difficult to determine from observations alone. Aims: We analyse simulated magnetograms from numerical simulations, which model the emergence and decay of active regions. These simulations have different experimental set-ups and include different physical processes, allowing us to investigate the relative importance of convection, magnetic buoyancy, magnetic twist, and braiding for flux emergence. Methods: We specifically studied the photospheric field distributions (probability densities found with a kernel density estimation analysis) and compared the results with those found from observations. Results: Simulations including convection most accurately reproduce the observed evolution of the photospheric field distributions during active region evolution. Conclusions: This indicates that convection may play an important role during the decay phase and also during the formation of active regions, particularly for low flux density values.

  4. Prediction of Active-Region CME Productivity from Magnetograms

    NASA Technical Reports Server (NTRS)

    Falconer, D. A.; Moore, R. L.; Gary, G. A.

    2004-01-01

    We report results of an expanded evaluation of whole-active-region magnetic measures as predictors of active-region coronal mass ejection (CME) productivity. Previously, in a sample of 17 vector magnetograms of 12 bipolar active regions observed by the Marshall Space Flight Center (MSFC) vector magnetograph, from each magnetogram we extracted a measure of the size of the active region (the active region s total magnetic flux a) and four measures of the nonpotentiality of the active region: the strong-shear length L(sub SS), the strong-gradient length L(sub SG), the net vertical electric current I(sub N), and the net-current magnetic twist parameter alpha (sub IN). This sample size allowed us to show that each of the four nonpotentiality measures was statistically significantly correlated with active-region CME productivity in time windows of a few days centered on the day of the magnetogram. We have now added a fifth measure of active-region nonpotentiality (the best-constant-alpha magnetic twist parameter (alpha sub BC)), and have expanded the sample to 36 MSFC vector magnetograms of 31 bipolar active regions. This larger sample allows us to demonstrate statistically significant correlations of each of the five nonpotentiality measures with future CME productivity, in time windows of a few days starting from the day of the magnetogram. The two magnetic twist parameters (alpha (sub 1N) and alpha (sub BC)) are normalized measures of an active region s nonpotentially in that they do not depend directly on the size of the active region, while the other three nonpotentiality measures (L(sub SS), L(sub SG), and I(sub N)) are non-normalized measures in that they do depend directly on active-region size. We find (1) Each of the five nonpotentiality measures is statistically significantly correlated (correlation confidence level greater than 95%) with future CME productivity and has a CME prediction success rate of approximately 80%. (2) None of the nonpotentiality

  5. Observed Helicity of Active Regions in Solar Cycle 21

    NASA Technical Reports Server (NTRS)

    Hagyard, M. J.; Pevtsov, A. A.; Blehm, Z.; Smith, J. E.; Six, Frank (Technical Monitor)

    2003-01-01

    We report the results of a study of helicity in solar active regions during the peak of activity in solar cycle 21 from observations with the Marshall Space Flight Center's solar vector magnetograph. Using the force-free parameter alpha as the proxy for helicity, we calculated an average value of alpha for each of 60 active regions from a total of 449 vector magnetograms that were obtained during the period 1980 March to November. The signs of these average values of alpha were correlated with the latitude of the active regions to test the hemispheric rule of helicity that has been proposed for solar magnetic fields: negative helicity predominant in northern latitudes, positive in the southern ones. We have found that of the 60 regions that were observed, 30 obey the hemispheric rule and 30 do not.

  6. Photospheric Magnetic Free Energy Density of Solar Active Regions

    NASA Astrophysics Data System (ADS)

    Zhang, Hongqi

    2016-12-01

    We present the photospheric energy density of magnetic fields in two solar active regions (one of them recurrent) inferred from observational vector magnetograms, and compare it with other available differently defined energy parameters of magnetic fields in the photosphere. We analyze the magnetic fields in Active Regions NOAA 6580-6619-6659 and 11158. The quantity 1/4π{B}n\\cdot{B}p is an important energy parameter that reflects the contribution of magnetic shear to the difference between the potential (Bp) and the non-potential magnetic field (Bn), and also the contribution to the free magnetic energy near the magnetic neutral lines in the active regions. It is found that the photospheric mean magnetic energy density shows clear changes before the powerful solar flares in Active Region NOAA 11158, which is consistent with the change in magnetic fields in the flaring lower atmosphere.

  7. A cytosolic activator of DNA replication is tyrosine phosphorylated in its active form.

    PubMed

    Fresa, K L; Autieri, M V; Coffman, F D; Georgoff, I; Cohen, S

    1993-04-01

    Cytosolic extracts from actively dividing lymphoid cells have been shown to induce DNA synthesis in isolated, quiescent nuclei. An initiating factor in such extracts (activator of DNA replication; ADR) is a > 90-kDa aprotinin-binding protein whose activity is inhibitable not only by aprotinin, but also by several other protease inhibitors as well. Although cytosol from non-proliferating lymphocytes is devoid of ADR activity, we have shown that these preparations can be induced to express ADR activity by brief exposure to a membrane-enriched fraction of spontaneously proliferating MOLT-4 cells via a kinase-dependent mechanism. In the present study, we examine the role of tyrosine kinases in this process. Three inhibitors of tyrosine kinases (genistein, kaempferol, and quercetin) can inhibit the in vitro generation of ADR activity. In vitro generation of ADR activity is associated with the de novo phosphorylation of several proteins, many of which are detectable using anti-phosphotyrosine monoclonal antibodies. ADR itself may be tyrosine phosphorylated in active form as immunoprecipitation using such monoclonal antibodies leads to the depletion of its activity. Moreover, immunoprecipitation results in the removal of several de novo tyrosine-phosphorylated proteins, including species at approximately 122, 105, 93, 86, 79, and 65 kDa. A subset of de novo-phosphorylated proteins, migrating at approximately 105, 93, and 70 kDa, also bound to aprotinin, suggesting that at least one of these proteins may represent ADR itself.

  8. THE COLD SHOULDER: EMISSION MEASURE DISTRIBUTIONS OF ACTIVE REGION CORES

    SciTech Connect

    Schmelz, J. T.; Pathak, S.

    2012-09-10

    The coronal heating mechanism for active region core loops is difficult to determine because these loops are often not resolved and cannot be studied individually. Rather, we concentrate on the 'inter-moss' areas between loop footpoints. We use observations from the Hinode EUV Imaging Spectrometer and the X-Ray Telescope to calculate the emission measure distributions of eight inter-moss areas in five different active regions. The combined data sets provide both high- and low-temperature constraints and ensure complete coverage in the temperature range appropriate for active regions. For AR 11113, the emission can be modeled with heating events that occur on timescales less than the cooling time. The loops in the core regions appear to be close to equilibrium and are consistent with steady heating. The other regions studied, however, appear to be dominated by nanoflare heating. Our results are consistent with the idea that active region age is an important parameter in determining whether steady or nanoflare heating is primarily responsible for the core emission, that is, older regions are more likely to be dominated by steady heating, while younger regions show more evidence of nanoflares.

  9. Star and jet multiplicity in the high-mass star forming region IRAS 05137+3919

    NASA Astrophysics Data System (ADS)

    Cesaroni, R.; Massi, F.; Arcidiacono, C.; Beltrán, M. T.; Persi, P.; Tapia, M.; Molinari, S.; Testi, L.; Busoni, L.; Riccardi, A.; Boutsia, K.; Bisogni, S.; McCarthy, D.; Kulesa, C.

    2015-09-01

    Context. We present a study of the complex high-mass star forming region IRAS 05137+3919 (also known as Mol8), where multiple jets and a rich stellar cluster have been described in previous works. Aims: Our goal is to determine the number of jets and shed light on their origin, and thus determine the nature of the young stars powering these jets. We also wish to analyse the stellar clusters by resolving the brightest group of stars. Methods: The star forming region was observed in various tracers and the results were complemented with ancillary archival data. The new data represent a substantial improvement over previous studies both in resolution and frequency coverage. In particular, adaptive optics provides us with an angular resolution of 80 mas in the near IR, while new mid- and far-IR data allow us to sample the peak of the spectral energy distribution and thus reliably estimate the bolometric luminosity. Results: Thanks to the near-IR continuum and millimetre line data we can determine the structure and velocity field of the bipolar jets and outflows in this star forming region. We also find that the stars are grouped into three clusters and the jets originate in the richest of these, whose luminosity is ~ 2.4 × 104L⊙. Interestingly, our high-resolution near-IR images allow us to resolve one of the two brightest stars (A and B) of the cluster into a double source (A1+A2). Conclusions: We confirm that there are two jets and establish that they are powered by B-type stars belonging to cluster C1. On this basis and on morphological and kinematical arguments, we conclude that the less extended jet is almost perpendicular to the line of sight and that it originates in the brightest star of the cluster, while the more extended one appears to be associated with the more extincted, double source A1+A2. We propose that this is not a binary system, but a small bipolar reflection nebula at the root of the large-scale jet, outlining a still undetected circumstellar

  10. Narrow-band Imaging of Massive Star-Forming Regions: Tracing Outflows and the Rate of Star-Formation

    NASA Astrophysics Data System (ADS)

    Hall, Kendall; Willis, Sarah; Hora, Joseph L.

    2016-01-01

    Narrowband images targeting ionized hydrogen (Brackett gamma, 2.17 microns) and molecular hydrogen (2.12 microns) were obtained for six massive star-forming regions within the Milky Way, NGC 6334, G305, G3333, G3264, G3266, and G351. These regions are within 1-4 kpc from our solar system. The narrowband flux in Brackett gamma was used as a star-formation tracer to calculate a star-formation rate for each region. This is compared with other star-formation rates found using other methods such as the count of young stars and YSOs, and rates calculated from using other tracers (e.g. 70 micron monochromatic luminosity). The molecular hydrogen narrowband images were manually searched to locate outflows from young stars. Once these outflows are identified, it may help to get a better survey of the young stellar population. A better understanding of the stellar population distribution can lead to more accurate star-formation rates to compare to those calculated from star-formation tracers. We found the regions NGC 6334 and G3266 to have the highest levels of ongoing star formation activity as indicated by the number of molecular hydrogen objects (MHOs) detected. There are a total of 279 cataloged MHOs in 181 categorized systems for the six regions. There are a total of 150 identified potential driving sources.This work was supported in part by the NSF REU and DoD ASSURE programs under NSF grant no. 1262851 and by the Smithsonian Institution.

  11. Economic determinants of urban form: resulting trade-offs between active and sedentary forms of travel.

    PubMed

    Frank, Lawrence D

    2004-10-01

    Economic factors have an impact on how the built environment is shaped, which in turn affects how we choose to travel. Regional transportation investment decisions are firmly rooted in economic "cost-benefit" trade-off considerations. The placement (central or outlying) and mode of transportation in which investments are made (transit, highway, sidewalks, or bikeways) influence where homes, businesses, schools, and other types of uses are located. Transportation investments create or limit access and establish a set of economic trade-offs that help determine if an area will be compact or dispersed, and mixed use or single use. Developers consider cost trade-offs between constructing connected street grids versus disconnected cul-de-sac networks, which determines if residents can walk to services and transit. Taken collectively, transportation investments and resulting land-use patterns determine if destinations are far apart or close together and linked with direct and safe sidewalks or bikeways. The end result is a built environment that determines whether walking and biking is feasible or perceived as more beneficial than driving or taking transit. This paper assesses (1) the economic forces that shape transportation investment decisions, (2) the economic impact of these investments on land use, and (3) how we as consumers choose to travel as a result of these transportation investment and land-use decisions.

  12. Active Ageing Level of Older Persons: Regional Comparison in Thailand

    PubMed Central

    Haque, Md. Nuruzzaman

    2016-01-01

    Active ageing level and its discrepancy in different regions (Bangkok, Central, North, Northeast, and South) of Thailand have been examined for prioritizing the policy agenda to be implemented. Attempt has been made to test preliminary active ageing models for Thai older persons and hence active ageing index (AAI, ranges from 0 to 1) has been estimated. Using nationally representative data and confirmatory factor analysis approach, this study justified active ageing models for female and male older persons in Thailand. Results revealed that active ageing level of Thai older persons is not high (mean AAIs for female and male older persons are 0.64 and 0.61, resp., and those are significantly different (p < 0.001)). Mean AAI in Central region is lower than North, Northeast, and South regions but there is no significant difference in the latter three regions of Thailand. Special emphasis should be given to Central region and policy should be undertaken for increasing active ageing level. Implementation of an Integrated Active Ageing Package (IAAP), containing policies for older persons to improve their health and economic security, to promote participation in social groups and longer working lives, and to arrange learning programs, would be helpful for increasing older persons' active ageing level in Thailand. PMID:27375903

  13. Solar Irradiance Variations on Active Region Time Scales

    NASA Technical Reports Server (NTRS)

    Labonte, B. J. (Editor); Chapman, G. A. (Editor); Hudson, H. S. (Editor); Willson, R. C. (Editor)

    1984-01-01

    The variations of the total solar irradiance is an important tool for studying the Sun, thanks to the development of very precise sensors such as the ACRIM instrument on board the Solar Maximum Mission. The largest variations of the total irradiance occur on time scales of a few days are caused by solar active regions, especially sunspots. Efforts were made to describe the active region effects on total and spectral irradiance.

  14. Photospheric Magnetic Diffusion by Measuring Moments of Active Regions

    NASA Astrophysics Data System (ADS)

    Engell, Alexander; Longcope, D.

    2013-07-01

    Photospheric magnetic surface diffusion is an important constraint for the solar dynamo. The HMI Active Region Patches (HARPs) program automatically identify all magnetic regions above a certain flux. In our study we measure the moments of ARs that are no longer actively emerging and can thereby give us good statistical constraints on photospheric diffusion. We also present the diffusion properties as a function of latitude, flux density, and single polarity (leading or following) within each HARP.

  15. THE BLAST VIEW OF THE STAR-FORMING REGION IN AQUILA (l = 45{sup 0}, b = 0{sup 0})

    SciTech Connect

    Rivera-Ingraham, Alana; Martin, Peter G.; Netterfield, Calvin B.; Ade, Peter A. R.; Griffin, Matthew; Hargrave, Peter C.; Mauskopf, Philip; Bock, James J.; Chapin, Edward L.; Halpern, Mark; Marsden, Gaelen; Scott, Douglas; Devlin, Mark J.; Dicker, Simon R.; Klein, Jeff; Rex, Marie; Gundersen, Joshua O.; Hughes, David H.; Olmi, Luca; Patanchon, Guillaume

    2010-11-01

    We have carried out the first general submillimeter analysis of the field toward GRSMC 45.46+0.05, a massive star-forming region in Aquila. The deconvolved 6 deg{sup 2} (3{sup 0} x 2{sup 0}) maps provided by BLAST in 2005 at 250, 350, and 500 {mu}m were used to perform a preliminary characterization of the clump population previously investigated in the infrared, radio, and molecular maps. Interferometric CORNISH data at 4.8 GHz have also been used to characterize the Ultracompact H II regions (UCHIIRs) within the main clumps. By means of the BLAST maps, we have produced an initial census of the submillimeter structures that will be observed by Herschel, several of which are known Infrared Dark Clouds. Our spectral energy distributions of the main clumps in the field, located at {approx}7 kpc, reveal an active population with temperatures of T{approx} 35-40 K and masses of {approx}10{sup 3} M{sub sun} for a dust emissivity index {beta} = 1.5. The clump evolutionary stages range from evolved sources, with extended H II regions and prominent IR stellar population, to massive young stellar objects, prior to the formation of an UCHIIR. The CORNISH data have revealed the details of the stellar content and structure of the UCHIIRs. In most cases, the ionizing stars corresponding to the brightest radio detections are capable of accounting for the clump bolometric luminosity, in most cases powered by embedded OB stellar clusters.

  16. The nature of chromospheric active regions on V410 Tauri

    NASA Astrophysics Data System (ADS)

    Mekkaden, M. V.; Pukalenthi, S.; Muneer, S.; Bastian, Anju Barbara

    2005-12-01

    We present spectroscopic observations in the region of H alpha and Li I lines of the weak emission T Tauri star V410 Tau obtained over 1999/2000, 2002/2003 and 2003/2004 seasons. The emission strength showed rotational modulation during the 1999/2000 season in such a way that the emis- sion strength is maximum at light minimum and vice versa. This indicates that the photospheric and chromospheric active regions overlap over shorter dura- tions of time and the lifetimes of chromospheric active regions are far shorter than the photospheric active regions. But the observations obtained during the 2003/2004 season do not follow the trend observed at earlier seasons. This can be due to the change in the location of chromospheric active regions. Another possibility is the occurrence of a major change in the photospheric active re- gions that have caused a redistribution of photospheric as well as chromospheric active regions. The Li I EW does not show any appreciable change over the four-year period.

  17. Studying the transfer of magnetic helicity in solar active regions

    NASA Astrophysics Data System (ADS)

    Dalmasse, Kevin; Valori, Gherardo; Jing, Ju; Pariat, Etienne; Demoulin, Pascal

    2017-08-01

    Analyzing the transfer of magnetic helicity in active regions is a key component for understanding the nature of its coronal storage and release and for identifying its role in the coronal dynamics of active regions. We recently developed a method for studying the photospheric flux of magnetic helicity in both 2D and 3D. The method takes into account the 3D nature of magnetic helicity by explicitly using knowledge of the magnetic field connectivity. Since the coronal magnetic field in active regions is not measured, we rely on the non-unique 3D solution obtained from force-free coronal magnetic field extrapolations to derive the magnetic field connectivity. In this poster, we apply the method to the complex and highly-flaring active region NOAA 11158 using the magnetic field connectivity derived from different force-free extrapolation models and implementations. We show that the calculations of photospheric flux of magnetic helicity are robust to different extrapolation methods and assumptions, in particular with regards to identifying regions of opposite magnetic helicity flux. Finally, we discuss the implications of our results for tracking the transfer of magnetic helicity in active regions and relate it to their flaring activity.

  18. Mechanically driven activation of polyaniline into its conductive form.

    PubMed

    Baytekin, Bilge; Baytekin, H Tarik; Grzybowski, Bartosz A

    2014-07-01

    Mechanical treatment of polymers produces surface cations and anions which, as demonstrated here for the first time, can drive chemical reactions. In particular, it is shown that such a mechanical treatment transforms nonconductive polyaniline into its conductive form. These results provide a mechanical means of patterning conductive polymers and also coating small polymer objects with conductive polyaniline films preventing accumulation of static electricity. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Twist of Magnetic Fields in Solar Active Regions

    NASA Astrophysics Data System (ADS)

    Zhang, Hongqi; Bao, Shudong; Kuzanyan, Kirill M.

    2002-05-01

    We study the twist properties of photospheric magnetic fields in solar active regions using magnetographic data on 422 active regions obtained at the Huairou Solar Observing Station in 1988 1997. We calculate the mean twist (force-free field αf) of the active regions and compare it with the mean current-helicity density of these same active regions, h c =B ∥·(∇×B)∥. The latitude and longitude distributions and time dependence of these quantities is analyzed. These parameters represent two different tracers of the α effect in dynamo theory, so we might expect them to possess similar properties. However, apart from differences in their definitions, they also display differences associated with the technique used to recalculate the magnetographic data and with their different physical meanings. The distributions of the mean αf and h c both show hemispherical asymmetry—negative (positive) values in the northern (southern) hemisphere—although this tendency is stronger for h c. One reason for these differences may be the averaging procedure, when twists of opposite sign in regions with weak fields make a small contribution to the mean current-helicity density. Such transequatorial regularity is in agreement with the expectations of dynamo theory. In some active regions, the average αf and h c do not obey this transequatorial rule. As a whole, the mean twist of the magnetic fields αf of active regions does not vary significantly with the solar cycle. Active regions that do not follow the general behavior for αf do not show any appreciable tendency to cluster at certain longitudes, in contrast to results for h c noted in previous studies. We analyze similarities and differences in the distributions of these two quantities. We conclude that using only one of these tracers, such as αf, to search for signatures of the α effect can have disadvantages, which should be taken into account in future studies.

  20. SDO/HMI survey of emerging active regions for helioseismology

    NASA Astrophysics Data System (ADS)

    Schunker, H.; Braun, D. C.; Birch, A. C.; Burston, R. B.; Gizon, L.

    2016-11-01

    Context. Observations from the Solar Dynamics Observatory (SDO) have the potential for allowing the helioseismic study of the formation of hundreds of active regions, which would enable us to perform statistical analyses. Aims: Our goal is to collate a uniform data set of emerging active regions observed by the SDO/HMI instrument suitable for helioseismic analysis, where each active region is centred on a 60° × 60° area and can be observed up to seven days before emergence. Methods: We restricted the sample to active regions that were visible in the continuum and emerged into quiet Sun largely avoiding pre-existing magnetic regions. As a reference data set we paired a control region (CR), with the same latitude and distance from central meridian, with each emerging active region (EAR). The control regions do not have any strong emerging flux within 10° of the centre of the map. Each region was tracked at the Carrington rotation rate as it crossed the solar disk, within approximately 65° from the central meridian and up to seven days before, and seven days after, emergence. The mapped and tracked data, consisting of line-of-sight velocity, line-of-sight magnetic field, and intensity as observed by SDO/HMI, are stored in datacubes that are 410 min in duration and spaced 320 min apart. We call this data set, which is currently comprised of 105 emerging active regions observed between May 2010 and November 2012, the SDO Helioseismic Emerging Active Region (SDO/HEAR) survey. Results: To demonstrate the utility of a data set of a large number of emerging active regions, we measure the relative east-west velocity of the leading and trailing polarities from the line-of-sight magnetogram maps during the first day after emergence. The latitudinally averaged line-of-sight magnetic field of all the EARs shows that, on average, the leading (trailing) polarity moves in a prograde (retrograde) direction with a speed of 121 ± 22 m s-1 (-70 ± 13 m s-1) relative to the

  1. The structure and early evolution of massive star forming regions. Substructure in the infrared dark cloud SDC13

    NASA Astrophysics Data System (ADS)

    McGuire, C.; Fuller, G. A.; Peretto, N.; Zhang, Q.; Traficante, A.; Avison, A.; Jimenez-Serra, I.

    2016-10-01

    Context. Investigations into the substructure of massive star forming regions are essential for understanding the observed relationships between core mass distributions and mass distributions in stellar clusters, differentiating between proposed mechanisms of massive star formation. Aims: We study the substructure in the two largest fragments (i.e. cores) MM1 and MM2, in the infrared dark cloud complex SDC13. As MM1 appears to be in a later stage of evolution than MM2, comparing their substructure provides an insight in to the early evolution of massive clumps. Methods: We report the results of high resolution SMA dust continuum observations towards MM1 and MM2. Combining these data with Herschel observations, we carry out RADMC-3D radiative transfer modelling to characterise the observed substructure. Results: SMA continuum data indicates 4 sub-fragments in the SDC13 region. The nature of the second brightest sub-fragment (B) is uncertain as it does not appear as prominent at the lower MAMBO resolution or at radio wavelengths. Statistical analysis indicates that it is unlikely to be a background source, an AGB star, or the free-free emission of a HII region. It is plausible that B is a runaway object ejected from MM1. MM1, which is actively forming stars, consists of two sub-fragments A and C. This is confirmed by 70 μmHerschel data. While MM1 and MM2 appear quite similar in previous low resolution observations, at high resolution, the sub-fragment at the centre of MM2 (D) is much fainter than sub-fragment at the centre of MM1 (A). RADMC-3D models of MM1 and MM2 are able to reproduce these results, modelling MM2 with a steeper density profile and higher mass than is required for MM1. The relatively steep density profile of MM2 depends on a significant temperature decrease in its centre, justified by the lack of star formation in MM2. A final stellar population for MM1 was extrapolated, indicating a star formation efficiency typical of regions of core and cluster

  2. The molecular composition of the planet-forming regions of protoplanetary disks across the luminosity regime

    NASA Astrophysics Data System (ADS)

    Walsh, Catherine; Nomura, Hideko; van Dishoeck, Ewine

    2015-10-01

    Context. Near- to mid-infrared observations of molecular emission from protoplanetary disks show that the inner regions are rich in small organic volatiles (e.g., C2H2 and HCN). Trends in the data suggest that disks around cooler stars (Teff ≈ 3000 K) are potentially (i) more carbon-rich; and (ii) more molecule-rich than their hotter counterparts (Teff ≳ 4000 K). Aims: We explore the chemical composition of the planet-forming region (<10 AU) of protoplanetary disks around stars over a range of spectral types (from M dwarf to Herbig Ae) and compare with the observed trends. Methods: Self-consistent models of the physical structure of a protoplanetary disk around stars of different spectral types are coupled with a comprehensive gas-grain chemical network to map the molecular abundances in the planet-forming zone. The effects of (i) N2 self shielding; (ii) X-ray-induced chemistry; and (iii) initial abundances, are investigated. The chemical composition in the "observable" atmosphere is compared with that in the disk midplane where the bulk of the planet-building reservoir resides. Results: M dwarf disk atmospheres are relatively more molecule rich than those for T Tauri or Herbig Ae disks. The weak far-UV flux helps retain this complexity which is enhanced by X-ray-induced ion-molecule chemistry. N2 self shielding has only a small effect in the disk molecular layer and does not explain the higher C2H2/HCN ratios observed towards cooler stars. The models underproduce the OH/H2O column density ratios constrained in Herbig Ae disks, despite reproducing (within an order of magnitude) the absolute value for OH: the inclusion of self shielding for H2O photodissociation only increases this discrepancy. One possible explanation is the adopted disk structure. Alternatively, the "hot" H2O (T ≳ 300 K) chemistry may be more complex than assumed. The results for the atmosphere are independent of the assumed initial abundances; however, the composition of the disk midplane

  3. Earth resources-regional transfer activity contracts review

    NASA Technical Reports Server (NTRS)

    Bensko, J., Jr.; Daniels, J. L.; Downs, S. W., Jr.; Jones, N. L.; Morton, R. R.; Paludan, C. T.

    1977-01-01

    A regional transfer activity contracts review held by the Earth Resources Office was summarized. Contracts in the earth resources field primarily directed toward applications of satellite data and technology in solution of state and regional problems were reviewed. A summary of the progress of each contract was given in order to share experiences of researchers across a seven state region. The region included Missouri, Kentucky, Tennessee, Mississippi, Alabama, Georgia, and North Carolina. Research in several earth science disciplines included forestry, limnology, water resources, land use, geology, and mathematical modeling. The use of computers for establishment of information retrieval systems was also emphasized.

  4. Statistical Distribution of Magnetic Flux Concentrations in an Active Region

    NASA Astrophysics Data System (ADS)

    Abramenko, V. I.

    2004-05-01

    Probability distribution functions (PDFs) of the unsigned magnetic flux content in flux concentrations in a mature active region NOAA 9077 were calculated by using a set of 248 high resolution SOHO/MDI magnetograms. Two independent routines to outline magnetic flux concentrations were elaborated. The analysis was performed with 4 different values of the threshold, p, of the magnetic flux density (p=25, 50, 75, 100 G). We have found that: i) the best analytical approximation of the observed PDFs in the range of low flux (1 x 1018 Mx < F < 150 x 1018 Mx ) is a lognormal distribution, LN(m ,s2), with the expected value m=(0.7-5) x 1018 Mx and the standard deviation s = (10-45) x 1018 Mx. The peak of the lognormal distribution tends to shift toward the lower flux as the threshold p decreases. This tendency suggests that the real expected value may be even smaller than 0.7 x 1018 Mx; ii) for the flux F > 150 x 1018 Mx the observed PDFs fall off slower than the lognormal approximation predicts. In this flux range, the power law is found to be the best analytical approximation with the power law index approximately equal to 2. The transition region between the lognormality and the power law shifts toward the lower flux as the threshold p is lowered. This implies that the functional form of the distribution changes continuously with the scale. The above findings are consistent with the concept of highly intermittent (or multifractal) nature of photospheric magnetic fields and offer a new tool to study their multifractality. SOHO is a project of international cooperation between ESA and NASA. This work was supported by NSF-ATM 0076602, 9903515 and NASA NAG5-12782 grants.

  5. The pore-forming toxin proaerolysin is activated by furin.

    PubMed

    Abrami, L; Fivaz, M; Decroly, E; Seidah, N G; Jean, F; Thomas, G; Leppla, S H; Buckley, J T; van der Goot, F G

    1998-12-04

    Aerolysin is secreted as an inactive dimeric precursor by the bacterium Aeromonas hydrophila. Proteolytic cleavage within a mobile loop near the C terminus of the protoxin is required for oligomerization and channel formation. This loop contains the sequence KVRRAR432, which should be recognized by mammalian proprotein convertases such as furin, PACE4, and PC5/6A. Here we show that these three proteases cleave proaerolysin after Arg-432 in vitro, yielding active toxin. We also investigated the potential role of these enzymes in the in vivo activation of the protoxin. We found that Chinese hamster ovary cells were able to convert the protoxin to aerolysin in the absence of exogenous proteases and that activation did not require internalization of the toxin. The furin inhibitor alpha1-antitrypsin Portland reduced the rate of proaerolysin activation in vivo, and proaerolysin processing was even further reduced in furin-deficient FD11 Chinese hamster ovary cells. The cells were also less sensitive to proaerolysin than wild type cells; however, transient transfection of FD11 cells with the cDNA encoding furin conferred normal sensitivity to the protoxin. Together these findings argue that furin catalyzes the cell-surface activation of proaerolysin in vivo.

  6. Active folded structures of the Western Caucasus (Sochi region)

    NASA Astrophysics Data System (ADS)

    Trikhunkov, Yaroslav; Zelenin, Egor

    2014-05-01

    The Western Caucasus as a margin segment of folded system of the Greater Caucasus was formed at the periphery of collision interaction of the Scythian Plate and the Transcaucasian Massif. The estimated age of the primary folded deformations of the initial surface of that territory ranges from the late Eocene to late Neogene. We have obtained new data on modern folded deformations of the anticlinal ridges, which prevail in Sochi region in the southern macroslope of the mountain system. Very similar Alek, Galitsinsky, Akhun, Nikolaevsky anticlinal ridges are uplifting in the main Caucasus direction (NW - SE) and are crossed by narrow antecedent river valleys. These ridges stand out contrasting to sinclinal depressions, where fluviatile accumulation prevails. At the intersection of the Mzymta river and the Galitsinsky anticlinal ridge a narrow Akhshtyr canyon with steep, 150 meters high slopes were formed. Downstream in the neighboring Akhshtyr synclinal depression the valley expands. Here the floodplain and two levels of terraces with the height of 20 - 30 and 50 - 60 m correspondingly were formed. The age of the first terrace was defined by archeologic data of V. Shchelinsky (2007) and by correlation with marine Black Sea Late Karangat terrace as a 135 - 90 ka (Eemian interglacial). The second terrace is apparently older and dates back to Middle Pleistocene. The field research and analysis of the elevations by ASTER GDEM allowed us to trace both terraces in the southern structural slope of the Galitsinsky ridge above the canyon, adjacent to the Akhshtyr depression, at the heights 70 and 110 m correspondingly. Alluvial deposits in outcrops of lower terrace (elongated pebbles, which look like modern alluvium of the Mzymta) were traced on the surface of the slope. Thereby, described fragments of the Mzymta terraces were uplifted above the level of the corresponding terraces in the synclinal depression as a result of dislocation on the slope of the actively uplifting

  7. THE FORMATION AND MAGNETIC STRUCTURES OF ACTIVE-REGION FILAMENTS OBSERVED BY NVST, SDO, AND HINODE

    SciTech Connect

    Yan, X. L.; Xue, Z. K.; Wang, J. C.; Xiang, Y. Y.; Kong, D. F.; Yang, L. H.; Pan, G. M.

    2015-08-15

    To better understand the properties of solar active-region filaments, we present a detailed study on the formation and magnetic structures of two active-region filaments in active region NOAA 11884 during a period of four days. It is found that the shearing motion of the opposite magnetic polarities and the rotation of the small sunspots with negative polarity play an important role in the formation of two active-region filaments. During the formation of these two active-region filaments, one foot of the filaments was rooted in a small sunspot with negative polarity. The small sunspot rotated not only around another small sunspot with negative polarity, but also around the center of its umbra. By analyzing the nonlinear force-free field extrapolation using the vector magnetic fields in the photosphere, twisted structures were found in the two active-region filaments prior to their eruptions. These results imply that the magnetic fields were dragged by the shearing motion between opposite magnetic polarities and became more horizontal. The sunspot rotation twisted the horizontal magnetic fields and finally formed the twisted active-region filaments.

  8. VLBA Determination of the Distance to Nearby Star-forming Regions. VII. Monoceros R2

    NASA Astrophysics Data System (ADS)

    Dzib, Sergio A.; Ortiz-León, Gisela N.; Loinard, Laurent; Mioduszewski, Amy J.; Rodríguez, Luis F.; Torres, Rosa M.; Deller, Adam

    2016-08-01

    We present a series of 16 Very Long Baseline Array high angular resolution observations of a cluster of suspected low-mass young stars in the Monoceros R2 region. Four compact and highly variable radio sources are detected; three of them in only one epoch, the fourth one a total of seven times. This latter source is seen in the direction of the previously known UC H ii region VLA 1, and has radio properties that resemble those of magnetically active stars; we shall call it VLA 1⋆. We model its displacement on the celestial sphere as a combination of proper motion and trigonometric parallax. The fit obtained using a uniform proper motion yields a parallax ϖ = 1.10 ± 0.18 mas, but with a fairly high post-fit dispersion. If acceleration terms (probably due to an undetected companion) are included, the quality of the fit improves dramatically, and the best estimate of the parallax becomes ϖ = 1.12 ± 0.05 mas. The magnitude of the fitted acceleration suggests an orbital period of the order of a decade. The measured parallax corresponds to a distance d = {893}-40+44 {pc} , in very good agreement with previous, indirect determinations.

  9. TRIGONOMETRIC PARALLAXES OF MASSIVE STAR-FORMING REGIONS. VI. GALACTIC STRUCTURE, FUNDAMENTAL PARAMETERS, AND NONCIRCULAR MOTIONS

    SciTech Connect

    Reid, M. J.; Sato, M.; Menten, K. M.; Brunthaler, A.; Xu, Y.; Choi, Y. K.; Zheng, X. W.; Zhang, B.; Moscadelli, L.; Honma, M.; Hirota, T.; Hachisuka, K.; Moellenbrock, G. A.; Bartkiewicz, A.

    2009-07-20

    We are using the Very Long Baseline Array and the Japanese VLBI Exploration of Radio Astronomy project to measure trigonometric parallaxes and proper motions of masers found in high-mass star-forming regions across the Milky Way. Early results from 18 sources locate several spiral arms. The Perseus spiral arm has a pitch angle of 16 deg. {+-} 3 deg., which favors four rather than two spiral arms for the Galaxy. Combining positions, distances, proper motions, and radial velocities yields complete three-dimensional kinematic information. We find that star-forming regions on average are orbiting the Galaxy {approx}15 km s{sup -1} slower than expected for circular orbits. By fitting the measurements to a model of the Galaxy, we estimate the distance to the Galactic center R {sub 0} = 8.4 {+-} 0.6 kpc and a circular rotation speed {theta}{sub 0} = 254 {+-} 16 km s{sup -1}. The ratio {theta}{sub 0}/R {sub 0} can be determined to higher accuracy than either parameter individually, and we find it to be 30.3 {+-} 0.9 km s{sup -1} kpc{sup -1}, in good agreement with the angular rotation rate determined from the proper motion of Sgr A*. The data favor a rotation curve for the Galaxy that is nearly flat or slightly rising with Galactocentric distance. Kinematic distances are generally too large, sometimes by factors greater than 2; they can be brought into better agreement with the trigonometric parallaxes by increasing {theta}{sub 0}/R {sub 0} from the IAU recommended value of 25.9 km s{sup -1} kpc{sup -1} to a value near 30 km s{sup -1} kpc{sup -1}. We offer a 'revised' prescription for calculating kinematic distances and their uncertainties, as well as a new approach for defining Galactic coordinates. Finally, our estimates of {theta}{sub 0} and {theta}{sub 0}/R{sub 0}, when coupled with direct estimates of R {sub 0}, provide evidence that the rotation curve of the Milky Way is similar to that of the Andromeda galaxy, suggesting that the dark matter halos of these two

  10. A Search for Companions to Brown Dwarfs in the Taurus and Chamaeleon Star-Forming Regions

    NASA Astrophysics Data System (ADS)

    Todorov, K. O.; Luhman, K. L.; Konopacky, Q. M.; McLeod, K. K.; Apai, D.; Ghez, A. M.; Pascucci, I.; Robberto, M.

    2014-06-01

    We have used WFPC2 on board the Hubble Space Telescope to obtain images of 47 members of the Taurus and Chamaeleon I star-forming regions that have spectral types of M6-L0 (M ~ 0.01-0.1 M ⊙). An additional late-type member of Taurus, FU Tau (M7.25+M9.25), was also observed with adaptive optics at Keck Observatory. In these images, we have identified promising candidate companions to 2MASS J04414489+2301513 (ρ = 0.''105/15 AU), 2MASS J04221332+1934392 (ρ = 0.''05/7 AU), and ISO 217 (ρ = 0.''03/5 AU). We reported the first candidate in a previous study, showing that it has a similar proper motion as the primary in images from WFPC2 and Gemini adaptive optics. We have collected an additional epoch of data with Gemini that further supports that result. By combining our survey with previous high-resolution imaging in Taurus, Chamaeleon I, and Upper Sco (τ ~ 10 Myr), we measure binary fractions of 14/93 = 0.15^{+0.05}_{-0.03} for M4-M6 (M ~ 0.1-0.3 M ⊙) and 4/108 = 0.04^{+0.03}_{-0.01} for >M6 (M <~ 0.1 M ⊙) at separations of >10 AU. Given the youth and low density of these regions, the lower binary fraction at later types is probably primordial rather than due to dynamical interactions among association members. The widest low-mass binaries (>100 AU) also appear to be more common in Taurus and Chamaeleon I than in the field, which suggests that the widest low-mass binaries are disrupted by dynamical interactions at >10 Myr, or that field brown dwarfs have been born predominantly in denser clusters where wide systems are disrupted or inhibited from forming. Based on observations performed with the NASA/ESA Hubble Space Telescope, Gemini Observatory, and the W. M. Keck Observatory. The Hubble observations are associated with proposal IDs 11203, 11204, and 11983 and were 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.

  11. A search for companions to brown dwarfs in the Taurus and Chamaeleon star-forming regions

    SciTech Connect

    Todorov, K. O.; Luhman, K. L.; Konopacky, Q. M.; McLeod, K. K.; Apai, D.; Pascucci, I.; Ghez, A. M.; Robberto, M.

    2014-06-10

    We have used WFPC2 on board the Hubble Space Telescope to obtain images of 47 members of the Taurus and Chamaeleon I star-forming regions that have spectral types of M6-L0 (M ∼ 0.01-0.1 M {sub ☉}). An additional late-type member of Taurus, FU Tau (M7.25+M9.25), was also observed with adaptive optics at Keck Observatory. In these images, we have identified promising candidate companions to 2MASS J04414489+2301513 (ρ = 0.''105/15 AU), 2MASS J04221332+1934392 (ρ = 0.''05/7 AU), and ISO 217 (ρ = 0.''03/5 AU). We reported the first candidate in a previous study, showing that it has a similar proper motion as the primary in images from WFPC2 and Gemini adaptive optics. We have collected an additional epoch of data with Gemini that further supports that result. By combining our survey with previous high-resolution imaging in Taurus, Chamaeleon I, and Upper Sco (τ ∼ 10 Myr), we measure binary fractions of 14/93 = 0.15{sub −0.03}{sup +0.05} for M4-M6 (M ∼ 0.1-0.3 M {sub ☉}) and 4/108 = 0.04{sub −0.01}{sup +0.03} for >M6 (M ≲ 0.1 M {sub ☉}) at separations of >10 AU. Given the youth and low density of these regions, the lower binary fraction at later types is probably primordial rather than due to dynamical interactions among association members. The widest low-mass binaries (>100 AU) also appear to be more common in Taurus and Chamaeleon I than in the field, which suggests that the widest low-mass binaries are disrupted by dynamical interactions at >10 Myr, or that field brown dwarfs have been born predominantly in denser clusters where wide systems are disrupted or inhibited from forming.

  12. HIGH-VELOCITY LINE FORMING REGIONS IN THE TYPE Ia SUPERNOVA 2009ig

    SciTech Connect

    Marion, G. H.; Foley, Ryan J.; Challis, Peter; Kirshner, Robert P.; Vinko, Jozsef; Wheeler, J. Craig; Silverman, Jeffrey M.; Hsiao, Eric Y.; Brown, Peter J.; Filippenko, Alexei V.; Garnavich, Peter; Landsman, Wayne B.; Parrent, Jerod T.; Pritchard, Tyler A.; Roming, Peter W. A.; Wang, Xiaofeng

    2013-11-01

    We report measurements and analysis of high-velocity (HVF) (>20,000 km s{sup –1}) and photospheric absorption features in a series of spectra of the Type Ia supernova (SN) 2009ig obtained between –14 days and +13 days with respect to the time of maximum B-band luminosity (B-max). We identify lines of Si II, Si III, S II, Ca II, and Fe II that produce both HVF and photospheric-velocity (PVF) absorption features. SN 2009ig is unusual for the large number of lines with detectable HVF in the spectra, but the light-curve parameters correspond to a slightly overluminous but unexceptional SN Ia (M{sub B} = –19.46 mag and Δm{sub 15}(B) = 0.90 mag). Similarly, the Si II λ6355 velocity at the time of B-max is greater than 'normal' for an SN Ia, but it is not extreme (v{sub Si} = 13,400 km s{sup –1}). The –14 days and –13 days spectra clearly resolve HVF from Si II λ6355 as separate absorptions from a detached line forming region. At these very early phases, detached HVF are prevalent in all lines. From –12 days to –6 days, HVF and PVF are detected simultaneously, and the two line forming regions maintain a constant separation of about 8000 km s{sup –1}. After –6 days all absorption features are PVF. The observations of SN 2009ig provide a complete picture of the transition from HVF to PVF. Most SNe Ia show evidence for HVF from multiple lines in spectra obtained before –10 days, and we compare the spectra of SN 2009ig to observations of other SNe. We show that each of the unusual line profiles for Si II λ6355 found in early-time spectra of SNe Ia correlate to a specific phase in a common development sequence from HVF to PVF.

  13. Offerings from the COMPLETE Survey of Star-Forming Regions, c. 2005

    NASA Astrophysics Data System (ADS)

    Goodman, A. A.; Alves, J. F.; Arce, H. G.; Bethell, T.; Borkin, M. A.; Caselli, P.; Di Francesco, J.; Foster, J. B.; Halle, M.; Heyer, M.; Johnstone, D.; Kirk, H.; Kosslyn, D. A.; Li, D.; Li, J.; Lombardi, M.; Pineda, J.; Ridge, N. A.; Schnee, S. L.; Tafalla, M.; Whitehorn, N.

    2005-12-01

    The COMPLETE (COordinated Molecular Probe Line Extinction Thermal Emission) Survey of Star-Forming Regions has now mapped the full extent (as defined by the Spitzer c2d Legacy Survey) of the Perseus, Ophiuchus, and Serpens star-forming regions in: 1) 12CO and 13CO maps (featuring >200,000 spectra) from FCRAO with 40 arcsec resolution; 2) extinction, using the ``NICER" method on 2MASS data; and 3) thermal emission using a combination of IRAS (60 and 100 micron) and SCUBA (850 micron) data. The molecular line maps give kinematic information, while the combination of the extinction and thermal emission maps give the most accurate view of the clouds' dust column density and temperature distributions to date. The COMPLETEd ``wide-field" maps represent ``Phase 1" of the Survey, and ``Phase 2," which offers close-up views of nearly all of the embedded ``cores" within the COMPLETE fields is well underway. Our key results to date include: 1) a new methodology for calibrating dust emission maps with extinction maps (Schnee et al. 2005); 2) a new appreciation of the fundamental uncertainty in the line-of-sight variations in dust temperature introduced into column-density measurements using dust emission (Schnee et al. 2006) 3) evidence for important interactions of spherical winds from B-type stars with molecular clouds (see Ridge et al. 2006a); 4) an extinction ``threshold" for star formation in Ophiuchus (Johnstone et al. 2004); 5) demonstration that extinction mapping routinely yields log-normal density distributions, which disagree with molecular-line map based density distributions, because the line data is biased by excitation and optical depth effects (Goodman et al. 2006); 6) the discovery of ubiquitous ``cloudshine" coming from dark clouds (Foster & Goodman 2005); 7) measurement and identification of uncertainties in the clump mass function for Perseus (Pineda et al. 2006); and 8) testing and new use of 3D medical-imaging software for identification and analysis of

  14. Large and small-scale magnetic fields in star-forming regions

    NASA Astrophysics Data System (ADS)

    Reissl, Stefan; Bertrang, Gesa; Wolf, Sebastian; Banerjee, Robi; Das, Himadri Sekhar; Seifried, Daniel; Körtgen, Bastian

    2013-07-01

    We present numerical and observational studies aimed at analyzing the potential of multi-wavelength high-spatial resolution continuum polarization measurements for constraining the multi-scale structure of magnetic fields in the interior and environment of molecular clouds. Numerical simulations: We developed an extended, adaptive grid version of the 3D Monte-Carlo radiation transfer code MC3D (Wolf et al., 1999, 2003) for multi-wavelength polarization simulations. On the basis of theoretical dust grain models, polarization due to dichroic extinction and reemission as well as scattering is considered. Multi-scale magneto-hydrodynamical (MHD) simulations of the interstellar medium (ISM) provide the complex distributions of the density, temperature, and magnetic field in star-forming regions. This type of sophisticated synthetic polarization modeling will allow us to prepare and properly analyze existing and future observations of the three-dimensional magnetic field structure in the ISM. Various kinds of dust grain properties and advanced MHD scenarios are considered to cover the broad variety of observable ISM characteristics. Observations: Bok globules represent an ideal environment to study the influence of magnetic fields on the process of low-mass star formation. The magnetic field strength and structure in the dense inner regions of the globules can be determined by observing the polarized reemission radiation of aligned dust grains in the sub-mm wavelength range. The magnetic field in the outer, less dense parts of the globules can be traced by observing polarized radiation of background stars in the optical or near-IR. We present polarimetric observations of two Bok globules, CB68 and B335, carried out in the near-IR (ISAAC/VLT) and in the optical (IFOSC/IGO). Together with archival sub-mm data (SCUBA/JCMT), we trace the magnetic fields in these objects from 10^3 AU scales up to 10^5-10^6 scales for the first time.

  15. The Depletion of Water During Dispersal of Planet-forming Disk Regions

    NASA Astrophysics Data System (ADS)

    Banzatti, A.; Pontoppidan, K. M.; Salyk, C.; Herczeg, G. J.; van Dishoeck, E. F.; Blake, G. A.

    2017-01-01

    We present a new velocity-resolved survey of 2.9 μm spectra of hot H2O and OH gas emission from protoplanetary disks, obtained with the Cryogenic Infrared Echelle Spectrometer at the VLT (R ∼ 96,000). With the addition of archival Spitzer-IRS spectra, this is the most comprehensive spectral data set of water vapor emission from disks ever assembled. We provide line fluxes at 2.9–33 μm that probe from the dust sublimation radius at ∼0.05 au out to the region of the water snow line. With a combined data set for 55 disks, we find a new correlation between H2O line fluxes and the radius of CO gas emission, as measured in velocity-resolved 4.7 μm spectra (R {}{co}), which probes molecular gaps in inner disks. We find that H2O emission disappears from 2.9 μm (hotter water) to 33 μm (colder water) as {R}{co} increases and expands out to the snow line radius. These results suggest that the infrared water spectrum is a tracer of inside-out water depletion within the snow line. It also helps clarify an unsolved discrepancy between water observations and models by finding that disks around stars of {M}\\star > 1.5 {M}ȯ generally have inner gaps with depleted molecular gas content. We measure radial trends in H2O, OH, and CO line fluxes that can be used as benchmarks for models to study the chemical composition and evolution of planet-forming disk regions at 0.05–20 au. We propose that JWST spectroscopy of molecular gas may be used as a probe of inner disk gas depletion, complementary to the larger gaps and holes detected by direct imaging and by ALMA.

  16. Companions and Environments of Low-Mass Stars: From Star-Forming Regions to the Field

    NASA Astrophysics Data System (ADS)

    Ward-Duong, Kimberly; Patience, Jenny; De Rosa, Robert J.; Bulger, Joanna; Rajan, Abhijith; Goodwin, Simon; Parker, Richard J.; McCarthy, Donald W.; Kulesa, Craig; van der Plas, Gerrit; Menard, Francois; Pinte, Christophe; Jackson, Alan Patrick; Bryden, Geoffrey; Turner, Neal J.; Harvey, Paul M.; Hales, Antonio

    2017-01-01

    We present results from two studies probing the multiplicity and environmental properties of low-mass stars: (1) The MinMs (M-dwarfs in Multiples) Survey, a large, volume-limited survey of 245 field M-dwarfs within 15 pc, and (2) the TBOSS (Taurus Boundary of Stellar/Substellar) Survey, an ongoing study of disk properties for the lowest-mass members within the Taurus star-forming region. The MinMs Survey provides new measurements of the companion star fraction, separation distribution, and mass ratio distribution for the nearest K7-M6 dwarfs, utilizing a combination of high-resolution adaptive optics imaging and digitized widefield archival plates to cover an unprecedented separation range of ~1-10,000 AU. Within these data, we also identify companions below the stellar/brown dwarf boundary, enabling characterization of the substellar companion population to low-mass field stars. For the much younger population in Taurus, we present results from ALMA Band 7 continuum observations of low-mass stellar and substellar Class II objects, spanning spectral types from M4-M7.75. The sub-millimeter detections of these disks provide key estimates of the dust mass in small grains, which is then assessed within the context of region age, environment, and viability for planet formation. This young population also includes a number of interesting young binary systems. Covering both young (1-2 Myr) and old (>5 Gyr) populations of low-mass stars, the results from these studies provide benchmark measurements on the population statistics of low-mass field stars, and on the early protoplanetary environments of their younger M-star counterparts.

  17. Predictions of active region flaring probability using subsurface helicity measurements

    NASA Astrophysics Data System (ADS)

    Reinard, A. A.; Komm, R.; Hill, F.

    2010-12-01

    Solar flares are responsible for a number of hazardous effects on the earth such as disabling high-frequency radio communications, interfering with GPS measurements, and disrupting satellites. However, forecasting flare occurrence is currently very difficult. One possible means for predicting flare occurrence lies in helioseismology, i.e. analysis of the region below the active region for signs of an impending flare. Time series helioseismic data collected by the Global Oscillation Network Group (GONG) has been analyzed for a subset of active regions that produce large flares and a subset with very high magnetic field strength that produce no flares. A predictive parameter has been developed and analyzed using discriminant analysis as well as traditional forecasting tools such as the Heidke skill score. Preliminary results show that this parameter predicts the flaring probability of an active region 2-3 days in advance with a relatively high degree of success.

  18. Ultraviolet events observed in active regions. I - Observations and scenario

    NASA Technical Reports Server (NTRS)

    Fontenla, Juan M.; Filipowski, Sharon; Tandberg-Hanssen, Einar; Reichmann, Edwin J.

    1989-01-01

    UV line data obtained in solar active regions on and near the limb, taken with the Ultraviolet Spectrometer and Polarimeter experiment on the Solar Maximum Mission are examined. The study provides insight into the physical processes behind sudden localized brightenings (or microflares) that occur within these active regions and their relation to surging activity. Time sequences of rasters and rasters through the line (taken in Ly-alpha and N V lines simultaneously) and C IV dopplergrams are the core of these data. They show the brightening events on the disk and Doppler shifts in dynamic events on the disk and above the limb. The study suggests, for the events, a localized energy deposition in a region of the chromosphere that heats the material and produces a pressure pulse. This mechanism explains the brightenings in transition region lines and also the observed surging behavior and jet-like events.

  19. Magnetic Separatrix as the Source Region of the Plasma Supply for an Active-region Filament

    NASA Astrophysics Data System (ADS)

    Zou, P.; Fang, C.; Chen, P. F.; Yang, K.; Cao, Wenda

    2017-02-01

    Solar filaments can be formed via chromospheric evaporation followed by condensation in the corona or by the direct injection of cool plasma from the chromosphere to the corona. We here confirm with high-resolution Hα data observed by the 1.6 m New Solar Telescope of the Big Bear Solar Observatory on 2015 August 21 that an active-region filament is maintained by the continuous injection of cold chromospheric plasma. We find that the filament is rooted along a bright ridge in Hα, which corresponds to the intersection of a magnetic quasi-separatrix layer with the solar surface. This bright ridge consists of many small patches whose sizes are comparable to the width of the filament threads. It is found that upflows originate from the brighter patches of the ridge, whereas the downflows move toward the weaker patches of the ridge. The whole filament is composed of two opposite-direction streams, implying that longitudinal oscillations are not the only cause of the counterstreamings, and unidirectional siphon flows with alternative directions are another possibility.

  20. Differential Magnetic Field Shear in an Active Region

    NASA Technical Reports Server (NTRS)

    Schmeider, B.; DeMoulin, P.; Aulanier, G.; Golub, Leon

    1997-01-01

    The three-dimensional extrapolation of magnetic field lines from a magnetogram obtained at Kitt Peak allows us to understand the global structure of the NOAA active region 6718, as observed in X-rays with the Normal Incidence X-ray Telescope (NIXT) and in Ha with the Multichannel Subtractive Double Pass spectrograph (MSDP) in Meudon on 1991 July 11. This active region was in a quiet stage. Bright X-ray loops connect plages having field strengths of approx. 300 G, while H-alpha fibriles connect penumbrae having strong spot fields to the surrounding network. Small, intense X-ray features in the moat region around a large spot, which could be called X-ray-bright points, are due mainly to the emergence of magnetic flux and merging of these fields with surrounding ones. A set of large-scale, sheared X-ray loops is observed in the central part of the active region. Based on the fit between the observed coronal structure and the field configurations (and assuming a linear force-free field), we propose a differential magnetic field shear model for this active region. The decreasing shear in outer portions of the active region may indicate a continual relaxation of the magnetic field to a lower energy state in the progressively older portions of the AR.

  1. Optical Properties of Active Regions in Terahertz Quantum Cascade Lasers

    NASA Astrophysics Data System (ADS)

    Dyksik, M.; Motyka, M.; Rudno-Rudziński, W.; Sęk, G.; Misiewicz, J.; Pucicki, D.; Kosiel, K.; Sankowska, I.; Kubacka-Traczyk, J.; Bugajski, M.

    2016-07-01

    In this work, AlGaAs/GaAs superlattice, with layers' sequence and compositions imitating the active and injector regions of a quantum cascade laser designed for emission in the terahertz spectral range, was investigated. Three independent absorption-like optical spectroscopy techniques were employed in order to study the band structure of the minibands formed within the conduction band. Photoreflectance measurements provided information about interband transitions in the investigated system. Common transmission spectra revealed, in the target range of intraband transitions, mainly a number of lines associated with the phonon-related processes, including two-phonon absorption. In contrast, differential transmittance realized by means of Fourier-transform spectroscopy was utilized to probe the confined states of the conduction band. The obtained energy separation between the second and third confined electron levels, expected to be predominantly contributing to the lasing, was found to be ~9 meV. The optical spectroscopy measurements were supported by numerical calculations performed in the effective mass approximation and XRD measurements for layers' width verification. The calculated energy spacings are in a good agreement with the experimental values.

  2. Far-infrared line coolants in massive star-forming regions

    NASA Astrophysics Data System (ADS)

    Leurini, Silvia

    2014-10-01

    The lines of [OI] and [CII] are powefulr tracers of different environments. In photo-dissociation regions (PDRs) their line ratio strongly depends on density; in molecular outflows from low-mass young stellar objects the luminosity of the [OI] line at 63 micron is directly proportional to the rate of mass outflow from the star and it is independent on visual extinction, inclination, and geometry of the outflow. In metal-rich galaxies, [OI] and [CII] lines are among the main coolants, and being very luminous, they are potentially powerful tracers of star formation rates (SFRs) even in galaxies at high z. However, [OI] and [CII] were till now observed only with very poor spectral resolution. They can be heavily affected by absorptions from the source or from different foreground clouds, and the contribution of outflows and PDRs cannot be quantified without resolved profiles. Therefore their diagnostic value is of limited use. We propose here to exploit the unprecedented resolution of the GREAT receiver aboard SOFIA for the first spectroscopically resolved observations of [OI] and [CII] of a sample of galactic massive star-forming clumps. The sources are a flux-limited sub-sample from the ATLASGAL continuum survey of the inner Galaxy and cover a broad range of evolutionary phases. Thanks to the wealth of already collected ancillary data (in particular water, high-J CO and NH3), the proposed observations will be fundamental to calibrate [OI] and [CII] as PDR, outflow and SFR tracers in a sample of sources rapresentative of the Galactic population of massive star-forming clumps. The data will answer the following questions: Which ISM components do [OI] and [CII] trace? How does the complete (CO+H2O+[OI]+[CII]) FIR cooling budget change with bolometric luminosity? Does [OI] show prominent high-velocity emission in massive sources or is ti dominated by PDR emission?

  3. SMA Observations of C2H in High-mass Star-forming Regions

    NASA Astrophysics Data System (ADS)

    Jiang, Xue-Jian; Liu, Hauyu Baobab; Zhang, Qizhou; Wang, Junzhi; Zhang, Zhi-Yu; Li, Juan; Gao, Yu; Gu, Qiusheng

    2015-08-01

    {{{C}}}2{{H}} is a representative hydrocarbon that is abundant and ubiquitous in the interstellar medium. To study its chemical properties, we present Submillimeter Array observations of the C2H N = 3-2 and HC3N J = 30-29 transitions and the 1.1 mm continuum emission toward four OB cluster-forming regions, AFGL 490, ON 1, W33 Main, and G10.6-0.4, which cover a bolometric luminosity range of ˜103-106 {L}⊙ . We found that on large scales, the C2H emission traces the dense molecular envelope. However, for all observed sources, the peaks of C2H emission are offset by several times 104 AU from the peaks of 1.1 mm continuum emission, where the most luminous stars are located. By comparing the distribution and profiles of C2H hyperfine lines and the 1.1 mm continuum emission, we find that the C2H column density (and abundance) around the 1.1 mm continuum peaks is lower than those in the ambient gas envelope. Chemical models suggest that C2H might be transformed to other species owing to increased temperature and density thus, its reduced abundance could be the signpost of the heated molecular gas in the ˜104 AU vicinity around the embedded high-mass stars. Our results support such theoretical prediction for centrally embedded ˜103-106 {L}⊙ OB star-forming cores, while future higher-resolution observations are required to examine the C2H transformation around the localized sites of high-mass star formation.

  4. Helium Line Formation and Abundance in a Solar Active Region

    NASA Astrophysics Data System (ADS)

    Mauas, P. J. D.; Andretta, V.; Falchi, A.; Falciani, R.; Teriaca, L.; Cauzzi, G.

    2005-01-01

    An observing campaign (SOHO JOP 139), coordinated between ground-based and Solar and Heliospheric Observatory (SOHO) instruments, has been planned to obtain simultaneous spectroheliograms of the same active region in several spectral lines. The chromospheric lines Ca II K, Hα, and Na I D, as well as He I 10830, 5876, 584, and He II 304 Å lines have been observed. The EUV radiation in the range λ<500 Å and in the range 260<λ<340 Å has also been measured at the same time. These simultaneous observations allow us to build semiempirical models of the chromosphere and low transition region of an active region, taking into account the estimated total number of photoionizing photons impinging on the target active region and their spectral distribution. We obtained a model that matches very well all the observed line profiles, using a standard value for the He abundance ([He]=0.1) and a modified distribution of microturbulence. For this model we study the influence of the coronal radiation on the computed helium lines. We find that, even in an active region, the incident coronal radiation has a limited effect on the UV He lines, while it is of fundamental importance for the D3 and 10830 Å lines. Finally, we build two more models, assuming values of He abundance [He]=0.07 and 1.5, only in the region where temperatures are >1×104 K. This region, between the chromosphere and transition region, has been indicated as a good candidate for processes that might be responsible for strong variations of [He]. The set of our observables can still be well reproduced in both cases, changing the atmospheric structure mainly in the low transition region. This implies that, to choose between different values of [He], it is necessary to constrain the transition region with different observables, independent of the He lines.

  5. 76 FR 31972 - Agency Information Collection Activities: Form I-508 and Form I-508F, Extension of a Currently...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-02

    ... SECURITY U.S. Citizenship and Immigration Services Agency Information Collection Activities: Form I-508 and... and Immigration Services (USCIS), will be submitting the following information collection request for... Immigration Services. (4) Affected public who will be asked or required to respond, as well as a...

  6. IFLA General Conference, 1985. Division on Regional Activities. Papers.

    ERIC Educational Resources Information Center

    International Federation of Library Associations, The Hague (Netherlands).

    Papers on regional library activities which were presented at the 1985 International Federation of Library Associations (IFLA) conference include: (1) "Importance of Information Resources in National Development with Particular Reference to the Asian Scene" (Yogendra P. Dubey, India); (2) "Report of the Activities of the Regional…

  7. IFLA General Conference, 1985. Division on Regional Activities. Papers.

    ERIC Educational Resources Information Center

    International Federation of Library Associations, The Hague (Netherlands).

    Papers on regional library activities which were presented at the 1985 International Federation of Library Associations (IFLA) conference include: (1) "Importance of Information Resources in National Development with Particular Reference to the Asian Scene" (Yogendra P. Dubey, India); (2) "Report of the Activities of the Regional…

  8. Universities and Economic Development Activities: A UK Regional Comparison

    ERIC Educational Resources Information Center

    Decter, Moira; Cave, Frank; Rose, Mary; Peers, Gill; Fogg, Helen; Smith, Susan M.

    2011-01-01

    A number of UK universities prioritize economic development or regeneration activities and for some of these universities such activities are the main focus of their knowledge transfer work. This study compares two regions of the UK--the North West and the South East of England--which have very different levels of economic performance.…

  9. Universities and Economic Development Activities: A UK Regional Comparison

    ERIC Educational Resources Information Center

    Decter, Moira; Cave, Frank; Rose, Mary; Peers, Gill; Fogg, Helen; Smith, Susan M.

    2011-01-01

    A number of UK universities prioritize economic development or regeneration activities and for some of these universities such activities are the main focus of their knowledge transfer work. This study compares two regions of the UK--the North West and the South East of England--which have very different levels of economic performance.…

  10. Forming a Learning Culture to Promote Fracture Prevention Activities

    ERIC Educational Resources Information Center

    Hjalmarson, Helene V.; Strandmark, Margaretha

    2012-01-01

    Purpose: The purpose of this paper is to explore interprofessional experiences of incorporating fracture prevention activities in clinical practice inspired by an empowerment approach. Design/methodology/approach: Data collection consisted primarily of focus groups interviews, systematized and analyzed by the grounded theory method. The study took…

  11. Forming a Learning Culture to Promote Fracture Prevention Activities

    ERIC Educational Resources Information Center

    Hjalmarson, Helene V.; Strandmark, Margaretha

    2012-01-01

    Purpose: The purpose of this paper is to explore interprofessional experiences of incorporating fracture prevention activities in clinical practice inspired by an empowerment approach. Design/methodology/approach: Data collection consisted primarily of focus groups interviews, systematized and analyzed by the grounded theory method. The study took…

  12. Constitutive Activity in an Ancestral Form of Abl Tyrosine Kinase.

    PubMed

    Aleem, Saadat U; Craddock, Barbara P; Miller, W Todd

    2015-01-01

    The c-abl proto-oncogene encodes a nonreceptor tyrosine kinase that is found in all metazoans, and is ubiquitously expressed in mammalian tissues. The Abl tyrosine kinase plays important roles in the regulation of mammalian cell physiology. Abl-like kinases have been identified in the genomes of unicellular choanoflagellates, the closest relatives to the Metazoa, and in related unicellular organisms. Here, we have carried out the first characterization of a premetazoan Abl kinase, MbAbl2, from the choanoflagellate Monosiga brevicollis. The enzyme possesses SH3, SH2, and kinase domains in a similar arrangement to its mammalian counterparts, and is an active tyrosine kinase. MbAbl2 lacks the N-terminal myristoylation and cap sequences that are critical regulators of mammalian Abl kinase activity, and we show that MbAbl2 is constitutively active. When expressed in mammalian cells, MbAbl2 strongly phosphorylates cellular proteins on tyrosine, and transforms cells much more potently than mammalian Abl kinase. Thus, MbAbl2 appears to lack the autoinhibitory mechanism that tightly constrains the activity of mammalian Abl kinases, suggesting that this regulatory apparatus arose more recently in metazoan evolution.

  13. Constitutive Activity in an Ancestral Form of Abl Tyrosine Kinase

    PubMed Central

    Miller, W. Todd

    2015-01-01

    The c-abl proto-oncogene encodes a nonreceptor tyrosine kinase that is found in all metazoans, and is ubiquitously expressed in mammalian tissues. The Abl tyrosine kinase plays important roles in the regulation of mammalian cell physiology. Abl-like kinases have been identified in the genomes of unicellular choanoflagellates, the closest relatives to the Metazoa, and in related unicellular organisms. Here, we have carried out the first characterization of a premetazoan Abl kinase, MbAbl2, from the choanoflagellate Monosiga brevicollis. The enzyme possesses SH3, SH2, and kinase domains in a similar arrangement to its mammalian counterparts, and is an active tyrosine kinase. MbAbl2 lacks the N-terminal myristoylation and cap sequences that are critical regulators of mammalian Abl kinase activity, and we show that MbAbl2 is constitutively active. When expressed in mammalian cells, MbAbl2 strongly phosphorylates cellular proteins on tyrosine, and transforms cells much more potently than mammalian Abl kinase. Thus, MbAbl2 appears to lack the autoinhibitory mechanism that tightly constrains the activity of mammalian Abl kinases, suggesting that this regulatory apparatus arose more recently in metazoan evolution. PMID:26090675

  14. A Comparison of Two Star Forming Regions: Probing the Energy Threshold of Triggered Star Formation

    NASA Astrophysics Data System (ADS)

    Alexander, Michael J.; Kobulnicky, H. A.; Kerton, C. R.

    2013-01-01

    Massive stars are believed to have a profound effect on star formation. Stellar winds and ionizing radiation, collectively known as feedback, sculpt the interstellar medium and theories and observations suggest that stellar feedback may trigger waves of star formation as it carves into molecular clouds. There is also conflicting evidence to suggest that stellar feedback has no effect or can even suppress star formation. In order to test the effects of stellar feedback, I chose two star forming regions in the Galactic plane of different feedback energy, G38.9-0.4 and G23.6+0.1. G38.9-0.4 hosts a series of IR-bright bubbles each blown by single late-O or early-B star, while G23.6+0.1 consists of two conjoined bubbles with a handful of O stars between them. If triggering enhances star formation, then one may expect to find more young stellar objects (YSOs) for a given amount of gas when compared to a region of spontaneous star formation. In order to test this, I examined the relation between the YSO mass surface density and the gas mass surface density. While there is a power-law correlation between YSO mass surface density and gas mass surface density, there is little difference between spontaneous and potentially-triggered regions. Initial results suggest that YSO distribution patterns may be more sensitive to the initial structure of molecular clouds than to structures created by stellar feedback. Furthermore, triggered star formation may become insignificant at the feedback energy produced by an O9.5V star (N_Lyc<10^47.88, L_wind < 10^32.34 erg s^-1) and below. During this investigation, I found an apparent cluster of stars deeply embedded in molecular gas. Further study revealed a total of 18 ultracompact embedded clusters (UCECs) spread throughout the northern Galactic plane. These clusters are characterized by bright, point-like mid-IR emission from the Spitzer Space Telescope, but are actually composed of small clusters as revealed by the higher resolution

  15. Evolution of Protoplanetary Disks in the Orion A Star-Forming Region

    NASA Astrophysics Data System (ADS)

    Kim, Kyoung Hee

    2014-01-01

    We present our investigation of the characteristics of Class II protoplanetary disks in Orion A star-forming region. Our major goal is to analyze a large sample of protoplanetary disks with near- and mid-IR spectra, by statistical approaches, to understand protoplanetary disk evolution in Orion A. For this work, 303 protoplanetary disks in Orion A region observed by IRS/Spitzer and the follow-up observation of 120 objects from SpeX/IRTF are used to reveal the characteristics of Class II disks in Orion A. For clues on environmental effects on disk evolution and planet formation, we compare the disk properties and dust properties of Orion A disks to that of Taurus disks and examine trends with respect to position within Orion A. We extract spectral indices, equivalent widths, and integrated fluxes from IRS spectra of Class II objects in Orion A which pertain to disk structure and dust composition. We measure mass accretion rates using hydrogen recombination lines in SpeX spectra of our targets. Utilizing the properties, we analyze the general distribution of properties of disks in ONC, L1641, and Taurus from their histograms. Our main findings are as follows. (1) From the high frequency (>20%) of transitional disks and the similar vertical structure of the Orion A disks to those of Taurus, we infer that giant planet formation and dust sedimentation is well under way, if not complete, even in the youngest Class II objects. (2) Less grain processing - crystallization and growth of grains to diameter of 1-10 μm - has occurred among the dust grains in the Orion A disks than in Taurus. The time scales for dust processing must therefore lie in the range of ages of the nearby clouds like Orion, NGC 1333, Taurus, Ophiuchus and Chamaeleon. (3) We detected PAH emission at 6-14 μm from disks around low-mass and low-luminosity young stars, excited externally by UV from the Trapezium stars. (4) As others have found for the Trapezium region of Orion, the disks of the surrounding

  16. Trigonometric parallaxes of high mass star forming regions: the structure and kinematics of the Milky Way

    SciTech Connect

    Reid, M. J.; Dame, T. M.; Menten, K. M.; Brunthaler, A.; Wu, Y.; Zhang, B.; Sanna, A.; Sato, M.; Choi, Y. K.; Immer, K.; Zheng, X. W.; Xu, Y.; Hachisuka, K.; Moscadelli, L.; Rygl, K. L. J.; Bartkiewicz, A.

    2014-03-10

    Over 100 trigonometric parallaxes and proper motions for masers associated with young, high-mass stars have been measured with the Bar and Spiral Structure Legacy Survey, a Very Long Baseline Array key science project, the European VLBI Network, and the Japanese VLBI Exploration of Radio Astrometry project. These measurements provide strong evidence for the existence of spiral arms in the Milky Way, accurately locating many arm segments and yielding spiral pitch angles ranging from about 7° to 20°. The widths of spiral arms increase with distance from the Galactic center. Fitting axially symmetric models of the Milky Way with the three-dimensional position and velocity information and conservative priors for the solar and average source peculiar motions, we estimate the distance to the Galactic center, R {sub 0}, to be 8.34 ± 0.16 kpc, a circular rotation speed at the Sun, Θ{sub 0}, to be 240 ± 8 km s{sup –1}, and a rotation curve that is nearly flat (i.e., a slope of –0.2 ± 0.4 km s{sup –1} kpc{sup –1}) between Galactocentric radii of ≈5 and 16 kpc. Assuming a 'universal' spiral galaxy form for the rotation curve, we estimate the thin disk scale length to be 2.44 ± 0.16 kpc. With this large data set, the parameters R {sub 0} and Θ{sub 0} are no longer highly correlated and are relatively insensitive to different forms of the rotation curve. If one adopts a theoretically motivated prior that high-mass star forming regions are in nearly circular Galactic orbits, we estimate a global solar motion component in the direction of Galactic rotation, V {sub ☉} = 14.6 ± 5.0 km s{sup –1}. While Θ{sub 0} and V {sub ☉} are significantly correlated, the sum of these parameters is well constrained, Θ{sub 0} + V {sub ☉} = 255.2 ± 5.1 km s{sup –1}, as is the angular speed of the Sun in its orbit about the Galactic center, (Θ{sub 0} + V {sub ☉})/R {sub 0} = 30.57 ± 0.43 km s{sup –1} kpc{sup –1}. These parameters improve the accuracy of

  17. Following the Water: the Evolution of Ice-forming Regions in the Early Solar Nebula

    NASA Technical Reports Server (NTRS)

    Davis, Sanford S.

    2006-01-01

    The abundances of water-vapor and water-ice during the first ten million years of the protoplanetary solar nebula are simulated using a new condensation/sublimation model. This study builds on a "snow line" model reported in ApJ 627 L153 (2005); it uses a simple phenomenological model where water vapor molecules evolve from solar atomic abundance and eventually condenses to ice at colder points in the nebula once the water-vapor partial pressure exceeds a value determined by the phase diagram for water. The synthesis of water vapor from elementary species is modeled with a chemical network consisting of about 400 species and 4000 reactions. The evolution of the icy zone (and its relative abundance of solid ice) is traced from a limited region in the early hotter disk to its final state at the time when the gas is expelled and a planetary system begins to form. Possible effects of this dynamic motion on disk chemistry and organic molecule formation are also described.

  18. Trigonometric parallaxes of star forming regions in the Scutum spiral arm

    SciTech Connect

    Sato, M.; Wu, Y. W.; Immer, K.; Zhang, B.; Sanna, A.; Brunthaler, A.; Menten, K. M.; Reid, M. J.; Dame, T. M.

    2014-10-01

    We report measurements of trigonometric parallaxes for six high-mass star-forming regions in the Scutum spiral arm of the Milky Way as part of the BeSSeL Survey. Combining our measurements with 10 previous measurements from the BeSSeL Survey yields a total sample of 16 sources in the Scutum arm with trigonometric parallaxes in the Galactic longitude range from 5° to 32°. Assuming a logarithmic spiral model, we estimate a pitch angle of 19.°8 ± 3.°1 for the Scutum arm, which is larger than pitch angles reported for other spiral arms. The high pitch angle of the arm may be due to the arm's proximity to the Galactic bar. The Scutum arm sources show an average peculiar motion of 4 km s{sup –1} slower than the Galactic rotation and 8 km s{sup –1} toward the Galactic center. While the direction of this non-circular motion has the same sign as determined for sources in other spiral arms, the motion toward the Galactic center is greater for the Scutum arm sources.

  19. Phosphorus-bearing molecules in solar-type star-forming regions: first PO detection

    NASA Astrophysics Data System (ADS)

    Lefloch, Bertrand; Vastel, C.; Viti, S.; Jimenez-Serra, I.; Codella, C.; Podio, L.; Ceccarelli, C.; Mendoza, E.; Lepine, J. R. D.; Bachiller, R.

    2016-11-01

    As part of the Large Program Astrochemical Surveys At IRAM, we have used the IRAM 30 m telescope to lead a systematic search for the emission of rotational transitions of P-bearing species between 80 and 350 GHz towards L1157-B1, a shock position in the solar-type star-forming region L1157. We report the detection of several transitions of PN and, for the first time, of pre-biotic molecule PO. None of these species are detected towards the driving protostar of the outflow L1157-mm. Analysis of the line profiles shows that PN arises from the outflow cavity, where SiO, a strong shock tracer, is produced. Radiative transfer analysis yields an abundance of 2.5 × 10-9 and 0.9 × 10-9 for PO and PN, respectively. These results imply a strong depletion (≈100) of phosphorus in the quiescent cloud gas. Shock modelling shows that atomic N plays a major role in the chemistry of PO and PN. The relative abundance of PO and PN brings constraints both on the duration of the pre-shock phase, which has to be ˜106 yr, and on the shock parameters. The maximum temperature in the shock has to be larger than 4000 K, which implies a shock velocity of 40 km s-1.

  20. YSOVAR: Mid-infrared variability in the star-forming region Lynds 1688

    SciTech Connect

    Günther, H. M.; Poppenhaeger, K.; Wolk, S. J.; Hora, J. L.; Cody, A. M.; Covey, K. R.; Hillenbrand, L. A.; Plavchan, P.; Rebull, L. M.; Stauffer, J. R.; Bayo, A.; Gutermuth, R. A.; Meng, H. Y. A.; Morales-Calderón, M.; Parks, J. R.; Song, Inseok

    2014-12-01

    The emission from young stellar objects (YSOs) in the mid-infrared (mid-IR) is dominated by the inner rim of their circumstellar disks. We present IR data from the Young Stellar Object VARiability (YSOVAR) survey of ∼800 objects in the direction of the Lynds 1688 (L1688) star-forming region over four visibility windows spanning 1.6 yr using the Spitzer Space Telescope in its warm mission phase. Among all light curves, 57 sources are cluster members identified based on their spectral energy distribution and X-ray emission. Almost all cluster members show significant variability. The amplitude of the variability is larger in more embedded YSOs. Ten out of 57 cluster members have periodic variations in the light curves with periods typically between three and seven days, but even for those sources, significant variability in addition to the periodic signal can be seen. No period is stable over 1.6 yr. Nonperiodic light curves often still show a preferred timescale of variability that is longer for more embedded sources. About half of all sources exhibit redder colors in a fainter state. This is compatible with time-variable absorption toward the YSO. The other half becomes bluer when fainter. These colors can only be explained with significant changes in the structure of the inner disk. No relation between mid-IR variability and stellar effective temperature or X-ray spectrum is found.

  1. Probing Dynamical Processes in the Planet-forming Region with Dust Mineralogy

    NASA Astrophysics Data System (ADS)

    McClure, M. K.; Manoj, P.; Calvet, N.; Adame, L.; Espaillat, C.; Watson, D. M.; Sargent, B.; Forrest, W. J.; D'Alessio, P.

    2012-11-01

    We present Herschel Space Observatory PACS spectra of GQ Lup, a protoplanetary disk in the Lupus star-forming region. Through spectral energy distribution fitting from 0.3 μm to 1.3 mm, we construct a self-consistent model of this system's temperature and density structures, finding that although it is 3 Myr old, its dust has not settled to the midplane substantially. The disk has a radial gradient in both the silicate dust composition and grain size, with large amorphous grains in the upper layers of the inner disk and an enhancement of submicron, crystalline grains in the outer disk. We detect an excess of emission in the Herschel PACS B2A band near 63 μm and model it with a combination of ~15-70 μm crystalline water ice grains with a size distribution consistent with ice recondensation-enhanced grain growth and a mass fraction half of that of our solar system. The combination of crystalline water ice and silicates in the outer disk is suggestive of disk-wide heating events or planetesimal collisions. If confirmed, this would be the first detection of water ice by Herschel.

  2. Externally Heated Protostellar Cores in the Ophiuchus Star-forming Region

    NASA Astrophysics Data System (ADS)

    Lindberg, Johan E.; Charnley, Steven B.; Jørgensen, Jes K.; Cordiner, Martin A.; Bjerkeli, Per

    2017-01-01

    We present APEX 218 GHz observations of molecular emission in a complete sample of embedded protostars in the Ophiuchus star-forming region. To study the physical properties of the cores, we calculate H2CO and c-C3H2 rotational temperatures, both of which are good tracers of the kinetic temperature of the molecular gas. We find that the H2CO temperatures range between 16 K and 124 K, with the highest H2CO temperatures toward the hot corino source IRAS 16293-2422 (69–124 K) and the sources in the ρ Oph A cloud (23–49 K) located close to the luminous Herbig Be star S1, which externally irradiates the ρ Oph A cores. On the other hand, the c-C3H2 rotational temperature is consistently low (7–17 K) in all sources. Our results indicate that the c-C3H2 emission is primarily tracing more shielded parts of the envelope whereas the H2CO emission (at the angular scale of the APEX beam; 3600 au in Ophiuchus) mainly traces the outer irradiated envelopes, apart from in IRAS 16293-2422, where the hot corino emission dominates. In some sources, a secondary velocity component is also seen, possibly tracing the molecular outflow. Based on observations with the Atacama Pathfinder EXperiment (APEX) telescope. APEX is a collaboration between the Max Planck Institute for Radio Astronomy, the European Southern Observatory, and the Onsala Space Observatory.

  3. YOUNG STELLAR OBJECTS IN THE LARGE MAGELLANIC CLOUD STAR-FORMING REGION N206

    SciTech Connect

    Romita, Krista Alexandra; Meixner, M.; Sewilo, M.; Shiao, B.; Carlson, Lynn Redding; Whitney, B.; Babler, B.; Meade, M.; Indebetouw, R.; Hora, J. L. E-mail: carlson@stsci.ed E-mail: brian@sal.wisc.ed E-mail: jhora@cfa.harvard.ed

    2010-09-20

    We present analysis of the energetic star-forming region Henize 206 (N206) located near the southern edge of the Large Magellanic Cloud (LMC) based on photometric data from the Spitzer Surveying the Agents of Galaxy Evolution (SAGE-LMC; IRAC 3.6, 4.5, 5.8, 8.0 {mu}m and MIPS 24 {mu}m), Infrared Survey Facility near-infrared survey (J, H, K{sub s}), and the Magellanic Clouds Photometric Survey (MCPS UBVI) covering a wavelength range of 0.36-24 {mu}m. Young stellar object (YSO) candidates are identified based upon their location in infrared color-magnitude space and classified by the shapes of their spectral energy distributions in comparison with a pre-computed grid of YSO models. We identify 116 YSO candidates: 102 are well characterized by the YSO models, predominately Stage I, and 14 may be multiple sources or young sources with transition disks. Careful examination of the individual sources and their surrounding environment allows us to identify a factor of {approx}14.5 more YSO candidates than have already been identified. The total mass of these well-fit YSO candidates is {approx}520 M{sub sun}. We calculate a current star formation rate of 0.27 x 10{sup -1} M{sub sun} yr{sup -1} kpc{sup -2}. The distribution of YSO candidates appears to follow shells of neutral material in the interstellar medium.

  4. Abnormal behavior of supercooled liquid region in bulk-forming metallic glasses

    NASA Astrophysics Data System (ADS)

    Park, E. S.; Na, J. H.; Kim, D. H.

    2010-09-01

    A metallic glass is often viewed as an amorphous alloy exhibiting a single endothermic reaction in the supercooled liquid region (SCLR, ΔTx=Tx-Tg). Here we discuss the origin and consequences of abnormal behavior of SCLR in various bulk-forming metallic glasses (BMGs). The two-stage-like endothermic reaction in Ni-based, Cu-based, Zr-based, and Mg-based BMGs can originate from the local immiscibility of liquids, which is closely related to chemical heterogeneity in as-cast BMG. These inflections can be attributed to the overlap of the exothermic reaction for the formation and growth of clusters in SCLR. The abnormal behavior of SCLR can be modulated by controlling cooling rate as well as by tailoring alloy composition, with the consequence that the modulated local heterogeneity in these BMGs can lead to enhanced flexibility of the BMGs. This correlation assists in understanding toughening mechanism and in guiding alloy design to alleviate brittleness of BMGs.

  5. Extreme infrared variables from UKIDSS - I. A concentration in star-forming regions

    NASA Astrophysics Data System (ADS)

    Contreras Peña, C.; Lucas, P. W.; Froebrich, D.; Kumar, M. S. N.; Goldstein, J.; Drew, J. E.; Adamson, A.; Davis, C. J.; Barentsen, G.; Wright, N. J.

    2014-04-01

    We present initial results of the first panoramic search for high-amplitude near-infrared variability in the Galactic plane. We analyse the widely separated two-epoch K-band photometry in the fifth and seventh data releases of the UKIDSS Galactic plane survey. We find 45 stars with ΔK > 1 mag, including two previously known OH/IR stars and a Nova. Even though the mid-plane is not yet included in the data set, we find the majority (66 per cent) of our sample to be within known star-forming regions (SFRs), with two large concentrations in the Serpens OB2 association (11 stars) and the Cygnus-X complex (12 stars). Sources in SFRs show spectral energy distributions that support classification as young stellar objects (YSOs). This indicates that YSOs dominate the Galactic population of high-amplitude infrared variable stars at low luminosities and therefore likely dominate the total high-amplitude population. Spectroscopic follow up of the DR5 sample shows at least four stars with clear characteristics of eruptive pre-main-sequence variables, two of which are deeply embedded. Our results support the recent concept of eruptive variability comprising a continuum of outburst events with different time-scales and luminosities, but triggered by a similar physical mechanism involving unsteady accretion. Also, we find what appears to be one of the most variable classical Be stars.

  6. YSOVAR: Mid-infrared Variability in the Star-forming Region Lynds 1688

    NASA Astrophysics Data System (ADS)

    Günther, H. M.; Cody, A. M.; Covey, K. R.; Hillenbrand, L. A.; Plavchan, P.; Poppenhaeger, K.; Rebull, L. M.; Stauffer, J. R.; Wolk, S. J.; Allen, L.; Bayo, A.; Gutermuth, R. A.; Hora, J. L.; Meng, H. Y. A.; Morales-Calderón, M.; Parks, J. R.; Song, Inseok

    2014-12-01

    The emission from young stellar objects (YSOs) in the mid-infrared (mid-IR) is dominated by the inner rim of their circumstellar disks. We present IR data from the Young Stellar Object VARiability (YSOVAR) survey of ~800 objects in the direction of the Lynds 1688 (L1688) star-forming region over four visibility windows spanning 1.6 yr using the Spitzer Space Telescope in its warm mission phase. Among all light curves, 57 sources are cluster members identified based on their spectral energy distribution and X-ray emission. Almost all cluster members show significant variability. The amplitude of the variability is larger in more embedded YSOs. Ten out of 57 cluster members have periodic variations in the light curves with periods typically between three and seven days, but even for those sources, significant variability in addition to the periodic signal can be seen. No period is stable over 1.6 yr. Nonperiodic light curves often still show a preferred timescale of variability that is longer for more embedded sources. About half of all sources exhibit redder colors in a fainter state. This is compatible with time-variable absorption toward the YSO. The other half becomes bluer when fainter. These colors can only be explained with significant changes in the structure of the inner disk. No relation between mid-IR variability and stellar effective temperature or X-ray spectrum is found.

  7. YSOVAR: Mid-IR variability in the star forming region Lynds 1688

    NASA Astrophysics Data System (ADS)

    Guenther, Hans Moritz

    2014-06-01

    The emission from young stellar objects (YSOs) in the mid-IR is dominated by the inner rim of their circumstellar disks. We present an IR-monitoring survey in the direction of the Lynds 1688 (L1688) star forming region over four visibility windows spanning 1.6 years using the Spitzer space telescope in its warm mission phase. Among the lightcurves, 57 sources are cluster members identified based on their spectral-energy distribution and X-ray emission. Almost all cluster members show significant variability. The amplitude of the variability is larger in more embedded YSOs. Ten out of 57 cluster members have periodic variations in the lightcurves with periods typically between three and seven days, but even for those sources, significant variability in addition to the periodic signal can be seen. No period is stable over 1.6 years. Non-periodic lightcurves often still show a preferred timescale of variability which is longer for more embedded sources. About half of all sources exhibit redder colors in a fainter state. This is compatible with time-variable absorption towards the YSO. The other half becomes bluer when fainter. These colors can only be explained with significant changes in the structure of the inner disk. No relation between mid-IR variability and stellar effective temperature or X-ray spectrum is found.

  8. Externally Heated Protostellar Cores in the Ophiuchus Star-Forming Region

    NASA Technical Reports Server (NTRS)

    Lindberg, Johan E.; Charnley, Steven B.; Jorgensen, Jes K.; Cordiner, Martin A.; Bjerkeli, Per

    2017-01-01

    We present APEX 218 GHz observations of molecular emission in a complete sample of embedded protostars in the Ophiuchus star-forming region. To study the physical properties of the cores, we calculate H2CO and c-C3H2 rotational temperatures, both of which are good tracers of the kinetic temperature of the molecular gas. We find that the H2CO temperatures range between 16K and 124K, with the highest H2CO temperatures toward the hot corino source IRAS 16293-2422 (69-124 K) and the sources in the rho Oph A cloud (23-49 K) located close to the luminous Herbig Be star S1, which externally irradiates the rho Oph A cores. On the other hand, the c-C3H2 rotational temperature is consistently low (7-17 K) in all sources. Our results indicate that the c-C3H2 emission is primarily tracing more shielded parts of the envelope whereas the H2CO emission (at the angular scale of the APEX beam; 3600 au in Ophiuchus) mainly traces the outer irradiated envelopes, apart from in IRAS?16293-2422, where the hot corino emission dominates. In some sources, a secondary velocity component is also seen, possibly tracing the molecular outflow.

  9. H i-to-H2 Transition Layers in the Star-forming Region W43

    NASA Astrophysics Data System (ADS)

    Bialy, Shmuel; Bihr, Simon; Beuther, Henrik; Henning, Thomas; Sternberg, Amiel

    2017-02-01

    The process of atomic-to-molecular (H i-to-H2) gas conversion is fundamental for molecular-cloud formation and star formation. 21 cm observations of the star-forming region W43 revealed extremely high H i column densities, of 120-180 {M}⊙ {{pc}}-2, a factor of 10-20 larger than predicted by H i-to-H2 transition theories. We analyze the observed H i with a theoretical model of the H i-to-H2 transition, and show that the discrepancy between theory and observation cannot be explained by the intense radiation in W43, nor be explained by variations of the assumed volume density or H2 formation rate coefficient. We show that the large observed H i columns are naturally explained by several (9-22) H i-to-H2 transition layers, superimposed along the sightlines of W43. We discuss other possible interpretations such as a non-steady-state scenario and inefficient dust absorption. The case of W43 suggests that H i thresholds reported in extragalactic observations are probably not associated with a single H i-to-H2 transition, but are rather a result of several transition layers (clouds) along the sightlines, beam-diluted with diffuse intercloud gas.

  10. Following the Water: the Evolution of Ice-forming Regions in the Early Solar Nebula

    NASA Technical Reports Server (NTRS)

    Davis, Sanford S.

    2006-01-01

    The abundances of water-vapor and water-ice during the first ten million years of the protoplanetary solar nebula are simulated using a new condensation/sublimation model. This study builds on a "snow line" model reported in ApJ 627 L153 (2005); it uses a simple phenomenological model where water vapor molecules evolve from solar atomic abundance and eventually condenses to ice at colder points in the nebula once the water-vapor partial pressure exceeds a value determined by the phase diagram for water. The synthesis of water vapor from elementary species is modeled with a chemical network consisting of about 400 species and 4000 reactions. The evolution of the icy zone (and its relative abundance of solid ice) is traced from a limited region in the early hotter disk to its final state at the time when the gas is expelled and a planetary system begins to form. Possible effects of this dynamic motion on disk chemistry and organic molecule formation are also described.

  11. Molecular maser flares in the high-mass star-forming region IRAS18566+0408

    NASA Astrophysics Data System (ADS)

    Halbe, Daniel M.

    We report results of a long-termmonitoring study of 6cmformaldehyde (H 2CO), 6.035GHz hydroxyl (OH), and 6.7GHz methanol (CH3OH) masers in the young high-mass protostellar object IRAS18566+0408 (G37.55+0.20). This is the only high-mass star-forming region where correlated variability of three different maser species has been reported. The observations were conducted with the 305m Arecibo Radio Telescope, and together with data from the literature, we present H2CO flux density measurements from 2002 to 2014, CH3OH data from 2006 to 2013, and discuss OH observations obtained between 2008 and 2012. Our extended monitoring observations of the H2CO maser agree with the quasi-periodic flare phenomenon and exponential decrease in quiescent and flare flux densities proposed by Araya and collaborators in 2010. We also confirm the occurrence of 6.035GHz OH flares and a time delay with respect to the H2CO flares. An analysis between the variability behavior of different CH3OH maser components and the H2CO maser suggests that multiple variability mechanisms are responsible for CH3OH flux density changes.

  12. [The dynamics of forming an active defensive reflex in cats].

    PubMed

    Fokin, V F

    1975-01-01

    Active defensive reflexes were elaborated in cats with pain stimulations of the forepaw by means of an electrical pricking device with a target attached to it. The elaboration was carried out during action of a flickering light used for the convenience of the EEG analysis. Repeated pain stimulation led to elaboration of an aggressive attacking reaction, chiefly manifested in the paw striking the target. At the beginning of the elaboration, passive-defensive reactions were manifest, which did not completely disappear even after formation of a stable attacking reflex. Two types of active defensive reflexes were elaborated: A-type reflex which helped the animal to get rid of the pain stimulation at the very beginning; B-type reflex which prevented the pain stimulation. The difference beteween these two types is discussed.

  13. Activated region fitting: a robust high-power method for fMRI analysis using parameterized regions of activation.

    PubMed

    Weeda, Wouter D; Waldorp, Lourens J; Christoffels, Ingrid; Huizenga, Hilde M

    2009-08-01

    An important issue in the analysis of fMRI is how to account for the spatial smoothness of activated regions. In this article a method is proposed to accomplish this by modeling activated regions with Gaussian shapes. Hypothesis tests on the location, spatial extent, and amplitude of these regions are performed instead of hypothesis tests of individual voxels. This increases power and eases interpretation. Simulation studies show robust hypothesis tests under misspecification of the shape model, and increased power over standard techniques especially at low signal-to-noise ratios. An application to real single-subject data also indicates that the method has increased power over standard methods.

  14. Dynamics of active regions observed with Hinode XRT

    NASA Astrophysics Data System (ADS)

    Sakao, Taro

    We present dynamics of active regions observed with the X-Ray Telescope (XRT) aboard Hinode. XRT is a grazing-incidence imager with a Walter Type-I-like mirror of 34 cm diameter with a back-illuminated CCD device. The XRT can image the X-ray corona of the Sun with angular resolution consistent with 1 arcsec CCD pixel size. In addition to this unprecedentedly-high angular resolution ever achieved as a solar X-ray telescope, enhanced sensitivity of the CCD towards longer X-ray wavelengths (particularly beyond 50 Angstroms) enables XRT to image, and perform temperature diagnostics on, a wide range of coronal plasmas from those as low as 1 MK to high-temperature plasmas even exceeding 10 MK. This adds a notable advantage to the XRT such that it can observe most, if not all, active phenomena taking place in and around active regions. Since the beginning of observations with XRT on 23 October 2006, the XRT has so far made various interesting observations regarding active regions. These include (1) continuous outflow of plasmas from the edge of a solar active region that is likely to be a source of (slow) solar wind, (2) clear signature of eruptions for activities even down to GOES B-level, (3) detailed structure and evolution of flaring loops, (4) formation of large-scale hot loops around active regions, and so on. Dynamic phenomena in and around active regions observed with Hinode XRT will be presented and their possible implications to the Sun-Earth connection investigation will be discussed.

  15. EVIDENCE OF IMPULSIVE HEATING IN ACTIVE REGION CORE LOOPS

    SciTech Connect

    Tripathi, Durgesh; Mason, Helen E.; Klimchuk, James A.

    2010-11-01

    Using a full spectral scan of an active region from the Extreme-Ultraviolet Imaging Spectrometer (EIS) we have obtained emission measure EM(T) distributions in two different moss regions within the same active region. We have compared these with theoretical transition region EMs derived for three limiting cases, namely, static equilibrium, strong condensation, and strong evaporation from Klimchuk et al. The EM distributions in both the moss regions are strikingly similar and show a monotonically increasing trend from log T[K] = 5.15-6.3. Using photospheric abundances, we obtain a consistent EM distribution for all ions. Comparing the observed and theoretical EM distributions, we find that the observed EM distribution is best explained by the strong condensation case (EM{sub con}), suggesting that a downward enthalpy flux plays an important and possibly dominant role in powering the transition region moss emission. The downflows could be due to unresolved coronal plasma that is cooling and draining after having been impulsively heated. This supports the idea that the hot loops (with temperatures of 3-5 MK) seen in the core of active regions are heated by nanoflares.

  16. A biochemically distinct form of cytochrome oxidase (COX) deficiency in the Saguenay-Lac-Saint-Jean region of Quebec.

    PubMed

    Merante, F; Petrova-Benedict, R; MacKay, N; Mitchell, G; Lambert, M; Morin, C; De Braekeleer, M; Laframboise, R; Gagné, R; Robinson, B H

    1993-08-01

    We report the results of biochemical and molecular investigations on a group of patients from the Saguenay-Lac-Saint-Jean region of Quebec who have an unusual form of cytochrome oxidase deficiency and Leigh disease. This group can be distinguished from the classical presentation of cytochrome oxidase deficiency with Leigh disease, by the severity of the biochemical defect in different tissues. The activity in skin fibroblasts, amniocytes, and skeletal muscle of cytochrome oxidase is 50% of normal, while in kidney and heart it is close to normal values. Brain and liver, on the other hand, have very low activities. The defect in activity appears to result from a failure of assembly of the cytochrome oxidase complex in liver, but levels of mRNA for both mitochondrially encoded and nuclear-encoded subunits in liver and skin fibroblasts were found to be the same as those in controls. The cDNA sequence of the liver-specific cytochrome oxidase subunits VIa and VIIa were determined in samples from patient liver and skin fibroblasts and showed normal coding sequence.

  17. Eruptions that Drive Coronal Jets in a Solar Active Region

    NASA Technical Reports Server (NTRS)

    Sterling, Alphonse C.; Moore, Ronald L.; Falconer, David A.; Panesar, Navdeep K.; Akiyama, Sachiko; Yashiro, Seiji; Gopalswamy, Nat

    2016-01-01

    Solar coronal jets are common in both coronal holes and in active regions (e.g., Shibata et al. 1992, Shimojo et al. 1996, Cirtain et al. 2007. Savcheva et al. 2007). Recently, Sterling et al. (2015), using data from Hinode/XRT and SDO/AIA, found that coronal jets originating in polar coronal holes result from the eruption of small-scale filaments (minifilaments). The jet bright point (JBP) seen in X-rays and hotter EUV channels off to one side of the base of the jet's spire develops at the location where the minifilament erupts, consistent with the JBPs being miniature versions of typical solar flares that occur in the wake of large-scale filament eruptions. Here we consider whether active region coronal jets also result from the same minifilament-eruption mechanism, or whether they instead result from a different mechanism (e.g. Yokoyama & Shibata 1995). We present observations of an on-disk active region (NOAA AR 11513) that produced numerous jets on 2012 June 30, using data from SDO/AIA and HMI, and from GOES/SXI. We find that several of these active region jets also originate with eruptions of miniature filaments (size scale 20'') emanating from small-scale magnetic neutral lines of the region. This demonstrates that active region coronal jets are indeed frequently driven by minifilament eruptions. Other jets from the active region were also consistent with their drivers being minifilament eruptions, but we could not confirm this because the onsets of those jets were hidden from our view. This work was supported by funding from NASA/LWS, NASA/HGI, and Hinode. A full report of this study appears in Sterling et al. (2016).

  18. Active Curved Polymers Form Vortex Patterns on Membranes

    NASA Astrophysics Data System (ADS)

    Denk, Jonas; Huber, Lorenz; Reithmann, Emanuel; Frey, Erwin

    2016-04-01

    Recent in vitro experiments with FtsZ polymers show self-organization into different dynamic patterns, including structures reminiscent of the bacterial Z ring. We model FtsZ polymers as active particles moving along chiral, circular paths by Brownian dynamics simulations and a Boltzmann approach. Our two conceptually different methods point to a generic phase behavior. At intermediate particle densities, we find self-organization into vortex structures including closed rings. Moreover, we show that the dynamics at the onset of pattern formation is described by a generalized complex Ginzburg-Landau equation.

  19. CO2 infrared emission as a diagnostic of planet-forming regions of disks

    NASA Astrophysics Data System (ADS)

    Bosman, Arthur D.; Bruderer, Simon; van Dishoeck, Ewine F.

    2017-05-01

    Context. The infrared ro-vibrational emission lines from organic molecules in the inner regions of protoplanetary disks are unique probes of the physical and chemical structure of planet-forming regions and the processes that shape them. These observed lines are mostly interpreted with local thermal equilibrium (LTE) slab models at a single temperature. Aims: We aim to study the non-LTE excitation effects of carbon dioxide (CO2) in a full disk model to evaluate: (i) what the emitting regions of the different CO2 ro-vibrational bands are; (ii) how the CO2 abundance can be best traced using CO2 ro-vibrational lines using future JWST data and; (iii) what the excitation and abundances tell us about the inner disk physics and chemistry. CO2 is a major ice component and its abundance can potentially test models with migrating icy pebbles across the iceline. Methods: A full non-LTE CO2 excitation model has been built starting from experimental and theoretical molecular data. The characteristics of the model are tested using non-LTE slab models. Subsequently the CO2 line formation was modelled using a two-dimensional disk model representative of T Tauri disks where CO2 is detected in the mid-infrared by the Spitzer Space Telescope. Results: The CO2 gas that emits in the 15 μm and 4.5 μm regions of the spectrum is not in LTE and arises in the upper layers of disks, pumped by infrared radiation. The v2 15 μm feature is dominated by optically thick emission for most of the models that fit the observations and increases linearly with source luminosity. Its narrowness compared with that of other molecules stems from a combination of the low rotational excitation temperature ( 250 K) and the inherently narrower feature for CO2. The inferred CO2 abundances derived for observed disks range from 3 × 10-9 to 1 × 10-7 with respect to total gas density for typical gas/dust ratios of 1000, similar to earlier LTE disk estimates. Line-to-continuum ratios are low, in the order of a

  20. Dual activity of quinolinate synthase: triose phosphate isomerase and dehydration activities play together to form quinolinate.

    PubMed

    Reichmann, Debora; Couté, Yohann; Ollagnier de Choudens, Sandrine

    2015-10-27

    Quinolinate synthase (NadA) is an Fe4S4 cluster-containing dehydrating enzyme involved in the synthesis of quinolinic acid (QA), the universal precursor of the essential coenzyme nicotinamide adenine dinucleotide. The reaction catalyzed by NadA is not well understood, and two mechanisms have been proposed in the literature that differ in the nature of the molecule (DHAP or G-3P) that condenses with iminoaspartate (IA) to form QA. In this article, using biochemical approaches, we demonstrate that DHAP is the triose that condenses with IA to form QA. The capacity of NadA to use G-3P is due to its previously unknown triose phosphate isomerase activity.

  1. Gamma-ray Bursts May Originate in Star-Forming Regions

    NASA Astrophysics Data System (ADS)

    2001-04-01

    New findings from two X-ray satellites suggest that gamma-ray bursts, some of the most intense blasts in the universe, may be created in the same area where stars are born. Dr. Luigi Piro of the Consiglio Nazionale delle Ricerche (CNR) in Rome, Italy, presented data from NASA's Chandra X-ray Observatory and the Italian-Dutch ASI BeppoSAX observatory today at the Gamma Ray 2001 conference in Baltimore, MD. "We know that when a gamma-ray burst explodes, it produces a blast of material called a fireball, which expands at relativistic speeds like a rapidly inflating bubble," said Piro, who works within CNR's Istituto di Astrofisica Spaziale. "Our team found evidence that the blast wave caused by the fireball brakes against a wall of very dense gas, which we believe is the crowded region where stars form." Several theories exist about what causes gamma-ray bursts. Among more popular theories are that gamma-ray bursts come from various combinations of merging neutron stars and black holes, or, from the explosion of massive stars, called hypernovae. "Because gamma-ray bursts are going off in extremely distant galaxies, it is difficult to 'see' the regions that harbor them," said Piro. "We can only gather circumstantial evidence as to where and how they form." Piro's observations support the hypernova model. Scientists believe that within dense star-forming regions, the massive star required for a hypernova explosion evolves extremely rapidly. On astronomical time scales, the supermassive star would evolve over the course of only about one million years. Thus, the hypernova explosion may occur in the same stellar environment that originally produced the massive star itself, and perhaps may trigger even more star formation. The hint that gamma-ray bursts can occur in dense media came during a Chandra observation of an afterglow that occurred on September 26, 2000. Prof. Gordon Garmire of Pennsylvania State University, University Park, PA, found X-ray emission to be greater

  2. Interplanetary planar magnetic structures associated with expanding active regions

    NASA Technical Reports Server (NTRS)

    Nakagawa, Tomoko; Uchida, Yutaka

    1995-01-01

    Planar magnetic structures are interplanetary objects whose magnetic field cannot be explained by Parker's solar wind model. They are characterized by two-dimensional structure of magnetic field that are highly variable and parallel to a plane which is inclined to the ecliptic plane. They appeared independently of interplanetary compression, solar flares, active prominences nor filament disappearances, but the sources often coincided with active regions. On the other hand, it has been discovered by the Yohkoh Soft X-ray telescope that active-region corona expand outwards at speeds of a few to a few tens of km/s near the Sun. The expansions occurred repeatedly, almost continually, even in the absence of any sizable flares. In the Yohkoh Soft X-ray images, the active-region corona seems to expand out into interplanetary space. Solar sources of interplanetary planar magnetic structures observed by Sakigake were examined by Yohkoh soft X-ray telescope. During a quiet period of the Sun from January 6 to November 11, 1993, there found 5 planar magnetic structures according to the criteria (absolute value of Bn)/(absolute value of B) less than 0.1 for planarity and (dB)/(absolute value of B) greater than 0.7 for variability of magnetic field, where Bn, dB, and the absolute value of B are field component normal to a plane, standard deviation, and average of the magnitude of the magnetic field, respectively. Sources of 4 events were on low-latitude (less than 5 degrees) active regions from which loop-like structures were expanding. The coincidence, 80%, is extremely high with respect to accidental coincidence, 7%, of Sakigake windows of solar wind observation with active regions. The last source was on loop-like features which seemed to be related with a mid-latitude (20 degrees) active region.

  3. 76 FR 81517 - Agency Information Collection Activities: Form I-131, Revision of an Existing Information...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-28

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    Federal Register 2010, 2011, 2012, 2013, 2014

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    Federal Register 2010, 2011, 2012, 2013, 2014

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    Federal Register 2010, 2011, 2012, 2013, 2014

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    Federal Register 2010, 2011, 2012, 2013, 2014

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  12. THE BOLOCAM GALACTIC PLANE SURVEY. VII. CHARACTERIZING THE PROPERTIES OF MASSIVE STAR-FORMING REGIONS

    SciTech Connect

    Dunham, Miranda K.; Rosolowsky, Erik; Evans II, Neal J.; Cyganowski, Claudia; Urquhart, James S.

    2011-11-10

    We present the results of a Green Bank Telescope survey of NH{sub 3}(1,1), (2,2), (3,3) lines toward 631 Bolocam Galactic Plane Survey (BGPS) sources at a range of Galactic longitudes in the inner Galaxy. We have detected the NH{sub 3}(1,1) line toward 72% of our targets (456), demonstrating that the high column density features identified in the BGPS and other continuum surveys accurately predict the presence of dense gas. We have determined kinematic distances and resolved the distance ambiguity for all BGPS sources detected in NH{sub 3}. The BGPS sources trace the locations of the Scutum and Sagittarius spiral arms, with the number of sources. We measure the physical properties of each source and find that depending on the distance, BGPS sources are primarily clumps, with some cores and clouds. We have examined the physical properties as a function of Galactocentric distance, and find a mean gas kinetic temperature of 15.6 K, and that the NH{sub 3} column density and abundance decrease by nearly an order of magnitude. Comparing sources at similar distances demonstrates that the physical properties are indistinguishable, which suggests a similarity in clump structure across the Galactic disk. We have also compared the BGPS sources to criteria for efficient star formation presented independently by Heiderman et al. and Lada et al., and for massive star formation presented by Kauffmann et al. Forty-eight percent of our sample should be forming stars (including massive stars) with high efficiency, and 87% contain subregions that should be efficiently forming stars. Indeed, we find that 67% of the sample exhibit signs of star formation activity based on an association with a mid-infrared source.

  13. RADIO JETS AND DISKS IN THE INTERMEDIATE-MASS STAR-FORMING REGION NGC2071IR

    SciTech Connect

    Trinidad, M. A.; Rodriguez, T.; Rodriguez, L. F.

    2009-11-20

    We report the results of simultaneous radio continuum and water maser observations toward the NGC 2071IR star-forming region, carried out with the VLA in its A configuration. We detect continuum emission toward the infrared sources IRS 1 and IRS 3 at 1.3 and 3.6 cm. In addition, a new continuum source, VLA 1, is also detected at both wavelengths, which is located between IRS 1 and IRS 3. IRS 1 breaks up into three continuum peaks (IRS 1E, 1C, and 1W), aligned in the east-west direction (P.A. = 100{sup 0}). IRS 1 is the central source, while the sources E and W seem to be condensations ejected by IRS 1. In the same way, IRS 3 is also forming a triple system (IRS 3N, 3C and 3S), which is elongated in the northeast-southwest direction and the condensations, IRS 3N and IRS 3S, are symmetrically located along the major axis. Based on the morphology and the continuum emission, we suggest that both IRS 1 and IRS 3 are radio jets, which have ejected condensations into the interstellar medium. Moreover, IRS 1 and IRS 3 seem to be the driving sources of the large-scale outflows observed in H{sub 2} and CO, respectively. In addition, we also detected water emission toward the systems IRS 1, IRS 3, and the new source VLA 1. Based on the spatial-kinematic distribution of the water masers, we find evidence that the water masers are tracing part of circumstellar disks around IRS 1C and IRS 3C. Moreover, we estimate that the sources IRS 1C and IRS 3C have central masses of approx5 and approx1 M {sub sun}, respectively. We conclude that the radio continuum and water maser emission are tracing disk-YSO-outflow systems toward IRS 1 and IRS 3, which are low- and intermediate-mass young stellar objects, respectively.

  14. Heat of Hydration of Low Activity Cementitious Waste Forms

    SciTech Connect

    Nasol, D.

    2015-07-23

    During the curing of secondary waste grout, the hydraulic materials in the dry mix react exothermally with the water in the secondary low-activity waste (LAW). The heat released, called the heat of hydration, can be measured using a TAM Air Isothermal Calorimeter. By holding temperature constant in the instrument, the heat of hydration during the curing process can be determined. This will provide information that can be used in the design of a waste solidification facility. At the Savannah River National Laboratory (SRNL), the heat of hydration and other physical properties are being collected on grout prepared using three simulants of liquid secondary waste generated at the Hanford Site. From this study it was found that both the simulant and dry mix each had an effect on the heat of hydration. It was also concluded that the higher the cement content in the dry materials mix, the greater the heat of hydration during the curing of grout.

  15. Bimanual passive movement: functional activation and inter-regional coupling.

    PubMed

    Macaluso, Emiliano; Cherubini, Andrea; Sabatini, Umberto

    2007-01-01

    The aim of this study was to investigate intra-regional activation and inter-regional connectivity during passive movement. During fMRI, a mechanic device was used to move the subject's index and middle fingers. We assessed four movement conditions (unimanual left/right, bimanual symmetric/asymmetric), plus Rest. A conventional intra-regional analysis identified the passive stimulation network, including motor cortex, primary and secondary somatosensory cortex, plus the cerebellum. The posterior (sensory) part of the sensory-motor activation around the central sulcus showed a significant modulation according to the symmetry of the bimanual movement, with greater activation for asymmetric compared to symmetric movements. A second set of fMRI analyses assessed condition-dependent changes of coupling between sensory-motor regions around the superior central sulcus and the rest of the brain. These analyses showed a high inter-regional covariation within the entire network activated by passive movement. However, the specific experimental conditions modulated these patterns of connectivity. Highest coupling was observed during the Rest condition, and the coupling between homologous sensory-motor regions around the left and right central sulcus was higher in bimanual than unimanual conditions. These findings demonstrate that passive movement can affect the connectivity within the sensory-motor network. We conclude that implicit detection of asymmetry during bimanual movement relies on associative somatosensory region in post-central areas, and that passive stimulation reduces the functional connectivity within the passive movement network. Our findings open the possibility to combine passive movement and inter-regional connectivity as a tool to investigate the functionality of the sensory-motor system in patients with very poor mobility.

  16. Surface active complexes formed between keratin polypeptides and ionic surfactants.

    PubMed

    Pan, Fang; Lu, Zhiming; Tucker, Ian; Hosking, Sarah; Petkov, Jordan; Lu, Jian R

    2016-12-15

    Keratins are a group of important proteins in skin and hair and as biomaterials they can provide desirable properties such as strength, biocompatibility, and moisture regaining and retaining. The aim of this work is to develop water-soluble keratin polypeptides from sheep wool and then explore how their surface adsorption behaves with and without surfactants. Successful preparation of keratin samples was demonstrated by identification of the key components from gel electrophoresis and the reproducible production of gram scale samples with and without SDS (sodium dodecylsulphate) during wool fibre dissolution. SDS micelles could reduce the formation of disulphide bonds between keratins during extraction, reducing inter-molecular crosslinking and improving keratin polypeptide solubility. However, Zeta potential measurements of the two polypeptide batches demonstrated almost identical pH dependent surface charge distributions with isoelectric points around pH 3.5, showing complete removal of SDS during purification by dialysis. In spite of different solubility from the two batches of keratin samples prepared, very similar adsorption and aggregation behavior was revealed from surface tension measurements and dynamic light scattering. Mixing of keratin polypeptides with SDS and C12TAB (dodecyltrimethylammonium bromide) led to the formation of keratin-surfactant complexes that were substantially more effective at reducing surface tension than the polypeptides alone, showing great promise in the delivery of keratin polypeptides via the surface active complexes. Neutron reflection measurements revealed the coexistence of surfactant and keratin polypeptides at the interface, thus providing the structural support to the observed surface tension changes associated with the formation of the surface active complexes.

  17. TARPs: Tracked Active Region Patches from SoHO/MDI

    NASA Astrophysics Data System (ADS)

    Turmon, M.; Hoeksema, J. T.; Bobra, M.

    2013-12-01

    We describe progress toward creating a retrospective MDI data product consisting of tracked magnetic features on the scale of solar active regions, abbreviated TARPs (Tracked Active Region Patches). The TARPs are being developed as a backward-looking extension (covering approximately 3500 regions spanning 1996-2010) to the HARP (HMI Active Region Patch) data product that has already been released for HMI (2010-present). Like the HARPs, the MDI TARP data set is designed to be a catalog of active regions (ARs), indexed by a region ID number, analogous to a NOAA AR number, and time. TARPs from MDI are computed based on the 96-minute synoptic magnetograms and pseudo-continuum intensitygrams. As with the related HARP data product, the approximate threshold for significance is 100G. Use of both image types together allows faculae and sunspots to be separated out as sub-classes of activity, in addition to identifying the overall active region that the faculae/sunspots are part of. After being identified in single images, the magnetically-active patches are grouped and tracked from image to image. Merges among growing active regions, as well as faint active regions hovering at the threshold of detection, are handled automatically. Regions are tracked from their inception until they decay within view, or transit off the visible disk. The final data product is indexed by a nominal AR number and time. For each active region and for each time, a bitmap image is stored containing the precise outline of the active region. Additionaly, metadata such as areas and integrated fluxes are stored for each AR and for each time. Because there is a calibration between the HMI and MDI magnetograms (Liu, Hoeksema et al. 2012), it is straightforward to use the same classification and tracking rules for the HARPs (from HMI) and the MDI TARPs. We anticipate that this will allow a consistent catalog spanning both instruments. We envision several uses for the TARP data product, which will be

  18. Active Region Moss: Doppler Shifts from Hinode/EIS Observations

    NASA Technical Reports Server (NTRS)

    Tripathi, Durgesh; Mason, Helen E.; Klimchuk, James A.

    2012-01-01

    Studying the Doppler shifts and the temperature dependence of Doppler shifts in moss regions can help us understand the heating processes in the core of the active regions. In this paper we have used an active region observation recorded by the Extreme-ultraviolet Imaging Spectrometer (EIS) onboard Hinode on 12-Dec- 2007 to measure the Doppler shifts in the moss regions. We have distinguished the moss regions from the rest of the active region by defining a low density cut-off as derived by Tripathi et al. (2010). We have carried out a very careful analysis of the EIS wavelength calibration based on the method described in Young, O Dwyer and Mason (2012). For spectral lines having maximum sensitivity between log T = 5.85 and log T = 6.25 K, we find that the velocity distribution peaks at around 0 km/s with an estimated error of 4 km/s. The width of the distribution decreases with temperature. The mean of the distribution shows a blue shift which increases with increasing temperature and the distribution also shows asymmetries towards blue-shift. Comparing these results with observables predicted from different coronal heating models, we find that these results are consistent with both steady and impulsive heating scenarios. Further observational constraints are needed to distinguish between these two heating scenarios.

  19. Active region moss. Basic physical parameters and their temporal variation

    NASA Astrophysics Data System (ADS)

    Tripathi, D.; Mason, H. E.; Del Zanna, G.; Young, P. R.

    2010-07-01

    Context. Active region moss are transition region phenomena, first noted in the images recorded by the Transition Region and Coronal Explorer (TRACE) in λ171. Moss regions are thought to be the footpoints of hot loops (3-5 MK) seen in the core of active regions. These hot loops appear “fuzzy” (unresolved). Therefore, it is difficult to study the physical plasma parameters in individual hot core loops and hence their heating mechanisms. Moss regions provide an excellent opportunity to study the physics of hot loops. In addition, they allow us to study the transition region dynamics in the footpoint regions. Aims: To derive the physical plasma parameters such as temperature, electron density, and filling factors in moss regions and to study their variation over a short (an hour) and a long time period (5 consecutive days). Methods: Primarily, we have analyzed spectroscopic observations recorded by the Extreme-ultraviolet Imaging Spectrometer (EIS) aboard Hinode. In addition we have used supplementary observations taken from TRACE and the X-Ray Telescope (XRT) aboard Hinode. Results: The moss emission is strongest in the Fe XII and Fe XIII lines. Based on analyses using line ratios and emission measure we found that moss regions have a characteristic temperature of log T[K] = 6.2. The temperature structure in moss region remains almost identical from one region to another and it does not change with time. The electron densities measured at different locations in the moss regions using Fe XII ratios are about 1-3 × 1010 cm-3 and about 2-4 × 109 cm-3 using Fe XIII and Fe XIV. The densities in the moss regions are similar in different places and show very little variation over short and long time scales. The derived electron density substantially increased (by a factor of about 3-4 or even more in some cases) when a background subtraction was performed. The filling factor of the moss plasma can vary between 0.1-1 and the path length along which the emission

  20. VLBI Observations and NH3 Mapping of the Star-forming Region NGC2264

    NASA Astrophysics Data System (ADS)

    Kamezaki, Tatsuya; Imura, Kenji; Nagayama, Takumi; Omodaka, Toshihiro; Handa, Toshihiro; Yamaguchi, Yoshiyuki; Chibueze, James O.; Sunada, Kazuyoshi; Nakano, Makoto

    2013-03-01

    We have measured the annual parallax of the water maser source associated with star forming region NGC2264 from observations with VLBI Exploration of Radio Astrometry (VERA). We detected masers at V LSR = 7.2 km s-1. We discussed its driving sources of detected maser spots. One of the maser spots was associated with a centimeter continuum source observed with VLA. Neither optical, infrared nor X-ray sources is catalogued near the spot. The other maser spot is located close to an X-ray source, although there is no optical or infrared counterpart. The proper motion of the former spot was (μα, μδ) = (23.91 ± 4.29, -29.81 ± 4.27) and the proper motion of latter spot was (μα, μδ) = (-0.96 ± 0.58, -6.05 ± 3.06). For the latter spot, the peculiar motion is ˜ 150 km s-1 and it has the high velocity and this may be a jet or an outflow from a young star. The observed parallax is 1.365 ± 0.098 mas, corresponding to the distance of 738+57 -50 pc. This value is constant with the photometric distance of NGC2264 previously measured. The fitting result of the parallax is shown in figure 1. We also observed in NH3 (1,1), (2,2), (3,3) lines of NGC2264 with the Kashima 34m telescope. We estimated the star formation efficiency (SFE) of NGC2264 from the dense molecular mass of NH3 and the stellar mass calculated by Teixeira et al. (2012). The SFE is 9 - 12% which is consistent with previous results.

  1. A Survey for Planetary-mass Brown Dwarfs in the Chamaeleon I Star-forming Region

    NASA Astrophysics Data System (ADS)

    Esplin, T. L.; Luhman, K. L.; Faherty, J. K.; Mamajek, E. E.; Bochanski, J. J.

    2017-08-01

    We have performed a search for planetary-mass brown dwarfs in the Chamaeleon I star-forming region using proper motions and photometry measured from optical and infrared images from the Spitzer Space Telescope, the Hubble Space Telescope, and ground-based facilities. Through near-IR spectroscopy at Gemini Observatory, we have confirmed six of the candidates as new late-type members of Chamaeleon I (≥M8). One of these objects, Cha J11110675-7636030, has the faintest extinction-corrected M K among known members, which corresponds to a mass of 3-6 {M}{Jup} according to evolutionary models. That object and two other new members have redder mid-IR colors than young photospheres at ≤M9.5, which may indicate the presence of disks. However, since those objects may be later than M9.5 and the mid-IR colors of young photospheres are ill-defined at those types, we cannot determine conclusively whether color excesses from disks are present. If Cha J11110675-7636030 does have a disk, it would be a contender for the least-massive known brown dwarf with a disk. Since the new brown dwarfs that we have found extend below our completeness limit of 6-10 M {}{Jup}, deeper observations are needed to measure the minimum mass of the initial mass function in Chamaeleon I. Based on observations made with the Spitzer Space Telescope, the NASA/ESA Hubble Space Telescope, Gemini Observatory, the ESO Telescopes at Paranal Observatory, Magellan Observatory, the Cerro Tololo Inter-American Observatory, and the ESA Gaia mission.

  2. SUB-STELLAR COMPANIONS AND STELLAR MULTIPLICITY IN THE TAURUS STAR-FORMING REGION

    SciTech Connect

    Daemgen, Sebastian; Bonavita, Mariangela; Jayawardhana, Ray; Lafrenière, David; Janson, Markus

    2015-02-01

    We present results from a large, high-spatial-resolution near-infrared imaging search for stellar and sub-stellar companions in the Taurus-Auriga star-forming region. The sample covers 64 stars with masses between those of the most massive Taurus members at ∼3 M {sub ☉} and low-mass stars at ∼0.2 M {sub ☉}. We detected 74 companion candidates, 34 of these reported for the first time. Twenty-five companions are likely physically bound, partly confirmed by follow-up observations. Four candidate companions are likely unrelated field stars. Assuming physical association with their host star, estimated companion masses are as low as ∼2 M {sub Jup}. The inferred multiplicity frequency within our sensitivity limits between ∼10-1500 AU is 26.3{sub −4.9}{sup +6.6}%. Applying a completeness correction, 62% ± 14% of all Taurus stars between 0.7 and 1.4 M {sub ☉} appear to be multiple. Higher order multiples were found in 1.8{sub −1.5}{sup +4.2}% of the cases, in agreement with previous observations of the field. We estimate a sub-stellar companion frequency of ∼3.5%-8.8% within our sensitivity limits from the discovery of two likely bound and three other tentative very low-mass companions. This frequency appears to be in agreement with what is expected from the tail of the stellar companion mass ratio distribution, suggesting that stellar and brown dwarf companions share the same dominant formation mechanism. Further, we find evidence for possible evolution of binary parameters between two identified sub-populations in Taurus with ages of ∼2 Myr and ∼20 Myr, respectively.

  3. Sub-stellar Companions and Stellar Multiplicity in the Taurus Star-forming Region

    NASA Astrophysics Data System (ADS)

    Daemgen, Sebastian; Bonavita, Mariangela; Jayawardhana, Ray; Lafrenière, David; Janson, Markus

    2015-02-01

    We present results from a large, high-spatial-resolution near-infrared imaging search for stellar and sub-stellar companions in the Taurus-Auriga star-forming region. The sample covers 64 stars with masses between those of the most massive Taurus members at ~3 M ⊙ and low-mass stars at ~0.2 M ⊙. We detected 74 companion candidates, 34 of these reported for the first time. Twenty-five companions are likely physically bound, partly confirmed by follow-up observations. Four candidate companions are likely unrelated field stars. Assuming physical association with their host star, estimated companion masses are as low as ~2 M Jup. The inferred multiplicity frequency within our sensitivity limits between ~10-1500 AU is 26.3+6.6-4.9%. Applying a completeness correction, 62% ± 14% of all Taurus stars between 0.7 and 1.4 M ⊙ appear to be multiple. Higher order multiples were found in 1.8+4.2-1.5% of the cases, in agreement with previous observations of the field. We estimate a sub-stellar companion frequency of ~3.5%-8.8% within our sensitivity limits from the discovery of two likely bound and three other tentative very low-mass companions. This frequency appears to be in agreement with what is expected from the tail of the stellar companion mass ratio distribution, suggesting that stellar and brown dwarf companions share the same dominant formation mechanism. Further, we find evidence for possible evolution of binary parameters between two identified sub-populations in Taurus with ages of ~2 Myr and ~20 Myr, respectively.

  4. THE PHYSICAL ENVIRONMENT OF THE MASSIVE STAR-FORMING REGION W42

    SciTech Connect

    Dewangan, L. K.; Luna, A.; Mayya, Y. D.; Ojha, D. K.; Mallick, K. K.; Anandarao, B. G.

    2015-10-01

    We present an analysis of multi-wavelength observations from various data sets and Galactic plane surveys to study the star-formation process in the W42 complex. A bipolar appearance of the W42 complex is evident due to the ionizing feedback from the O5–O6 type star in a medium that is highly inhomogeneous. The Very Large Telescope/NACO adaptive-optics K and L{sup ′} images (resolutions ∼0.″2–0.″1) resolved this ionizing source into multiple point-like sources below ∼5000 AU scale. The position angle ∼15° of the W42 molecular cloud is consistent with the H-band starlight mean polarization angle, which in turn is close to the Galactic magnetic field, suggesting the influence of the Galactic field on the evolution of the W42 molecular cloud. Herschel sub-millimeter data analysis reveals three clumps located along the waist axis of the bipolar nebula, with the peak column densities of ∼(3–5) × 10{sup 22} cm{sup −2} corresponding to visual extinctions of A{sub V} ∼ 32–53.5 mag. The Herschel temperature map traces a temperature gradient in W42, revealing regions of 20 K, 25 K, and 30–36 K. Herschel maps reveal embedded filaments (length ∼1–3 pc) that appear to be radially pointed to the denser clump associated with the O5–O6 star, forming a hub-filament system. A total of 512 candidate young stellar objects (YSOs) are identified in the complex, ∼40% of which are present in clusters distributed mainly within the molecular cloud, including the Herschel filaments. Our data sets suggest that the YSO clusters, including the massive stars, are located at the junction of the filaments, similar to those seen in the Rosette Molecular Cloud.

  5. Chromospheric Magnetic Field of Exploding Solar Active Regions

    NASA Astrophysics Data System (ADS)

    Choudhary, Debi P.

    2013-07-01

    How changes in the three-dimensional magnetic field of solar active region are related to Coronal Mass Ejections (CME) is an important question for contemporary solar physics. Complex active regions are the predominant source of powerful high-speed CMEs, which can result in strong geomagnetic storms. In this paper we present the properties of chromospheric magnetic field of active regions that produced solar flares and CMEs using observations of the Synoptic Optical Long-term Investigations of the Sun (SOLIS) facility operated by the National Solar Observatory. Currently, the SOLIS Vector Spectromagnetograph (VSM) is the only instrument that is capable of obtaining full Stokes profiles in both the photospheric Fe I λ630.2 nm and chromospheric Ca II λ854.2 nm lines on a daily basis. VSM also has the capability of making rapid scans covering an area sufficiently large to contain an active region. We shall present the Stokes profile characteristics of photospheric and chromospheric lines of few CME source regions.

  6. Chromospheric Magnetic Field of Exploding Solar Active Regions

    NASA Astrophysics Data System (ADS)

    Choudhary, Debi Prasad

    How changes in the three-dimensional magnetic field of solar active region are related to Coronal Mass Ejections (CME) is an important question for contemporary solar physics. Complex active regions are the predominant source of powerful high-speed CMEs, which can result in strong geomagnetic storms. In this paper we present the properties of chromospheric magnetic field of active regions that produced solar flares and CMEs using observations of the Synoptic Optical Long-term Investigations of the Sun (SOLIS) facility operated by the National Solar Observatory. Currently, the SOLIS Vector Spectromagnetograph (VSM) is the only instrument that is capable of obtaining full Stokes profiles in both the photospheric Fe I 630.2 nm and chromospheric Ca II 854.2 nm lines on a daily basis. VSM also has the capability of making rapid scans covering an area sufficiently large to contain an active region. We shall present the Stokes profile characteristics of photospheric and chromospheric lines of few CME source regions.

  7. 77 FR 14817 - Agency Information Collection Activities: Form I-829, Extension of a Currently Approved...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-13

    ... SECURITY Citizenship and Immigration Services Agency Information Collection Activities: Form I-829, Extension of a Currently Approved Information Collection; Comment Request ACTION: 60-Day Notice of Information Collection Under Review: Form I- 829, Petition by Entrepreneur to Remove Conditions. The...

  8. Lymphocyte Activation Dynamics Is Shaped by Hereditary Components at Chromosome Region 17q12-q21

    PubMed Central

    Carreras-Sureda, Amado; Rubio-Moscardo, Fanny; Olvera, Alex; Argilaguet, Jordi; Kiefer, Kerstin; Mothe, Beatriz; Meyerhans, Andreas; Brander, Christian

    2016-01-01

    Single nucleotide polymorphisms (SNPs) located in the chromosome region 17q12-q21 are risk factors for asthma. Particularly, there are cis-regulatory haplotypes within this region that regulate differentially the expression levels of ORMDL3, GSDMB and ZPBP2 genes. Remarkably, ORMDL3 has been shown to modulate lymphocyte activation parameters in a heterologous expression system. In this context, it has been shown that Th2 and Th17 cytokine production is affected by SNPs in this region. Therefore, we aim to assess the impact of hereditary components within region 17q12-q21 on the activation profile of human T lymphocytes, focusing on the haplotype formed by allelic variants of SNPs rs7216389 and rs12936231. We measured calcium influx and activation markers, as well as the proliferation rate upon T cell activation. Haplotype-dependent differences in mRNA expression levels of IL-2 and INF-γ were observed at early times after activation. In addition, the allelic variants of these SNPs impacted on the extent of calcium influx in resting lymphocytes and altered proliferation rates in a dose dependent manner. As a result, the asthma risk haplotype carriers showed a lower threshold of saturation during activation. Finally, we confirmed differences in activation marker expression by flow cytometry using phytohemagglutinin, a strong polyclonal stimulus. Altogether, our data suggest that the genetic component of pro-inflammatory pathologies present in this chromosome region could be explained by different T lymphocyte activation dynamics depending on individual allelic heredity. PMID:27835674

  9. Distribution of 26Al in the CR chondrite chondrule-forming region of the protoplanetary disk