VizieR Online Data Catalog: RR Lyrae in 15 Galactic globular clusters (Dambis+, 2014)

NASA Astrophysics Data System (ADS)

Dambis, A. K.; Rastorguev, A. S.; Zabolotskikh, M. V.

2014-11-01

Last year, the WISE All-Sky Data Release (Cutri et al., 2012, Cat. II/328) was made public, mapping the entire sky in four mid-infrared bands W1, W2, W3 and W4 with the effective wavelengths of 3.368, 4.618, 12.082 and 22.194um, respectively. We cross-correlated the WISE single-exposure data base with the Catalogue of Galactic globular-cluster variables by Clement et al. (2001AJ....122.2587C), the Catalogue of Accurate Equatorial Coordinates for Variable Stars in Globular Clusters by Samus et al. (2009PASP..121.1378S, Cat. J/PASP/121/1378) and the catalogue of Sawyer Hogg (1973PDDO....3....6S, Cat. V/97) (for ω Cen, NGC 6723 and NGC 6934) to compute (via Fourier fits) the intensity-mean average W1- and W2-band magnitudes, and , for a total of 357 and 272 RR Lyrae type variables in 15 and 9 Galactic globular clusters, respectively. (1 data file).

Analysis of fundamental parameters for V477 Lyr

NASA Astrophysics Data System (ADS)

Shimansky, V. V.; Pozdnyakova, S. A.; Borisov, N. V.; Bikmaev, I. F.; Galeev, A. I.; Sakhibullin, N. A.; Spiridonova, O. I.

2008-06-01

We analyze the photometric and spectroscopic observations of the young pre-cataclysmic variable (pre-CV) V477 Lyr. The masses of both binary components have been corrected by analyzing their radial velocity curves. We show that agreement between the theoretical and observed light curves of the object is possible for several sets of its physical parameters corresponding to the chosen temperature of the primary component. The final parameters of V477 Lyr have been established by comparing observational data with evolutionary tracks for planetary nebula nuclei. The derived effective temperature of the O subdwarf is higher than that estimated by analyzing the object’s ultraviolet spectra by more than 10000 K. This is in agreement with the analogous results obtained previously for the young pre-CVs V664 Cas and UU Sge. The secondary component of V477 Lyr has been proven to have a more than 25-fold luminosity excess compared to main-sequence stars of similar mass. Comparison of the physical parameters for the cool stars in young pre-CVs indicates that their luminosities do not correlate with the masses of the objects. The observed luminosity excesses in such stars show a close correlation with the post-common-envelope lifetime of the systems and should be investigated within the framework of the theory of their relaxation to the state of main-sequence stars.

On a New Theoretical Framework for RR Lyrae Stars. II. Mid-infrared Period–Luminosity–Metallicity Relations

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

Neeley, Jillian R.; Marengo, Massimo; Trueba, Nicolas

2017-06-01

We present new theoretical period–luminosity–metallicity (PLZ) relations for RR Lyræ stars (RRLs) at Spitzer and WISE wavelengths. The PLZ relations were derived using nonlinear, time-dependent convective hydrodynamical models for a broad range of metal abundances ( Z = 0.0001–0.0198). In deriving the light curves, we tested two sets of atmospheric models and found no significant difference between the resulting mean magnitudes. We also compare our theoretical relations to empirical relations derived from RRLs in both the field and in the globular cluster M4. Our theoretical PLZ relations were combined with multi-wavelength observations to simultaneously fit the distance modulus, μ {submore » 0}, and extinction, A {sub V}, of both the individual Galactic RRL and of the cluster M4. The results for the Galactic RRL are consistent with trigonometric parallax measurements from Gaia ’ s first data release. For M4, we find a distance modulus of μ {sub 0} = 11.257 ± 0.035 mag with A {sub V}= 1.45 ± 0.12 mag, which is consistent with measurements from other distance indicators. This analysis has shown that, when considering a sample covering a range of iron abundances, the metallicity spread introduces a dispersion in the PL relation on the order of 0.13 mag. However, if this metallicity component is accounted for in a PLZ relation, the dispersion is reduced to ∼0.02 mag at mid-infrared wavelengths.« less

Establishing binarity amongst Galactic RV Tauri stars with a disc⋆

NASA Astrophysics Data System (ADS)

Manick, Rajeev; Van Winckel, Hans; Kamath, Devika; Hillen, Michel; Escorza, Ana

2017-01-01

Context. Over the last few decades it has become more evident that binarity is a prevalent phenomenon amongst RV Tauri stars with a disc. This study is a contribution to comprehend the role of binarity upon late stages of stellar evolution. Aims: In this paper we determine the binary status of six Galactic RV Tauri stars, namely DY Ori, EP Lyr, HP Lyr, IRAS 17038-4815, IRAS 09144-4933, and TW Cam, which are surrounded by a dusty disc. The radial velocities are contaminated by high-amplitude pulsations. We disentangle the pulsations from the orbital signal in order to determine accurate orbital parameters. We also place them on the HR diagram, thereby establishing their evolutionary nature. Methods: We used high-resolution spectroscopic time series obtained from the HERMES and CORALIE spectrographs mounted on the Flemish Mercator and Swiss Leonhard Euler Telescopes, respectively. An updated ASAS/AAVSO photometric time series is analysed to complement the spectroscopic pulsation search and to clean the radial velocities from the pulsations. The pulsation-cleaned orbits are fitted with a Keplerian model to determine the spectroscopic orbital parameters. We also calibrated a PLC relationship using type II cepheids in the LMC and apply the relation to our Galactic sample to obtain accurate distances and hence luminosities. Results: All six of the Galactic RV Tauri stars included in this study are binaries with orbital periods ranging between 650 and 1700 days and with eccentricities between 0.2 and 0.6. The mass functions range between 0.08 to 0.55 M⊙ which points to an unevolved low-mass companion. In the photometric time series we detect a long-term variation on the timescale of the orbital period for IRAS 17038-4815, IRAS 09144-4933, and TW Cam. Our derived stellar luminosities indicate that all except DY Ori and EP Lyr are post-AGB stars. DY Ori and EP Lyr are likely examples of the recently discovered dusty post-RGB stars. Conclusions: The orbital parameters

A helium P-Cygni profile in RR Lyrae stars?

NASA Astrophysics Data System (ADS)

Gillet, D.; Sefyani, F. L.; Benhida, A.; Fabas, N.; Mathias, P.; Benkhaldoun, Z.; Daassou, A.

2016-03-01

Context. Until 2006, helium emission lines had never been observed in RR Lyrae stars. For the first time, a pre-maximum helium emission in 11 RRab stars was observed during rising light (around the pulsation phase 0.92) and the reappearance of helium emission near maximum light (phase 0.0) in one RRab star: RV Oct. This post-maximum emission has been only observed in the He I λ5875.66 (D3) line. Its intensity is very weak, and its profile mimics a P-Cygni profile with the emission peak centered at the laboratory wavelength. The physical explanation for this unexpected line profile has not been proposed yet. Aims: Using new observations of RR Lyr, we investigate the physical origin of the presence of a P-Cygni profile in the He I λ5875.66 (D3) line. Methods: High-resolution spectra of RR Lyr, collected with a spectrograph eShel/C14 at the Oukaïmeden Observatory (Morocco) in 2013, were analyzed to understand the origin of the observed P-Cygni profile at D3. Results: When the shock intensity is moderate, helium emission cannot be produced in the shock wake, and consequently, the two consecutive helium emissions (pre- and post-maximum light emissions) are not observed. This is the most frequent case. When the shock intensity becomes high enough, a pre-maximum He I emission first occurs, which can be followed by the appearance of a P-Cygni profile if the shock intensity is still strong in the high atmosphere. The observation of a P-Cygni profile means that the shock wave is already detached from the photosphere. It is shown that the shock strongly first decelerates between the pulsation phases 0.90 and 1.04 from 130 km s-1 to 60 km s-1, probably before accelerating again to 80 km s-1 near phase 1.30. Conclusions: The presence of the P-Cygni profile seems to be a natural consequence of the large extension of the expanding atmosphere, which is induced by strong (radiative) shock waves propagating toward the high atmosphere. This kind of P-Cygni profile has already been

Standard Galactic Field RR Lyrae. I. Optical to Mid-infrared Phased Photometry

NASA Astrophysics Data System (ADS)

Monson, Andrew J.; Beaton, Rachael L.; Scowcroft, Victoria; Freedman, Wendy L.; Madore, Barry F.; Rich, Jeffrey A.; Seibert, Mark; Kollmeier, Juna A.; Clementini, Gisella

2017-03-01

We present a multi-wavelength compilation of new and previously published photometry for 55 Galactic field RR Lyrae variables. Individual studies, spanning a time baseline of up to 30 years, are self-consistently phased to produce light curves in 10 photometric bands covering the wavelength range from 0.4 to 4.5 microns. Data smoothing via the GLOESS technique is described and applied to generate high-fidelity light curves, from which mean magnitudes, amplitudes, rise times, and times of minimum and maximum light are derived. 60,000 observations were acquired using the new robotic Three-hundred MilliMeter Telescope (TMMT), which was first deployed at the Carnegie Observatories in Pasadena, CA, and is now permanently installed and operating at Las Campanas Observatory in Chile. We provide a full description of the TMMT hardware, software, and data reduction pipeline. Archival photometry contributed approximately 31,000 observations. Photometric data are given in the standard Johnson UBV, Kron-Cousins {R}C{I}C, 2MASS JHK, and Spitzer [3.6] and [4.5] bandpasses.

VizieR Online Data Catalog: Standard Galactic field RR Lyrae. I. Photometry (Monson+, 2017)

NASA Astrophysics Data System (ADS)

Monson, A. J.; Beaton, R. L.; Scowcroft, V.; Freedman, W. L.; Madore, B. F.; Rich, J. A.; Seibert, M.; Kollmeier, J. A.; Clementini, G.

2017-06-01

The Three-hundred MilliMeter Telescope (TMMT) is a fully robotic, 300mm telescope at Las Campanas Observatory (LCO), for which the nightly operation and data processing have been completely automated. Over the course of two years data were collected on 179 individual nights for our sample of the 55 RR Lyrae in the B, V, and IC broadband filters. Of these nights, 76 were under photometric conditions and calibrated directly. The 103 nonphotometric nights were roughly calibrated by using the default transformation equations, but only provide differential photometry relative to the calibrated frames. This resulted in 59698 final individual observations. Individual data points have a typical photometric precision of 0.02mag. The statistical error falls rapidly with hundreds of observations, with the zero-point uncertainties being the largest source of uncertainty in the final reported mean magnitude. To compare the results of our TMMT campaign to previous studies of these RR Lyrae (RRL) and to fill gaps in our TMMT phase coverage, we have compiled available broadband data from literature published over the past 30 years and spanning our full wavelength coverage (0.4 to 4.5μm) from the optical to mid-infrared. We have homogenized these diverse data sets to the following filter systems: Johnson UBV, Kron-Cousins RI, 2MASS J,H,Ks, and Spitzer [3.6], [4.5]. The All Sky Automated Survey (ASAS; http://www.astrouw.edu.pl/asas/) is a long-term project monitoring all stars brighter than V~14mag. The program covers both hemispheres, with telescopes at Las Campanas Observatory in Chile and Haleakala on Maui, both of which provide simultaneous I and V photometry. The GEOS RR Lyr Survey (http://www.ast.obs-mip.fr/users/leborgne/dbRR/grrs.html) is a long-term program utilizing TAROT (http://tarot.obs-hp.fr/) at Calern Observatory (Nice University, France). Annual data releases from this project add times for maximum light for program stars over the last year of observations. In

Changing Amplitudes: Detecting RR Lyrae Light Curve Shape Variations in the Galactic Disk and Inner Halo

NASA Astrophysics Data System (ADS)

De Lee, Nathan M.; Kinemuchi, K.; Pepper, J.; Rodriguez, J. E.

2014-01-01

In this poster we will discuss our ongoing program to use extant light curves from the Kilodegree Extremely Little Telescope (KELT) survey to find and characterize RR Lyrae (RRL) stars in the disk and inner halo of the Milky Way. RRL stars are of particular interest because they are standard candles and can be used to map out structure in the galaxy. The periods and shape of RRL light curves also contain information about their Oosterhoff type, which can probe galactic formation history, and metallicity respectively. Although there have been several large photometric surveys for RR Lyrae in the nearby galaxy (OGLE, NSVS, ASAS, and MACHO to name a few), they have each been limited in either sky coverage or number of epochs. The KELT survey represents a new generation of surveys that has many epochs over a large portion of the sky. KELT samples 60% of the sky in both northern and southern hemispheres, and has a long-time-baseline of 4-8 years with a very high cadence rate of less than 20 minutes. This translates into 4,000 to 9,000 epochs per light curve with completeness out to 3 kpc from the Sun. Recent results from both Kepler and ground based surveys results suggest that as many as 50% of RR Lyrae stars show long-term modulation of their light curve shapes (Blazhko effect). These stars combined with RRL stars that pulsate in more than one mode give a sample of objects that the KELT survey is uniquely suited to explore. This poster concentrates on a pilot project to examine RRL stars in a limited number of KELT fields. In particular, we focus on, detecting RR Lyrae, developing a light curve shape-metallicity relationship in the KELT band-pass, and some initial characterization of RRL with either amplitude-modulated or period-modulated light curves.

Kepler Observations of V447 Lyr: an Eclipsing U Gem Cataclysmic Variable

NASA Technical Reports Server (NTRS)

Ramsay, Gavin; Cannizzo, John K.; Howell, Steve B.; Wood, Matt A.; Still, Martin; Barclay, Thomas; Smale, Alan

2012-01-01

We present the results of an analysis of Kepler data covering 1.5 yr of the dwarf nova V447 Lyr. We detect eclipses of the accretion disc by the mass donating secondary star every 3.74 h which is the binary orbital period. V447 Lyr is therefore the first dwarf nova in the Kepler field to show eclipses.We also detect five long outbursts and six short outbursts showing V447 Lyr is a U Gem-type dwarf nova. We show that the orbital phase of the mid-eclipse occurs earlier during outbursts compared to quiescence and that the width of the eclipse is greater during outburst. This suggests that the bright spot is more prominent during quiescence and that the disc is larger during outburst than quiescence. This is consistent with an expansion of the outer disc radius due to the presence of high viscosity material associated with the outburst, followed by a contraction in quiescence due to the accretion of low angular momentum material. We note that the long outbursts appear to be triggered by a short outburst, which is also observed in the super-outbursts of SU UMa dwarf novae as observed using Kepler.

A HIGH-VELOCITY BULGE RR LYRAE VARIABLE ON A HALO-LIKE ORBIT

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

Kunder, Andrea; Storm, J.; Rich, R. M.

2015-07-20

We report on the RR Lyrae variable star, MACHO 176.18833.411, located toward the Galactic bulge and observed within the data from the ongoing Bulge RR Lyrae Radial Velocity Assay, which has the unusual radial velocity of −372 ± 8 km s{sup −1} and true space velocity of −482 ± 22 km s{sup −1} relative to the Galactic rest frame. Located less than 1 kpc from the Galactic center and toward a field at (l, b) = (3, −2.5), this pulsating star has properties suggesting it belongs to the bulge RR Lyrae star population, yet a velocity indicating it is abnormal,more » at least with respect to bulge giants and red clump stars. We show that this star is most likely a halo interloper and therefore suggest that halo contamination is not insignificant when studying metal-poor stars found within the bulge area, even for stars within 1 kpc of the Galactic center. We discuss the possibility that MACHO 176.18833.411 is on the extreme edge of the bulge RR Lyrae radial velocity distribution, and also consider a more exotic scenario in which it is a runaway star moving through the Galaxy.« less

A Near-infrared RR Lyrae Census along the Southern Galactic Plane: The Milky Way’s Stellar Fossil Brought to Light

NASA Astrophysics Data System (ADS)

Dékány, István; Hajdu, Gergely; Grebel, Eva K.; Catelan, Márcio; Elorrieta, Felipe; Eyheramendy, Susana; Majaess, Daniel; Jordán, Andrés

2018-04-01

RR Lyrae stars (RRLs) are tracers of the Milky Way’s fossil record, holding valuable information on its formation and early evolution. Owing to the high interstellar extinction endemic to the Galactic plane, distant RRLs lying at low Galactic latitudes have been elusive. We attained a census of 1892 high-confidence RRLs by exploiting the near-infrared photometric database of the VVV survey’s disk footprint spanning ∼70° of Galactic longitude, using a machine-learned classifier. Novel data-driven methods were employed to accurately characterize their spatial distribution using sparsely sampled multi-band photometry. The RRL metallicity distribution function (MDF) was derived from their K s -band light-curve parameters using machine-learning methods. The MDF shows remarkable structural similarities to both the spectroscopic MDF of red clump giants and the MDF of bulge RRLs. We model the MDF with a multi-component density distribution and find that the number density of stars associated with the different model components systematically changes with both the Galactocentric radius and vertical distance from the Galactic plane, equivalent to weak metallicity gradients. Based on the consistency with results from the ARGOS survey, three MDF modes are attributed to the old disk populations, while the most metal-poor RRLs are probably halo interlopers. We propose that the dominant [Fe/H] component with a mean of ‑1 dex might correspond to the outskirts of an ancient Galactic spheroid or classical bulge component residing in the central Milky Way. The physical origins of the RRLs in this study need to be verified by kinematical information.

Galactic archaeology for amateur astronomers: RR Lyrae stars as tracers of the Milky Way formation

NASA Astrophysics Data System (ADS)

Carballo-Bello, Julio A.; Martínez-Delgado, David; Fliri, Jürgen

2011-06-01

Cosmological models predict that large galaxies like the Milky Way formed from the accretion of smaller stellar systems. The most spectacular of these merger events are stellar tidal streams, rivers of stars and dark matter that envelop the discs of spiral galaxies. We present a research project for a collaboration with amateur astronomers in the study of the formation process of our Galaxy. The main objective is the search for RR Lyrae variable stars in the known stellar streams (Sagitarius, Monoceros, Orphan, etc) a project that can be carried out using small telescopes. The catalogue of candidate variable stars were selected from SDSS data based in colour criteria and it will be sent to interested amateur astronomers who wish to participate in scientific research in one of the most active and competitive topics in Galactic astronomy.

RR Lyrae in XSTPS: The halo density profile in the north galactic cap

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

Faccioli, L.; Smith, M. C.; Yuan, H.-B.

We present a catalog of RR Lyrae stars (RRLs) observed by the Xuyi Schmidt Telescope Photometric Survey (XSTPS). The area we consider is located in the north Galactic cap, covering ≈376.75 deg{sup 2} at α ≈ 150° and δ ≈ 27° down to a magnitude limit of i ≈ 19. Using the variability information afforded by the multi-epoch nature of our XSTPS data, combined with colors from the Sloan Digital Sky Survey, we are able to identify candidate RRLs. We find 318 candidates, derive distances to them, and estimate the detection efficiency. The majority of our candidates have more thanmore » 12 observations, and for these we are able to calculate periods. These also allow us to estimate our contamination level, which we predict is between 30% and 40%. Finally, we use the sample to probe the halo density profile in the 9-49 kpc range and find that it can be well fitted by a double power law. We find good agreement between this model and the models derived for the south Galactic cap using the Watkins et al. and Sesar et al. RRL data sets, after accounting for possible contamination in our data set from Sagittarius stream members. We consider non-spherical double power-law models of the halo density profile and again find agreement with literature data sets, although we have limited power to constrain the flattening due to our small survey area. Much tighter constraints will be placed by current and future wide-area surveys, most notably ESA's astrometric Gaia mission. Our analysis demonstrates that surveys with a limited number of epochs can effectively be mined for RRLs. Our complete sample is provided as accompanying online material; as an example the first few entries of each electronic table are shown in the text.« less

RR Lyrae in XSTPS: The Halo Density Profile in the North Galactic Cap

NASA Astrophysics Data System (ADS)

Faccioli, L.; Smith, M. C.; Yuan, H.-B.; Zhang, H.-H.; Liu, X.-W.; Zhao, H.-B.; Yao, J.-S.

2014-06-01

We present a catalog of RR Lyrae stars (RRLs) observed by the Xuyi Schmidt Telescope Photometric Survey (XSTPS). The area we consider is located in the north Galactic cap, covering ≈376.75 deg2 at α ≈ 150° and δ ≈ 27° down to a magnitude limit of i ≈ 19. Using the variability information afforded by the multi-epoch nature of our XSTPS data, combined with colors from the Sloan Digital Sky Survey, we are able to identify candidate RRLs. We find 318 candidates, derive distances to them, and estimate the detection efficiency. The majority of our candidates have more than 12 observations, and for these we are able to calculate periods. These also allow us to estimate our contamination level, which we predict is between 30% and 40%. Finally, we use the sample to probe the halo density profile in the 9-49 kpc range and find that it can be well fitted by a double power law. We find good agreement between this model and the models derived for the south Galactic cap using the Watkins et al. and Sesar et al. RRL data sets, after accounting for possible contamination in our data set from Sagittarius stream members. We consider non-spherical double power-law models of the halo density profile and again find agreement with literature data sets, although we have limited power to constrain the flattening due to our small survey area. Much tighter constraints will be placed by current and future wide-area surveys, most notably ESA's astrometric Gaia mission. Our analysis demonstrates that surveys with a limited number of epochs can effectively be mined for RRLs. Our complete sample is provided as accompanying online material; as an example the first few entries of each electronic table are shown in the text.

Image-Subtraction Photometry of Variable Stars in the Field of the Globular Cluster NGC 6934

NASA Astrophysics Data System (ADS)

Kaluzny, J.; Olech, A.; Stanek, K. Z.

2001-03-01

We present CCD BVI photometry of 85 variable stars from the field of the globular cluster NGC 6934. The photometry was obtained with the image subtraction package ISIS. 35 variables are new identifications: 24 RRab stars, five RRc stars, two eclipsing binaries of W UMa-type, one SX Phe star, and three variables of other types. Both detected contact binaries are foreground stars. The SX Phe variable belongs most likely to the group of cluster blue stragglers. Large number of newly found RR Lyr variables in this cluster, as well as in other clusters recently observed by us, indicates that total RR Lyr population identified up to date in nearby galactic globular clusters is significantly (>30%) incomplete. Fourier decomposition of the light curves of RR Lyr variables was used to estimate the basic properties of these stars. From the analysis of RRc variables we obtain a mean mass of M=0.63 Msolar, luminosity logL/Lsolar=1.72, effective temperature Teff=7300 and helium abundance Y=0.27. The mean values of the absolute magnitude, metallicity (on Zinn's scale) and effective temperature for RRab variables are MV=0.81, [Fe/H]=-1.53 and Teff=6450, respectively. From the B-V color at minimum light of the RRab variables we obtained the color excess to NGC 6934 equal to E(B-V)=0.09+/-0.01. Different calibrations of absolute magnitudes of RRab and RRc available in literature were used to estimate apparent distance modulus of the cluster: (m-M)V=16.09+/-0.06. We note a likely error in the zero point of the HST-based V-band photometry of NGC 6934 recently presented by Piotto et al. Among analyzed sample of RR Lyr stars we have detected a short period and low amplitude variable which possibly belongs to the group of second overtone pulsators (RRe subtype variables). The BVI photometry of all variables is available electronically via anonymous ftp. The complete set of the CCD frames is available upon request. Based on observations obtained with the 1.2 m Telescope at the F. L

VizieR Online Data Catalog: MV Lyr - bursts and periods (Pavlenko, 1998)

NASA Astrophysics Data System (ADS)

Pavlenko, E. P.

2001-01-01

The analysis of photometric behavior of the nova-like star MV Lyr in B in the low brightness state in 1995-1996 based on the observations performed at the Crimean Astrophysical Observatory with the MTM-500 television system was presented. (1 data file).

RR Lyrae Stars in M4

NASA Astrophysics Data System (ADS)

Kuehn, Charles A.; Moskalik, Pawel; Drury, Jason A.

2017-10-01

Observations by Kepler/K2 have revolutionized the study of RR Lyrae stars by allowing the detection of new phenomna, such as low amplitude additional modes and period doubling, which had not previously been seen from the ground. During campaign 2, K2 observed the globular cluster M4, providiing the first opportunity to study a sizeable group of RR Lyrae stars that belong to a single population; the other RR Lyrae stars that have been observed from space are field stars in the galactic halo and thus belong to an assortment of populations. In this poster we present the results of our study of the RR Lyrae variables in M4 from K2 photometry. We have identified additional, low amplitude pulsation modes in both observed RRc stars. In 3 RRab stars we have found the Blazhko effect with periods of 16.6d, 22.4d, and 44.5d.

WEAK GALACTIC HALO-DWARF SPHEROIDAL CONNECTION FROM RR LYRAE STARS

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

Fiorentino, Giuliana; Bono, Giuseppe; Monelli, Matteo

2015-01-01

We discuss the role that dwarf galaxies may have played in the formation of the Galactic halo (Halo) using RR Lyrae stars (RRL) as tracers of their ancient stellar component. The comparison is performed using two observables (periods, luminosity amplitudes) that are reddening and distance independent. Fundamental mode RRL in 6 dwarf spheroidals (dSphs) and 11 ultra faint dwarf galaxies (∼1300) show a Gaussian period distribution well peaked around a mean period of (Pab) = 0.610 ± 0.001 days (σ = 0.03). The Halo RRL (∼15,000) are characterized by a broader period distribution. The fundamental mode RRL in all the dSphs apart from Sagittariusmore » are completely lacking in High Amplitude Short Period (HASP) variables, defined as those having P ≲ 0.48 days and A{sub V} ≥ 0.75 mag. Such variables are not uncommon in the Halo and among the globular clusters and massive dwarf irregulars. To further interpret this evidence, we considered 18 globulars covering a broad range in metallicity (–2.3 ≲ [Fe/H] ≲ –1.1) and hosting more than 35 RRL each. The metallicity turns out to be the main parameter, since only globulars more metal-rich than [Fe/H] ∼ –1.5 host RRL in the HASP region. This finding suggests that dSphs similar to the surviving ones do not appear to be the major building-blocks of the Halo. Leading physical arguments suggest an extreme upper limit of ∼50% to their contribution. On the other hand, massive dwarfs hosting an old population with a broad metallicity distribution (Large Magellanic Cloud, Sagittarius) may have played a primary role in the formation of the Halo.« less

Galactic bulge population II Cepheids in the VVV survey: period-luminosity relations and a distance to the Galactic centre

NASA Astrophysics Data System (ADS)

Bhardwaj, A.; Rejkuba, M.; Minniti, D.; Surot, F.; Valenti, E.; Zoccali, M.; Gonzalez, O. A.; Romaniello, M.; Kanbur, S. M.; Singh, H. P.

2017-09-01

Context. Multiple stellar populations of different ages and metallicities reside in the Galactic bulge that trace its structure and provide clues to its formation and evolution. Aims: We present the near-infrared observations of population II Cepheids in the Galactic bulge from VISTA Variables in the Vía Láctea (VVV) survey. The JHKs photometry together with optical data from Optical Gravitational Lensing Experiment (OGLE) survey provide an independent estimate of the distance to the Galactic centre. The old, metal-poor and low-mass population II Cepheids are also investigated as useful tracers for the structure of the Galactic bulge. Methods: We identify 340 population II Cepheids in the VVV survey Galactic bulge catalogue based on their match with the OGLE-III Catalogue. The single-epoch JH and multi-epoch Ks observations complement the accurate periods and optical (VI) mean-magnitudes from OGLE. The sample consisting of BL Herculis and W Virginis subtypes is used to derive period-luminosity relations after correcting mean-magnitudes for the extinction. Our Ks-band period-luminosity relation, Ks = -2.189(0.056) [log (P)-1] + 11.187(0.032), is consistent with published work for BL Herculis and W Virginis variables in the Large Magellanic Cloud. Results: We present a combined OGLE-III and VVV catalogue with periods, classification, mean magnitudes, and extinction for 264 Galactic bulge population II Cepheids that have good-quality Ks-band light curves. The absolute magnitudes for population II Cepheids and RR Lyraes calibrated using Gaia and Hubble Space Telescope parallaxes, together with calibrated magnitudes for Large Magellanic Cloud population II Cepheids, are used to obtain a distance to the Galactic centre, R0 = 8.34 ± 0.03(stat.) ± 0.41(syst.), which changes by with different extinction laws. While noting the limitation of small number statistics, we find that the present sample of population II Cepheids in the Galactic bulge shows a nearly spheroidal

Blazhko Effect

NASA Technical Reports Server (NTRS)

Teays, Terry

1996-01-01

The cause of the Blazhko effect, the long-term modulation of the light and radial velocity curves of some RR Lyr stars, is still not understood. The observational characteristics of the Blazhko effect are discussed. Some preliminary results are presented from two recent campaigns to observe RR Lyr, using the International Ultraviolet Explorer along with ground-based spectroscopy and photometry, throughout a pulsation cycle, at a variety of Blazhko phases. A set of ultraviolet light curves have been generated from low dispersion IUE spectra. In addition, the (visual) light curves from IUE's Fine Error Sensor are analyzed using the Fourier decomposition technique. The values of the parameters Psi(sub 21) and R(sub 21) at different Blazhko phases of RR Lyr span the range of values found for non-Blazhko variables of similar period.

VizieR Online Data Catalog: Gaia DR1 and OGLE variable stars (Udalski+, 2016)

NASA Astrophysics Data System (ADS)

Udalski, A.; Soszynski, I.; Skowron, D. M.; Skowron, J.; Pietrukowicz, P.; Mroz, P.; Poleski, R.; Szymanski, M. K.; Kozlowski, S.; Wyrzykowski, L.; Ulaczyk, K.; Pawlak, M.

2018-04-01

To assess the Gaia dataset of Cepheids and RR Lyr stars presented in the Gaia DR1 (Clementini et al., 2016A&A...595A.133C, Cat. I/337) we cross-identified the sample of 3194 variable stars presented on the final Gaia pipeline list (599 Cepheid and 2595 RR Lyr candidates) with the OGLE detected objects using RA/DEC coordinates provided within Gaia DR1. (4 data files).

Machine-learned Identification of RR Lyrae Stars from Sparse, Multi-band Data: The PS1 Sample

NASA Astrophysics Data System (ADS)

Sesar, Branimir; Hernitschek, Nina; Mitrović, Sandra; Ivezić, Željko; Rix, Hans-Walter; Cohen, Judith G.; Bernard, Edouard J.; Grebel, Eva K.; Martin, Nicolas F.; Schlafly, Edward F.; Burgett, William S.; Draper, Peter W.; Flewelling, Heather; Kaiser, Nick; Kudritzki, Rolf P.; Magnier, Eugene A.; Metcalfe, Nigel; Tonry, John L.; Waters, Christopher

2017-05-01

RR Lyrae stars may be the best practical tracers of Galactic halo (sub-)structure and kinematics. The PanSTARRS1 (PS1) 3π survey offers multi-band, multi-epoch, precise photometry across much of the sky, but a robust identification of RR Lyrae stars in this data set poses a challenge, given PS1's sparse, asynchronous multi-band light curves (≲ 12 epochs in each of five bands, taken over a 4.5 year period). We present a novel template fitting technique that uses well-defined and physically motivated multi-band light curves of RR Lyrae stars, and demonstrate that we get accurate period estimates, precise to 2 s in > 80 % of cases. We augment these light-curve fits with other features from photometric time-series and provide them to progressively more detailed machine-learned classification models. From these models, we are able to select the widest (three-fourths of the sky) and deepest (reaching 120 kpc) sample of RR Lyrae stars to date. The PS1 sample of ˜45,000 RRab stars is pure (90%) and complete (80% at 80 kpc) at high galactic latitudes. It also provides distances that are precise to 3%, measured with newly derived period-luminosity relations for optical/near-infrared PS1 bands. With the addition of proper motions from Gaia and radial velocity measurements from multi-object spectroscopic surveys, we expect the PS1 sample of RR Lyrae stars to become the premier source for studying the structure, kinematics, and the gravitational potential of the Galactic halo. The techniques presented in this study should translate well to other sparse, multi-band data sets, such as those produced by the Dark Energy Survey and the upcoming Large Synoptic Survey Telescope Galactic plane sub-survey.

VizieR Online Data Catalog: Field RR Lyrae stars (Liska+, 2016)

NASA Astrophysics Data System (ADS)

Liska, J.; Skarka, M.; Zejda, M.; Mikulasek, Z.; de Villiers, S. N.

2016-05-01

Differential photometry for VX Her in 'table1.dat' file. New photometric measurements for VX Her were performed at Masaryk University Observatory, Brno, Czech Republic during 13 nights (April-August 2014) with 0.6-m (24-inch) Newtonian telescope, CCD G2-0402, in BVRI bands. CCD images were calibrated in a standard way (dark frame and flat field corrections). The C-Munipack software (Motl 2009) was used for this processing as well as for differential photometry. TYC 1510-269-1 and TYC 1510-149-1 were used as comparison and check stars, respectively. Differential photometry for AT Ser and SS Leo is in 'table2.dat' file. New photometric measurements for these two stars were obtained using 1-inch refractor (a photographic lens Sonnar 4/135mm, lens focal ratio/focal length) and ATIK 16IC CCD camera with green photometric filter with similar throughput as the Johnson V filter. Exposures were 30s and each five frames were combined to a single image to achieve a better signal-to-noise ratio. The time resolution of a such combined frame is about 170s. The comparison stars were HD 142799 for AT Ser and HD 100763 for SS Leo. List with candidates for binaries with RR Lyrae component - RRLyrBinCan database (version 2016 May 5) is in 'table3.dat' file. 'table4.dat' file contains false-positives binary candidates among RR Lyrae stars. 'table5.dat' and 'table6.dat' files contain used maxima timings given in GEOS RR Lyr database, or newly determined in this study. (7 data files).

V571 Lyr is a Multiple System (Abstract)

NASA Astrophysics Data System (ADS)

Billings, G.

2016-12-01

(Abstract only) V571 Lyr (GSC 3116-1047) was discovered by the ROTSE survey to be an EA-type eclipsing binary with 1.25-day period. Primary and secondary eclipses are very similar, with depth V = 0.58 magnitude. In 2000, the then-active AAVSO "EB Team" started observing it, to refine the period estimate. A few eclipses were readily found, and a revised period computed. Subsequent eclipses diverged from the revised linear ephemeris by more than the expected amount of error, so observations were continued. Now, more than 100 time-of-minimum observations, over 15 years, clearly show that V571 Lyr is a triple system, with a third-body orbital period of 5.013 ± 0.008 years, and eccentricity of 0.74 ± 0.03. Our orbit fit also yields a period for the close pair, of 1.252 596 66(6) days. After removing the third-body light-time effect, the eclipse-time residuals still show larger than expected scatter, and possibly non-randomness, perhaps due to significant starspots and/or additional bodies in the system. The color of the system is B-V = 0.52 ± 0.01, corresponding to spectral type F7V, and we obtained a spectrum that we classify as F7V ± 2. The mass function computed from the fitted third-body orbit yields a minimum mass of 1.0 ± 0.1 Msolar, corresponding to a spectral range of F9V to G5V for the third star. We assume the two stars of the close pair are very similar, so the remaining light in eclipses (59%) is consistent with total eclipses and 3rd light from a star slightly dimmer than each of the pair.

Studying RR Lyrae Stars in M4 with K2

NASA Astrophysics Data System (ADS)

Kuehn, Charles A.; Drury, Jason; Moskalik, Pawel

2017-01-01

Observations by Kepler/K2 have revolutionized the study of RR Lyrae stars by allowing the detection of new phenomena, such as low amplitude additional modes and period doubling, which had not previously been seen from the ground. During its campaign 2, K2 observed the globular cluster M4, providing the first opportunity to study a sizeable group of RR Lyrae stars that belong to a single population; the other RR Lyrae stars that have been observed from space are field stars in the galactic halo and thus belong to an assortment of populations. We present the results of our study of the RR Lyrae variables in M4 from K2 photometry. We have identified additional, low amplitude pulsation modes in the two observed RRc stars. In three RRab stars we have found the Blazhko effect with periods of 16.6 days, 22.4 days, and 44.5 days.

The first all-sky view of the Milky Way stellar halo with Gaia+2MASS RR Lyrae

NASA Astrophysics Data System (ADS)

Iorio, G.; Belokurov, V.; Erkal, D.; Koposov, S. E.; Nipoti, C.; Fraternali, F.

2018-02-01

We exploit the first Gaia data release to study the properties of the Galactic stellar halo as traced by RR Lyrae. We demonstrate that it is possible to select a pure sample of RR Lyrae using only photometric information available in the Gaia+2MASS catalogue. The final sample contains about 21 600 RR Lyrae covering an unprecedented fraction ( ˜ 60 per cent) of the volume of the Galactic inner halo (R < 28 kpc). We study the morphology of the stellar halo by analysing the RR Lyrae distribution with parametric and non-parametric techniques. Taking advantage of the uniform all-sky coverage, we test halo models more sophisticated than usually considered in the literature, such as those with varying flattening, tilts and/or offset of the halo with respect to the Galactic disc. A consistent picture emerges: the inner halo is well reproduced by a smooth distribution of stars settled on triaxial density ellipsoids. The shortest axis is perpendicular to the Milky Way's disc, while the longest axis forms an angle of ˜70° with the axis connecting the Sun and the Galactic Centre. The elongation along the major axis is mild (p = 1.27), and the vertical flattening is shown to evolve from a squashed state with q ≈ 0.57 in the centre to a more spherical q ≈ 0.75 at the outer edge of our data set. Within the radial range probed, the density profile of the stellar halo is well approximated by a single power law with exponent α = -2.96. We do not find evidence of tilt or offset of the halo with respect to the Galaxy's disc.

Establishing the Galactic Centre distance using VVV Bulge RR Lyrae variables

NASA Astrophysics Data System (ADS)

Majaess, D.; Dékány, I.; Hajdu, G.; Minniti, D.; Turner, D.; Gieren, W.

2018-06-01

This study's objective was to exploit infrared VVV (VISTA Variables in the Via Lactea) photometry for high latitude RRab stars to establish an accurate Galactic Centre distance. RRab candidates were discovered and reaffirmed (n=4194) by matching Ks photometry with templates via χ 2 minimization, and contaminants were reduced by ensuring targets adhered to a strict period-amplitude (Δ Ks) trend and passed the Elorietta et al. classifier. The distance to the Galactic Centre was determined from a high latitude Bulge subsample (|b|>4°, R_{GC}=8.30 ± 0.36 kpc, random uncertainty is relatively negligible), and importantly, the comparatively low color-excess and uncrowded location mitigated uncertainties tied to the extinction law, the magnitude-limited nature of the analysis, and photometric contamination. Circumventing those problems resulted in a key uncertainty being the M_{Ks} relation, which was derived using LMC RRab stars (M_{Ks}=-(2.66± 0.06) log {P}-(1.03± 0.06), (J-Ks)0=(0.31± 0.04) log {P} + (0.35± 0.02), assuming μ _{0,LMC}=18.43). The Galactic Centre distance was not corrected for the cone-effect. Lastly, a new distance indicator emerged as brighter overdensities in the period-magnitude-amplitude diagrams analyzed, which arise from blended RRab and red clump stars. Blending may thrust faint extragalactic variables into the range of detectability.

Distant Galactic Halo Substructures Observed by the Palomar Transient Factory

NASA Astrophysics Data System (ADS)

Sesar, Branimir

2013-01-01

Characterization of Galactic halo substructures is important as their kinematic and chemical properties help constrain the properties of the Galactic dark matter halo, the formation history of the Milky Way, and the galaxy formation process in general. The best practical choice for finding distant halo substructures are pulsating RR Lyrae stars, due to their intrinsic brightness (M_V = 0.6 mag) and distinct light curves. I will present kinematic and chemical properties of two distant halo substructures that were traced using RR Lyrae stars observed by the Palomar Transient Factory. One of these substructures, located at 90 kpc from the Sun in the Cancer constellation, consists of two groups of RR Lyrae stars moving away from the Galaxy at ~80 and ~20 km/s, respectively. The second substructure is located at ~65 kpc from the Sun in the Hercules constellation. The kinematics of RR Lyrae stars tracing this substructure suggest a presence of 2 or 3 stellar streams extending in the similar direction on the sky. Due to their spatial extent, both of these substructures are clearly disrupted and would be very difficult to detect using tradiitonal techniques such as the color-magnitude diagram filtering.

HST/ACS Observations of RR Lyrae Stars in Six Ultra-Deep Fields of M31

NASA Technical Reports Server (NTRS)

Jeffery, E. J.; Smith, E.; Brown, T. M.; Sweigart, A. V.; Kalirai, J. S.; Ferguson, H. C.; Guhathakurta, P.; Renzini, A.; Rich, R. M.

2010-01-01

We present HST/ACS observations of RR Lyrae variable stars in six ultra deep fields of the Andromeda galaxy (M31), including parts of the halo, disk, and giant stellar stream. Past work on the RR Lyrae stars in M31 has focused on various aspects of the stellar populations that make up the galaxy s halo, including their distances and metallicities. This study builds upon this previous work by increasing the spatial coverage (something that has been lacking in previous studies) and by searching for these variable stars in constituents of the galaxy not yet explored. Besides the 55 RR Lyrae stars we found in our initial field located 11kpc from the galactic nucleus, we find additional RR Lyrae stars in four of the remaining five ultra deep fields as follows: 21 in the disk, 24 in the giant stellar stream, 3 in the halo field 21kpc from the galactic nucleus, and 5 in one of the halo fields at 35kpc. No RR Lyrae were found in the second halo field at 35kpc. The RR Lyrae populations of these fields appear to mostly be of Oosterhoff I type, although the 11kpc field appears to be intermediate or mixed. We will discuss the properties of these stars including period and reddening distributions. We calculate metallicities and distances for the stars in each of these fields using different methods and compare the results, to an extent that has not yet been done. We compare these methods not just on RR Lyrae in our M31 fields, but also on a data set of Milky Way field RR Lyrae stars.

Relationship between the Elemental Abundances and the Kinematics of Galactic-Field RR Lyrae Stars

NASA Astrophysics Data System (ADS)

Marsakov, V. A.; Gozha, M. L.; Koval, V. V.

2018-01-01

Data of our compiled catalog containing the positions, velocities, and metallicities of 415 RR Lyrae variable stars and the relative abundances [el/Fe] of 12 elements for 101 RR Lyrae stars, including four α elements (Mg, Ca, Si, and Ti), are used to study the relationships between the chemical and spatial-kinematic properties of these stars. In general, the dependences of the relative abundances of α elements on metallicity and velocity for the RR Lyrae stars are approximately the same as those for field dwarfs. Despite the usual claim that these stars are old, among them are representatives of the thin disk, which is the youngest subsystem of the Galaxy. Attention is called to the problem of lowmetallicity RR Lyrae stars. Most RR Lyrae stars that have the kinematic properties of thick disk stars have metallicities [Fe/H] < -1.0 and high ratios [α/Fe] ≈ 0.4, whereas only about 10% of field dwarfs belonging to the so-called "low-metallicity tail" have this chemical composition. At the same time, there is a sharp change in [α/Fe] in RR Lyrae stars belonging just to the thick disk, providing evidence for a long period of formation of this subsystem. The chemical compositions of SDSS J1707+58, V455 Oph, MACHO176.18833.411, V456 Ser, and BPSCS 30339-046 do not correspond to their kinematics.While the first three of these stars belong to the halo, according to their kinematics, the last two belong to the thick disk. It is proposed that they are all most likely extragalactic, but the possible appearance of some of them in the solar neighborhood as a result of the gravitational action of the bar on field stars cannot be ruled out.

Pushing the boundaries: probing the halo of the Milky Way beyond 100 kpc with RR Lyrae

NASA Astrophysics Data System (ADS)

Carlin, Jeffrey L.; Medina, Gustavo; Munoz, Ricardo R.; Vivas, Anna Katherina; Willman, Beth

2018-01-01

Stars in the outermost halo of the Milky Way are vital tracers of the mass of our Galaxy. Furthermore, beyond ~100 kpc from the Galactic center, most (or perhaps all) of the stars are likely to be in faint dwarf galaxies or tidal debris from recently accreted dwarfs, making the outer reaches of the Galaxy important for understanding the Milky Way’s accretion history. However, confirmed stars are scarce at these distances because they are difficult to securely identify among the more numerous foreground stars. Pulsating variables such as RR Lyrae are ideal probes of the distant halo because they are readily identified in time-series data, are intrinsically bright and thus can be seen at large distances, and follow well-known period-luminosity relations that enable precise distance measurements. We present results from our program to find RR Lyrae using deep DECam time series data (from the HiTS supernova survey as well as our own observing program) covering ~300 square degrees. Our sample of distant RR Lyrae more than doubles the number of known Milky Way stars beyond distances of ~150 kpc. Among these, we find two distinct groups of two and three stars that are members of the Leo IV and Leo V ultra-faint dwarf galaxies, located at distances of ~145 kpc and ~175 kpc, respectively. We derive the stellar density as a function of Galactocentric radius, extending to more than 250 kpc from the Galactic center. This sample of RR Lyrae provides a set of important probes of the mass of the Milky Way and the accretion origin of the outer Galactic halo.

The Palomar Transient Factory and RR Lyrae: The Metallicity–Light Curve Relation Based on ab-type RR Lyrae in the Kepler Field

NASA Astrophysics Data System (ADS)

Ngeow, Chow-Choong; Yu, Po-Chieh; Bellm, Eric; Yang, Ting-Chang; Chang, Chan-Kao; Miller, Adam; Laher, Russ; Surace, Jason; Ip, Wing-Huen

2016-12-01

The wide-field synoptic sky surveys, known as the Palomar Transient Factory (PTF) and the intermediate Palomar Transient Factory (iPTF), will accumulate a large number of known and new RR Lyrae. These RR Lyrae are good tracers to study the substructure of the Galactic halo if their distance, metallicity, and galactocentric velocity can be measured. Candidates of halo RR Lyrae can be identified from their distance and metallicity before requesting spectroscopic observations for confirmation. This is because both quantities can be obtained via their photometric light curves, because the absolute V-band magnitude for RR Lyrae is correlated with metallicity, and the metallicity can be estimated using a metallicity–light curve relation. To fully utilize the PTF and iPTF light-curve data in related future work, it is necessary to derive the metallicity–light curve relation in the native PTF/iPTF R-band photometric system. In this work, we derived such a relation using the known ab-type RR Lyrae located in the Kepler field, and it is found to be {[{Fe}/{{H}}]}PTF}=-4.089{--}7.346P+1.280{φ }31 (where P is pulsational period and {φ }31 is one of the Fourier parameters describing the shape of the light curve), with a dispersion of 0.118 dex. We tested our metallicity–light curve relation with new spectroscopic observations of a few RR Lyrae in the Kepler field, as well as several data sets available in the literature. Our tests demonstrated that the derived metallicity–light curve relation could be used to estimate metallicities for the majority of the RR Lyrae, which are in agreement with the published values.

The Milky Way's Circular Velocity Curve and Its Constraint on the Galactic Mass with RR Lyrae Stars

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

Ablimit, Iminhaji; Zhao, Gang, E-mail: iminhaji@nao.cas.cn, E-mail: gzhao@nao.cas.cn

We present a sample of 1148 ab-type RR Lyrae (RRLab) variables identified from Catalina Surveys Data Release 1, combined with SDSS DR8 and LAMOST DR4 spectral data. We first use a large sample of 860 Galactic halo RRLab stars and derive the circular velocity distributions for the stellar halo. With the precise distances and carefully determined radial velocities (the center-of-mass radial velocities) and by considering the pulsation of the RRLab stars in our sample, we can obtain a reliable and comparable stellar halo circular velocity curve. We follow two different prescriptions for the velocity anisotropy parameter β in the Jeansmore » equation to study the circular velocity curve and mass profile. Additionally, we test two different solar peculiar motions in our calculation. The best result we obtained with the adopted solar peculiar motion 1 of ( U , V , W ) = (11.1, 12, 7.2) km s{sup −1} is that the enclosed mass of the Milky Way within 50 kpc is (3.75 ± 1.33) × 10{sup 11} M {sub ⊙} based on β = 0 and the circular velocity 180 ± 31.92 (km s{sup −1}) at 50 kpc. This result is consistent with dynamical model results, and it is also comparable to the results of previous similar works.« less

The eclipsing system V404 Lyr: Light-travel times and γ Doradus pulsations

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

Lee, Jae Woo; Kim, Seung-Lee; Hong, Kyeongsoo

We present the physical properties of V404 Lyr exhibiting eclipse timing variations and multiperiodic pulsations from all historical data including the Kepler and SuperWASP observations. Detailed analyses of 2922 minimum epochs showed that the orbital period has varied through a combination of an upward-opening parabola and two sinusoidal variations, with periods of P {sub 3} = 649 days and P {sub 4} = 2154 days and semi-amplitudes of K {sub 3} = 193 s and K {sub 4} = 49 s, respectively. The secular period increase at a rate of +1.41 × 10{sup –7} days yr{sup –1} could be interpretedmore » as a combination of the secondary to primary mass transfer and angular momentum loss. The most reasonable explanation for both sinusoids is a pair of light-travel-time effects due to two circumbinary objects with projected masses of M {sub 3} = 0.47 M {sub ☉} and M {sub 4} = 0.047 M {sub ☉}. The third-body parameters are consistent with those calculated using the Wilson-Devinney binary code. For the orbital inclinations i {sub 4} ≳ 43°, the fourth component has a mass within the hydrogen-burning limit of ∼0.07 M {sub ☉}, which implies that it is a brown dwarf. A satisfactory model for the Kepler light curves was obtained by applying a cool spot to the secondary component. The results demonstrate that the close eclipsing pair is in a semi-detached, but near-contact, configuration; the primary fills approximately 93% of its limiting lobe and is larger than the lobe-filling secondary. Multiple frequency analyses were applied to the light residuals after subtracting the synthetic eclipsing curve from the Kepler data. This revealed that the primary component of V404 Lyr is a γ Dor type pulsating star, exhibiting seven pulsation frequencies in the range of 1.85-2.11 day{sup –1} with amplitudes of 1.38-5.72 mmag and pulsation constants of 0.24-0.27 days. The seven frequencies were clearly identified as high-order low-degree gravity-mode oscillations which might be

The Search for RR Lyrae Variables in the Dark Energy Survey

NASA Astrophysics Data System (ADS)

Nielsen, Chandler; Marshall, Jennifer L.; Long, James

2017-01-01

RR Lyrae variables are stars with a characteristic relationship between magnitude and phase and whose distances can be easily determined, making them extremely valuable in mapping and analyzing galactic substructure. We present our method of searching for RR Lyrae variable stars using data extracted from the Dark Energy Survey (DES). The DES probes for stars as faint as i = 24.3. Finding such distant RR Lyrae allows for the discovery of objects such as dwarf spheroidal tidal streams and dwarf galaxies; in fact, at least one RR Lyrae has been discovered in each of the probed dwarf spheroidal galaxies orbiting the Milky Way (Baker & Willman 2015). In turn, these discoveries may ultimately resolve the well-known missing satellite problem, in which theoretical simulations predict many more dwarf satellites than are observed in the local Universe. Using the Lomb-Scargle periodogram to determine the period of the star being analyzed, we could display the relationship between magnitude and phase and visually determine if the star being analyzed was an RR Lyrae. We began the search in frequently observed regions of the DES footprint, known as the supernova fields. We then moved our search to known dwarf galaxies found during the second year of the DES. Unfortunately, we did not discover RR Lyrae in the probed dwarf galaxies; this method should be tried again once more observations are taken in the DES.

Wide-Field Variability Survey of the Globular Cluster M 79 and a New Period-Luminosity Relation for SX Phe Stars

NASA Astrophysics Data System (ADS)

Kopacki, G.

2015-03-01

We present the results of a search for variable stars in a 26×39 arcmin2 field around globular cluster M 79 (NGC 1904). The search was made by means of an extended version of image subtraction, which allows us to analyze in a uniform manner CCD frames obtained with different telescopes and cameras of different sizes and resolutions. The search resulted in finding 20 new variable stars, among which 13 are cluster members. The members include one new RR Lyr star of subtype c, three SX Phe stars, and nine variable red giants. We also show that V7 is a W Vir star with a period of 13.985 d. Revised mean periods of RRab and RRc stars, ab=0.71 d and c=0.34 d, respectively, and relative percentage of RRc stars, Nc/(Nab+Nc)=45% confirm that M 79 belongs to the Oosterhoff II group of globular clusters. The mean V magnitude of the horizontal branch of M 79 based on ten RR Lyr stars has been estimated to be VHB=RR=16.11±0.03 mag. In one RRc star, V9, light changes with three close frequencies were detected, indicating excitation of nonradial modes. An SX Phe star, V18, is a double-mode pulsator with two radial modes excited, fundamental and first overtone. Moreover, we have discovered two SX Phe or δ Sct stars and one W UMa type system, all likely field objects. We also studied the period-luminosity relation for SX Phe stars. Using 62 fundamental and fundamentalized periods of radial double-mode and high-amplitude SX Phe stars known in Galactic globular clusters, we have derived the slope and zero point of this relation to be, -3.3±0.27 and 2.68±0.03 mag (at log(P/d)=-1.24), respectively.

Abundance of Chemical Elements in RR Lyrae Variables and their Kinematic Parameters

NASA Astrophysics Data System (ADS)

Gozha, M. L.; Marsakov, V. A.; Koval', V. V.

2018-03-01

A catalog of the chemical and spatial-kinematic parameters of 415 RR Lyrae variables (Lyrids) in the galactic field is compiled. Spectroscopic determinations of the relative abundances of 13 chemical elements in 101 of the RR Lyrae variables are collected from 25 papers published between 1995 and 2017. The data from different sources are reduced to a single solar abundance scale. The mean weighted chemical abundances are calculated with coefficients inversely proportional to the reported errors. An analysis of the deviations in the published relative abundances in each star from the mean square values calculated from them reveals an absence of systematic biases among the results from the various articles. The rectangular coordinates of 407 of the RR Lyrae variables and the components of the three-dimensional (3D) velocities of 401 of the stars are calculated using data from several sources. The collected data on the abundances of chemical elements produced by various nuclear fusion processes for the RR Lyrae variables of the field, as well as the calculated 3D velocities, can be used for studying the evolution of the Galaxy.

DISCOVERY OF RR LYRAE STARS IN THE NUCLEAR BULGE OF THE MILKY WAY

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

Minniti, Dante; Ramos, Rodrigo Contreras; Zoccali, Manuela

Galactic nuclei, such as that of the Milky Way, are extreme regions with high stellar densities, and in most cases, the hosts of a supermassive black hole. One of the scenarios proposed for the formation of the Galactic nucleus is merging of primordial globular clusters. An implication of this model is that this region should host stars that are characteristically found in old Milky Way globular clusters. RR Lyrae stars are primary distance indicators, well known representatives of old and metal-poor stellar populations, and therefore are regularly found in globular clusters. Here we report the discovery of a dozen RRmore » Lyrae type ab stars in the vicinity of the Galactic center, i.e., in the so-called nuclear stellar bulge of the Milky Way. This discovery provides the first direct observational evidence that the Galactic nuclear stellar bulge contains ancient stars (>10 Gyr old). Based on this we conclude that merging globular clusters likely contributed to the build-up of the high stellar density in the nuclear stellar bulge of the Milky Way.« less

VizieR Online Data Catalog: RR Lyrae in SDSS Stripe 82 (Suveges+, 2012)

NASA Astrophysics Data System (ADS)

Suveges, M.; Sesar, B.; Varadi, M.; Mowlavi, N.; Becker, A. C.; Ivezic, Z.; Beck, M.; Nienartowicz, K.; Rimoldini, L.; Dubath, P.; Bartholdi, P.; Eyer, L.

2013-05-01

We propose a robust principal component analysis framework for the exploitation of multiband photometric measurements in large surveys. Period search results are improved using the time-series of the first principal component due to its optimized signal-to-noise ratio. The presence of correlated excess variations in the multivariate time-series enables the detection of weaker variability. Furthermore, the direction of the largest variance differs for certain types of variable stars. This can be used as an efficient attribute for classification. The application of the method to a subsample of Sloan Digital Sky Survey Stripe 82 data yielded 132 high-amplitude delta Scuti variables. We also found 129 new RR Lyrae variables, complementary to the catalogue of Sesar et al., extending the halo area mapped by Stripe 82 RR Lyrae stars towards the Galactic bulge. The sample also comprises 25 multiperiodic or Blazhko RR Lyrae stars. (8 data files).

A cautionary tale of interpreting O-C diagrams: period instability in a classical RR Lyr Star Z CVn mimicking as a distant companion

NASA Astrophysics Data System (ADS)

Skarka, M.; Liška, J.; Dřevěný, R.; Guggenberger, E.; Sódor, Á.; Barnes, T. G.; Kolenberg, K.

2018-02-01

We present a comprehensive study of Z CVn, an RR Lyrae star that shows long-term cyclic variations of its pulsation period. A possible explanation suggested from the shape of the O-C diagram is the light travel-time effect, which we thoroughly examine. We used original photometric and spectroscopic measurements and investigated the period evolution using available maximum times spanning more than one century. If the binary hypothesis is valid, Z CVn orbits around a black hole with minimal mass of 56.5 M_{⊙} on a very wide (Porbit = 78.3 yr) and eccentric orbit (e = 0.63). We discuss the probability of the formation of a black hole-RR Lyrae pair, and, although we found it possible, there is no observational evidence of the black hole in the direction to Z CVn. However, the main objection against the binary hypothesis is the comparison of the systemic radial velocity curve model and spectroscopic observations that clearly show that Z CVn cannot be bound in such a binary. Therefore, the variations of pulsation period are likely intrinsic to the star. This finding represents a discovery/confirmation of a new type of cyclic period changes in RR Lyrae stars. By the analysis of our photometric data, we found that the Blazhko modulation with period of 22.931 d is strongly dominant in amplitude. The strength of the phase modulation varies and is currently almost undetectable. We also estimated photometric physical parameters of Z CVn and investigated their variations during the Blazhko cycle using the inverse Baade-Wesselink method.

Fourier Analysis of First-Overtone RR Lyrae Variables in the LMC

NASA Astrophysics Data System (ADS)

Clement, C. M.; Muzzin, A. V.; Rowe, J. F.; MACHO Collaboration

2002-05-01

Simon's (1989, ApJ, 343, L17) Fourier decomposition technique has been applied to the V magnitudes of the first-overtone RR Lyrae (RR1) variables in 16 LMC fields observed by the MACHO collaboration. The Fourier coefficients R21 and φ 31 derived for these stars have been compared with the coefficients of RR1 variables in the galactic globular clusters Omega Centauri, M2, M3, M5, M68, M107 (NGC 6171) and NGC 6441. Our analysis indicates that the majority of the LMC RR1 variables have coefficients similar to those in the Oosterhoff type I (OoI) clusters M3 and M5 and to the OoI variables in Omega Centauri. In a study of hydrodynamic pulsation models of first overtone RR Lyrae variables, Simon & Clement (1993, ApJ, 410, 526) found that the Fourier phase parameter φ 31 depends essentially on mass and luminosity. From this, we conclude that the masses and luminosities of most of the RR1 variables in the LMC are comparable to those of the OoI RR1 variables in Omega Centauri, M3 and M5, a fact that should be considered when RR Lyrae variables are used for determining the distance to the LMC. The MACHO collaboration includes C. Alcock, R. A. Allsman, D. R. Alves, T. S. Axelrod, A. C. Becker, D. P. Bennet, K. H. Cook, A. J. Drake, K. C. Freeman, M. Geha, K. Griest, M. J. Lehner, S. L. Marshall, D. Minniti, C. A. Nelson, B. A. Peterson, P. Popowski, M. R. Pratt, P. J. Quinn, C. W. Stubbs, W. Sutherland, T. Vandehel and D. L. Welch. This research has been supported in part by the Natural Sciences and Engineering Research Council of Canada.

A Data-driven Study of RR Lyrae Near-IR Light Curves: Principal Component Analysis, Robust Fits, and Metallicity Estimates

NASA Astrophysics Data System (ADS)

Hajdu, Gergely; Dékány, István; Catelan, Márcio; Grebel, Eva K.; Jurcsik, Johanna

2018-04-01

RR Lyrae variables are widely used tracers of Galactic halo structure and kinematics, but they can also serve to constrain the distribution of the old stellar population in the Galactic bulge. With the aim of improving their near-infrared photometric characterization, we investigate their near-infrared light curves, as well as the empirical relationships between their light curve and metallicities using machine learning methods. We introduce a new, robust method for the estimation of the light-curve shapes, hence the average magnitudes of RR Lyrae variables in the K S band, by utilizing the first few principal components (PCs) as basis vectors, obtained from the PC analysis of a training set of light curves. Furthermore, we use the amplitudes of these PCs to predict the light-curve shape of each star in the J-band, allowing us to precisely determine their average magnitudes (hence colors), even in cases where only one J measurement is available. Finally, we demonstrate that the K S-band light-curve parameters of RR Lyrae variables, together with the period, allow the estimation of the metallicity of individual stars with an accuracy of ∼0.2–0.25 dex, providing valuable chemical information about old stellar populations bearing RR Lyrae variables. The methods presented here can be straightforwardly adopted for other classes of variable stars, bands, or for the estimation of other physical quantities.

The soundtrack of RR Lyrae in omega Cen at high-frequency.

NASA Astrophysics Data System (ADS)

Calamida, A.; Randall, S. K.; Monelli, M.; Bono, G.; Buonanno, R.; Strampelli, G.; Catelan, M.; Van Grootel, V.; Alonso, M. L.; Stetson, P. B.; Stellingwerf, R. F.

We present preliminary Sloan u',g'-band light curves for a sample of known RR Lyrae variables in the Galactic globular cluster omega Cen. Results are based on the partial reduction of multi-band time series photometric data collected during six consecutive nights with the visitor instrument ULTRACAM mounted on the New Technology Telescope (La Silla, ESO). This facility allowed us to simultaneously observe in three different bands (Sloan u',g',r') a field of view of ˜ 6×6 arcminutes. The telescope and the good seeing conditions allowed us to sample the light curves every 15 seconds. We ended up with a data set of ˜ 6,000 images per night per filter, for a total of more than 200,000 images of the selected field. This data set allowed us to detect different kind of variables, such as RR-Lyraes, SX Phoenicis, eclipsing binaries, semi-regulars. More importantly, we were able for the first time to sample at high-frequency cluster RR Lyraes in the u',g'-band and to show in detail the pulsation phases across the dip located along the rising branch of RR-Lyraes. Based on data collected with ULTRACAM@NTT (La Silla, ESO, PID: 087.D-0216)

The solar type deep low mass-ratio contact binary V658 Lyr: Photometric solution and preliminary elements

NASA Astrophysics Data System (ADS)

Martignoni, M.; Barani, C.; Acerbi, F.

2018-07-01

We present the first light curve analysis of the eclipsing binary V658 Lyr. B, V and Ic photometric observations made from 2014 to 2017 of this W UMa-type binary star are collected, the complete light curves were obtained in 2015 (4 nights) and 2016 (11 nights) and are used for a detailed photometric analysis to determine orbital and physical parameters using the Wilson-Devinney code. The results obtained indicates that V658 Lyr is an A-type overcontact binary system with both components of spectral type (G2 + G4). Based on our 17 ToM the short orbital period of the eclipsing binary was confirmed and revised to P = 0.3302577 days. The orbital period was found to show a cyclic variations and a decrease rate of dP/dt = - 2.97 × 10 -7 days yr-1 , which can be interpreted as a mass transfer from the more massive component to the less massive one. We have not found an asymmetry of the light curves. The mass of the primary and secondary stars are calculated to be M1 = 1.18M⊙( ± 0.08) and M2 = 0.21M⊙( ± 0.01) indicating the primary to be underluminous for its mass and the secondary to be overluminous for its mass.

Peculiar double-periodic pulsation in RR Lyrae stars of the OGLE collection - II. Short-period stars with a dominant radial fundamental mode

NASA Astrophysics Data System (ADS)

Prudil, Z.; Smolec, R.; Skarka, M.; Netzel, H.

2017-03-01

We report the discovery of a new group of double-periodic stars in the OGLE Galactic bulge photometry. In 38 stars identified as fundamental-mode RR Lyrae and four classified as first-overtone RR Lyrae, we detected an additional shorter periodicity. The periods of the dominant variability in the newly discovered group are 0.28 < PD < 0.41 d. Period ratios (0.68-0.72) are smaller than the period ratios of the Galactic bulge RRd stars. The typical amplitude ratio (of the additional to the dominant periodicity) is 20 per cent for the stars identified as fundamental-mode RR Lyrae and 50 per cent for stars classified as first-overtone RR Lyrae. 10 stars from our sample exhibit equidistant peaks in the frequency spectrum, which suggests the Blazhko-type modulation of the main pulsation frequency and/or additional periodicity. The Fourier coefficients R21 and R31 are some of the lowest among fundamental-mode RR Lyrae stars, but among the highest for the first-overtone pulsators. For the phase Fourier coefficients φ21 and φ31, our stars lie between RRab and RRc stars. The stars discussed were compared with radial linear pulsation models. Their position in the Petersen diagram cannot be reproduced by assuming that two radial modes are excited and their physical parameters are like those characteristic of RR Lyrae stars. The non-radial-mode scenario also faces difficulties. We conclude that the dominant variability is most likely due to pulsation in the radial fundamental mode, which applies to stars classified as first-overtone mode pulsators. At this point, we cannot explain the nature of the additional periodicity. Even more, the classification of the stars as RR Lyrae should be treated as tentative.

Discovery of Distant RR Lyrae Stars in the Milky Way Using DECam

NASA Astrophysics Data System (ADS)

Medina, Gustavo E.; Muñoz, Ricardo R.; Vivas, A. Katherina; Carlin, Jeffrey L.; Förster, Francisco; Martínez, Jorge; Galbany, Lluís; González-Gaitán, Santiago; Hamuy, Mario; de Jaeger, Thomas; Maureira, Juan Carlos; San Martín, Jaime

2018-03-01

We report the discovery of distant RR Lyrae stars, including the most distant known in the Milky Way, using data taken in the g-band with the Dark Energy Camera as part of the High cadence Transient Survey (HiTS; 2014 campaign). We detect a total of 173 RR Lyrae stars over a ∼120 deg2 area, including both known RR Lyrae and new detections. The heliocentric distances d H of the full sample range from 9 to >200 kpc, with 18 of them beyond 90 kpc. We identify three sub-groups of RR Lyrae as members of known systems: the Sextans dwarf spheroidal galaxy, for which we report 46 new discoveries, and the ultra-faint dwarf galaxies Leo IV and Leo V. Following an MCMC methodology, we fit spherical and ellipsoidal profiles of the form ρ(R) ∼ R n to the radial density distribution of RR Lyrae in the Galactic halo. The best fit corresponds to the spherical case, for which we obtain a simple power-law index of n=-{4.17}-0.20+0.18, consistent with recent studies made with samples covering shorter distances. The pulsational properties of the outermost RR Lyrae in the sample (d H > 90 kpc) differ from the ones in the halo population at closer distances. The distribution of the stars in a period-amplitude diagram suggest they belong to Oosterhoff-intermediate or Oosterhoff II groups, similar to what is found in the ultra-faint dwarf satellites around the Milky Way. The new distant stars discovered represent an important addition to the few existing tracers of the Milky Way potential in the outer halo.

Chromospherically active stars. IV - HD 178450 = V478 Lyr: An early-type BY Draconis type binary

NASA Technical Reports Server (NTRS)

Fekel, Francis C.

1988-01-01

It is shown that the variable star HD 178450 = V478 Lyr is a chromospherically active G8 V single-lined spectroscopic binary with a period of 2.130514 days. This star is characterized by strong UV emission features and a filled-in H-alpha absorption line which is variable in strength. Classified as an early-type BY Draconis system, it is similar to the BY Dra star HD 175742 = V775 Her. The unseen secondary of HD 178450 has a mass of about 0.3 solar masses and is believed to be an M2-M3 dwarf.

Long term evolution of surface features on the unusual close binary V361 Lyr

NASA Astrophysics Data System (ADS)

Lister, T. A.

2009-02-01

V361 Lyr has been recognized as an unusual, possibly unique, pre-contact binary which is though to be evolving from a detached binary system into a W UMa contact binary system due to Angular Momentum Loss (AML) and mass transfer. The mass transfer and resulting hot spot on the secondary star allow the physics of accretion to be studied without the normal difficulties of disks and winds that are present in T Tauri stars. I present light curves obtained over a 10 year period as part of long term monitoring program obtained with a variety of telescopes, collect all available times of minima from the literature along with those determined from the light curves and determine the rate of period change.

Rms-flux relation and fast optical variability simulations of the nova-like system MV Lyr

NASA Astrophysics Data System (ADS)

Dobrotka, A.; Mineshige, S.; Ness, J.-U.

2015-03-01

The stochastic variability (flickering) of the nova-like system (subclass of cataclysmic variable) MV Lyr yields a complicated power density spectrum with four break frequencies. Scaringi et al. analysed high-cadence Kepler data of MV Lyr, taken almost continuously over 600 d, giving the unique opportunity to study multicomponent Power Density Spectra (PDS) over a wide frequency range. We modelled this variability with our statistical model based on disc angular momentum transport via discrete turbulent bodies with an exponential distribution of the dimension scale. Two different models were used, a full disc (developed from the white dwarf to the outer radius of ˜1010 cm) and a radially thin disc (a ring at a distance of ˜1010 cm from the white dwarf) that imitates an outer disc rim. We succeed in explaining the two lowest observed break frequencies assuming typical values for a disc radius of 0.5 and 0.9 times the primary Roche lobe and an α parameter of 0.1-0.4. The highest observed break frequency was also modelled, but with a rather small accretion disc with a radius of 0.3 times the primary Roche lobe and a high α value of 0.9 consistent with previous findings by Scaringi. Furthermore, the simulated light curves exhibit the typical linear rms-flux proportionality linear relation and the typical log-normal flux distribution. As the turbulent process is generating fluctuations in mass accretion that propagate through the disc, this confirms the general knowledge that the typical rms-flux relation is mainly generated by these fluctuations. In general, a higher rms is generated by a larger amount of superposed flares which is compatible with a higher mass accretion rate expressed by a larger flux.

A machine learned classifier for RR Lyrae in the VVV survey

NASA Astrophysics Data System (ADS)

Elorrieta, Felipe; Eyheramendy, Susana; Jordán, Andrés; Dékány, István; Catelan, Márcio; Angeloni, Rodolfo; Alonso-García, Javier; Contreras-Ramos, Rodrigo; Gran, Felipe; Hajdu, Gergely; Espinoza, Néstor; Saito, Roberto K.; Minniti, Dante

2016-11-01

Variable stars of RR Lyrae type are a prime tool with which to obtain distances to old stellar populations in the Milky Way. One of the main aims of the Vista Variables in the Via Lactea (VVV) near-infrared survey is to use them to map the structure of the Galactic Bulge. Owing to the large number of expected sources, this requires an automated mechanism for selecting RR Lyrae, and particularly those of the more easily recognized type ab (I.e., fundamental-mode pulsators), from the 106-107 variables expected in the VVV survey area. In this work we describe a supervised machine-learned classifier constructed for assigning a score to a Ks-band VVV light curve that indicates its likelihood of being ab-type RR Lyrae. We describe the key steps in the construction of the classifier, which were the choice of features, training set, selection of aperture, and family of classifiers. We find that the AdaBoost family of classifiers give consistently the best performance for our problem, and obtain a classifier based on the AdaBoost algorithm that achieves a harmonic mean between false positives and false negatives of ≈7% for typical VVV light-curve sets. This performance is estimated using cross-validation and through the comparison to two independent datasets that were classified by human experts.

Sonification of Kepler Field SU UMa Cataclysmic Variable Stars V344 Lyr and V1504 Cyg

NASA Technical Reports Server (NTRS)

Tutchton, Roxanne M.; Wood, Matt A.; Still, Martin D.; Howell, Steve B.; Cannizzo, John K.; Smale, Alan P.

2012-01-01

Sonification is the conversion of quantitative data into sound. In this work we explain the methods used in the sonification of light curves provided by the Kepler instrument from Q2 through Q6 for the cataclysmic variable systems V344 Lyr and V1504 Cyg . Both systems are SU UMa stars showing dwarf nova outbursts and superoutbursts as well as positive and negative superhumps. Focused sonifications were done from average pulse shapes of each superhump, and separate sonifications of the full, residual light curves were done for both stars. The audio of these data reflected distinct patterns within the evolutions of supercycles and superhumps that matched pervious observations and proved to be effective aids in data analysis.

The Kepler Light Curve of V344 LYR: Constraining the Thermal-Viscous Limit Cycle Instability

NASA Technical Reports Server (NTRS)

Cannizzo, J. K.; Still, M. D.; Howell, S. B.; Wood, M. A.; Smale, A. P.

2010-01-01

We present time dependent modeling based on the accretion disk limit cycle model for a 90 d light curve of the short period SU UMa-type dwarf nova V344 Lyr taken by Kepler. The unprecedented precision and cadence (1 minute) far surpass that generally available for long term light curves. The data encompass a super outburst, preceded by three normal (i.e., short) outbursts and followed by two normal outbursts. The main decay of the super outburst is nearly perfectly exponential, decaying at a rate approx.12 d/mag, while the much more rapid decays of the normal outbursts exhibit a faster-than-exponential shape. We show that the standard limit cycle model can account for the light curve, without the need for either the thermal-tidal instability or enhanced mass transfer.

Field 1: A First Look at the KELT RR Lyrae Project

NASA Astrophysics Data System (ADS)

De Lee, Nathan M.; Kinemuchi, Karen; Pepper, Joshua; Rodriguez, Joseph E.; Paegert, Martin

2015-01-01

In this poster we will discuss our ongoing program to use extant light curves from the Kilodegree Extremely Little Telescope (KELT) survey to find and characterize RR Lyrae (RRL) stars in the disk and inner halo of the Milky Way. We will focus on initial results from our testbed region, Field 1. RRL stars are of particular interest because they are standard candles and can be used to map out structure in the galaxy. The periods and shape of RRL light curves also contain information about their Oosterhoff type, which can probe galactic formation history, and metallicity respectively. Although there have been several large photometric surveys for RR Lyrae in the nearby galaxy (OGLE, NSVS, ASAS, and MACHO to name a few), they have each been limited in either sky coverage or number of epochs. The KELT survey represents a new generation of surveys that has many epochs over a large portion of the sky. KELT samples 60% of the sky in both northern and southern hemispheres, and has a long-time-baseline of 4-8 years with a very high cadence rate of less than 20 minutes. This translates into 4,000 to 9,000 epochs per light curve with completeness out to 3 kpc from the Sun.Recent results from both Kepler and ground based surveys results suggest that as many as 50% of RR Lyrae stars show long-term modulation of their light curve shapes (Blazhko effect). These stars combined with RRL stars that pulsate in more than one mode give a sample of objects that the KELT survey is uniquely suited to explore. This poster uses the RR Lyrae stars in Field 1 of the KELT survey to compare detection methods to previous variable star surveys of the same region. We also discuss the individual RR Lyrae found in Field 1. In particular, we focus on initial characterization of RRL light curves including those with amplitude-modulated or period-modulated light curves. We uses these initial results to discuss future plans for this survey.

Galactic Astronomy in the Ultraviolet

NASA Astrophysics Data System (ADS)

Rastorguev, A. S.; Sachkov, M. E.; Zabolotskikh, M. V.

2017-12-01

We propose a number of prospective observational programs for the ultraviolet space observatory WSO-UV, which seem to be of great importance to modern galactic astronomy. The programs include the search for binary Cepheids; the search and detailed photometric study and the analysis of radial distribution of UV-bright stars in globular clusters ("blue stragglers", blue horizontal-branch stars, RR Lyrae variables, white dwarfs, and stars with UV excesses); the investigation of stellar content and kinematics of young open clusters and associations; the study of spectral energy distribution in hot stars, including calculation of the extinction curves in the UV, optical and NIR; and accurate definition of the relations between the UV-colors and effective temperature. The high angular resolution of the observatory allows accurate astrometric measurements of stellar proper motions and their kinematic analysis.

Anatomy of the Orphan Stream using RR Lyrae Stars

NASA Astrophysics Data System (ADS)

Hendel, David; Johnston, Kathryn; Scowcroft, Victoria; SMHASH

2018-01-01

Stellar tidal streams provide an opportunity to study the motion and structure of the disrupting galaxy as well as the gravitational potential of its host. Streams around the Milky Way are especially promising as new datasets make additional phase space dimensions available as constraints. We present observations of 32 stars thought to be RR Lyrae in the Orphan tidal stream as part of the {\\it Spitzer} Merger History and Shape of the Galactic Halo (SMHASH) program. The extremely tight correlation between the periods, luminosities, and metallicities of RR Lyrae variable stars in the {\\it Spitzer} IRAC $3.6\\mu$m band allows the determination of precise distances to individual stars; the median statistical distance uncertainty in this sample is $2.5\\%$. By fitting orbits in an example potential we obtain an upper limit on the mass of the Milky Way interior to 60 kpc of $\\mathrm{3.9_{-0.8}^{+1.2}\\times 10^{11} M_\\odot}$, bringing estimates based on the Orphan stream in line with those using other tracers. The SMHASH data also resolves the stream in line-of-sight depth, allowing unprecedented access its internal structure. Comparing this structure with n-body models we find that Orphan had an initial dark halo mass $\\sim \\mathrm{3 \\times 10^{9} M_\\odot}$, placing the progenitor amongst the classical dwarf spheriodals.

SMHASH: Anatomy of the Orphan Stream using RR Lyrae stars

NASA Astrophysics Data System (ADS)

Hendel, David; Scowcroft, Victoria; Johnston, Kathryn V.; Fardal, Mark A.; van der Marel, Roeland P.; Sohn, Sangmo Tony; Price-Whelan, Adrian M.; Beaton, Rachael L.; Besla, Gurtina; Bono, Giuseppe; Cioni, Maria-Rosa L.; Clementini, Gisella; Cohen, Judith G.; Fabrizio, Michele; Freedman, Wendy L.; Garofalo, Alessia; Grillmair, Carl J.; Kallivayalil, Nitya; Kollmeier, Juna A.; Law, David R.; Madore, Barry F.; Majewski, Steven R.; Marengo, Massimo; Monson, Andrew J.; Neeley, Jillian R.; Nidever, David L.; Pietrzyński, Grzegorz; Seibert, Mark; Sesar, Branimir; Smith, Horace A.; Soszyński, Igor; Udalski, Andrzej

2018-06-01

Stellar tidal streams provide an opportunity to study the motion and structure of the disrupting galaxy as well as the gravitational potential of its host. Streams around the Milky Way are especially promising as phase space positions of individual stars will be measured by ongoing or upcoming surveys. Nevertheless, it remains a challenge to accurately assess distances to stars farther than 10 kpc from the Sun, where we have the poorest knowledge of the Galaxy's mass distribution. To address this we present observations of 32 candidate RR Lyrae stars in the Orphan tidal stream taken as part of the Spitzer Merger History and Shape of the Galactic Halo (SMHASH) program. The extremely tight correlation between the periods, luminosities, and metallicities of RR Lyrae variable stars in the Spitzer IRAC 3.6μm band allows the determination of precise distances to individual stars; the median statistical relative distance uncertainty to each RR Lyrae star is 2.5%. By fitting orbits in an example potential we obtain an upper limit on the mass of the Milky Way interior to 60 kpc of 5.6_{-1.1^{+1.2}× 10^{11} M_⊙ }, bringing estimates based on the Orphan Stream in line with those using other tracers. The SMHASH data also resolve the stream in line-of-sight depth, allowing a new perspective on the internal structure of the disrupted dwarf galaxy. Comparing with N-body models we find that the progenitor had an initial dark halo mass of approximately 3.2 × 109 M⊙, placing the Orphan Stream's progenitor amongst the classical dwarf spheroidals.

KELT RR Lyrae Variable Stars Observed by the NKU Schneider Observatory

NASA Astrophysics Data System (ADS)

De Lee, Nathan M.; Russell, Neil; Kinemuchi, Karen; Pepper, Joshua; Rodriguez, Joseph E.; Paegert, Martin

2016-01-01

In this poster we will discuss our ongoing program to use extant light curves from the Kilodegree Extremely Little Telescope (KELT) survey to find and characterize RR Lyrae (RRL) stars in the disk and inner halo of the Milky Way. RRL stars are of particular interest because they are standard candles and can be used to map out structure in the galaxy. The periods and shape of RRL light curves also contain information about their Oosterhoff type, which can probe galactic formation history, and metallicity respectively. Although there have been several large photometric surveys for RR Lyrae in the nearby galaxy (OGLE, NSVS, ASAS, and MACHO to name a few), they have each been limited in either sky coverage or number of epochs. The KELT survey represents a new generation of surveys that has many epochs over a large portion of the sky. KELT samples over 60% of the sky in both northern and southern hemispheres, and has a long-time-baseline of 4-10 years with a very high cadence rate of less than 20 minutes. This translates into 4,000 to 10,000+ epochs per light curve with completeness out to 3 kpc from the Sun. This poster will present follow-up data taken of RR Lyrae candidate stars found in the KELT survey. These stars were observed using an 11inch telescope at the NKU Schneider Observatory. We will discuss photometric accuracies, cadence, and initial analysis of these stars. We will also discuss the capabilities of our new observatory as well as future follow-up and analysis plans.

High-resolution spectroscopy of the extremely iron-poor post-AGB star CC Lyr

NASA Astrophysics Data System (ADS)

Aoki, Wako; Matsuno, Tadafumi; Honda, Satoshi; Parthasarathy, Mudumba; Li, Haining; Suda, Takuma

2017-04-01

High-resolution optical spectroscopy was conducted for the metal-poor post-AGB star CC Lyr to determine its chemical abundances and spectral line profiles. Our standard abundance analysis confirms its extremely low metallicity ([Fe/H] < -3.5) and a clear correlation between abundance ratios and the condensation temperature for 11 elements, indicating that dust depletion is the cause of the abundance anomaly of this object. The very low abundances of Sr and Ba, which are detected for the first time for this object, suggest that heavy neutron-capture elements are not significantly enhanced in this object by the s-process during its evolution through the AGB phase. The radial velocity of this object and profiles of some atomic absorption lines show variations depending on pulsation phases, which could be formed by dynamics of the atmosphere rather than by binarity or contributions of circumstellar absorption. On the other hand, the Hα emission with double peaks shows no evident velocity shift, suggesting that the emission is originating from the circumstellar matter, presumably the rotating disk around the object.

Exploring the Milky Way halo with SDSS-II SN survey RR Lyrae stars

NASA Astrophysics Data System (ADS)

De Lee, Nathan

This thesis details the creation of a large catalog of RR Lyrae stars, their lightcurves, and their associated photometric and kinematic parameters. This catalog contains 421 RR Lyrae stars with 305 RRab and 116 RRc. Of these, 241 stars have stellar spectra taken with either the Blanco 4m RC spectrograph or the SDSS/SEGUE survey, and in some cases taken by both. From these spectra and photometric methods derived from them, an analysis is conducted of the RR lyrae's distribution, metallicity, kinematics, and photometric properties within the halo. All of these RR Lyrae originate from the SDSS-II Supernova Survey. The SDSS-II SN Survey covers a 2.5 degree equatorial stripe ranging from -60 to +60 degrees in RA. This corresponds to relatively high southern galactic latitudes in the anti-center direction. The full catalog ranges from g 0 magnitude 13 to 20 which covers a distance of 3 to 95 kpc from the sun. Using this sample, we explore the Oosterhoff dichotomy through the D log P method as a function of | Z | distance from the plane. This results in a clear division of the RRab stars into OoI and OoII groups at lower | Z |, but the population becomes dominated by OoI stars at higher | Z |. The idea of a dual halo is explored primarily in the context of radial velocity distributions as a function of | Z |. In particular, V gsr , the radial velocity in the galactic standard of rest, is used as a proxy for V [straight phi] , the cylindrical rotational velocity. This is then compared against a single halo model galaxy, which results in very similar V gsr histograms for both at low to medium | Z |. However, at high | Z | there is a clear separation into two distinct velocity groups for the data without a corresponding separation in the model, suggesting that at least a two-component model for the halo is necessary. The final part of the analysis involves [Fe/H] measurements from both spectra and photometric relations cut in both | Z | and radial velocity. In this case

RR Lyrae Stars as High-Precision Standard Candles in the Mid-Infrared

NASA Astrophysics Data System (ADS)

Neeley, Jillian Rose

In this work, we provide the theoretical and empirical framework to establish RR Lyrae stars (RRL) as the anchor of a Population II distance scale. We present new theoretical period-luminosity-metallicity (PLZ) relations for RRL at Spitzer and WISE wavelengths. The PLZ relations were derived using nonlinear, time-dependent convective hydrodynamical models for a broad range in metal abundances (Z = 0.0001 to 0.0198). We also compare our theoretical relations to empirical relations derived from RRL in the field. Our theoretical PLZ relations were combined with multi-wavelength observations to simultaneously fit the distance modulus and extinction of each individual Galactic RRL in our sample. The results are consistent with trigonometric parallax measurements from the Gaia mission's first data release. This analysis has shown that when considering a sample covering a typical range of iron abundances for RRL, the metallicity spread introduces a dispersion in the PL relation on the order of 0.13 mag. However, if this metallicity component is accounted for in a PLZ relation, the dispersion is reduced to 0.02 mag at MIR wavelengths. On the empirical side, we present the analysis of five clusters from the Carnegie RR Lyrae Program (CRRP) sample (M4, NGC 3201, M5, M15, and M14). M4, the nearest one of the most well studied clusters, was used as a test case to develop a new data analysis pipeline for CRRP. Following the analysis of the five clusters, the resulting calibration PL relations are M[3.6] = -2.424 +/- 0.079 log P -1.205 +/- 0.057 and M [4.5] = -2.245 +/- 0.076 - 1.225 +/- 0.057. The slope of the PL relations was determined from the weighted average of the cluster results, and the zero point was fixed using five Galactic RRL with geometric parallaxes measured by Hubble Space Telescope. The dispersion of the RRL around the PL relations ranges from 0.05 mag in M4 to 0.3 mag in M14. The resulting band-averaged distance moduli for the five clusters agree well with

STELLAR ARCHEOLOGY IN THE GALACTIC HALO WITH ULTRA-FAINT DWARFS. VII. HERCULES

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

Musella, Ilaria; Ripepi, Vincenzo; Marconi, Marcella, E-mail: ilaria@na.astro.it, E-mail: ripepi@na.astro.it, E-mail: marcella@na.astro.it

2012-09-10

We present the first time-series study of the ultra-faint dwarf galaxy Hercules. Using a variety of telescope/instrument facilities we secured about 50 V and 80 B epochs. These data allowed us to detect and characterize 10 pulsating variable stars in Hercules. Our final sample includes six fundamental-mode (ab-type) and three first-overtone (c-type) RR Lyrae stars, and one Anomalous Cepheid. The average period of the ab-type RR Lyrae stars, (P{sub ab}) = 0.68 days ({sigma} = 0.03 days), places Hercules in the Oosterhoff II group, as found for almost the totality of the ultra-faint dwarf galaxies investigated so far for variability.more » The RR Lyrae stars were used to obtain independent estimates of the metallicity, reddening, and distance to Hercules, for which we find [Fe/H] = -2.30 {+-} 0.15 dex, E(B - V) = 0.09 {+-} 0.02 mag, and (m - M){sub 0} = 20.6 {+-} 0.1 mag, in good agreement with the literature values. We have obtained a V, B - V color-magnitude diagram (CMD) of Hercules that reaches V {approx} 25 mag and extends beyond the galaxy's half-light radius over a total area of 40' Multiplication-Sign 36'. The CMD and the RR Lyrae stars indicate the presence of a population as old and metal-poor as (at least) the Galactic globular cluster M68.« less

Near-infrared variability study of the central 2.3 × 2.3 arcmin2 of the Galactic Centre - II. Identification of RR Lyrae stars in the Milky Way nuclear star cluster

NASA Astrophysics Data System (ADS)

Dong, Hui; Schödel, Rainer; Williams, Benjamin F.; Nogueras-Lara, Francisco; Gallego-Cano, Eulalia; Gallego-Calvente, Teresa; Wang, Q. Daniel; Rich, R. Michael; Morris, Mark R.; Do, Tuan; Ghez, Andrea

2017-11-01

Because of strong and spatially highly variable interstellar extinction and extreme source crowding, the faint (K ≥ 15) stellar population in the Milky Way's nuclear star cluster is still poorly studied. RR Lyrae stars provide us with a tool to estimate the mass of the oldest, relative dim stellar population. Recently, we analysed HST/WFC3/IR observations of the central 2.3 × 2.3 arcmin2 of the Milky Way and found 21 variable stars with periods between 0.2 and 1 d. Here, we present a further comprehensive analysis of these stars. The period-luminosity relationship of RR Lyrae is used to derive their extinctions and distances. Using multiple approaches, we classify our sample as 4 RRc stars, 4 RRab stars, 3 RRab candidates and 10 binaries. Especially, the four RRab stars show sawtooth light curves and fall exactly on to the Oosterhoff I division in the Bailey diagram. Compared to the RRab stars reported by Minniti et al., our new RRab stars have higher extinction (AK > 1.8) and should be closer to the Galactic Centre. The extinction and distance of one RRab stars match those for the Milky Way's nuclear star cluster given in previous works. We perform simulations and find that after correcting for incompleteness, there could be not more than 40 RRab stars within the Milky Way's nuclear star cluster and in our field of view. Through comparing with the known globular clusters of the Milky Way, we estimate that if there exists an old, metal-poor (-1.5 < [Fe/H] < -1) stellar population in the Milky Way nuclear star cluster on a scale of 5 × 5 pc, then it contributes at most 4.7 × 105 M⊙, I.e. ˜18 per cent of the stellar mass.

Metal Abundances, Radial Velocities, and Other Physical Characteristics for the RR Lyrae Stars in The Kepler Field

NASA Astrophysics Data System (ADS)

Nemec, James M.; Cohen, Judith G.; Ripepi, Vincenzo; Derekas, Aliz; Moskalik, Pawel; Sesar, Branimir; Chadid, Merieme; Bruntt, Hans

2013-08-01

Spectroscopic iron-to-hydrogen ratios, radial velocities, atmospheric parameters, and new photometric analyses are presented for 41 RR Lyrae stars (and one probable high-amplitude δ Sct star) located in the field-of-view of the Kepler space telescope. Thirty-seven of the RR Lyrae stars are fundamental-mode pulsators (i.e., RRab stars) of which sixteen exhibit the Blazhko effect. Four of the stars are multiperiodic RRc pulsators oscillating primarily in the first-overtone mode. Spectroscopic [Fe/H] values for the 34 stars for which we were able to derive estimates range from -2.54 ± 0.13 (NR Lyr) to -0.05 ± 0.13 dex (V784 Cyg), and for the 19 Kepler-field non-Blazhko stars studied by Nemec et al. the abundances agree will with their photometric [Fe/H] values. Four non-Blazhko RR Lyrae stars that they identified as metal-rich (KIC 6100702, V2470 Cyg, V782 Cyg and V784 Cyg) are confirmed as such, and four additional stars (V839 Cyg, KIC 5520878, KIC 8832417, KIC 3868420) are also shown here to be metal-rich. Five of the non-Blazhko RRab stars are found to be more metal-rich than [Fe/H] ~-0.9 dex while all of the 16 Blazhko stars are more metal-poor than this value. New P-\\phi _31^s-[Fe/H] relationships are derived based on ~970 days of quasi-continuous high-precision Q0-Q11 long- and short-cadence Kepler photometry. With the exception of some Blazhko stars, the spectroscopic and photometric [Fe/H] values are in good agreement. Several stars with unique photometric characteristics are identified, including a Blazhko variable with the smallest known amplitude and frequency modulations (V838 Cyg). Based in part on observations made at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Keck Observatory was made possible by the generous financial support of the W.M. Keck Foundation. Also, based in part on

Inter-Longitude Astronomy (ILA) Project: Current Highlights And Perspectives. I. Magnetic vs. Non-Magnetic Interacting Binary Stars

NASA Astrophysics Data System (ADS)

Andronov, I. L.; Antoniuk, K. A.; Baklanov, A. V.; Breus, V. V.; Burwitz, V.; Chinarova, L. L.; Chochol, D.; Dubovsky, P. A.; Han, W.; Hegedus, T.; Henden, A.; Hric, L.; Chun-Hwey, Kim; Yonggi, Kim; Kolesnikov, S. V.; Kudzej, I.; Liakos, A.; Niarchos, P. G.; Oksanen, A.; Patkos, L.; Petrik, K.; Pit', N. V.; Shakhovskoy, N. M.; Virnina, N. A.; Yoon, J.; Zola, S.

2010-12-01

We present a review of highlights of our photometric and photo-polarimetric monitoring and mathematical modeling of interacting binary stars of different types classical, asynchronous, intermedi ate polars with 25 timescales corresponding to differ ent physical mechanisms and their combinations (part "Polar"); negative and positive superhumpers in nova- like and dwarf novae stars ("Superhumper"); symbiotic ("Symbiosis"); eclipsing variables with and without ev idence for a current mass transfer ("Eclipser") with a special emphasis on systems with a direct impact of the stream into the gainor star's atmosphere, which we propose to call "Impactors", or V361 Lyr-type stars. Other parts of the ILA project are "Stellar Bell" (pul sating variables of different types and periods - M, SR, RV Tau, RR Lyr, Delta Sct) and "New Variable".

RR Lyrae Variables in Stellar Systems

NASA Astrophysics Data System (ADS)

Smith, Horace A.; Catelan, Márcio; Clementini, Gisella

2009-09-01

The pioneering studies of RR Lyrae stars in globular clusters by Oosterhoff and by Sawyer Hogg in the 1930s and 1940s called attention to interesting systematic differences among RR Lyrae populations in different systems. When such studies were extended to the dwarf spheroidal companions of the Milky Way in the 1960s, it was found that the average properties of their RR Lyrae stars were often different from those that had previously been observed in globular clusters. Observations of RR Lyrae stars have now extended to the Andromeda Galaxy and other Local Group systems, with still greater variety being apparent. Our understanding of the reasons for these differences among the RR Lyrae populations in different systems is by no means complete, but properties of RR Lyrae stars within these different systems are tied to differing horizontal branch morphologies and also shed light upon scenarios for the formation of the Galaxy.

KELT RR Lyrae Variable Stars Observed by NKU Schneider and Michigan State Observatories

NASA Astrophysics Data System (ADS)

De Lee, Nathan M.; Brueneman, Stacy; Hicks, Logan; Russell, Neil; Kinemuchi, Karen; Pepper, Joshua; Rodriguez, Joseph; Paegert, Martin; Smith, Horace A.

2017-01-01

In this poster we will discuss our ongoing program to use extant light curves from the Kilodegree Extremely Little Telescope (KELT) survey to find and characterize RR Lyrae (RRL) stars in the disk and inner halo of the Milky Way. RRL stars are of particular interest because they are standard candles and can be used to map out structure in the galaxy. The periods and shape of RRL light curves also contain information about their Oosterhoff type, which can probe galactic formation history, and metallicity respectively. Although there have been several large photometric surveys for RR Lyrae in the nearby galaxy (OGLE, NSVS, ASAS, and MACHO to name a few), they have each been limited in either sky coverage or number of epochs. The KELT survey represents a new generation of surveys that has many epochs over a large portion of the sky. KELT samples over 70% of the entire sky, and has a long-time-baseline of up to 11 years with a very high cadence rate of less than 20 minutes. This translates to upwards of 11,000 epochs per light curve with completeness out to 3 kpc from the Sun. This poster will present follow-up multi-color photometry taken of RR Lyrae candidate stars found in the KELT survey. These stars were observed using an 11inch telescope at the NKU Schneider Observatory. We also have archival photometry of these stars from the Michigan State Observatory. We will discuss photometric accuracies, cadence, and initial analysis of these stars. We will also discuss the capabilities of our new observatory as well as future follow-up and analysis plans.

Chemical Abundances of Metal-poor RR Lyrae Stars in the Magellanic Clouds

NASA Astrophysics Data System (ADS)

Haschke, Raoul; Grebel, Eva K.; Frebel, Anna; Duffau, Sonia; Hansen, Camilla J.; Koch, Andreas

2012-09-01

We present for the first time a detailed spectroscopic study of chemical element abundances of metal-poor RR Lyrae stars in the Large and Small Magellanic Cloud (LMC and SMC). Using the MagE echelle spectrograph at the 6.5 m Magellan telescopes, we obtain medium resolution (R ~ 2000-6000) spectra of six RR Lyrae stars in the LMC and three RR Lyrae stars in the SMC. These stars were chosen because their previously determined photometric metallicities were among the lowest metallicities found for stars belonging to the old populations in the Magellanic Clouds. We find the spectroscopic metallicities of these stars to be as low as [Fe/H]spec = -2.7 dex, the lowest metallicity yet measured for any star in the Magellanic Clouds. We confirm that for metal-poor stars, the photometric metallicities from the Fourier decomposition of the light curves are systematically too high compared to their spectroscopic counterparts. However, for even more metal-poor stars below [Fe/H]phot < -2.8 dex this trend is reversed and the spectroscopic metallicities are systematically higher than the photometric estimates. We are able to determine abundance ratios for 10 chemical elements (Fe, Na, Mg, Al, Ca, Sc, Ti, Cr, Sr, and Ba), which extend the abundance measurements of chemical elements for RR Lyrae stars in the Clouds beyond [Fe/H] for the first time. For the overall [α/Fe] ratio, we obtain an overabundance of 0.36 dex, which is in very good agreement with results from metal-poor stars in the Milky Way halo as well as from the metal-poor tail in dwarf spheroidal galaxies. Comparing the abundances with those of the stars in the Milky Way halo we find that the abundance ratios of stars of both populations are consistent with another. Therefore, we conclude that from a chemical point of view early contributions from Magellanic-type galaxies to the formation of the Galactic halo as claimed in cosmological models are plausible. This paper includes data gathered with the 6.5 meter Magellan

Discovering Cepheid and RR Lyrae Stars: Pan-STARRS Science Archive @ STScI and Robotically Controlled Telescopes

NASA Astrophysics Data System (ADS)

Johnson, Elizabeth; Strolger, Louis-Gregory; Engle, Scott G.; Anderson, Richard I.; Rest, Armin; Calamida, Annalisa; Dosovitz Fox, Ori; Laney, David

2017-01-01

Cepheid and RR Lyrae stars are an integral part of the cosmic distance ladder and are also useful for studying galactic structure and stellar ages. This project aims to greatly expand the number of known periodic variables in our galaxy by identifying candidates in the PanSTARRS-1 3pi catalog, and carrying out systematically targeted characterization with robotically controlled telescopes. Candidate targets are selected from available detection tables based on color and variability indices and are then fully vetted using robotic telescopes: the RCT 1.3 meter (Kitt Peak National Observatory) and RATIR 1.5 meter (Mexico). Here we present work to develop a full, semi-automated prescription for candidate selection, targeted follow-up photometry, cataloging, and classification, which allows the review of approximately 25 variable candidates every two weeks. We make comparisons of our sample selection and purity from a similar study based on Pan-STARRS data (Hernitschek et al. 2016), as well as candidates identified in Gaia DR1. The goal, through continued observation and analysis, is to identify at least 10,000 new variables, hundreds of which will be new Cepheid and RR Lyrae stars.

RR Lyrae type stars

NASA Astrophysics Data System (ADS)

Samus, N. N.

Basic observational data on RR Lyrae type stars are reviewed. It is noted that these stars are used widely to investigate the structure and kinematics of the spherical and intermediate components of the Galaxy, with correct data on the absolute magnitude of these variables being decisive. Attention is given to the relationship between the orbit eccentricity and inclination of osculating RR Lyrae type stars in the Galaxy and their metallicity index.

Galactic gamma-ray observations and galactic structure

NASA Technical Reports Server (NTRS)

Stecker, F. W.

1975-01-01

Recent observations of gamma-rays originating in the galactic disk together with radio observations, support an emerging picture of the overall structure of our galaxy with higher interstellar gas densities and star formation rates in a region which corresponds to that of the inner arms. The emerging picture is one where molecular clouds make up the dominant constituent of the interstellar gas in the inner galaxy and play a key role in accounting for the gamma-rays and phenomena associated with the production of young stars and other population 1 objects. In this picture, cosmic rays are associated with supernovae and are primarily of galactic origin. These newly observed phenomena can be understood as consequences of the density wave theories of spiral structure. Based on these new developments, the suggestion is made that a new galactic population class, Population O, be added to the standard Populations 1 and 2 in order to recognize important differences in dynamics and distribution between diffuse galactic H1 and interstellar molecular clouds.

Radial Velocities of RR Lyrae Stars in and around NGC 6441

NASA Astrophysics Data System (ADS)

Kunder, Andrea; Mills, Arthur; Edgecomb, Joseph; Thomas, Mathew; Schilter, Levi; Boyle, Craig; Parker, Stephen; Bellevue, Gordon; Rich, R. Michael; Koch, Andreas; Johnson, Christian I.; Nataf, David M.

2018-04-01

Detailed elemental abundance patterns of metal-poor ([Fe/H] ∼ ‑1 dex) stars in the Galactic bulge indicate that a number of them are consistent with globular cluster (GC) stars and may be former members of dissolved GCs. This would indicate that a few per cent of the Galactic bulge was built up from destruction and/or evaporation of GCs. Here, an attempt is made to identify such presumptive stripped stars originating from the massive, inner Galaxy GC NGC 6441 using its rich RR Lyrae variable star (RRL) population. We present radial velocities of 40 RRLs centered on the GC NGC 6441. All 13 of the RRLs observed within the cluster tidal radius have velocities consistent with cluster membership, with an average radial velocity of 24 ± 5 km s‑1 and a star-to-star scatter of 11 km s‑1. This includes two new RRLs that were previously not associated with the cluster. Eight RRLs with radial velocities consistent with cluster membership but up to three time the distance from the tidal radius are also reported. These potential extra-tidal RRLs also have exceptionally long periods, which is a curious characteristic of the NGC 6441 RRL population that hosts RRLs with periods longer than seen anywhere else in the Milky Way. As expected of stripped cluster stars, most are inline with the cluster’s orbit. Therefore, either the tidal radius of NGC 6441 is underestimated and/or we are seeing dissolving cluster stars stemming from NGC 6441 that are building up the old spheroidal bulge.

ON THE DISTANCE OF THE GLOBULAR CLUSTER M4 (NGC 6121) USING RR LYRAE STARS. I. OPTICAL AND NEAR-INFRARED PERIOD-LUMINOSITY AND PERIOD-WESENHEIT RELATIONS

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

Braga, V. F.; Bono, G.; Buonanno, R.

2015-02-01

We present new distance determinations to the nearby globular M4 (NGC 6121) based on accurate optical and near-infrared (NIR) mean magnitudes for fundamental (FU) and first overtone (FO) RR Lyrae variables (RRLs), and new empirical optical and NIR period-luminosity (PL) and period-Wesenheit (PW) relations. We have found that optical-NIR and NIR PL and PW relations are affected by smaller standard deviations than optical relations. The difference is the consequence of a steady decrease in the intrinsic spread of cluster RRL apparent magnitudes at fixed period as longer wavelengths are considered. The weighted mean visual apparent magnitude of 44 cluster RRLs ismore » =13.329 ± 0.001 (standard error of the mean) ±0.177 (weighted standard deviation) mag. Distances were estimated using RR Lyr itself to fix the zero-point of the empirical PL and PW relations. Using the entire sample (FU+FO) we found weighted mean true distance moduli of 11.35 ± 0.03 ± 0.05 mag and 11.32 ± 0.02 ± 0.07 mag. Distances were also evaluated using predicted metallicity dependent PLZ and PWZ relations. We found weighted mean true distance moduli of 11.283 ± 0.010 ± 0.018 mag (NIR PLZ) and 11.272 ± 0.005 ± 0.019 mag (optical-NIR and NIR PWZ). The above weighted mean true distance moduli agree within 1σ. The same result is found from distances based on PWZ relations in which the color index is independent of the adopted magnitude (11.272 ± 0.004 ± 0.013 mag). These distances agree quite well with the geometric distance provided by Kaluzny et al. based on three eclipsing binaries. The available evidence indicates that this approach can provide distances to globulars hosting RRLs with a precision better than 2%-3%.« less

VizieR Online Data Catalog: Theoretical framework for RR Lyrae. II. MIR data (Neeley+, 2017)

NASA Astrophysics Data System (ADS)

Neeley, J. R.; Marengo, M.; Bono, G.; Braga, V. F.; Dall'Ora, M.; Magurno, D.; Marconi, M.; Trueba, N.; Tognelli, E.; Moroni, P. G. P.; Beaton, R. L.; Freedman, W. L.; Madore, B. F.; Monson, A. J.; Scowcroft, V.; Seibert, M.; Stetson, P. B.

2018-01-01

We compiled multi-wavelength observations for a sample of 55 nearby Galactic RRLs. Most of the observations were collected as part of the Carnegie RR Lyrae Program (CRRP, PID 90002), and were published in Monson+ (2017, J/AJ/153/96). See section 3 for further details. For this work, we have also performed new photometry of single-epoch archival observations of M4 from Spitzer's cryogenic mission 5.8 and 8.0um bands. We elected to use the single epoch observation as the estimated mean magnitude with an uncertainty equal to half the amplitude in the 3.6 or 4.5um bands. These results as well as the updated mean magnitudes from Neeley+ (2015, J/ApJ/808/11) are available in Table 7. (6 data files).

Classification of ROTSE Variable Stars using Machine Learning

NASA Astrophysics Data System (ADS)

Wozniak, P. R.; Akerlof, C.; Amrose, S.; Brumby, S.; Casperson, D.; Gisler, G.; Kehoe, R.; Lee, B.; Marshall, S.; McGowan, K. E.; McKay, T.; Perkins, S.; Priedhorsky, W.; Rykoff, E.; Smith, D. A.; Theiler, J.; Vestrand, W. T.; Wren, J.; ROTSE Collaboration

2001-12-01

We evaluate several Machine Learning algorithms as potential tools for automated classification of variable stars. Using the ROTSE sample of ~1800 variables from a pilot study of 5% of the whole sky, we compare the effectiveness of a supervised technique (Support Vector Machines, SVM) versus unsupervised methods (K-means and Autoclass). There are 8 types of variables in the sample: RR Lyr AB, RR Lyr C, Delta Scuti, Cepheids, detached eclipsing binaries, contact binaries, Miras and LPVs. Preliminary results suggest a very high ( ~95%) efficiency of SVM in isolating a few best defined classes against the rest of the sample, and good accuracy ( ~70-75%) for all classes considered simultaneously. This includes some degeneracies, irreducible with the information at hand. Supervised methods naturally outperform unsupervised methods, in terms of final error rate, but unsupervised methods offer many advantages for large sets of unlabeled data. Therefore, both types of methods should be considered as promising tools for mining vast variability surveys. We project that there are more than 30,000 periodic variables in the ROTSE-I data base covering the entire local sky between V=10 and 15.5 mag. This sample size is already stretching the time capabilities of human analysts.

Galactic plane gamma-radiation

NASA Technical Reports Server (NTRS)

Hartman, R. C.; Kniffen, D. A.; Thompson, D. J.; Fichtel, C. E.; Ogelman, H. B.; Tumer, T.; Ozel, M. E.

1979-01-01

Analysis of the SAS 2 data together with the COS B results shows that the distribution of galactic gamma-radiation has several similarities to that of other large-scale tracers of galactic structure. The radiation is primarily confined to a thin disc which exhibits offsets from b = 0 degrees similar to warping at radio frequencies. The principal distinction of the gamma-radiation is a stronger contrast in intensity between the region from 310 to 45 degrees in longitude and the regions away from the center that can be attributed to a variation in cosmic-ray density as a function of position in Galaxy. The diffuse galactic gamma-ray energy spectrum shows no significant variation in direction, and the spectrum seen along the plane is the same as that for the galactic component of the gamma-radiation at high altitudes. The uniformity of the galactic gamma-ray spectrum, the smooth decrease in intensity as a function of altitude, and the absence of any galactic gamma-ray sources at high altitudes indicate a diffuse origin for bulk of the galactic gamma-radiation rather than a collection of localized sources.

Galactic bulge preferred over dark matter for the Galactic centre gamma-ray excess

NASA Astrophysics Data System (ADS)

Macias, Oscar; Gordon, Chris; Crocker, Roland M.; Coleman, Brendan; Paterson, Dylan; Horiuchi, Shunsaku; Pohl, Martin

2018-05-01

An anomalous gamma-ray excess emission has been found in the Fermi Large Area Telescope data1 covering the centre of the Galaxy2,3. Several theories have been proposed for this `Galactic centre excess'. They include self-annihilation of dark-matter particles4, an unresolved population of millisecond pulsars5, an unresolved population of young pulsars6, or a series of burst events7. Here, we report on an analysis that exploits hydrodynamical modelling to register the position of interstellar gas associated with diffuse Galactic gamma-ray emission. We find evidence that the Galactic centre excess gamma rays are statistically better described by the stellar over-density in the Galactic bulge and the nuclear stellar bulge, rather than a spherical excess. Given its non-spherical nature, we argue that the Galactic centre excess is not a dark-matter phenomenon but rather associated with the stellar population of the Galactic bulge and the nuclear bulge.

Galactic Winds

NASA Astrophysics Data System (ADS)

Veilleux, Sylvain

Galactic winds have become arguably one of the hottest topics in extragalactic astronomy. This enthusiasm for galactic winds is due in part to the detection of winds in many, if not most, high-redshift galaxies. Galactic winds have also been invoked by theorists to (1) suppress the number of visible dwarf galaxies and avoid the "cooling catastrophe" at high redshift that results in the overproduction of massive luminous galaxies, (2) remove material with low specific angular momentum early on and help enlarge gas disks in CDM + baryons simulations, (3) reduce the dark mass concentrations in galaxies, (4) explain the mass-metallicity relation of galaxies from selective loss of metal-enriched gas from smaller galaxies, (5) enrich and "preheat" the ICM, (6) enrich the IGM without disturbing the Lyαforest significantly, and (7) inhibit cooling flows in galaxy clusters with active cD galaxies. The present paper highlights a few key aspects of galactic winds taken from a recent ARAA review by Veilleux, Cecil, &Bland-Hawthorn (2005; herafter VCBH). Readers interested in a more detailed discussion of this topic are encouraged to refer to the original ARAA article.

RR Lyrae in the UMi dSph Galaxy

NASA Astrophysics Data System (ADS)

Kuehn, Charles; Kinemuchi, Karen; Jeffery, Elizabeth; Grabowski, Kathleen; Nemec, James; Herrera, Daniel

2018-01-01

Over the past two years we have obtained observations of the Ursa Minor dwarf spheroidal galaxy with the goal of completing an updated catalog of the variable stars in the dwarf galaxy. In addition to finding new variable stars, this updated catalog will allow us to look at period changes in the variables and to determine stellar characteristic for the RR Lyrae stars in the dSph. We will compare the RR Lyrae stellar characteristics to other RR Lyrae stars found in the Local Group dSph galaxies; these comparisons can give us insights to the near-field cosmology of the Local Group. In this poster we present our updated catalog of RR Lyrae stars in the UMi dSph; the updated catalog includes Fourier decomposition parameters, metallicities, and other physical properties for the RR Lyrae stars.

A Detailed Study of the Variable Stars in Five Galactic Globular Clusters: IC4499, NGC4833, NGC6171 (M107), NGC6402 (M14), and NGC6584

NASA Astrophysics Data System (ADS)

Murphy, Brian W.; Darragh, Andrew; Hettinger, Paul; Hibshman, Adam; Johnson, Elliott W.; Liu, Z. J.; Pajkos, Michael A.; Stephenson, Hunter R.; Vondersaar, John R.; Conroy, Kyle E.; McCombs, Thayne A.; Reinhardt, Erik D.; Toddy, Joseph

2015-08-01

We present the results of an extensive study intended to search for and properly classify the variable stars in five galactic globular clusters. Each of the five clusters was observed hundreds to thousands of times over a time span ranging from 2 to 4 years using the SARA 0.6m located at Cerro Tololo Interamerican Observatory. The images were analyzed using the image subtract method of Alard (2000) to identify and produce light curves of all variables found in each cluster. In total we identified 373 variables with 140 of these being newly discovered increasing the number of known variables stars in these clusters by 60%. Of the total we have identified 312 RR Lyrae variables (187 RR0, 18 RR01, 99 RR1, 8 RR2), 9 SX Phe stars, 6 Cepheid variables, 11 eclipsing variables, and 35 long period variables. For IC4499 we identified 64 RR0, 18 RR01, 14 RR1, 4 RR2, 1 SX Phe, 1 eclipsing binary, and 2 long period variables. For NGC4833 we identified 10 RR0, 7 RR1, 2 RR2, 6 SX Phe, 5 eclipsing binaries, and 9 long period variables. For NGC6171 (M107) we identified 13 RR0, 7 RR1, and 1 SX Phe. For NGC6402 (M14) we identified 52 RR0, 56 RR1, 1 RR2, 1 SX Phe, 6 Cepheids, 1 eclipsing binary, and 15 long period variables. For NGC6584 we identified 48 RR0, 15 RR1, 1 RR2, 5 eclipsing binaries, and 9 long period variables. Using the RR Lyrae variables we found the mean V magnitude of the horizontal branch to be VHB = ⟨V ⟩RR = 17.63, 15.51, 15.72, 17.13, and 16.37 magnitudes for IC4499, NGC4833, NGC6171 (M107), NGC6402 (M14), and NGC6584, respectively. From our extensive data set we were able to obtain sufficient temporal and complete phase coverage of the RR Lyrae variables. This has allowed us not only to properly classify each of the RR Lyrae variables but also to use Fourier decomposition of the light curves to further analyze the properties of the variable stars and hence physical properties of each clusters. In this poster we will give the temperature, radius, stellar mass

Active galactic nuclei

PubMed Central

Fabian, Andrew C.

1999-01-01

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

HIREGS observations of the Galactic center and Galactic plane: Separation of the diffuse Galactic hard X-ray continuum from the point source spectra

NASA Technical Reports Server (NTRS)

Boggs, S. E.; Lin, R. P.; Coburn, W.; Feffer, P.; Pelling, R. M.; Schroeder, P.; Slassi-Sennou, S.

1997-01-01

The balloon-borne high resolution gamma ray and X-ray germanium spectrometer (HIREGS) was used to observe the Galactic center and two positions along the Galactic plane from Antarctica in January 1995. For its flight, the collimators were configured to measure the Galactic diffuse hard X-ray continuum between 20 and 200 keV by directly measuring the point source contributions to the wide field of view flux for subtraction. The hard X-ray spectra of GX 1+4 and GRO J1655-40 were measured with the diffuse continuum subtracted off. The analysis technique for source separation is discussed and the preliminary separated spectra for these point sources and the Galactic diffuse emission are presented.

Seven new carbon-enhanced metal-poor RR Lyrae stars

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

Kennedy, Catherine R.; Stancliffe, Richard J.; Kuehn, Charles

2014-05-20

We report estimated carbon-abundance ratios, [C/Fe], for seven newly discovered carbon-enhanced metal-poor (CEMP) RR Lyrae stars. These are well-studied RRab stars that had previously been selected as CEMP candidates based on low-resolution spectra. For this pilot study, we observed eight of these CEMP RR Lyrae candidates with the Wide Field Spectrograph on the ANU 2.3 m telescope. Prior to this study, only two CEMP RR Lyrae stars had been discovered: TY Gru and SDSS J1707+58. We compare our abundances to new theoretical models of the evolution of low-mass stars in binary systems. These simulations evolve the secondary stars, post accretionmore » from an asymptotic giant-branch (AGB) donor, all the way to the RR Lyrae stage. The abundances of CEMP RR Lyrae stars can be used as direct probes of the nature of the donor star, such as its mass, and the amount of material accreted onto the secondary. We find that the majority of the sample of CEMP RR Lyrae stars is consistent with AGB donor masses of around 1.5-2.0 M {sub ☉} and accretion masses of a few hundredths of a solar mass. Future high-resolution studies of these newly discovered CEMP RR Lyrae stars will help disentangle the effects of the proposed mixing processes that occur in such objects.« less

RR-Interval variance of electrocardiogram for atrial fibrillation detection

NASA Astrophysics Data System (ADS)

Nuryani, N.; Solikhah, M.; Nugoho, A. S.; Afdala, A.; Anzihory, E.

2016-11-01

Atrial fibrillation is a serious heart problem originated from the upper chamber of the heart. The common indication of atrial fibrillation is irregularity of R peak-to-R-peak time interval, which is shortly called RR interval. The irregularity could be represented using variance or spread of RR interval. This article presents a system to detect atrial fibrillation using variances. Using clinical data of patients with atrial fibrillation attack, it is shown that the variance of electrocardiographic RR interval are higher during atrial fibrillation, compared to the normal one. Utilizing a simple detection technique and variances of RR intervals, we find a good performance of atrial fibrillation detection.

RR Lyrae period luminosity relations with Spitzer

NASA Astrophysics Data System (ADS)

Neeley, Jillian R.; Marengo, Massimo; CRRP Team

2017-01-01

RR Lyrae variable stars have long been known to be valuable distance indicators, but only recently has a well defined period luminosity relationship been utilized at infrared wavelengths. In my thesis, I am combining Spitzer Space Telescope data of RR Lyrae stars obtained as part of the Carnegie RR Lyrae Program with ground based NIR data to characterize the period-luminosity-metallicity (PLZ) relation and provide an independent Population II calibration of the cosmic distance scale. I will discuss the ongoing efforts to calibrate this relation using objects such as M4 and NGC 6441 and how the first data release from the Gaia mission impacts our findings. I will also compare my preliminary empirical relations to theoretical PLZ relations derived from stellar pulsation models.

V1327 Aquilae: A New RR Lyrae variable with an extremely high radial velocity

NASA Astrophysics Data System (ADS)

Galeev, A. I.; Bikmaev, I. F.; Borisov, N. V.; Zhuchkov, R. Ya.; Shimanskii, V. V.; Khabibullina, M. L.; Sakhibullin, N. A.

2008-07-01

We have carried out photometry and spectroscopy of the star V1327 Aql ( R = 16 m ) as part of our program of observations of poorly studied cataclysmic variables using the 1.5-m optical Russian—Turkish telescope (RTT-150, Turkey) and the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences. After analyzing our photometry, we have re-classified the variable as an RR Lyrae star. Our BV R photometry during 10 nights reveals brightness variations with the period 12h49m, with the B, V, and R amplitudes being 1.36 m , 1.13 m , and 1.11 m , respectively. We derived the first estimates of the star’s atmospheric parameters from our moderate-resolution spectra: T eff = 6280 K, log g = 3.3, [M/H] = -1.05. The extremely high radial velocity of the star’s motion ( V R = -470 km/s) and the star’s large distances to the Galactic center (13.1 kpc) and disk (4.2 kpc) testify to a probable extragalactic origin of this object.

RR Lyrae stars in and around NGC 6441: signatures of dissolving cluster stars

NASA Astrophysics Data System (ADS)

Kunder, Andrea

2018-06-01

Detailed elemental abundance patterns of metal-poor ([Fe/H]~ -1 dex) stars in the Galactic bulge indicate that a number of them are consistent with globular cluster (GC) stars and may be former members of dissolved GCs. This would indicate that a few per cent of the Galactic bulge was built up from destruction and/or evaporation of globular clusters. Here an attempt is made to identify such presumptive destroyed stars originating from the massive, inner Galaxy globular cluster NGC~6441 using its rich RR Lyrae variable star (RRL) population. We present radial velocities of forty RRLs centered on the globular cluster NGC~6441. All of the 13 RRLs observed within the cluster tidal radius have velocities consistent with cluster membership, with an average radial velocity of 24 +- 5~km/s and a star-to-star scatter of 11~km/s. This includes two new RRLs that were previously not associated with the cluster. Eight RRLs with radial velocities consistent with cluster membership but up to three time the distance from the tidal radius are also reported. These potential extra-tidal RRLs also have exceptionally long periods, which is a curious characteristic of the NGC~6441 RRL population that hosts RRLs with periods longer than seen anywhere else in the Milky Way. As expected of stripped cluster stars, most are inline with the cluster's orbit. Therefore, either the tidal radius of NGC~6441 is underestimated and/or we are seeing dissolving cluster stars stemming from NGC~6441 that are building up the old spheroidal bulge. Both the mean velocity of the cluster as well as the underlying field population is consistent with belonging to an old spheroidal bulge with low rotation and high velocity dispersion that formed before the bar.

Intermittent behavior of galactic dynamo activities

NASA Technical Reports Server (NTRS)

Ko, C. M.; Parker, E. N.

1989-01-01

Recent observations by Beck and Golla of far-infrared and radio continuum emission from nearby spiral galaxies suggest that the galactic magnetic field strength is connected to the current star formation rate. The role of star formation on the generation of large-scale galactic magnetic field is studied in this paper. Using a simple galactic model, it is shown how the galactic dynamo depends strongly on the turbulent velocity of the interstellar medium. When the star formation efficiency is high, the ISM is churned which in turn amplifies the galactic magnetic field. Between active star formation epochs, the magnetic field is in dormant state and decays at a negligible rate. If density waves trigger star formation, then they also turn on the otherwise dormant dynamo.

MACHO RR Lyrae in the Inner Halo and Bulge

NASA Astrophysics Data System (ADS)

Minniti, Dante; Alcock, Charles; Allsman, Robyn A.; Alves, David; Axelrod, Tim S.; Becker, Andrew C.; Bennett, David; Cook, Kem H.; Drake, Andrew J.; Freeman, Ken C.; Griest, Kim; Lehner, Matt; Marshall, Stuart; Peterson, Bruce; Pratt, Mark; Quinn, Peter; Rodgers, Alex; Stubbs, Chris; Sutherland, Will; Tomaney, Austin; Vandehei, Thor; Welch, Doug L.

The RR Lyrae in the bulge have been proposed to be the oldest populations in the Milky Way, tracers of how the galaxy formed. We study here the distribution of ~1600 bulge RR Lyrae stars found by the MACHO Project. The RR Lyrae with Galactocentric radius 0.4

Search for EeV protons of galactic origin

NASA Astrophysics Data System (ADS)

Abbasi, R. U.; Abe, M.; Abu-Zayyad, T.; Allen, M.; Azuma, R.; Barcikowski, E.; Belz, J. W.; Bergman, D. R.; Blake, S. A.; Cady, R.; Cheon, B. G.; Chiba, J.; Chikawa, M.; Fujii, T.; Fukushima, M.; Goto, T.; Hanlon, W.; Hayashi, Y.; Hayashi, M.; Hayashida, N.; Hibino, K.; Honda, K.; Ikeda, D.; Inoue, N.; Ishii, T.; Ishimori, R.; Ito, H.; Ivanov, D.; Jui, C. C. H.; Kadota, K.; Kakimoto, F.; Kalashev, O.; Kasahara, K.; Kawai, H.; Kawakami, S.; Kawana, S.; Kawata, K.; Kido, E.; Kim, H. B.; Kim, J. H.; Kim, J. H.; Kishigami, S.; Kitamura, S.; Kitamura, Y.; Kuzmin, V.; Kwon, Y. J.; Lan, J.; Lubsandorzhiev, B.; Lundquist, J. P.; Machida, K.; Martens, K.; Matsuda, T.; Matsuyama, T.; Matthews, J. N.; Minamino, M.; Mukai, K.; Myers, I.; Nagasawa, K.; Nagataki, S.; Nakamura, T.; Nonaka, T.; Nozato, A.; Ogio, S.; Ogura, J.; Ohnishi, M.; Ohoka, H.; Oki, K.; Okuda, T.; Ono, M.; Onogi, R.; Oshima, A.; Ozawa, S.; Park, I. H.; Pshirkov, M. S.; Rodriguez, D. C.; Rubtsov, G.; Ryu, D.; Sagawa, H.; Saito, K.; Saito, Y.; Sakaki, N.; Sakurai, N.; Scott, L. M.; Sekino, K.; Shah, P. D.; Shibata, T.; Shibata, F.; Shimodaira, H.; Shin, B. K.; Shin, H. S.; Smith, J. D.; Sokolsky, P.; Stokes, B. T.; Stratton, S. R.; Stroman, T. A.; Suzawa, T.; Takahashi, Y.; Takamura, M.; Takeda, M.; Takeishi, R.; Taketa, A.; Takita, M.; Tameda, Y.; Tanaka, M.; Tanaka, K.; Tanaka, H.; Thomas, S. B.; Thomson, G. B.; Tinyakov, P.; Tirone, A. H.; Tkachev, I.; Tokuno, H.; Tomida, T.; Troitsky, S.; Tsunesada, Y.; Tsutsumi, K.; Uchihori, Y.; Udo, S.; Urban, F.; Wong, T.; Yamane, R.; Yamaoka, H.; Yamazaki, K.; Yang, J.; Yashiro, K.; Yoneda, Y.; Yoshida, S.; Yoshii, H.; Zollinger, R.; Zundel, Z.

2017-01-01

Cosmic rays in the energy range 1018.0-1018.5 eV are thought to have a light, probably protonic, composition. To study their origin one can search for anisotropy in their arrival directions. Extragalactic cosmic rays should be isotropic, but galactic cosmic rays of this type should be seen mostly along the galactic plane, and there should be a shortage of events coming from directions near the galactic anticenter. This is due to the fact that, under the influence of the galactic magnetic field, the transition from ballistic to diffusive behavior is well advanced, and this qualitative picture persists over the whole energy range. Guided by models of the galactic magnetic field that indicate that the enhancement along the galactic plane should have a standard deviation of about 20° in galactic latitude, and the deficit in the galactic anticenter direction should have a standard deviation of about 50° in galactic longitude, we use the data of the Telescope Array surface detector in 1018.0 to 1018.5 eV energy range to search for these effects. The data are isotropic. Neither an enhancement along the galactic plane nor a deficit in the galactic anticenter direction is found. Using these data we place an upper limit on the fraction of EeV cosmic rays of galactic origin at 1.3% at 95% confidence level.

Ventricular Cycle Length Characteristics Estimative of Prolonged RR Interval during Atrial Fibrillation

PubMed Central

CIACCIO, EDWARD J.; BIVIANO, ANGELO B.; GAMBHIR, ALOK; EINSTEIN, ANDREW J.; GARAN, HASAN

2014-01-01

Background When atrial fibrillation (AF) is incessant, imaging during a prolonged ventricular RR interval may improve image quality. It was hypothesized that long RR intervals could be predicted from preceding RR values. Methods From the PhysioNet database, electrocardiogram RR intervals were obtained from 74 persistent AF patients. An RR interval lengthened by at least 250 ms beyond the immediately preceding RR interval (termed T0 and T1, respectively) was considered prolonged. A two-parameter scatterplot was used to predict the occurrence of a prolonged interval T0. The scatterplot parameters were: (1) RR variability (RRv) estimated as the average second derivative from 10 previous pairs of RR differences, T13–T2, and (2) Tm–T1, the difference between Tm, the mean from T13 to T2, and T1. For each patient, scatterplots were constructed using preliminary data from the first hour. The ranges of parameters 1 and 2 were adjusted to maximize the proportion of prolonged RR intervals within range. These constraints were used for prediction of prolonged RR in test data collected during the second hour. Results The mean prolonged event was 1.0 seconds in duration. Actual prolonged events were identified with a mean positive predictive value (PPV) of 80% in the test set. PPV was >80% in 36 of 74 patients. An average of 10.8 prolonged RR intervals per 60 minutes was correctly identified. Conclusions A method was developed to predict prolonged RR intervals using two parameters and prior statistical sampling for each patient. This or similar methodology may help improve cardiac imaging in many longstanding persistent AF patients. PMID:23998759

Spectral of electrocardiographic RR intervals to indicate atrial fibrillation

NASA Astrophysics Data System (ADS)

Nuryani, Nuryani; Satrio Nugroho, Anto

2017-11-01

Atrial fibrillation is a serious heart diseases, which is associated on the risk of death, and thus an early detection of atrial fibrillation is necessary. We have investigated spectral pattern of electrocardiogram in relation to atrial fibrillation. The utilized feature of electrocardiogram is RR interval. RR interval is the time interval between a two-consecutive R peaks. A series of RR intervals in a time segment is converted to a signal with a frequency domain. The frequency components are investigated to find the components which significantly associate to atrial fibrillation. A segment is defined as atrial fibrillation or normal segments by considering a defined number of atrial fibrillation RR in the segment. Using clinical data of 23 patients with atrial fibrillation, we find that the frequency components could be used to indicate atrial fibrillation.

The annihilation of galactic positrons

NASA Technical Reports Server (NTRS)

Bussard, R.; Rematy, R.

1978-01-01

The probabilities of various channels of galactic positron annihilation were evaluated and the spectrum of the resulting radiation was calculated. The narrow width (FWHM less than 3.2 keV) of the 0.511 MeV line observed from the galactic center implies that a large fraction of positrons should annihilate in a medium of temperature less than 100,000 K and ionization fraction greater than 0.05. HII regions at the galactic center could be possible sites of annihilation.

Degradation of microcystin-RR using boron-doped diamond electrode.

PubMed

Zhang, Chunyong; Fu, Degang; Gu, Zhongze

2009-12-30

Microcystins (MCs), produced by blue-green algae, are one of the most common naturally occurring toxins found in natural environment. The presence of MCs in drinking water sources poses a great threat to people's health. In this study, the degradation behavior of microcystin-RR on boron-doped diamond (BDD) electrode was investigated under galvanostatic conditions. Such parameters as reaction time, supporting electrolyte and applied current density were varied in order to determine their effects on this oxidation process. The experimental results revealed the suitability of electrochemical processes employing BDD electrode for removing MC-RR from the solution. However, the efficient removal of MC-RR only occurred in the presence of sodium chloride that acted as redox mediators and the reaction was mainly affected by the chloride concentration (c(NaCl)) and applied current density (I(appl)). Full and quick removal of 0.50 microg/ml MC-RR in solution was achieved when the operating conditions of c(NaCl) and I(appl) were 20mM and 46.3 mA/cm(2), or 35 mM and 18.2 mA/cm(2) respectively. The kinetics for MC-RR degradation followed a pesudo-first order reaction in most cases, indicating the process was under mass transfer control. As a result of its excellent performance, the BDD technology could be considered as a promising alternative to promote the degradation of MC-RR than chlorination in drinking water supplies.

Petersen diagram revolution

NASA Astrophysics Data System (ADS)

Smolec, Radoslaw; Dziembowski, Wojciech; Moskalik, Pawel; Netzel, Henryka; Prudil, Zdenek; Skarka, Marek; Soszynski, Igor

2017-09-01

Over the recent years, the Petersen diagram for classical pulsators, Cepheids and RR Lyr stars, populated with a few hundreds of new multiperiodic variables. We review our analyses of the OGLE data, which resulted in a significant extension of the known, and in the discovery of a few new and distinct forms of multiperiodic pulsation. The showcase includes not only radial mode pulsators, but also radial-non-radial pulsators and stars with significant modulation observed on top of the beat pulsation. First theoretical models explaining the new forms of stellar variability are briefly discussed.

Finding Distant Galactic HII Regions

NASA Astrophysics Data System (ADS)

Anderson, L. D.; Armentrout, W. P.; Johnstone, B. M.; Bania, T. M.; Balser, Dana S.; Wenger, Trey V.; Cunningham, V.

2015-12-01

The WISE Catalog of Galactic H ii Regions contains ˜2000 H ii region candidates lacking ionized gas spectroscopic observations. All candidates have the characteristic H ii region mid-infrared morphology of WISE 12 μ {{m}} emission surrounding 22 μ {{m}} emission, and additionally have detected radio continuum emission. We here report Green Bank Telescope hydrogen radio recombination line and radio continuum detections in the X-band (9 GHz; 3 cm) of 302 WISE H ii region candidates (out of 324 targets observed) in the zone 225^\\circ ≥slant {\\ell }≥slant -20^\\circ , | {\\text{}}b| ≤slant 6^\\circ . Here we extend the sky coverage of our H ii region Discovery Survey, which now contains nearly 800 H ii regions distributed across the entire northern sky. We provide LSR velocities for the 302 detections and kinematic distances for 131 of these. Of the 302 new detections, 5 have ({\\ell },{\\text{}}b,v) coordinates consistent with the Outer Scutum-Centaurus Arm (OSC), the most distant molecular spiral arm of the Milky Way. Due to the Galactic warp, these nebulae are found at Galactic latitudes >1° in the first Galactic quadrant, and therefore were missed in previous surveys of the Galactic plane. One additional region has a longitude and velocity consistent with the OSC but lies at a negative Galactic latitude (G039.183-01.422 -54.9 {km} {{{s}}}-1). With Heliocentric distances >22 kpc and Galactocentric distances >16 kpc, the OSC H ii regions are the most distant known in the Galaxy. We detect an additional three H ii regions near {\\ell }≃ 150^\\circ whose LSR velocities place them at Galactocentric radii >19 kpc. If their distances are correct, these nebulae may represent the limit to Galactic massive star formation.

The additional-mode garden of RR Lyrae stars

NASA Astrophysics Data System (ADS)

Molnár, László; Plachy, Emese; Klagyivik, Péter; Juhász, Áron L.; Szabó, Róbert; D'Alessandro, Zachary; Kratz, Benjamin; Ortega, Justin; Kanbur, Shashi

2017-10-01

Space-based photometric missions revealed a surprising abundance of millimagnitude-level additional modes in RR Lyrae stars. The modes that appear in the modulated fundamental-mode (RRab) stars can be ordered into four major categories. Here we present the distribution of these groups in the Petersen diagram, and discuss their characteristics and connections to additional modes observed in other RR Lyrae stars.

RR Lyrae stars in eclipsing systems -- historical candidates

NASA Astrophysics Data System (ADS)

Liška, J.; Skarka, M.; Hájková, P.; Auer, R. F.

2016-03-01

Discovery of binary systems among RR Lyrae stars belongs to challenges of present astronomy. So far, none of classical RR Lyrae stars was clearly confirmed, that it is a part of an eclipsing system. From this reason we studied two RR Lyrae stars, VX Her and RW Ari, in which changes assigned to eclipses were detected in sixties and seventies of the 20th century. In this paper our preliminary results based on analysis of new photometric measurements are presented as well as the results from the detailed analysis of original measurements. A new possible eclipsing system, RZ Cet was identified in the archive data. Our analysis rather indicates errors in measurements and reductions of the old data than real changes for all three stars.

Observing the Next Galactic Supernova

NASA Astrophysics Data System (ADS)

Adams, Scott M.; Kochanek, C. S.; Beacom, John F.; Vagins, Mark R.; Stanek, K. Z.

2013-12-01

No supernova (SN) in the Milky Way has been observed since the invention of the optical telescope, instruments for other wavelengths, neutrino detectors, or gravitational wave observatories. It would be a tragedy to miss the opportunity to fully characterize the next one. To aid preparations for its observations, we model the distance, extinction, and magnitude probability distributions of a successful Galactic core-collapse supernova (ccSN), its shock breakout radiation, and its massive star progenitor. We find, at very high probability (sime 100%), that the next Galactic SN will easily be detectable in the near-IR and that near-IR photometry of the progenitor star very likely (sime 92%) already exists in the Two Micron All Sky Survey. Most ccSNe (98%) will be easily observed in the optical, but a significant fraction (43%) will lack observations of the progenitor due to a combination of survey sensitivity and confusion. If neutrino detection experiments can quickly disseminate a likely position (~3°), we show that a modestly priced IR camera system can probably detect the shock breakout radiation pulse even in daytime (64% for the cheapest design). Neutrino experiments should seriously consider adding such systems, both for their scientific return and as an added and internal layer of protection against false triggers. We find that shock breakouts from failed ccSNe of red supergiants may be more observable than those of successful SNe due to their lower radiation temperatures. We review the process by which neutrinos from a Galactic ccSN would be detected and announced. We provide new information on the EGADS system and its potential for providing instant neutrino alerts. We also discuss the distance, extinction, and magnitude probability distributions for the next Galactic Type Ia supernova (SN Ia). Based on our modeled observability, we find a Galactic ccSN rate of 3.2^{+7.3}_{-2.6} per century and a Galactic SN Ia rate of 1.4^{+1.4}_{-0.8} per century for a

Open star clusters and Galactic structure

NASA Astrophysics Data System (ADS)

Joshi, Yogesh C.

2018-04-01

In order to understand the Galactic structure, we perform a statistical analysis of the distribution of various cluster parameters based on an almost complete sample of Galactic open clusters yet available. The geometrical and physical characteristics of a large number of open clusters given in the MWSC catalogue are used to study the spatial distribution of clusters in the Galaxy and determine the scale height, solar offset, local mass density and distribution of reddening material in the solar neighbourhood. We also explored the mass-radius and mass-age relations in the Galactic open star clusters. We find that the estimated parameters of the Galactic disk are largely influenced by the choice of cluster sample.

Registration and Release of Syn1RR tall fescue

USDA-ARS?s Scientific Manuscript database

The Agricultural Research Service of the United States DepaRRment of Agriculture announces the release of the new tall fescue [Festuca arundinacea (syn., Lolium arundinaceum Darbyshire; Schedonorus phoenix (Scop.) Holub)] cultivar Syn1RR. Syn1RR is a rust tolerant tall fescue cultivar that exhibits...

Galactic cosmic ray composition

NASA Technical Reports Server (NTRS)

Meyer, J. P.

1986-01-01

An assessment is given of the galactic cosmic ray source (GCRS) elemental composition and its correlation with first ionization potential. The isotopic composition of heavy nuclei; spallation cross sections; energy spectra of primary nuclei; electrons; positrons; local galactic reference abundances; comparison of solar energetic particles and solar coronal compositions; the hydrogen; lead; nitrogen; helium; and germanium deficiency problems; and the excess of elements are among the topics covered.

Mechanisms underlying very-low-frequency RR-interval oscillations in humans

NASA Technical Reports Server (NTRS)

Taylor, J. A.; Carr, D. L.; Myers, C. W.; Eckberg, D. L.

1998-01-01

BACKGROUND: Survival of post-myocardial infarction patients is related inversely to their levels of very-low-frequency (0.003 to 0.03 Hz) RR-interval variability. The physiological basis for such oscillations is unclear. In our study, we used blocking drugs to evaluate potential contributions of sympathetic and vagal mechanisms and the renin-angiotensin-aldosterone system to very-low-frequency RR-interval variability in 10 young healthy subjects. METHODS AND RESULTS: We recorded RR intervals and arterial pressures during three separate sessions, with the patient in supine and 40 degree upright tilt positions, during 20-minute frequency (0.25 Hz) and tidal volume-controlled breathing after intravenous injections: saline (control), atenolol (0.2 mg/kg, beta-adrenergic blockade), atropine sulfate (0.04 mg/kg, parasympathetic blockade), atenolol and atropine (complete autonomic blockade), and enalaprilat (0.02 mg/kg, ACE blockade). We integrated fast Fourier transform RR-interval spectral power at very low (0.003 to 0.03 Hz), low (0.05 to 0. 15 Hz), and respiratory (0.2 to 0.3 Hz) frequencies. Beta-adrenergic blockade had no significant effect on very-low- or low-frequency RR-interval power but increased respiratory frequency power 2-fold. ACE blockade had no significant effect on low or respiratory frequency RR-interval power but modestly (approximately 21%) increased very-low-frequency power in the supine (but not upright tilt) position (P<0.05). The most profound effects were exerted by parasympathetic blockade: Atropine, given alone or with atenolol, abolished nearly all RR-interval variability and decreased very-low-frequency variability by 92%. CONCLUSIONS: Although very-low-frequency heart period rhythms are influenced by the renin-angiotensin-aldosterone system, as low and respiratory frequency RR-interval rhythms, they depend primarily on the presence of parasympathetic outflow. Therefore the prognostic value of very-low-frequency heart period oscillations may

Anisotropy and corotation of galactic cosmic rays.

PubMed

Amenomori, M; Ayabe, S; Bi, X J; Chen, D; Cui, S W; Danzengluobu; Ding, L K; Ding, X H; Feng, C F; Feng, Zhaoyang; Feng, Z Y; Gao, X Y; Geng, Q X; Guo, H W; He, H H; He, M; Hibino, K; Hotta, N; Hu, Haibing; Hu, H B; Huang, J; Huang, Q; Jia, H Y; Kajino, F; Kasahara, K; Katayose, Y; Kato, C; Kawata, K; Labaciren; Le, G M; Li, A F; Li, J Y; Lou, Y-Q; Lu, H; Lu, S L; Meng, X R; Mizutani, K; Mu, J; Munakata, K; Nagai, A; Nanjo, H; Nishizawa, M; Ohnishi, M; Ohta, I; Onuma, H; Ouchi, T; Ozawa, S; Ren, J R; Saito, T; Saito, T Y; Sakata, M; Sako, T K; Sasaki, T; Shibata, M; Shiomi, A; Shirai, T; Sugimoto, H; Takita, M; Tan, Y H; Tateyama, N; Torii, S; Tsuchiya, H; Udo, S; Wang, B; Wang, H; Wang, X; Wang, Y G; Wu, H R; Xue, L; Yamamoto, Y; Yan, C T; Yang, X C; Yasue, S; Ye, Z H; Yu, G C; Yuan, A F; Yuda, T; Zhang, H M; Zhang, J L; Zhang, N J; Zhang, X Y; Zhang, Y; Zhang, Yi; Zhaxisangzhu; Zhou, X X

2006-10-20

The intensity of Galactic cosmic rays is nearly isotropic because of the influence of magnetic fields in the Milky Way. Here, we present two-dimensional high-precision anisotropy measurement for energies from a few to several hundred teraelectronvolts (TeV), using the large data sample of the Tibet Air Shower Arrays. Besides revealing finer details of the known anisotropies, a new component of Galactic cosmic ray anisotropy in sidereal time is uncovered around the Cygnus region direction. For cosmic-ray energies up to a few hundred TeV, all components of anisotropies fade away, showing a corotation of Galactic cosmic rays with the local Galactic magnetic environment. These results have broad implications for a comprehensive understanding of cosmic rays, supernovae, magnetic fields, and heliospheric and Galactic dynamic environments.

Testing Galactic Cosmic Ray Models

NASA Technical Reports Server (NTRS)

Adams, James H., Jr.

2009-01-01

Models of the Galactic Cosmic Ray Environment are used for designing and planning space missions. The existing models will be reviewed. Spectral representations from these models will be compared with measurements of galactic cosmic ray spectra made on balloon flights and satellite flights over a period of more than 50 years.

Testing Galactic Cosmic Ray Models

NASA Technical Reports Server (NTRS)

Adams, James H., Jr.

2010-01-01

Models of the Galactic Cosmic Ray Environment are used for designing and planning space missions. The exising models will be reviewed. Spectral representations from these models will be compared with measurements of galactic cosmic ray spectra made on balloon flights and satellite flights over a period of more than 50 years.

A precursive study of the time-domain survey of the Galactic Anti-center using the Nanshan 1-meter telescope with variable stars detected

NASA Astrophysics Data System (ADS)

Ma, Shu-Guo; Esamdin, Ali; Ma, Lu; Niu, Hu-Biao; Fu, Jian-Ning; Zhang, Yu; Liu, Jin-Zhong; Yang, Tao-Zhi; Song, Fang-Fang; Pu, Guang-Xin

2018-04-01

Following the LAMOST Spectroscopic Survey and the Xuyi's Photometric Survey of the Galactic Anti-center, we plan to carry out a time-domain survey of the Galactic Anti-center (TDS-GAC) to study variable stars by using the Nanshan 1-meter telescope. Before the beginning of TDS-GAC, a precursive sky survey (PSS) has been executed. The goal of the PSS is to optimize the observation strategy of TDS-GAC and to detect some strong transient events, as well as to find some short time-scale variable stars of different types. By observing a discontinuous sky area of 15.03 deg2 with the standard Johnson-Cousin-Bessel V filter, 48 variable stars are found and the time series are analyzed. Based on the behaviors of the light curves, 28 eclipsing binary stars, 10 RR Lyraes, 3 periodic pulsating variables of other types have been classified. The rest 7 variables stay unclassified with deficient data. In addition, the observation strategy of TD-GAC is described, and the pipeline of data reduction is tested.

Black-hole model of galactic nuclei

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

Norman, C.A.; ter Haar, D.

1973-04-01

It is shown that the observed large infrared emission from some galactic nuclei finds a natural explanation, if one takes plasma turbulence into account in Lynden-Bell and Rees' blackhole model of galactic nuclei. (auth)

Exploring the Variable Sky with LINEAR. II. Halo Structure and Substructure Traced by RR Lyrae Stars to 30 kpc

NASA Astrophysics Data System (ADS)

Sesar, Branimir; Ivezić, Željko; Stuart, J. Scott; Morgan, Dylan M.; Becker, Andrew C.; Sharma, Sanjib; Palaversa, Lovro; Jurić, Mario; Wozniak, Przemyslaw; Oluseyi, Hakeem

2013-08-01

We present a sample of ~5000 RR Lyrae stars selected from the recalibrated LINEAR data set and detected at heliocentric distances between 5 kpc and 30 kpc over ~8000 deg2 of sky. The coordinates and light curve properties, such as period and Oosterhoff type, are made publicly available. We analyze in detail the light curve properties and Galactic distribution of the subset of ~4000 type ab RR Lyrae (RRab) stars, including a search for new halo substructures and the number density distribution as a function of Oosterhoff type. We find evidence for the Oosterhoff dichotomy among field RR Lyrae stars, with the ratio of the type II and I subsamples of about 1:4, but with a weaker separation than for globular cluster stars. The wide sky coverage and depth of this sample allow unique constraints for the number density distribution of halo RRab stars as a function of galactocentric distance: it can be described as an oblate ellipsoid with an axis ratio q = 0.63 and with either a single or a double power law with a power-law index in the range -2 to -3. Consistent with previous studies, we find that the Oosterhoff type II subsample has a steeper number density profile than the Oosterhoff type I subsample. Using the group-finding algorithm EnLink, we detected seven candidate halo groups, only one of which is statistically spurious. Three of these groups are near globular clusters (M53/NGC 5053, M3, M13), and one is near a known halo substructure (Virgo Stellar Stream); the remaining three groups do not seem to be near any known halo substructures or globular clusters and seem to have a higher ratio of Oosterhoff type II to Oosterhoff type I RRab stars than what is found in the halo. The extended morphology and the position (outside the tidal radius) of some of the groups near globular clusters are suggestive of tidal streams possibly originating from globular clusters. Spectroscopic follow-up of detected halo groups is encouraged.

Gamma ray constraints on the Galactic supernova rate

NASA Technical Reports Server (NTRS)

Hartmann, D.; The, L.-S.; Clayton, Donald D.; Leising, M.; Mathews, G.; Woosley, S. E.

1991-01-01

We perform Monte Carlo simulations of the expected gamma ray signatures of Galactic supernovae of all types to estimate the significance of the lack of a gamma ray signal due to supernovae occurring during the last millenium. Using recent estimates of the nuclear yields, we determine mean Galactic supernova rates consistent with the historic supernova record and the gamma ray limits. Another objective of these calculations of Galactic supernova histories is their application to surveys of diffuse Galactic gamma ray line emission.

Gamma ray constraints on the galactic supernova rate

NASA Technical Reports Server (NTRS)

Hartmann, D.; The, L.-S.; Clayton, D. D.; Leising, M.; Mathews, G.; Woosley, S. E.

1992-01-01

Monte Carlo simulations of the expected gamma-ray signatures of galactic supernovae of all types are performed in order to estimate the significance of the lack of a gamma-ray signal due to supernovae occurring during the last millenium. Using recent estimates of nuclear yields, we determine galactic supernova rates consistent with the historic supernova record and the gamma-ray limits. Another objective of these calculations of galactic supernova histories is their application to surveys of diffuse galactic gamma-ray line emission.

ARCADE 2 Observations of Galactic Radio Emission

NASA Technical Reports Server (NTRS)

Kogut, A.; Fixsen, D. J.; Levin, S. M.; Limon, M.; Lubin, P. M.; Mirel, P.; Seiffert, M.; Singal, J.; Villela, T.; Wollack, E.;

Metal-rich RRc Stars in the Carnegie RR Lyrae Survey

NASA Astrophysics Data System (ADS)

Sneden, Christopher; Preston, George W.; Kollmeier, Juna A.; Crane, Jeffrey D.; Morrell, Nidia; Prieto, José L.; Shectman, Stephen A.; Skowron, Dorota M.; Thompson, Ian B.

2018-01-01

We describe and employ a stacking procedure to investigate abundances derived from the low signal-to-noise ratio spectra obtained in the Carnegie RR Lyrae Survey (CARRS). We find iron metallicities that extend from [Fe/H] ∼ ‑2.5 to values at least as large as [Fe/H] ∼ ‑0.5 in the 274-spectrum CARRS RRc data set. We consider RRc sample contamination by high amplitude solar metallicity δ Scuti stars (HADS) at periods less than 0.3 days, where photometric discrimination between RRc and δ Scuti stars has proven to be problematic. We offer a spectroscopic discriminant, the well-marked overabundance of heavy elements, principally [Ba/H], that is a common, if not universal, characteristic of HADS of all periods and axial rotations. No bona fide RRc stars known to us have verified heavy-element overabundances. Three out of 34 stars in our sample with [Fe/H] > ‑0.7 exhibit anomalously strong features of Sr, Y, Zr, Ba, and many rare earths. However, carbon is not enhanced in these three stars, and we conclude that their elevated n-capture abundances have not been generated in interior neutron-capture nucleosynthesis. Contamination by HADS appears to be unimportant, and metal-rich RRc stars occur in approximately the same proportion in the Galactic field as do metal-rich RRab stars. An apparent dearth of metal-rich RRc is probably a statistical fluke. Finally, we show that RRc stars have a similar inverse period–metallicity relationship as has been found for RRab stars.

Imbalanced Learning for RR Lyrae Stars Based on SDSS and GALEX Databases

NASA Astrophysics Data System (ADS)

Zhang, Jingyi; Zhang, Yanxia; Zhao, Yongheng

2018-03-01

We apply machine learning and Convex-Hull algorithms to separate RR Lyrae stars from other stars like main-sequence stars, white dwarf stars, carbon stars, CVs, and carbon-lines stars, based on the Sloan Digital Sky Survey and Galaxy Evolution Explorer (GALEX). In low-dimensional spaces, the Convex-Hull algorithm is applied to select RR Lyrae stars. Given different input patterns of (u ‑ g, g ‑ r), (g ‑ r, r ‑ i), (r ‑ i, i ‑ z), (u ‑ g, g ‑ r, r ‑ i), (g ‑ r, r ‑ i, i ‑ z), (u ‑ g, g ‑ r, i ‑ z), and (u ‑ g, r ‑ i, i ‑ z), different convex hulls can be built for RR Lyrae stars. Comparing the performance of different input patterns, u ‑ g, g ‑ r, i ‑ z is the best input pattern. For this input pattern, the efficiency (the fraction of true RR Lyrae stars in the predicted RR Lyrae sample) is 4.2% with a completeness (the fraction of recovered RR Lyrae stars in the whole RR Lyrae sample) of 100%, increases to 9.9% with 97% completeness and to 16.1% with 53% completeness by removing some outliers. In high-dimensional spaces, machine learning algorithms are used with input patterns (u ‑ g, g ‑ r, r ‑ i, i ‑ z), (u ‑ g, g ‑ r, r ‑ i, i ‑ z, r), (NUV ‑ u, u ‑ g, g ‑ r, r ‑ i, i ‑ z), and (NUV ‑ u, u ‑ g, g ‑ r, r ‑ i, i ‑ z, r). RR Lyrae stars, which belong to the class of interest in our paper, are rare compared to other stars. For the highly imbalanced data, cost-sensitive Support Vector Machine, cost-sensitive Random Forest, and Fast Boxes is used. The results show that information from GALEX is helpful for identifying RR Lyrae stars, and Fast Boxes is the best performer on the skewed data in our case.

The physics of galactic winds driven by active galactic nuclei

NASA Astrophysics Data System (ADS)

Faucher-Giguère, Claude-André; Quataert, Eliot

2012-09-01

Active galactic nuclei (AGN) drive fast winds in the interstellar medium of their host galaxies. It is commonly assumed that the high ambient densities and intense radiation fields in galactic nuclei imply short cooling times, thus making the outflows momentum conserving. We show that cooling of high-velocity shocked winds in AGN is in fact inefficient in a wide range of circumstances, including conditions relevant to ultraluminous infrared galaxies (ULIRGs), resulting in energy-conserving outflows. We further show that fast energy-conserving outflows can tolerate a large amount of mixing with cooler gas before radiative losses become important. For winds with initial velocity vin ≳ 10 000 km s-1, as observed in ultraviolet and X-ray absorption, the shocked wind develops a two-temperature structure. While most of the thermal pressure support is provided by the protons, the cooling processes operate directly only on the electrons. This significantly slows down inverse Compton cooling, while free-free cooling is negligible. Slower winds with vin ˜ 1000 km s-1, such as may be driven by radiation pressure on dust, can also experience energy-conserving phases but under more restrictive conditions. During the energy-conserving phase, the momentum flux of an outflow is boosted by a factor ˜vin/2vs by work done by the hot post-shock gas, where vs is the velocity of the swept-up material. Energy-conserving outflows driven by fast AGN winds (vin ˜ 0.1c) may therefore explain the momentum fluxes Ṗ≫LAGN/c of galaxy-scale outflows recently measured in luminous quasars and ULIRGs. Shocked wind bubbles expanding normal to galactic discs may also explain the large-scale bipolar structures observed in some systems, including around the Galactic Centre, and can produce significant radio, X-ray and γ-ray emission. The analytic solutions presented here will inform implementations of AGN feedback in numerical simulations, which typically do not include all the important

Acceleration of petaelectronvolt protons in the Galactic Centre

NASA Astrophysics Data System (ADS)

HESS Collaboration; Abramowski, A.; Aharonian, F.; Benkhali, F. Ait; Akhperjanian, A. G.; Angüner, E. O.; Backes, M.; Balzer, A.; Becherini, Y.; Tjus, J. Becker; Berge, D.; Bernhard, S.; Bernlöhr, K.; Birsin, E.; Blackwell, R.; Böttcher, M.; Boisson, C.; Bolmont, J.; Bordas, P.; Bregeon, J.; Brun, F.; Brun, P.; Bryan, M.; Bulik, T.; Carr, J.; Casanova, S.; Chakraborty, N.; Chalme-Calvet, R.; Chaves, R. C. G.; Chen, A.; Chrétien, M.; Colafrancesco, S.; Cologna, G.; Conrad, J.; Couturier, C.; Cui, Y.; Davids, I. D.; Degrange, B.; Deil, C.; Dewilt, P.; Djannati-Ataï, A.; Domainko, W.; Donath, A.; Drury, L. O'C.; Dubus, G.; Dutson, K.; Dyks, J.; Dyrda, M.; Edwards, T.; Egberts, K.; Eger, P.; Ernenwein, J.-P.; Espigat, P.; Farnier, C.; Fegan, S.; Feinstein, F.; Fernandes, M. V.; Fernandez, D.; Fiasson, A.; Fontaine, G.; Förster, A.; Füßling, M.; Gabici, S.; Gajdus, M.; Gallant, Y. A.; Garrigoux, T.; Giavitto, G.; Giebels, B.; Glicenstein, J. F.; Gottschall, D.; Goyal, A.; Grondin, M.-H.; Grudzińska, M.; Hadasch, D.; Häffner, S.; Hahn, J.; Hawkes, J.; Heinzelmann, G.; Henri, G.; Hermann, G.; Hervet, O.; Hillert, A.; Hinton, J. A.; Hofmann, W.; Hofverberg, P.; Hoischen, C.; Holler, M.; Horns, D.; Ivascenko, A.; Jacholkowska, A.; Jamrozy, M.; Janiak, M.; Jankowsky, F.; Jung-Richardt, I.; Kastendieck, M. A.; Katarzyński, K.; Katz, U.; Kerszberg, D.; Khélifi, B.; Kieffer, M.; Klepser, S.; Klochkov, D.; Kluźniak, W.; Kolitzus, D.; Komin, Nu.; Kosack, K.; Krakau, S.; Krayzel, F.; Krüger, P. P.; Laffon, H.; Lamanna, G.; Lau, J.; Lefaucheur, J.; Lefranc, V.; Lemiére, A.; Lemoine-Goumard, M.; Lenain, J.-P.; Lohse, T.; Lopatin, A.; Lu, C.-C.; Lui, R.; Marandon, V.; Marcowith, A.; Mariaud, C.; Marx, R.; Maurin, G.; Maxted, N.; Mayer, M.; Meintjes, P. J.; Menzler, U.; Meyer, M.; Mitchell, A. M. W.; Moderski, R.; Mohamed, M.; Morå, K.; Moulin, E.; Murach, T.; de Naurois, M.; Niemiec, J.; Oakes, L.; Odaka, H.; Öttl, S.; Ohm, S.; Opitz, B.; Ostrowski, M.; Oya, I.; Panter, M.; Parsons, R. D.; Arribas, M. Paz; Pekeur, N. W.; Pelletier, G.; Petrucci, P.-O.; Peyaud, B.; Pita, S.; Poon, H.; Prokoph, H.; Pühlhofer, G.; Punch, M.; Quirrenbach, A.; Raab, S.; Reichardt, I.; Reimer, A.; Reimer, O.; Renaud, M.; de Los Reyes, R.; Rieger, F.; Romoli, C.; Rosier-Lees, S.; Rowell, G.; Rudak, B.; Rulten, C. B.; Sahakian, V.; Salek, D.; Sanchez, D. A.; Santangelo, A.; Sasaki, M.; Schlickeiser, R.; Schüssler, F.; Schulz, A.; Schwanke, U.; Schwemmer, S.; Seyffert, A. S.; Simoni, R.; Sol, H.; Spanier, F.; Spengler, G.; Spies, F.; Stawarz, Ł.; Steenkamp, R.; Stegmann, C.; Stinzing, F.; Stycz, K.; Sushch, I.; Tavernet, J.-P.; Tavernier, T.; Taylor, A. M.; Terrier, R.; Tluczykont, M.; Trichard, C.; Tuffs, R.; Valerius, K.; van der Walt, J.; van Eldik, C.; van Soelen, B.; Vasileiadis, G.; Veh, J.; Venter, C.; Viana, A.; Vincent, P.; Vink, J.; Voisin, F.; Völk, H. J.; Vuillaume, T.; Wagner, S. J.; Wagner, P.; Wagner, R. M.; Weidinger, M.; Weitzel, Q.; White, R.; Wierzcholska, A.; Willmann, P.; Wörnlein, A.; Wouters, D.; Yang, R.; Zabalza, V.; Zaborov, D.; Zacharias, M.; Zdziarski, A. A.; Zech, A.; Zefi, F.; Żywucka, N.

2016-03-01

Galactic cosmic rays reach energies of at least a few petaelectronvolts (of the order of 1015 electronvolts). This implies that our Galaxy contains petaelectronvolt accelerators (‘PeVatrons’), but all proposed models of Galactic cosmic-ray accelerators encounter difficulties at exactly these energies. Dozens of Galactic accelerators capable of accelerating particles to energies of tens of teraelectronvolts (of the order of 1013 electronvolts) were inferred from recent γ-ray observations. However, none of the currently known accelerators—not even the handful of shell-type supernova remnants commonly believed to supply most Galactic cosmic rays—has shown the characteristic tracers of petaelectronvolt particles, namely, power-law spectra of γ-rays extending without a cut-off or a spectral break to tens of teraelectronvolts. Here we report deep γ-ray observations with arcminute angular resolution of the region surrounding the Galactic Centre, which show the expected tracer of the presence of petaelectronvolt protons within the central 10 parsecs of the Galaxy. We propose that the supermassive black hole Sagittarius A* is linked to this PeVatron. Sagittarius A* went through active phases in the past, as demonstrated by X-ray outburstsand an outflow from the Galactic Centre. Although its current rate of particle acceleration is not sufficient to provide a substantial contribution to Galactic cosmic rays, Sagittarius A* could have plausibly been more active over the last 106-107 years, and therefore should be considered as a viable alternative to supernova remnants as a source of petaelectronvolt Galactic cosmic rays.

The Selection of RR Lyrae Stars Using POSS and SDSS

NASA Astrophysics Data System (ADS)

Fraser, Oliver J.; Barton, J. R.; Oldfield, B. J.; Biesiadzinski, T. P.; Horning, D. A.; Baerny, J. K.; Kiuchi, F.; Krogsrud, D.; Longhurst, D. S.; McCommas, L. P.; Scheidt, J. A.; Covarrubias, R.; Covey, K.; Laws, C.; Sesar, B.; Ivezic, Z.

2006-12-01

We test a method for identifying candidate RR Lyrae stars based on a comparison of POSS and SDSS photometry (Sesar et. al. 2005). Our candidate stars range in SDSS g magnitude from 14.4--16, or a distance of 6--12 kpc. Follow-up photometry obtained at Manastash Ridge Observatory typically includes 30-40 points per light curve. We find that at least two thirds of our sample of 23 objects are clearly variable, with light curves consistent with RR Lyrae. Candidate RR Lyrae were selected using stars that had brightened at least 0.3 magnitudes between POSS and SDSS, and which had SDSS magnitudes and colors consistent with the cuts in Ivezic et al. 2004.

Characterizing artifacts in RR stress test time series.

PubMed

Astudillo-Salinas, Fabian; Palacio-Baus, Kenneth; Solano-Quinde, Lizandro; Medina, Ruben; Wong, Sara

2016-08-01

Electrocardiographic stress test records have a lot of artifacts. In this paper we explore a simple method to characterize the amount of artifacts present in unprocessed RR stress test time series. Four time series classes were defined: Very good lead, Good lead, Low quality lead and Useless lead. 65 ECG, 8 lead, records of stress test series were analyzed. Firstly, RR-time series were annotated by two experts. The automatic methodology is based on dividing the RR-time series in non-overlapping windows. Each window is marked as noisy whenever it exceeds an established standard deviation threshold (SDT). Series are classified according to the percentage of windows that exceeds a given value, based upon the first manual annotation. Different SDT were explored. Results show that SDT close to 20% (as a percentage of the mean) provides the best results. The coincidence between annotators classification is 70.77% whereas, the coincidence between the second annotator and the automatic method providing the best matches is larger than 63%. Leads classified as Very good leads and Good leads could be combined to improve automatic heartbeat labeling.

18. BLUEPRINT, RR BRIDGE Tombigbee R. MISSISSIPPI, CLAY CO., WAVERLY ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

18. BLUEPRINT, RR BRIDGE Tombigbee R. MISSISSIPPI, CLAY CO., WAVERLY 1.5 mi. S of MS 50 Detail: 'Georgia Pacific Rwy. -- Tombigbee River Bridge Elevation' with river profile, May 16, 1888. Credit: Columbus and Greenville Rr, Columbus, Ms. DWG = S-3-342. Sarcone Photography, Columbus, Ms Sep 1978. - Bridges of the Upper Tombigbee River Valley, Columbus, Lowndes County, MS

Galactic Train Wrecks

NASA Image and Video Library

2011-05-25

This montage combines observations from NASA Spitzer Space Telescope and NASA Galaxy Evolution Explorer GALEX spacecraft showing three examples of colliding galaxies from a new photo atlas of galactic train wrecks.

Galactic Winds and the Role Played by Massive Stars

NASA Astrophysics Data System (ADS)

Heckman, Timothy M.; Thompson, Todd A.

Galactic winds from star-forming galaxies play at key role in the evolution of galaxies and the intergalactic medium. They transport metals out of galaxies, chemically enriching the intergalactic medium and modifying the chemical evolution of galaxies. They affect the surrounding interstellar and circumgalactic media, thereby influencing the growth of galaxies though gas accretion and star formation. In this contribution we first summarize the physical mechanisms by which the momentum and energy output from a population of massive stars and associated supernovae can drive galactic winds. We use the prototypical example of M 82 to illustrate the multiphase nature of galactic winds. We then describe how the basic properties of galactic winds are derived from the data, and summarize how the properties of galactic winds vary systematically with the properties of the galaxies that launch them. We conclude with a brief discussion of the broad implications of galactic winds.

The galactic contribution to IceCube's astrophysical neutrino flux

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

Denton, Peter B.; Marfatia, Danny; Weiler, Thomas J., E-mail: peterbd1@gmail.com, E-mail: dmarf8@hawaii.edu, E-mail: tom.weiler@vanderbilt.edu

2017-08-01

High energy neutrinos have been detected by IceCube, but their origin remains a mystery. Determining the sources of this flux is a crucial first step towards multi-messenger studies. In this work we systematically compare two classes of sources with the data: galactic and extragalactic. We assume that the neutrino sources are distributed according to a class of Galactic models. We build a likelihood function on an event by event basis including energy, event topology, absorption, and direction information. We present the probability that each high energy event with deposited energy E {sub dep}>60 TeV in the HESE sample is Galactic,more » extragalactic, or background. For Galactic models considered the Galactic fraction of the astrophysical flux has a best fit value of 1.3% and is <9.5% at 90% CL. A zero Galactic flux is allowed at <1σ.« less

Global dynamics and diffusion in triaxial galactic models

NASA Astrophysics Data System (ADS)

Papaphilippou, Y.

We apply the Frequency Map Analysis method to the 3--dimensional logarithmic galactic potential in order to clarify the dynamical behaviour of triaxial power--law galactic models. All the fine dynamical details are displayed in the complete frequency map, a direct representation of the system's Arnol'd web. The influence of resonant lines and the extent of the chaotic zones are directly associated with the physical space of the system. Some new results related with the diffusion of galactic orbits are also discussed. This approach reveals many unknown dynamical features of triaxial galactic potentials and provides strong indications that chaos should be an innate characteristic of triaxial configurations.

The Planck Catalogue of Galactic Cold Clumps : PGCC

NASA Astrophysics Data System (ADS)

Montier, L.

The Planck satellite has provided an unprecedented view of the submm sky, allowing us to search for the dust emission of Galactic cold sources. Combining Planck-HFI all-sky maps in the high frequency channels with the IRAS map at 100um, we built the Planck catalogue of Galactic Cold Clumps (PGCC, Planck 2015 results. XXVIII), counting 13188 sources distributed over the whole sky, and following mainly the Galactic structures at low and intermediate latitudes. This is the first all-sky catalogue of Galactic cold sources obtained with a single instrument at this resolution and sensitivity, which opens a new window on star-formation processes in our Galaxy.

Contamination of RR Lyrae stars from Binary Evolution Pulsators

NASA Astrophysics Data System (ADS)

Karczmarek, Paulina; Pietrzyński, Grzegorz; Belczyński, Krzysztof; Stępień, Kazimierz; Wiktorowicz, Grzegorz; Iłkiewicz, Krystian

2016-06-01

Binary Evolution Pulsator (BEP) is an extremely low-mass member of a binary system, which pulsates as a result of a former mass transfer to its companion. BEP mimics RR Lyrae-type pulsations but has different internal structure and evolution history. We present possible evolution channels to produce BEPs, and evaluate the contamination value, i.e. how many objects classified as RR Lyrae stars can be undetected BEPs. In this analysis we use population synthesis code StarTrack.

Pitch angle of galactic spiral arms

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

Michikoshi, Shugo; Kokubo, Eiichiro, E-mail: michiko@mail.doshisha.ac.jp, E-mail: kokubo@th.nao.ac.jp

2014-06-01

One of the key parameters that characterizes spiral arms in disk galaxies is a pitch angle that measures the inclination of a spiral arm to the direction of galactic rotation. The pitch angle differs from galaxy to galaxy, which suggests that the rotation law of galactic disks determines it. In order to investigate the relation between the pitch angle of spiral arms and the shear rate of galactic differential rotation, we perform local N-body simulations of pure stellar disks. We find that the pitch angle increases with the epicycle frequency and decreases with the shear rate and obtain the fittingmore » formula. This dependence is explained by the swing amplification mechanism.« less

The distances of the Galactic Novae

NASA Astrophysics Data System (ADS)

Ozdonmez, Aykut; Guver, Tolga; Cabrera-Lavers, Antonio; Ak, Tansel

2016-07-01

Using location of the RC stars on the CMDs obtained from the UKIDSS, VISTA and 2MASS photometry, we have derived the reddening-distance relations towards each Galactic nova for which at least one independent reddening measurement exists. We were able to determine the distances of 72 Galactic novae and set lower limits on the distances of 45 systems. The reddening curves of the systems are presented. These curves can be also used to estimate reddening or the distance of any source, whose location is close to the position of the nova in our sample. The distance measurement method in our study can be easily applicable to any source, especially for ones that concentrated along the Galactic plane.

20. BLUEPRINT, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY L.% MI. ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

20. BLUEPRINT, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY L.% MI. S of MS. 50 Proposed bridge, by Phoenis Bridge Co., Phoenixville, Pa. 218-foot turn span, with load bearing. 21 May 1914. Act. size: 16X35 in. Credit: Columbus and Greenville RR, Columbus, Ms. Sarcone Photography, Columbus, Ms. Sept 1978. - Bridges of the Upper Tombigbee River Valley, Columbus, Lowndes County, MS

The Galactic Club or Galactic Cliques? Exploring the limits of interstellar hegemony and the Zoo Hypothesis

NASA Astrophysics Data System (ADS)

Forgan, Duncan H.

2017-10-01

The Zoo solution to Fermi's Paradox proposes that extraterrestrial intelligences (ETIs) have agreed to not contact the Earth. The strength of this solution depends on the ability for ETIs to come to agreement, and establish/police treaties as part of a so-called `Galactic Club'. These activities are principally limited by the causal connectivity of a civilization to its neighbours at its inception, i.e. whether it comes to prominence being aware of other ETIs and any treaties or agreements in place. If even one civilization is not causally connected to the other members of a treaty, then they are free to operate beyond it and contact the Earth if wished, which makes the Zoo solution `soft'. We should therefore consider how likely this scenario is, as this will give us a sense of the Zoo solution's softness, or general validity. We implement a simple toy model of ETIs arising in a Galactic Habitable Zone, and calculate the properties of the groups of culturally connected civilizations established therein. We show that for most choices of civilization parameters, the number of culturally connected groups is >1, meaning that the Galaxy is composed of multiple Galactic Cliques rather than a single Galactic Club. We find in our models for a single Galactic Club to establish interstellar hegemony, the number of civilizations must be relatively large, the mean civilization lifetime must be several millions of years, and the inter-arrival time between civilizations must be a few million years or less.

The Formation of Galactic Bulges

NASA Astrophysics Data System (ADS)

Carollo, C. Marcella; Ferguson, Henry C.; Wyse, Rosemary F. G.

2000-03-01

Part I. Introduction: What are galactic bulges?; Part II. The Epoch of Bulge Formation: Origin of bulges; Deep sub-mm surveys: High-z ULIRGs and the formation of spheroids; Ages and metallicities for stars in the galactic bulge; Integrated stellar populations of bulges: First results; HST-NICMOS observations of galactic bulges: Ages and dust; Inside-out bulge formation and the origin of the Hubble sequence; Part III. The Timescales of Bulge Formation: Constraints on the bulge formation timescale from stellar populations; Bulge building with mergers and winds; Role of winds, starbursts, and activity in bulge formation; Dynamical timescales of bulge formation; Part IV. Physical Processes in Bulge Formation: the role of bars for secular bulge formation; Bars and boxy/peanut-shaped bulges: an observational point of view; Boxy- and peanut-shaped bulges; A new class of bulges; The role of secondary bars in bulge formation; Radial transport of molecular gas to the nuclei of spiral galaxies; Dynamical evolution of bulge shapes; Two-component stellar systems: Phase-space constraints; Central NGC 2146 - a firehose-type bending instability?; Bulge formation: the role of the multi-phase ISM; Global evolution of a self-gravitating multi-phase ISM in the central kpc region of galaxies; Part V. Bulge Phenomenology: Bulge-disk decomposition of spiral galaxies in the near-infrared; The triaxial bulge of NGC 1371; The bulge-disk orthogonal decoupling in galaxies: NGC 4698 and NGC 4672; The kinematics and the origin of the ionized gas in NGC 4036; Optically thin thermal plasma in the galactic bulge; X-ray properties of bulges; The host galaxies of radio-loud AGN; The centers of radio-loud early-type galaxies with HST; Central UV spikes in two galactic spheroids; Conference summary: where do we stand?

[Heart rate variability study based on a novel RdR RR Intervals Scatter Plot].

PubMed

Lu, Hongwei; Lu, Xiuyun; Wang, Chunfang; Hua, Youyuan; Tian, Jiajia; Liu, Shihai

2014-08-01

On the basis of Poincare scatter plot and first order difference scatter plot, a novel heart rate variability (HRV) analysis method based on scatter plots of RR intervals and first order difference of RR intervals (namely, RdR) was proposed. The abscissa of the RdR scatter plot, the x-axis, is RR intervals and the ordinate, y-axis, is the difference between successive RR intervals. The RdR scatter plot includes the information of RR intervals and the difference between successive RR intervals, which captures more HRV information. By RdR scatter plot analysis of some records of MIT-BIH arrhythmias database, we found that the scatter plot of uncoupled premature ventricular contraction (PVC), coupled ventricular bigeminy and ventricular trigeminy PVC had specific graphic characteristics. The RdR scatter plot method has higher detecting performance than the Poincare scatter plot method, and simpler and more intuitive than the first order difference method.

Galactic Haze seen by Planck and Galactic Bubbles seen by Fermi

NASA Image and Video Library

2012-02-13

This all-sky image shows the distribution of the galactic haze seen by ESA Planck mission at microwave frequencies superimposed over the high-energy sky, as seen by NASA Fermi Gamma-ray Space Telescope.

Star formation around active galactic nuclei

NASA Technical Reports Server (NTRS)

Keel, William C.

1987-01-01

Active galactic nuclei (Seyfert nuclei and their relatives) and intense star formation can both deliver substantial amounts of energy to the vicinity of a galactic nucleus. Many luminous nuclei have energetics dominated by one of these mechanisms, but detailed observations show that some have a mixture. Seeing both phenomena at once raises several interesting questions: (1) Is this a general property of some kinds of nuclei? How many AGNs have surround starbursts, and vice versa? (2) As in 1, how many undiscovered AGNs or starbursts are hidden by a more luminous instance of the other? (3) Does one cause the other, and by what means, or do both reflect common influences such as potential well shape or level of gas flow? (4) Can surrounding star formation tell us anything about the central active nuclei, such as lifetimes, kinetic energy output, or mechanical disturbance of the ISM? These are important points in the understanding of activity and star formation in galactic nuclei. Unfortunately, the observational ways of addressing them are as yet not well formulated. Some preliminary studies are reported, aimed at clarifying the issues involved in study of the relationships between stellar and nonstellar excitement in galactic nuclei.

New bound on neutrino dipole moments from globular-cluster stars

NASA Technical Reports Server (NTRS)

Raffelt, Georg G.

1990-01-01

Neutrino dipole moments mu(nu) would increase the core mass of red giants at the helium flash by delta(Mc) = 0.015 solar mass x mu(nu)/10 to the -12th muB (where muB is the Bohr magneton) because of enhanced neutrino losses. Existing measurements of the bolometric magnitudes of the brightest red giants in 26 globular clusters, number counts of horizontal-branch stars and red giants in 15 globular clusters, and statistical parallax determinations of field RR Lyr luminosities yield delta(Mc) = 0.009 + or - 0.012 solar mass, so that conservatively mu(nu) is less than 3 x 10 to the -12th muB.

Molecular diagnostics of Galactic star-formation regions

NASA Astrophysics Data System (ADS)

Loenen, Edo; Baan, Willem; Spaans, Marco

2007-10-01

We propose a sensitive spectral survey of Galactic star-formation regions. Using the broadband correlator at two different frequencies, we expect to detect the (1-0) transition of CO, CN, HNC, HCN, HCO+, and HCO and various of their isotopes lines, as well as the (12-11) and (10-9) transitions of HC3N. The purpose of these observations is to create a consistent (public) database of molecular emission from galactic star-formation regions. The data will be interpreted using extensive physical and chemical modeling of the whole ensemble of lines, in order to get an accurate description of the molecular environment of these regions. In particular, this diagnostic approach will describe the optical depths, the densities, and the radiation fields in the medium and will allow the establishment of dominant temperature gradients. These observations are part of a program to study molecular emission on all scales, going from individual Galactic star-formation regions, through resolved nearby galaxies, to unresolved extra-galactic emission.

Parameters of Six Selected Galactic Potential Models

NASA Astrophysics Data System (ADS)

Bajkova, Anisa; Bobylev, Vadim

2017-11-01

This paper is devoted to the refinement of the parameters of the six three-component (bulge, disk, halo) axisymmetric Galactic gravitational potential models on the basis of modern data on circular velocities of Galactic objects located at distances up to 200 kpc from the Galactic center. In all models the bulge and disk are described by the Miyamoto-Nagai expressions. To describe the halo, the models of Allen-Santillán (I), Wilkinson-Evans (II), Navarro- Frenk-White (III), Binney (IV), Plummer (V), and Hernquist (VI) are used. The sought-for parameters of potential models are determined by fitting the model rotation curves to the measured velocities, taking into account restrictions on the local dynamical matter density p⊙ - 0.1M⊙ pc-3 and the vertical force |Kz=1.1|/2πG = 77M⊙ pc-2. A comparative analysis of the refined potential models is made and for each of the models the estimates of a number of the Galactic characteristics are presented.

EXPLORING THE VARIABLE SKY WITH LINEAR. II. HALO STRUCTURE AND SUBSTRUCTURE TRACED BY RR LYRAE STARS TO 30 kpc

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

Sesar, Branimir; Ivezic, Zeljko; Morgan, Dylan M.

We present a sample of {approx}5000 RR Lyrae stars selected from the recalibrated LINEAR data set and detected at heliocentric distances between 5 kpc and 30 kpc over {approx}8000 deg{sup 2} of sky. The coordinates and light curve properties, such as period and Oosterhoff type, are made publicly available. We analyze in detail the light curve properties and Galactic distribution of the subset of {approx}4000 type ab RR Lyrae (RRab) stars, including a search for new halo substructures and the number density distribution as a function of Oosterhoff type. We find evidence for the Oosterhoff dichotomy among field RR Lyraemore » stars, with the ratio of the type II and I subsamples of about 1:4, but with a weaker separation than for globular cluster stars. The wide sky coverage and depth of this sample allow unique constraints for the number density distribution of halo RRab stars as a function of galactocentric distance: it can be described as an oblate ellipsoid with an axis ratio q = 0.63 and with either a single or a double power law with a power-law index in the range -2 to -3. Consistent with previous studies, we find that the Oosterhoff type II subsample has a steeper number density profile than the Oosterhoff type I subsample. Using the group-finding algorithm EnLink, we detected seven candidate halo groups, only one of which is statistically spurious. Three of these groups are near globular clusters (M53/NGC 5053, M3, M13), and one is near a known halo substructure (Virgo Stellar Stream); the remaining three groups do not seem to be near any known halo substructures or globular clusters and seem to have a higher ratio of Oosterhoff type II to Oosterhoff type I RRab stars than what is found in the halo. The extended morphology and the position (outside the tidal radius) of some of the groups near globular clusters are suggestive of tidal streams possibly originating from globular clusters. Spectroscopic follow-up of detected halo groups is encouraged.« less

19. BLUEPRINT, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5 mi. ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

19. BLUEPRINT, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5 mi. S of Ms. 50 Map of Tombigbee River at Waverly, 'Proposed Crossing.' 12 May 1888. Credt: Columbus & Greenville, RR, Columbus, Ms. DWG S-3-343. Sarcone Photography, ColumbuS, Ms. Sept 1978. - Bridges of the Upper Tombigbee River Valley, Columbus, Lowndes County, MS

Identification of atrial fibrillation using electrocardiographic RR-interval difference

NASA Astrophysics Data System (ADS)

Eliana, M.; Nuryani, N.

2017-11-01

Automated detection of atrial fibrillation (AF) is an interesting topic. It is an account of very dangerous, not only as a trigger of embolic stroke, but it’s also related to some else chronical disease. In this study, we analyse the presence of AF by determining irregularities of RR-interval. We utilize the interval comparison to measure the degree of irregularities of RR-interval in a defined segment. The series of RR-interval is segmented with the length of 10 of them. In this study, we use interval comparison for the method. We were comparing all of the intervals there each other. Then we put the threshold to define the low difference and high difference (δ). A segment is defined as AF or Normal Sinus by the number of high δ, so we put the tolerance (β) of high δ there. We have used this method to test the 23 patients data from MIT-BIH. Using the approach and the clinical data we find accuracy, sensitivity, and specificity of 84.98%, 91.99%, and 77.85% respectively.

Important influence of respiration on human R-R interval power spectra is largely ignored

NASA Technical Reports Server (NTRS)

Brown, T. E.; Beightol, L. A.; Koh, J.; Eckberg, D. L.

1993-01-01

Frequency-domain analyses of R-R intervals are used widely to estimate levels of autonomic neural traffic to the human heart. Because respiration modulates autonomic activity, we determined for nine healthy subjects the influence of breathing frequency and tidal volume on R-R interval power spectra (fast-Fourier transform method). We also surveyed published literature to determine current practices in this burgeoning field of scientific inquiry. Supine subjects breathed at rates of 6, 7.5, 10, 15, 17.1, 20, and 24 breaths/min and with nominal tidal volumes of 1,000 and 1,500 ml. R-R interval power at respiratory and low (0.06-0.14 Hz) frequencies declined significantly as breathing frequency increased. R-R interval power at respiratory frequencies was significantly greater at a tidal volume of 1,500 than 1,000 ml. Neither breathing frequency nor tidal volume influenced average R-R intervals significantly. Our review of studies reporting human R-R interval power spectra showed that 51% of the studies controlled respiratory rate, 11% controlled tidal volume, and 11% controlled both respiratory rate and tidal volume. The major implications of our analyses are that breathing parameters strongly influence low-frequency as well as respiratory frequency R-R interval power spectra and that this influence is largely ignored in published research.

Galactic-scale civilization

NASA Technical Reports Server (NTRS)

Kuiper, T. B. H.

1980-01-01

Evolutionary arguments are presented in favor of the existence of civilization on a galactic scale. Patterns of physical, chemical, biological, social and cultural evolution leading to increasing levels of complexity are pointed out and explained thermodynamically in terms of the maximization of free energy dissipation in the environment of the organized system. The possibility of the evolution of a global and then a galactic human civilization is considered, and probabilities that the galaxy is presently in its colonization state and that life could have evolved to its present state on earth are discussed. Fermi's paradox of the absence of extraterrestrials in light of the probability of their existence is noted, and a variety of possible explanations is indicated. Finally, it is argued that although mankind may be the first occurrence of intelligence in the galaxy, it is unjustified to presume that this is so.

Recent progress in the theoretical modelling of Cepheids and RR Lyrae stars

NASA Astrophysics Data System (ADS)

Marconi, Marcella

2017-09-01

Cepheids and RR Lyrae are among the most important primary distance indicators to calibrate the extragalactic distance ladder and excellent stellar population tracers, for Population I and Population II, respectively. In this paper I first mention some recent theoretical studies of Cepheids and RR Lyrae obtained with different theoretical tools. Then I focus the attention on new results based on nonlinear convective pulsation models in the context of some international projects, including VMC@VISTA and the Gaia collaboration. The open problems for both Cepheids and RR Lyrae are briefly discussed together with some challenging future application.

Evolution of the Oort Cloud under Galactic Perturbations

NASA Astrophysics Data System (ADS)

Higuchi, A.; Kokubo, E.; Mukai, T.

2005-08-01

The Oort cloud is a spherical comet reservoir surrounding the solar system. There is general agreement that the Oort cloud comets are the residual planetesimals of planet formation. The standard scenario of the Oort cloud formation consists of two dynamical stages: (1) giant planets raise the aphelia of planetesimals to the outer region of the solar system and (2) the galactic tide, passing stars, and giant molecular clouds pull up their perihelia out of the planetary region and randomize their inclinations. Here we show the orbital evolution of planetesimals due to the galactic tide. Planetesimals with large aphelion distances change their perihelion distances toward the outside of the planetary region by the galactic tide and become members of the Oort cloud. We consider only the vertical component of the galactic tide because it is dominant compared to other components. Then, under such an axi-symmetric assumption, some planetesimals may show the librations around ω (argument of perihelion)=π /2 or 3π /2 (the Kozai mechanism). The alternate increases of eccentricity and inclination of the Kozai mechanism are effective to form the Oort cloud. Using the secular perturbation theory, we can understand the motion of the planetesimals analytically. We applied the Kozai mechanism to the galactic tide and found that the galactic tide raise perihelia and randomize inclinations of planetesimals with semimajor axes larger than ˜ 103 AU in 5Gyr. We take into account time evolution of the local galactic density, which is thought to be denser in the early stage of the sun than the current one. This work was supported by the 21st Century COE Program Origin and Evolution of Planetary Systems of the Ministry of Education, Culture, Sports, Science, and Technology, Japan, and JSPS Research Fellowship for Young Scientists.

30. RAILROAD, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5 mi. ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

30. RAILROAD, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5 mi. S of MS. 50 Detail: Turn machinery. DWG S-3-325. Contr. #7236. Lower right quarter of sheet: Lateral elevation of turn table. July 1914. Credit: Columbus and Greenville RR, Columbus, MS. Sarcone Photography, Columbus, Ms. Sep 1978. - Bridges of the Upper Tombigbee River Valley, Columbus, Lowndes County, MS

31. RAILROAD, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5 mi. ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

31. RAILROAD, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5 mi. S of MS. 50 Detail: Turn machinery. DWG S-3-325. Contr. #7236. Upper left quarter of sheet: plan and longitudinal elevation of Wedges. July 1914. Credit: Columbus and Greenville RR, Columbus, Ms. Sarcone Photography, Columbus, Ms. Sep 1978 - Bridges of the Upper Tombigbee River Valley, Columbus, Lowndes County, MS

29. RAILROAD, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5. mi. ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

29. RAILROAD, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5. mi. S of MS. 50 Detail: Turn machinery. DWG S-3-325. Contr. #7236. Lower right quarter of sheet: Lateral elevation of turn table. July 1914. Credit: Columbus and Greenville RR, Columbus, Ms. Sarcone Photography, Columbus, Ms. Sep 1978. - Bridges of the Upper Tombigbee River Valley, Columbus, Lowndes County, MS

22. RAILROAD, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5 mi. ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

22. RAILROAD, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5 mi. S of MS. 50 Proposed 218-foot turn span, submitted by the Wisconsin Bridge & Iron Co., Milwaukee, Wisconsin 8 May 1914. Act size: approx. 23x34 in. Credit: Columbus & Greenville RR, Columbus, Ms. Sarcone Photography, Columbus, MS. Sep 1978. - Bridges of the Upper Tombigbee River Valley, Columbus, Lowndes County, MS

21. RAILROAD, RR. BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5 mi. ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

21. RAILROAD, RR. BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5 mi. S of Ms. 50 Proposed 218-foot turn span, design #2339 of Virginia Bridge and Iron Co., Roanoke, Va. 13 May 1914. Act. size: 16x11 in. Credit: Columbus & Greenville RR, Columbus, Ms. Sarcone Photography, Columbus, Ms. - Bridges of the Upper Tombigbee River Valley, Columbus, Lowndes County, MS

27. RAILROAD, RR. BRIDGE MISSISSIPPI, CLAY CO. WAVERLY 1.5 mi. ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

27. RAILROAD, RR. BRIDGE MISSISSIPPI, CLAY CO. WAVERLY 1.5 mi. S of MS. 50 Stress Sheet of 1888 Bridge: Conroy & Sinks, Consulting Engineers, Chicago. July 21, 1910. DWG #978. Act. size around border: 18x11 in. Credit: Columbus and Greenville RR, Columbus, Ms. Sarcone Photography, Columbus, Ms. Sep 1978. - Bridges of the Upper Tombigbee River Valley, Columbus, Lowndes County, MS

77 FR 27085 - R.R. Donnelley, Inc., Bloomsburg, PA; Notice of Negative Determination on Reconsideration

Federal Register 2010, 2011, 2012, 2013, 2014

2012-05-08

... DEPARTMENT OF LABOR Employment and Training Administration [TA-W-80,485] R.R. Donnelley, Inc... workers of R.R. Donnelley, Inc., Bloomsburg, Pennsylvania (subject firm). The Department's Notice of... eligibility to apply for worker adjustment assistance for workers and former workers of R.R. Donnelley, Inc...

Polarization of the diffuse galactic light.

NASA Technical Reports Server (NTRS)

Sparrow, J. G.; Ney, E. P.

1972-01-01

Polarization measurements made from the satellite OSO-5 show that the polarized intensity in the direction of the Scutum arm of the Galaxy is different in intensity and direction of the polarization from that observed due to the zodiacal light. The observations are consistent with polarized diffuse galactic light superposed on the zodiacal light. The results are interpreted in terms of a model in which the galactic starlight is scattered by interstellar dust.

The Galactic Magnetic Field and its lensing of Ultrahigh Energy and Galactic Cosmic Rays

NASA Astrophysics Data System (ADS)

Farrar, Glennys

2015-08-01

It has long been recognized that magnetic fields play an important role in many astrophysical environments, but the magnetic field strength and structure has only been quantitatively determined for relatively few systems beyond our solar system.Our understanding of the Galactic magnetic field (GMF) has improved tremendously in recent years. The Jansson-Farrar (2012) (JF12) GMF model is the most realistic and comprehensive model available. It was constrained by fitting all-sky Faraday Rotation Measures of ~40k extragalactic sources, simultaneously with WMAP polarized (Q,U) and total synchrotron emission maps - together providing a total of more than 10,000 independent datapoints, each with measured astrophysical variance. In addition to disk and toroidal halo components, a previously overlooked coherent poloidal halo field proves to be necessary to account for the RM, Q and U data. Moreover a “striated” random component is needed in addition to a fully random component, in both disk and halo.The talk will give a concise review of the JF12 model and its derivation, with emphasis on which features of the GMF are well or poorly established. I will show that the data unambiguously demand a large scale coherent component to the halo field which is a diverging-spiral centered on the Galactic center, with field lines running from Southern to Northern hemispheres. The puzzles posed by the large scale coherent halo and disk magnetic fields, and their possible origins, will be discussed.Having a good model of the Galactic magnetic field is crucial for determining the sources of UHECRs, for modeling the transport of Galactic CRs (the halo field provides a heretofore-overlooked escape route for by diffusion along its field lines), and for calculating the background to dark matter and CMB-cosmology studies. I will present new results on the lensing effect of the GMF on UHECRs, which produces multiple images and dramatic magnification and demagnification that varies with

Complexity of the heart rhythm after heart transplantation by entropy of transition network for RR-increments of RR time intervals between heartbeats.

PubMed

Makowiec, Danuta; Struzik, Zbigniew; Graff, Beata; Wdowczyk-Szulc, Joanna; Zarczynska-Buchnowiecka, Marta; Gruchala, Marcin; Rynkiewicz, Andrzej

2013-01-01

Network models have been used to capture, represent and analyse characteristics of living organisms and general properties of complex systems. The use of network representations in the characterization of time series complexity is a relatively new but quickly developing branch of time series analysis. In particular, beat-to-beat heart rate variability can be mapped out in a network of RR-increments, which is a directed and weighted graph with vertices representing RR-increments and the edges of which correspond to subsequent increments. We evaluate entropy measures selected from these network representations in records of healthy subjects and heart transplant patients, and provide an interpretation of the results.

The Galactic Nova Rate Revisited

NASA Astrophysics Data System (ADS)

Shafter, A. W.

2017-01-01

Despite its fundamental importance, a reliable estimate of the Galactic nova rate has remained elusive. Here, the overall Galactic nova rate is estimated by extrapolating the observed rate for novae reaching m≤slant 2 to include the entire Galaxy using a two component disk plus bulge model for the distribution of stars in the Milky Way. The present analysis improves on previous work by considering important corrections for incompleteness in the observed rate of bright novae and by employing a Monte Carlo analysis to better estimate the uncertainty in the derived nova rates. Several models are considered to account for differences in the assumed properties of bulge and disk nova populations and in the absolute magnitude distribution. The simplest models, which assume uniform properties between bulge and disk novae, predict Galactic nova rates of ˜50 to in excess of 100 per year, depending on the assumed incompleteness at bright magnitudes. Models where the disk novae are assumed to be more luminous than bulge novae are explored, and predict nova rates up to 30% lower, in the range of ˜35 to ˜75 per year. An average of the most plausible models yields a rate of {50}-23+31 yr-1, which is arguably the best estimate currently available for the nova rate in the Galaxy. Virtually all models produce rates that represent significant increases over recent estimates, and bring the Galactic nova rate into better agreement with that expected based on comparison with the latest results from extragalactic surveys.

26. RAILROAD, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5 mi. ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

26. RAILROAD, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5 mi. S of MS. 50 Proposed 218-foot deck, plate-girder turn span, submitted by the Wisconsin Bridge and Iron Co., Milwaukee, Wisc. May 15 1914. Act size: approx. 23x34 in. Credit: columbus and Greenville RR, Columbus, Ms. Sarcone Photography, Columbus, Ms. Sep 1978. - Bridges of the Upper Tombigbee River Valley, Columbus, Lowndes County, MS

23. RAILROAD, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5 mi. ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

23. RAILROAD, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5 mi. S of MS. 50 Southern R'wy Co. in Ms. Repairs to Tombigbee River Bridge' gears and turn machinery. DWG # S. 30303. Scale: 1-1/2' = l'. July 21, 1913. Credit: Columbus & Greenville RR, Columbus, Ms. Sarcone Photography, Columbus, Ms. Sep 1978. - Bridges of the Upper Tombigbee River Valley, Columbus, Lowndes County, MS

25. RAILROAD, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5 mi. ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

25. RAILROAD, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5 mi. S of MS. 50 Proposed 218-foot turn span, submitted by the American Bridge Co., Pittsburg, Pa., 15 May 1914. Inquiry # P-19242. Act. size: approx: 23x24 in. Credit: Columbus and Greenville RR, columbus, MS. Sarcone Photography, Columbus, Ms. Sep 1978. - Bridges of the Upper Tombigbee River Valley, Columbus, Lowndes County, MS

Galactic Surveys in the Gaia Era

NASA Astrophysics Data System (ADS)

Wyse, Rosemary F. G.

2018-04-01

The final astrometric data from the Gaia mission will transform our view of the stellar content of the Galaxy, particularly when complemented with spectroscopic surveys providing stellar parameters, line-of-sight kinematics and elemental abundances. Analyses with Gaia DR1 are already demonstrating the insight gained and the promise of what is to come with future Gaia releases. I present a brief overview of results and puzzles from recent Galactic Archaeology surveys for context, focusing on the Galactic discs.

75 FR 63727 - Airworthiness Directives; Rolls-Royce plc (RR) RB211-524 Series Turbofan Engines

Federal Register 2010, 2011, 2012, 2013, 2014

2010-10-18

... models that have not been repaired to RR Field Repair Scheme FRS5367/B, and A mandatory terminating... Repaired Using RR Field Repair Scheme FRS5367/B (h) If the combustion liner head section was previously repaired using RR Field Repair Scheme FRS5367/B, do the following: (1) Borescope-inspect combustion liner...

Variable Stars Observed in the Galactic Disk by AST3-1 from Dome A, Antarctica

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

Wang, Lingzhi; Ma, Bin; Hu, Yi

AST3-1 is the second-generation wide-field optical photometric telescope dedicated to time-domain astronomy at Dome A, Antarctica. Here, we present the results of an i -band images survey from AST3-1 toward one Galactic disk field. Based on time-series photometry of 92,583 stars, 560 variable stars were detected with i magnitude ≤16.5 mag during eight days of observations; 339 of these are previously unknown variables. We tentatively classify the 560 variables as 285 eclipsing binaries (EW, EB, and EA), 27 pulsating variable stars ( δ Scuti, γ Doradus, δ Cephei variable, and RR Lyrae stars), and 248 other types of variables (unclassifiedmore » periodic, multiperiodic, and aperiodic variable stars). Of the eclipsing binaries, 34 show O’Connell effects. One of the aperiodic variables shows a plateau light curve and another variable shows a secondary maximum after peak brightness. We also detected a complex binary system with an RS CVn-like light-curve morphology; this object is being followed-up spectroscopically using the Gemini South telescope.« less

Modelling of RR Lyrae instability strips

NASA Astrophysics Data System (ADS)

Szabo, Robert; Csubry, Zoltan

2001-02-01

Recent studies indicates that the slope of the empirical blue edge of the RR Lyrae fundamental mode instability strip is irreconcilable with the theoretical blue edges. Nonlinear hydrodynamical pulsational code involving turbulent convection was used to follow fundamental/first overtone mode selection mechanism. This method combined with the results of horizontal branch evolutionary computations was applied to rethink the problem.

Star formation inside a galactic outflow.

PubMed

Maiolino, R; Russell, H R; Fabian, A C; Carniani, S; Gallagher, R; Cazzoli, S; Arribas, S; Belfiore, F; Bellocchi, E; Colina, L; Cresci, G; Ishibashi, W; Marconi, A; Mannucci, F; Oliva, E; Sturm, E

2017-04-13

Recent observations have revealed massive galactic molecular outflows that may have the physical conditions (high gas densities) required to form stars. Indeed, several recent models predict that such massive outflows may ignite star formation within the outflow itself. This star-formation mode, in which stars form with high radial velocities, could contribute to the morphological evolution of galaxies, to the evolution in size and velocity dispersion of the spheroidal component of galaxies, and would contribute to the population of high-velocity stars, which could even escape the galaxy. Such star formation could provide in situ chemical enrichment of the circumgalactic and intergalactic medium (through supernova explosions of young stars on large orbits), and some models also predict it to contribute substantially to the star-formation rate observed in distant galaxies. Although there exists observational evidence for star formation triggered by outflows or jets into their host galaxy, as a consequence of gas compression, evidence for star formation occurring within galactic outflows is still missing. Here we report spectroscopic observations that unambiguously reveal star formation occurring in a galactic outflow at a redshift of 0.0448. The inferred star-formation rate in the outflow is larger than 15 solar masses per year. Star formation may also be occurring in other galactic outflows, but may have been missed by previous observations owing to the lack of adequate diagnostics.

Detection of sulfur in the galactic center

NASA Technical Reports Server (NTRS)

Herter, T.; Briotta, D. A., Jr.; Gull, G. E.; Shure, M. A.; Houck, J. R.

1983-01-01

A strong detection at the S III forbidden 18.71 micron line is reported for the galactic center region, Sgr A West. A line flux of 1.7 + or - 0.2 x 10 to the -17th W/sq cm is found for a 20 inch beam size measurement centered on IRS 1. A preliminary analysis indicates that the S III abundance relative to hydrogen is consistent with the cosmic abundance of sulfur, 0.000016, if a filling factor of unity within the known clumps is assumed. However, the sulfur abundance in the galactic center may be as much as a factor of 3 overabundant if a filling factor of 0.03 is adopted, a value found to hold for some galactic H II regions.

Introducing CGOLS: The Cholla Galactic Outflow Simulation Suite

NASA Astrophysics Data System (ADS)

Schneider, Evan E.; Robertson, Brant E.

2018-06-01

We present the Cholla Galactic OutfLow Simulations (CGOLS) suite, a set of extremely high resolution global simulations of isolated disk galaxies designed to clarify the nature of multiphase structure in galactic winds. Using the GPU-based code Cholla, we achieve unprecedented resolution in these simulations, modeling galaxies over a 20 kpc region at a constant resolution of 5 pc. The simulations include a feedback model designed to test the effects of different mass- and energy-loading factors on galactic outflows over kiloparsec scales. In addition to describing the simulation methodology in detail, we also present the results from an adiabatic simulation that tests the frequently adopted analytic galactic wind model of Chevalier & Clegg. Our results indicate that the Chevalier & Clegg model is a good fit to nuclear starburst winds in the nonradiative region of parameter space. Finally, we investigate the role of resolution and convergence in large-scale simulations of multiphase galactic winds. While our largest-scale simulations show convergence of observable features like soft X-ray emission, our tests demonstrate that simulations of this kind with resolutions greater than 10 pc are not yet converged, confirming the need for extreme resolution in order to study the structure of winds and their effects on the circumgalactic medium.

Adipose tissue (P)RR regulates insulin sensitivity, fat mass and body weight.

PubMed

Shamansurova, Zulaykho; Tan, Paul; Ahmed, Basma; Pepin, Emilie; Seda, Ondrej; Lavoie, Julie L

2016-10-01

We previously demonstrated that the handle-region peptide, a prorenin/renin receptor [(P)RR] blocker, reduces body weight and fat mass and may improve insulin sensitivity in high-fat fed mice. We hypothesized that knocking out the adipose tissue (P)RR gene would prevent weight gain and insulin resistance. An adipose tissue-specific (P)RR knockout (KO) mouse was created by Cre-loxP technology using AP2-Cre recombinase mice. Because the (P)RR gene is located on the X chromosome, hemizygous males were complete KO and had a more pronounced phenotype on a normal diet (ND) diet compared to heterozygous KO females. Therefore, we challenged the female mice with a high-fat diet (HFD) to uncover certain phenotypes. Mice were maintained on either diet for 9 weeks. KO mice had lower body weights compared to wild-types (WT). Only hemizygous male KO mice presented with lower total fat mass, higher total lean mass as well as smaller adipocytes compared to WT mice. Although food intake was similar between genotypes, locomotor activity during the active period was increased in both male and female KO mice. Interestingly, only male KO mice had increased O2 consumption and CO2 production during the entire 24-hour period, suggesting an increased basal metabolic rate. Although glycemia during a glucose tolerance test was similar, KO males as well as HFD-fed females had lower plasma insulin and C-peptide levels compared to WT mice, suggesting improved insulin sensitivity. Remarkably, all KO animals exhibited higher circulating adiponectin levels, suggesting that this phenotype can occur even in the absence of a significant reduction in adipose tissue weight, as observed in females and, thus, may be a specific effect related to the (P)RR. (P)RR may be an important therapeutic target for the treatment of obesity and its associated complications such as type 2 diabetes.

Galactic Neighborhood and Laboratory Astrophysics

NASA Astrophysics Data System (ADS)

Wang, Q. D.

2011-05-01

The galactic neighborhood, extending from the Milky Way to redshifts of about 0.1, is our unique local laboratory for detailed study of galaxies and their interplay with the environment. Such study provides a foundation of knowledge for interpreting observations of more distant galaxies and their environment. The Astro 2010 Science Frontier Galactic Neighborhood Panel identified four key sci- entific questions: 1) What are the flows of matter and energy in the circumgalac- tic medium? 2) What controls the mass-energy-chemical cycles within galaxies? 3) What is the fossil record of galaxy assembly from first stars to present? 4) What are the connections between dark and luminous matter? These questions, essential to the understanding of galaxies as interconnected complexes, can be addressed most effectively and/or uniquely in the galactic neighborhood. The panel also highlighted the discovery potential of time-domain astronomy and astrometry with powerful new techniques and facilities to greatly advance our understanding of the precise connections among stars, galaxies, and newly dis- covered transient events. The relevant needs for laboratory astrophysics will be emphasized, especially in the context of supporting NASA missions.

Active Galactic Nucleus

NASA Image and Video Library

2017-09-14

SCI2017_0007: Artist illustration of the thick ring of dust that can obscure the energetic processes that occur near the supermassive black hole of an active galactic nuclei. The SOFIA studies suggest that the dust distribution is about 30 percent smaller than previously thought. Credit: NASA/SOFIA/Lynette Cook

AL Pictoris and FR Piscium: Two Regular Blazhko RR Lyrae Stars

NASA Astrophysics Data System (ADS)

de Ponthière, P.; Hambsch, F.-J.; Menzies, K.; Sabo, R.

2014-12-01

The results presented are a continuation of observing campaigns conducted by a small group of amateur astronomers interested in the Blazhko effect of RR Lyrae stars. The goal of these observations is to confirm the RR Lyrae Blazhko effect and to detect any additional Blazhko modulation which cannot be identified from all sky survey data-mining. The Blazhko effect of the two observed stars is confirmed, but no additional Blazhko modulations have been detected. The observation of the RR Lyrae star AL Pictoris during 169 nights was conducted from San Pedro de Atacama (Chile). From the observed light curve, 49 pulsation maxima have been measured. Fourier analyses of (O-C), magnitude at maximum light (Mmax), and the complete light curve have provided a confirmation of published pulsation and Blazhko periods, 0.548622 and 34.07 days, respectively. The second multi-longitude observation campaign focused on the RR Lyrae star FR Piscium and was performed from Europe, the United States, and Chile. Fourier analyses of the light curve and of 59 measured brightness maxima have improved the accuracy of pulsation and Blazhko periods to 0.45568 and 51.31 days, respectively. For both stars, no additional Blazhko modulations have been detected.

The structure and content of the galaxy and galactic gamma rays. [conferences

NASA Technical Reports Server (NTRS)

Fichtel, C. E.; Stecker, F. W.

1976-01-01

Papers are presented dealing with galactic structure drawing on all branches of galactic astronomy with emphasis on the implications of the new gamma ray observations. Topics discussed include: (1) results from the COS-B gamma ray satellite; (2) results from SAS-2 on gamma ray pulsar, Cygnus X-3, and maps of the galactic diffuse flux; (3) recent data from CO surveys of the galaxy; (4) high resolution radio surveys of external galaxies; (5) results on the galactic distribution of pulsars; and (6) theoretical work on galactic gamma ray emission.

Nonlinear Convective Models of RR Lyrae Stars

NASA Astrophysics Data System (ADS)

Feuchtinger, M.; Dorfi, E. A.

The nonlinear behavior of RR Lyrae pulsations is investigated using a state-of-the-art numerical technique solving the full time-dependent system of radiation hydrodynamics. Grey radiative transfer is included by a variable Eddington-factor method and we use the time-dependent turbulent convection model according to Kuhfuss (1986, A&A 160, 116) in the version of Wuchterl (1995, Comp. Phys. Comm. 89, 19). OPAL opacities extended by the Alexander molecule opacities at temperatures below 6000 K and an equation of state according to Wuchterl (1990, A&A 238, 83) close the system. The resulting nonlinear system is discretized on an adaptive mesh developed by Dorfi & Drury (1987, J. Comp. Phys. 69, 175), which is important to provide the necessary spatial resolution in critical regions like ionization zones and shock waves. Additionally, we employ a second order advection scheme, a time centered temporal discretizaton and an artificial tensor viscosity in order to treat discontinuities. We compute fundamental as well first overtone models of RR Lyrae stars for a grid of stellar parameters both with and without convective energy transport in order to give a detailed picture of the pulsation-convection interaction. In order to investigate the influence of the different features of the convection model calculations with and without overshooting, turbulent pressure and turbulent viscosity are performed and compared with each other. A standard Fourier decomposition is used to confront the resulting light and radial velocity variations with recent observations and we show that the well known RR Lyrae phase discrepancy problem (Simon 1985, ApJ 299, 723) can be resolved with these stellar pulsation computations.

Orbital Evolution of Planetesimals by the Galactic Tide

NASA Astrophysics Data System (ADS)

Higuchi, A.; Kokubo, E.; Mukai, T.

2005-05-01

The Oort cloud is a spherical comet reservoir surrounding the solar system. There is general agreement that the Oort cloud comets are the residual planetesimals of planet formation. The standard scenario of the Oort cloud formation consists of two dynamical stages: (1) giant planets raise the aphelia of planetesimals to the outer region of the solar system and (2) the galactic tide, passing stars, and giant molecular clouds pull up their perihelia out of the planetary region. Here we show the orbital evolution of planetesimals by the galactic tide. Planetesimals with large aphelion distances change their perihelion distances toward the outside of the planetary region by the galactic tide and become members of the Oort cloud. The effect of the galactic tide on the planetesimals with semimajor axes of ˜ 104AU is about 10-3 of the solar gravity. The timescale of the orbital evolution is ˜ 108 years. We consider only the vertical component of the galactic tide. Under the axisymmetric potential, some planetesimals may show the librations around ω (argument of perihelion)=π /2 and 3π /2 (the Kozai mechanism). The alternate increases of eccentricity and inclination of the Kozai mechanism are effective to form the Oort cloud. The secular perturbation theory demonstrates the Kozai mechanism and we can understand the motion of the planetesimals analytically. We apply the Kozai mechanism to the galactic tide and discuss the property of the Oort cloud formed by the Kozai mechanizm. This work was supported by the 21st Century COE Program Origin and Evolution of Planetary Systems of the Ministry of Education, Culture, Sports, Science, and Technology, Japan, and JSPS Research Fellowship for Young Scientists.

Anomalous double-mode RR Lyrae stars in the Magellanic Clouds

NASA Astrophysics Data System (ADS)

Soszyński, I.; Smolec, R.; Dziembowski, W. A.; Udalski, A.; Szymański, M. K.; Wyrzykowski, Ł.; Ulaczyk, K.; Poleski, R.; Pietrukowicz, P.; Kozłowski, S.; Skowron, D.; Skowron, J.; Mróz, P.; Pawlak, M.

2016-12-01

We report the discovery of a new subclass of double-mode RR Lyrae stars in the Large and Small Magellanic Clouds. The sample of 22 pulsating stars has been extracted from the latest edition of the Optical Gravitational Lensing Experiment collection of RR Lyrae variables in the Magellanic System. The stars pulsating simultaneously in the fundamental (F) and first-overtone (1O) modes have distinctly different properties than regular double-mode RR Lyrae variables (RRd stars). The P1O/PF period ratios of our anomalous RRd stars are within a range of 0.725-0.738, while `classical' double-mode RR Lyrae variables have period ratios in the range of 0.742-0.748. In contrast to the typical RRd stars, in the majority of the anomalous pulsators, the F-mode amplitudes are higher than the 1O-mode amplitudes. The light curves associated with the F-mode in the anomalous RRd stars show different morphology than the light curves of, both, regular RRd stars and single-mode RRab stars. Most of the anomalous double-mode stars show long-term modulations of the amplitudes (Blazhko-like effect). Translating the period ratios into the abundance parameter, Z, we find for our stars Z ∈ (0.002, 0.005) - an order of magnitude higher values than typical for RR Lyrae stars. The mass range of the RRd stars inferred from the WI versus PF diagram is (0.55-0.75) M⊙. These parameters cannot be accounted for with single star evolution assuming a Reimers-like mass-loss. Much greater mass-loss caused by interaction with other stars is postulated. We blame the peculiar pulsation properties of our stars to the parametric resonance instability of the 1O-mode to excitation of the F- and 2O-modes as with the inferred parameters of the stars 2ω1O ≈ ωF + ω2O.

Detection of sulphur in the galactic center

NASA Technical Reports Server (NTRS)

Herter, T.; Briotta, D. A., Jr.; Gull, G. E.; Shure, M. A.; Houck, J. R.

1983-01-01

A strong detection at the (SIII) 18.71 micron line is reported for the Galactic Center region, Sgr A West. A line flux of 1.7 + or - 0.2x10 to the -17th power W cm(-2) is found for a 20-arc second beam-size measurement centered on IRS 1. A preliminary analysis indicates that the SIII abundance relative to hydrogen is consistent with the cosmic abundance of sulfur, 1.6x10 to the -5th power, if a filling factor of unity within the known clumps is assumed. However, the sulfur abundance in the Galactic Center may be as much as a factor of 3 overabundant if a filling factor of 0.03 is adopted, a value found to hold for some galactic HII regions.

Starburst clusters in the Galactic center

NASA Astrophysics Data System (ADS)

Habibi, Maryam

2014-09-01

The central region of the Galaxy is the most active site of star formation in the Milky Way, where massive stars have formed very recently and are still forming today. The rich population of massive stars in the Galactic center provide a unique opportunity to study massive stars in their birth environment and probe their initial mass function, which is the spectrum of stellar masses at their birth. The Arches cluster is the youngest among the three massive clusters in the Galactic center, providing a collection of high-mass stars and a very dense core which makes this cluster an excellent site to address questions about massive star formation, the stellar mass function and the dynamical evolution of massive clusters in the Galactic center. In this thesis, I perform an observational study of the Arches cluster using K_{s}-band imaging obtained with NAOS/CONICA at the VLT combined with Subaru/Cisco J-band data to gain a full understanding of the cluster mass distribution out to its tidal radius for the first time. Since the light from the Galactic center reaches us through the Galactic disc, the extinction correction is crucial when studying this region. I use a Bayesian method to construct a realistic extinction map of the cluster. It is shown in this study that the determination of the mass of the most massive star in the Arches cluster, which had been used in previous studies to establish an upper mass limit for the star formation process in the Milky Way, strongly depends on the assumed slope of the extinction law. Assuming the two regimes of widely used infrared extinction laws, I show that the difference can reach up to 30% for individually derived stellar masses and Δ A_{Ks}˜ 1 magnitude in acquired K_{s}-band extinction, while the present-day mass function slope changes by ˜ 0.17 dex. The present-day mass function slope derived assuming the more recent extinction law, which suggests a steeper wavelength dependence for the infrared extinction law, reveals

The VMC survey - XXVI. Structure of the Small Magellanic Cloud from RR Lyrae stars

NASA Astrophysics Data System (ADS)

Muraveva, T.; Subramanian, S.; Clementini, G.; Cioni, M.-R. L.; Palmer, M.; van Loon, J. Th.; Moretti, M. I.; de Grijs, R.; Molinaro, R.; Ripepi, V.; Marconi, M.; Emerson, J.; Ivanov, V. D.

2018-01-01

We present results from the analysis of 2997 fundamental mode RR Lyrae variables located in the Small Magellanic Cloud (SMC). For these objects, near-infrared time series photometry from the VISTA survey of the Magellanic Clouds system (VMC) and visual light curves from the OGLE IV (Optical Gravitational Lensing Experiment IV) survey are available. In this study, the multi-epoch Ks-band VMC photometry was used for the first time to derive intensity-averaged magnitudes of the SMC RR Lyrae stars. We determined individual distances to the RR Lyrae stars from the near-infrared period-absolute magnitude-metallicity (PM_{K_s}Z) relation, which has some advantages in comparison with the visual absolute magnitude-metallicity (MV-[Fe/H]) relation, such as a smaller dependence of the luminosity on interstellar extinction, evolutionary effects and metallicity. The distances we have obtained were used to study the three-dimensional structure of the SMC. The distribution of the SMC RR Lyrae stars is found to be ellipsoidal. The actual line-of-sight depth of the SMC is in the range 1-10 kpc, with an average depth of 4.3 ± 1.0 kpc. We found that RR Lyrae stars in the eastern part of the SMC are affected by interactions of the Magellanic Clouds. However, we do not see a clear bimodality observed for red clump stars, in the distribution of RR Lyrae stars.

Mechanism of blood pressure and R-R variability: insights from ganglion blockade in humans

NASA Technical Reports Server (NTRS)

Zhang, Rong; Iwasaki, Kenichi; Zuckerman, Julie H.; Behbehani, Khosrow; Crandall, Craig G.; Levine, Benjamin D.; Blomqvist, C. G. (Principal Investigator)

2002-01-01

Spontaneous blood pressure (BP) and R-R variability are used frequently as 'windows' into cardiovascular control mechanisms. However, the origin of these rhythmic fluctuations is not completely understood. In this study, with ganglion blockade, we evaluated the role of autonomic neural activity versus other 'non-neural' factors in the origin of BP and R-R variability in humans. Beat-to-beat BP, R-R interval and respiratory excursions were recorded in ten healthy subjects (aged 30 +/- 6 years) before and after ganglion blockade with trimethaphan. The spectral power of these variables was calculated in the very low (0.0078-0.05 Hz), low (0.05-0.15 Hz) and high (0.15-0.35 Hz) frequency ranges. The relationship between systolic BP and R-R variability was examined by cross-spectral analysis. After blockade, R-R variability was virtually abolished at all frequencies; however, respiration and high frequency BP variability remained unchanged. Very low and low frequency BP variability was reduced substantially by 84 and 69 %, respectively, but still persisted. Transfer function gain between systolic BP and R-R interval variability decreased by 92 and 88 % at low and high frequencies, respectively, while the phase changed from negative to positive values at the high frequencies. These data suggest that under supine resting conditions with spontaneous breathing: (1) R-R variability at all measured frequencies is predominantly controlled by autonomic neural activity; (2) BP variability at high frequencies (> 0.15 Hz) is mediated largely, if not exclusively, by mechanical effects of respiration on intrathoracic pressure and/or cardiac filling; (3) BP variability at very low and low frequencies (< 0.15 Hz) is probably mediated by both sympathetic nerve activity and intrinsic vasomotor rhythmicity; and (4) the dynamic relationship between BP and R-R variability as quantified by transfer function analysis is determined predominantly by autonomic neural activity rather than other

RR Lyrae in Sagittarius Dwarf Globular Clusters (Poster abstract)

NASA Astrophysics Data System (ADS)

Pritzl, B. J.; Gehrman, T. J.; Bell, E.; Salinas, R.; Smith, H. A.; Catelan, M.

2016-12-01

(Abstract only) The Milky Way Galaxy was built up in part by the cannibalization of smaller dwarf galaxies. Some of them likely contained globular clusters. The Sagittarius dwarf galaxy provides a unique opportunity to study a system of globular clusters that originated outside the Milky Way. We have investigated the RR Lyrae populations in two Sagittarius globular clusters, Arp 2 and Terzan 8. The RR Lyrae are used to study the properties of the clusters and to compare this system to Milky Way globular clusters. We will discuss whether or not dwarf galaxies similar to the Sagittarius dwarf galaxy could have played a role in the formation of the Milky Way Galaxy.

Fundamental relations between short-term RR interval and arterial pressure oscillations in humans

NASA Technical Reports Server (NTRS)

Taylor, J. A.; Eckberg, D. L.

1996-01-01

BACKGROUND: One of the principal explanations for respiratory sinus arrhythmia is that it reflects arterial baroreflex buffering of respiration-induced arterial pressure fluctuations. If this explanation is correct, then elimination of RR interval fluctuations should increase respiratory arterial pressure fluctuations. METHODS AND RESULTS: We measured RR interval and arterial pressure fluctuations during normal sinus rhythm and fixed-rate atrial pacing at 17.2+/-1.8 (SEM) beats per minute greater than the sinus rate in 16 healthy men and 4 healthy women, 20 to 34 years of age. Measurements were made during controlled-frequency breathing (15 breaths per minute or 0.25 Hz) with subjects in the supine and 40 degree head-up tilt positions. We characterized RR interval and arterial pressure variabilities in low-frequency (0.05 to 0.15 Hz) and respiratory-frequency (0.20 to 0.30 Hz) ranges with fast Fourier transform power spectra and used cross-spectral analysis to determine the phase relation between the two signals. As expected, cardiac pacing eliminated beat-to-beat RR interval variability. Against expectations, however, cardiac pacing in the supine position significantly reduced arterial pressure oscillations in the respiratory frequency (systolic, 6.8+/-1.8 to 2.9 +/-0.6 mm Hg2/Hz, P=.017). In contrast, cardiac pacing in the 40 degree tilt position increased arterial pressure variability (systolic, 8.0+/-1.8 to 10.8 +/-2.6, P=.027). Cross-spectral analysis showed that 40 degree tilt shifted the phase relation between systolic pressure and RR interval at the respiratory frequency from positive to negative (9 +/-7 degrees versus -17+/-11 degrees, P=.04); that is, in the supine position, RR interval changes appeared to lead arterial pressure changes, and in the upright position, RR interval changes appeared to follow arterial pressure changes. CONCLUSIONS: These results demonstrate that respiratory sinus arrhythmia can actually contribute to respiratory arterial

ECG R-R peak detection on mobile phones.

PubMed

Sufi, F; Fang, Q; Cosic, I

2007-01-01

Mobile phones have become an integral part of modern life. Due to the ever increasing processing power, mobile phones are rapidly expanding its arena from a sole device of telecommunication to organizer, calculator, gaming device, web browser, music player, audio/video recording device, navigator etc. The processing power of modern mobile phones has been utilized by many innovative purposes. In this paper, we are proposing the utilization of mobile phones for monitoring and analysis of biosignal. The computation performed inside the mobile phone's processor will now be exploited for healthcare delivery. We performed literature review on RR interval detection from ECG and selected few PC based algorithms. Then, three of those existing RR interval detection algorithms were programmed on Java platform. Performance monitoring and comparison studies were carried out on three different mobile devices to determine their application on a realtime telemonitoring scenario.

[The characteristics of RR-Lorenz plot in persistent atrial fibrillation patients complicating with escape beats and rhythm].

PubMed

Pan, Yunping; Zhang, Fangfang; Liu, Ru; Jing, Yan; Shen, Jihong; Li, Zhongjian; Zhu, Huaijie

2014-06-01

To explore the characteristics of RR-Lorenz plot in persistent atrial fibrillation (AF) patients complicating with escape beats and rhythm though ambulatory electrocardiogram. The 24-hour ambulatory electrocardiogram of 291 persistent AF patients in second affiliated hospital of Zhengzhou university from July 2005 to April 2013 were retrospectively analyzed and the RR interval and the QRS wave were measured. Patients were divided into two groups according to the distribution of the RR-Lorenz point [AF without escape beats and rhythm group (Group A, n = 259) and AF with escape beats and rhythm group (Group B, n = 32)]. The characteristics of RR-Lorenz plot between the two groups were compared. (1) Fan-shaped RR-Lorenz plots were evidenced in Group A. (2)In Group B, 30 cases showed fan-shaped with L-shaped and a short dense rods along 45° line. The proportion of escape beats and rhythm was 0.28% (275/98 369) -14.06% (11 263/80 112) . The other 2 cases in group B showed no typical RR-Lorenz plots features. RR-Lorenz plot could help to quickly diagnose persistent AF complicating with escape beats and rhythm according to the typical RR-Lorenz plot characteristics in 24-hour ambulatory electrocardiogram.

The Use of Radiation Response (RR) in Selecting the Method of Treatment of Carcinoma Cervicis Uteri

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

Chesterman, John N.

1963-03-01

Attempts were made to determine the choice treatment of cervical squamous carcinoma (surgery, radiation, or surgery with radiation) in Stages I and II. A study of 50 patients showed good results from surgery in patients with poor radiation response (RR) and that the RR, estimated by a precise and uniform technique, will identify those patients who will not respond well to complete radiation therapy. Moreover, it will do this after a first radium application of moderate dosage, at a time when it is still possible to interrupt this therapy. A radiation dose of at least 1000 r at the cervixmore » will be followed by the maximum RR, in a good response, between the 8th and 14th (especially 10th to 12th) days. A poor RR will reach its maximum earlier than a good one, on about the 10th day after radium implantation. When deciding the definition of good RR, it was found that the radiation changes present in a count of 100 cells were seen in more than 70 cells. There is evidence that age, menopause, and hormonal status influence the radiation reaction. If poor RR is more frequently found with high estrogenic activity, young patients treated by radiation should be expected to have a worse survival rate than old. The survival rate is about 1/3) in the young patient as against 1/2 in the postmenopausal. A good sensitization response (SR) was, in most cases, followed by good RR after radiation. Of 39 patients with good SR, 34 had good RR after one application of radium. However, this correlation was absent when the SR was poor. Of 41 patients with poor SR, 18 remained poor after radiation and 23 developed good RR. Finally, this SR should not be taken alone as a guide to treatment, but all patients should be given the first radium application and the RR assessed.« less

JASMINE: constructor of the dynamical structure of the Galactic bulge

NASA Astrophysics Data System (ADS)

Gouda, N.; Kobayashi, Y.; Yamada, Y.; Yano, T.; Tsujimoto, T.; Suganuma, M.; Niwa, Y.; Yamauchi, M.

2008-07-01

We introduce a Japanese space astrometry project which is called JASMINE. JASMINE (Japan Astrometry Satellite Mission for INfrared Exploration) will measure distances and tangential motions of stars in the Galactic bulge with yet unprecedented precision. JASMINE will operate in z-band whose central wavelength is 0.9 micron. It will measure parallaxes, positions with accuracy of about 10 micro-arcsec and proper motions with accuracy of about 10 micro- arcsec/year for the stars brighter than z=14 mag. The number of stars observed by JASMINE with high accuracy of parallaxes in the Galactic bulge is much larger than that observed in other space astrometry projects operating in optical bands. With the completely new “map of the Galactic bulge” including motions of bulge stars, we expect that many new exciting scientific results will be obtained in studies of the Galactic bulge. One of them is the construction of the dynamical structure of the Galactic bulge. Kinematics and distance data given by JASMINE are the closest approach to a view of the exact dynamical structure of the Galactic bulge. Presently, JASMINE is in a development phase, with a target launch date around 2016. We comment on the outline of JASMINE mission, scientific targets and a preliminary design of JASMINE in this paper.

How supernovae launch galactic winds?

NASA Astrophysics Data System (ADS)

Fielding, Drummond; Quataert, Eliot; Martizzi, Davide; Faucher-Giguère, Claude-André

2017-09-01

We use idealized three-dimensional hydrodynamic simulations of global galactic discs to study the launching of galactic winds by supernovae (SNe). The simulations resolve the cooling radii of the majority of supernova remnants (SNRs) and thus self-consistently capture how SNe drive galactic winds. We find that SNe launch highly supersonic winds with properties that agree reasonably well with expectations from analytic models. The energy loading (η _E= \\dot{E}_wind/ \\dot{E}_SN) of the winds in our simulations are well converged with spatial resolution while the wind mass loading (η _M= \\dot{M}_wind/\\dot{M}_\\star) decreases with resolution at the resolutions we achieve. We present a simple analytic model based on the concept that SNRs with cooling radii greater than the local scaleheight break out of the disc and power the wind. This model successfully explains the dependence (or lack thereof) of ηE (and by extension ηM) on the gas surface density, star formation efficiency, disc radius and the clustering of SNe. The winds our simulations are weaker than expected in reality, likely due to the fact that we seed SNe preferentially at density peaks. Clustering SNe in time and space substantially increases the wind power.

24. RAILROAD, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5 mi. ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

24. RAILROAD, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5 mi. S of MS. 50 Southern R'wy; Co., in Ms. Present and proposed draw bridge over Tombigbee River.' Elevations and Plan, with falsework. Wisconsin Bridge and Iron Co., Milwaukee, Wisc., DWG #S. 3-303. Last Revision, Jan. 11 1915. Act. size: 23x34 in. Credit: Columbus and Greenville Rr, Columbus, Ms. Sarcone Photography, Columbus, MS. Sep 1978. - Bridges of the Upper Tombigbee River Valley, Columbus, Lowndes County, MS

New detections of embedded clusters in the Galactic halo

NASA Astrophysics Data System (ADS)

Camargo, D.; Bica, E.; Bonatto, C.

2016-09-01

Context. Until recently it was thought that high Galactic latitude clouds were a non-star-forming ensemble. However, in a previous study we reported the discovery of two embedded clusters (ECs) far away from the Galactic plane (~ 5 kpc). In our recent star cluster catalogue we provided additional high and intermediate latitude cluster candidates. Aims: This work aims to clarify whether our previous detection of star clusters far away from the disc represents just an episodic event or whether star cluster formation is currently a systematic phenomenon in the Galactic halo. We analyse the nature of four clusters found in our recent catalogue and report the discovery of three new ECs each with an unusually high latitude and distance from the Galactic disc midplane. Methods: The analysis is based on 2MASS and WISE colour-magnitude diagrams (CMDs), and stellar radial density profiles (RDPs). The CMDs are built by applying a field-star decontamination procedure, which uncovers the cluster's intrinsic CMD morphology. Results: All of these clusters are younger than 5 Myr. The high-latitude ECs C 932, C 934, and C 939 appear to be related to a cloud complex about 5 kpc below the Galactic disc, under the Local arm. The other clusters are above the disc, C 1074 and C 1100 with a vertical distance of ~3 kpc, C 1099 with ~ 2 kpc, and C 1101 with ~1.8 kpc. Conclusions: According to the derived parameters ECs located below and above the disc occur, which gives evidence of widespread star cluster formation throughout the Galactic halo. This study therefore represents a paradigm shift, by demonstrating that a sterile halo must now be understood as a host for ongoing star formation. The origin and fate of these ECs remain open. There are two possibilities for their origin, Galactic fountains or infall. The discovery of ECs far from the disc suggests that the Galactic halo is more actively forming stars than previously thought. Furthermore, since most ECs do not survive the infant

Imprints to the terrestrial environment at galactic arm crossings of the solar system

NASA Astrophysics Data System (ADS)

Fahr, H. J.; Fichtner, H.; Scherer, K.; Stawicki, O.

At its itinerary through our milky way galaxy the solar system moves through highly variable interstellar environments. Due to its orbital revolution around the galactic center, the solar system also crosses periodically the spiral arms of our galactic plane and thereby expe riences pronounced enviromental changes. Gas densities, magnetic fields and galactic cosmic ray intensities are substantially higher there compared to interarm conditions. Here we present theoretical calculations describing the SN-averaged galactic cosmic ray spectrum for regions inside and outside of galactic arms which then allow to predict how periodic passages of the solar system through galactic arms should be reflected by enhanced particle irradiations of the earth`s atmosphere and by correlated terrestrial Be-10 production rates.

The age of the galactic disk

NASA Technical Reports Server (NTRS)

Sandage, Allan

1988-01-01

The galactic disk is a dissipative structure and must, therefore be younger than the halo if galaxy formation generally proceeds by collapse. Just how much younger the oldest stars in the galactic disk are than the oldest halo stars remains an open question. A fast collapse (on a time scale no longer than the rotation period of the extended protogalaxy) permits an age gap of the order of approximately 10 to the 9th power years. A slow collapse, governed by the cooling rate of the partially pressure supported falling gas that formed into what is now the thick stellar disk, permits a longer age gap, claimed by some to be as long as 6 Gyr. Early methods of age dating the oldest components of the disk contain implicit assumptions concerning the details of the age-metallicity relation for stars in the solar neighborhood. The discovery that this relation for open clusters outside the solar circle is different that in the solar neighborhood (Geisler 1987), complicates the earlier arguments. The oldest stars in the galactic disk are at least as old as NGC 188. The new data by Janes on NGC 6791, shown first at this conference, suggest a disk age of at least 12.5 Gyr, as do data near the main sequence termination point of metal rich, high proper motion stars of low orbital eccentricity. Hence, a case can still be made that the oldest part of the galactic thick disk is similar in age to the halo globular clusters, if their ages are the same as 47 Tuc.

Conversion of gas into stars in the Galactic center

NASA Astrophysics Data System (ADS)

Longmore, S. N.

2014-05-01

The star formation rate in the central 500 pc of the Milky Way is lower by a factor of > 10 than expected for the substantial amount of dense gas it contains, which challenges current star formation theories. I discuss which physical mechanisms could be causing this observation and put forward a self-consistent cycle of star formation in the Galactic center, in which the plausible star formation inhibitors are combined. Their ubiquity suggests that the perception of a lowered central SFR should be a common phenomenon in other galaxies with direct implications for galactic star formation and also potentially supermassive black hole growth. I then describe a scenario to explain the presence of super star clusters in the Galactic center environment, in which their formation is triggered by gas streams passing close to the minimum of the global Galactic gravitational potential at the location of the central supermassive black hole, Sgr A*. If this triggering mechanism can be verified, we can use the known time interval since closest approach to Sgr A* to study the physics of stellar mass assembly in an extreme environment as a function of absolute time. I outline the first results from detailed numerical simulations testing this scenario. Finally, I describe a study showing that in terms of the baryonic composition, kinematics, and densities, the gas in the Galactic center is indistinguishable from high-redshift clouds and galaxies. As such, the Galactic center clouds may be used as a template to understand the evolution (and possibly the life cycle) of high-redshift clouds and galaxies.

Iterative Structural and Functional Synergistic Resolution Recovery (iSFS-RR) Applied to PET-MR Images in Epilepsy

NASA Astrophysics Data System (ADS)

Silva-Rodríguez, J.; Cortés, J.; Rodríguez-Osorio, X.; López-Urdaneta, J.; Pardo-Montero, J.; Aguiar, P.; Tsoumpas, C.

2016-10-01

Structural Functional Synergistic Resolution Recovery (SFS-RR) is a technique that uses supplementary structural information from MR or CT to improve the spatial resolution of PET or SPECT images. This wavelet-based method may have a potential impact on the clinical decision-making of brain focal disorders such as refractory epilepsy, since it can produce images with better quantitative accuracy and enhanced detectability. In this work, a method for the iterative application of SFS-RR (iSFS-RR) was firstly developed and optimized in terms of convergence and input voxel size, and the corrected images were used for the diagnosis of 18 patients with refractory epilepsy. To this end, PET/MR images were clinically evaluated through visual inspection, atlas-based asymmetry indices (AIs) and SPM (Statistical Parametric Mapping) analysis, using uncorrected images and images corrected with SFS-RR and iSFS-RR. Our results showed that the sensitivity can be increased from 78% for uncorrected images, to 84% for SFS-RR and 94% for the proposed iSFS-RR. Thus, the proposed methodology has demonstrated the potential to improve the management of refractory epilepsy patients in the clinical routine.

Massive stellar content of some Galactic supershells

NASA Astrophysics Data System (ADS)

Kaltcheva, Nadejda; Golev, Valeri

2015-08-01

The giant Galactic H II regions provide a unique opportunity to study the OB-star influence on the surrounding interstellar matter. In this contribution, several multi-wavelength surveys (Wisconsin H-α Mapper Northern Sky Survey, Southern H-α Sky Survey Atlas, MSX Mid-IR Galactic Plane Survey, WISE All-Sky Data Release, CO survey of the Milky Way, and the Southern Galactic Plane HI Survey) are combined with available intermediate-band uvbyβ photometry to attempt a precise spatial correlation between the OB-stars and the neutral and ionized material. Our study is focused on the H I supershell GSH 305+01-24 in Centaurus, the Car OB2 supershell, the Cygnus star-forming complex and the GSH 224-01+24 shell toward the GMN 39/Seagull nebula region. We refine the massive stellar content of these star-forming fields and study the energetics of its interaction with the shells’ material.

Electromagnetic dissociation effects in galactic heavy-ion fragmentation

NASA Technical Reports Server (NTRS)

Norbury, J. W.; Townsend, L. W.

1986-01-01

Methods for calculating cross sections for the breakup of galactic heavy ions by the Coulomb fields of the interacting nuclei are presented. By using the Weizsacker-Williams method of virtual quanta, estimates of electromagnetic dissociation cross sections for a variety of reactions applicable to galactic cosmic ray shielding studies are presented and compared with other predictions and with available experimental data.

Morphological and ultrastructural changes in tobacco BY-2 cells exposed to microcystin-RR.

PubMed

Huang, Wenmin; Xing, Wei; Li, Dunhai; Liu, Yongding

2009-08-01

Tobacco BY-2 cells were exposed to microcystin-RR (MC-RR) at two concentrations, 60 microg mL(-1) and 120 microg mL(-1), to study the changes in morphology and ultrastructure of cells as a result of the exposure. Exposure to the lower concentration for 5 d led to typical apoptotic morphological changes including condensation of nuclear chromatin, creation of a characteristic 'half moon' structure, and cytoplasm shrinkage and decreased cell volume, as revealed through light microscopy, fluorescence microscopy, and transmission electron microscopy, respectively. Exposure to the higher concentration, on the other hand, led to morphological and ultrastructural changes typical of necrosis, such as rupture of the plasma membrane and the nuclear membrane and a marked swelling of cells. The presence of many vacuoles containing unusual deposits points to the involvement of vacuoles in detoxifying MC-RR. Results of the present study indicate that exposure of tobacco BY-2 cells to MC-RR at a lower concentration (60 microg mL(-1)) results in apoptosis and that to a higher concentration (120 microg mL(-1)), in necrosis.

IUE short-wavelength high-dispersion line list for the symbiotic nova RR Telescopii

NASA Technical Reports Server (NTRS)

Aufdenberg, Jason P.

1993-01-01

An 820 minute and other long-exposure archival SWP IUE high-dispersion spectra of symbiotic star RR Tel have been combined to form a composite spectrum. In most of these spectra many lines are saturated, but weaker features appear above the continuum. Their wavelengths were measured from the composite spectrum and compared with the line list from a thorough study of RR Tel by Penston et al. (1983). Among the revised line list are 22 new line identifications from ions C III, O I, N I, Mg VI, Si I, S I, S IV, Fe II, and Ni II. N I exists inside RR Tel's H II region and is pumped by the hot component's continuum. The fluxes for all the lines in each of the spectra are presented. All of the observed ions show a secular flux decrease between 1978 and 1988. A list of SWP high-dispersion camera artifacts is also presented. The list was generated by comparing RR Tel spectra to a long-exposure sky flat.

The Galactic interstellar medium: foregrounds and star formation

NASA Astrophysics Data System (ADS)

Miville-Deschênes, Marc-Antoine

2018-05-01

This review presents briefly two aspects of Galactic interstellar medium science that seem relevant for studying EoR. First, we give some statistical properties of the Galactic foreground emission in the diffuse regions of the sky. The properties of the emission observed in projection on the plane of the sky are then related to how matter is organised along the line of sight. The diffuse atomic gas is multi-phase, with dense filamentary structures occupying only about 1% of the volume but contributing to about 50% of the emission. The second part of the review presents aspect of structure formation in the Galactic interstellar medium that could be relevant for the subgrid physics used to model the formation of the first stars.

Mitochondrial electron transport chain is involved in microcystin-RR induced tobacco BY-2 cells apoptosis.

PubMed

Huang, Wenmin; Li, Dunhai; Liu, Yongding

2014-09-01

Microcystin-RR (MC-RR) has been suggested to induce apoptosis in tobacco BY-2 cells through mitochondrial dysfunction including the loss of mitochondrial membrane potential (ΔΨm). To further elucidate the mechanisms involved in MC-RR induced apoptosis in tobacco BY-2 cells, we have investigated the role of mitochondrial electron transport chain (ETC) as a potential source for reactive oxygen species (ROS). Tobacco BY-2 cells after exposure to MC-RR (60mg/L) displayed apoptotic changes in association with an increased production of ROS and loss of ΔΨm. All of these adverse effects were significantly attenuated by ETC inhibitors including Rotenone (2μmol/L, complex I inhibitor) and antimycin A (0.01μmol/L, complex III inhibitor), but not by thenoyltrifluoroacetone (5μmol/L, complex II inhibitor). These results suggest that mitochondrial ETC plays a key role in mediating MC-RR induced apoptosis in tobacco BY-2 cells through an increased mitochondrial production of ROS. Copyright © 2014. Published by Elsevier B.V.

QT-RR relationships and suitable QT correction formulas for halothane-anesthetized dogs.

PubMed

Tabo, Mitsuyasu; Nakamura, Mikiko; Kimura, Kazuya; Ito, Shigeo

2006-10-01

Several QT correction (QTc) formulas have been used for assessing the QT liability of drugs. However, they are known to under- and over-correct the QT interval and tend to be specific to species and experimental conditions. The purpose of this study was to determine a suitable formula for halothane-anesthetized dogs highly sensitive to drug-induced QT interval prolongation. Twenty dogs were anesthetized with 1.5% halothane and the relationship between the QT and RR intervals were obtained by changing the heart rate under atrial pacing conditions. The QT interval was corrected for the RR interval by applying 4 published formulas (Bazett, Fridericia, Van de Water, and Matsunaga); Fridericia's formula (QTcF = QT/RR(0.33)) showed the least slope and lowest R(2) value for the linear regression of QTc intervals against RR intervals, indicating that it dissociated changes in heart rate most effectively. An optimized formula (QTcX = QT/RR(0.3879)) is defined by analysis of covariance and represents a correction algorithm superior to Fridericia's formula. For both Fridericia's and the optimized formula, QT-prolonging drugs (d,l-sotalol, astemizole) showed QTc interval prolongation. A non-QT-prolonging drug (d,l-propranolol) failed to prolong the QTc interval. In addition, drug-induced changes in QTcF and QTcX intervals were highly correlated with those of the QT interval paced at a cycle length of 500 msec. These findings suggest that Fridericia's and the optimized formula, although the optimized is a little bit better, are suitable for correcting the QT interval in halothane-anesthetized dogs and help to evaluate the potential QT prolongation of drugs with high accuracy.

On the origin of period changes in RR Lyrae stars

NASA Technical Reports Server (NTRS)

Renzini, A.; Sweigart, A. V.

1980-01-01

The observed period changes are explained with respect to the behavior of the semiconductive zone (SCZ) within the core of an RR Lyrae star. General consideration are given which suggest that the composition changes occuring within the SCZ during the horizontal-branch evolution result from many small mixing events, each of which slightly perturbs the pulsation period. Results indicate that small mixing events within the core of an RR Lyrae star can produce changes in the pulsation period comparable with those typically observed. It is further indicated that these mixing events together with the nuclear burning between them can produce period changes of both signs.

VizieR Online Data Catalog: RR Lyraes in SDSS stripe 82 (Watkins+, 2009)

NASA Astrophysics Data System (ADS)

Watkins, L. L.; Evans, N. W.; Belokurov, V.; Smith, M. C.; Hewett, P. C.; Bramich, D. M.; Gilmore, G. F.; Irwin, M. J.; Vidrih, S.; Wyrzykowski, L.; Zucker, D. B.

2015-10-01

In this paper, we select first the variable objects in Stripe 82 and then the subset of RR Lyraes, using the Bramich et al. (2008MNRAS.386..887B, Cat. V/141) light-motion curve catalogue (LMCC) and HLC. We make a selection of the variable objects and an identification of RR Lyrae stars. (2 data files).

R-R interval variations influence the degree of mitral regurgitation in dogs with myxomatous mitral valve disease.

PubMed

Reimann, M J; Møller, J E; Häggström, J; Markussen, B; Holen, A E W; Falk, T; Olsen, L H

2014-03-01

Mitral regurgitation (MR) due to myxomatous mitral valve disease (MMVD) is a frequent finding in Cavalier King Charles Spaniels (CKCSs). Sinus arrhythmia and atrial premature complexes leading to R-R interval variations occur in dogs. The aim of the study was to evaluate whether the duration of the R-R interval immediately influences the degree of MR assessed by echocardiography in dogs. Clinical examination including echocardiography was performed in 103 privately-owned dogs: 16 control Beagles, 70 CKCSs with different degree of MR and 17 dogs of different breeds with clinical signs of congestive heart failure due to MMVD. The severity of MR was evaluated in apical four-chamber view using colour Doppler flow mapping (maximum % of the left atrium area) and colour Doppler M-mode (duration in ms). The influence of the ratio between present and preceding R-R interval on MR severity was evaluated in 10 consecutive R-R intervals using a linear mixed model for repeated measurements. MR severity was increased when a short R-R interval was followed by a long R-R interval in CKCSs with different degrees of MR (P<0.005 when adjusted for multiple testing). The relationship was not significant in control dogs with minimal MR and in dogs with severe MR and clinical signs of heart failure. In conclusion, MR severity increases in long R-R intervals when these follow a short R-R interval in CKCSs with different degrees of MR due to asymptomatic MMVD. Thus, R-R interval variations may affect the echocardiographic grading of MR in CKCSs. Copyright © 2014 Elsevier Ltd. All rights reserved.

Galactic dual population models of gamma-ray bursts

NASA Technical Reports Server (NTRS)

Higdon, J. C.; Lingenfelter, R. E.

1994-01-01

We investigate in more detail the properties of two-population models for gamma-ray bursts in the galactic disk and halo. We calculate the gamma-ray burst statistical properties, mean value of (V/V(sub max)), mean value of cos Theta, and mean value of (sin(exp 2) b), as functions of the detection flux threshold for bursts coming from both Galactic disk and massive halo populations. We consider halo models inferred from the observational constraints on the large-scale Galactic structure and we compare the expected values of mean value of (V/V(sub max)), mean value of cos Theta, and mean value of (sin(exp 2) b), with those measured by Burst and Transient Source Experiment (BATSE) and other detectors. We find that the measured values are consistent with solely Galactic populations having a range of halo distributions, mixed with local disk distributions, which can account for as much as approximately 25% of the observed BATSE bursts. M31 does not contribute to these modeled bursts. We also demonstrate, contrary to recent arguments, that the size-frequency distributions of dual population models are quite consistent with the BATSE observations.

Relativistic Dark Matter at the Galactic Center

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

Amin, Mustafa A.; /Stanford U., Phys. Dept. /KIPAC, Menlo Park; Wizansky, Tommer

2007-11-16

In a large region of the supersymmetry parameter space, the annihilation cross section for neutralino dark matter is strongly dependent on the relative velocity of the incoming particles. We explore the consequences of this velocity dependence in the context of indirect detection of dark matter from the galactic center. We find that the increase in the annihilation cross section at high velocities leads to a flattening of the halo density profile near the galactic center and an enhancement of the annihilation signal.

The effect of Livermore OPAL opacities on the evolutionary masses of RR Lyrae stars

NASA Technical Reports Server (NTRS)

Yi, Sukyoung; Lee, Young-Wook; Demarque, Pierre

1993-01-01

We have investigated the effect of the new Livermore OPAL opacities on the evolution of horizontal-branch (HB) stars. This work was motivated by the recent stellar pulsation calculations using the new Livermore opacities, which suggest that the masses of double-mode RR Lyrae stars are 0.1-0.2 solar mass larger than those based on earlier opacities. Unlike the pulsation calculations, we find that the effect of opacity change on the evolution of HB stars is not significant. In particular, the effect of the mean masses of RR Lyrae stars is very small, showing a decrease of only 0.01-0.02 solar mass compared to the models based on old Cox-Stewart opacities. Consequently, with the new Livermore OPAL opacities, both the stellar pulsation and evolution models now predict approximately the same masses for the RR Lyrae stars. Our evolutionary models suggest that the mean masses of the RR Lyrae stars are about 0.76 and about 0.71 solar mass for M15 (Oosterhoff group II) and M3 (group I), respectively. If (alpha/Fe) = 0.4, these values are decreased by about 0.03 solar mass. Variations of the mean masses of RR Lyrae stars with HB morphology and metallicity are also presented.

Large-scale gas dynamical processes affecting the origin and evolution of gaseous galactic halos

NASA Technical Reports Server (NTRS)

Shapiro, Paul R.

1991-01-01

Observations of galactic halo gas are consistent with an interpretation in terms of the galactic fountain model in which supernova heated gas in the galactic disk escapes into the halo, radiatively cools and forms clouds which fall back to the disk. The results of a new study of several large-scale gas dynamical effects which are expected to occur in such a model for the origin and evolution of galactic halo gas will be summarized, including the following: (1) nonequilibrium absorption line and emission spectrum diagnostics for radiatively cooling halo gas in our own galaxy, as well the implications of such absorption line diagnostics for the origin of quasar absorption lines in galactic halo clouds of high redshift galaxies; (2) numerical MHD simulations and analytical analysis of large-scale explosions ad superbubbles in the galactic disk and halo; (3) numerical MHD simulations of halo cloud formation by thermal instability, with and without magnetic field; and (4) the effect of the galactic fountain on the galactic dynamo.

Elusive active galactic nuclei

NASA Astrophysics Data System (ADS)

Maiolino, R.; Comastri, A.; Gilli, R.; Nagar, N. M.; Bianchi, S.; Böker, T.; Colbert, E.; Krabbe, A.; Marconi, A.; Matt, G.; Salvati, M.

2003-10-01

A fraction of active galactic nuclei do not show the classical Seyfert-type signatures in their optical spectra, i.e. they are optically `elusive'. X-ray observations are an optimal tool to identify this class of objects. We combine new Chandra observations with archival X-ray data in order to obtain a first estimate of the fraction of elusive active galactic nuclei (AGN) in local galaxies and to constrain their nature. Our results suggest that elusive AGN have a local density comparable to or even higher than optically classified Seyfert nuclei. Most elusive AGN are heavily absorbed in the X-rays, with gas column densities exceeding 1024 cm-2, suggesting that their peculiar nature is associated with obscuration. It is likely that in elusive AGN the nuclear UV source is completely embedded and the ionizing photons cannot escape, which prevents the formation of a classical narrow-line region. Elusive AGN may contribute significantly to the 30-keV bump of the X-ray background.

GLOBAL SIMULATIONS OF GALACTIC WINDS INCLUDING COSMIC-RAY STREAMING

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

Ruszkowski, Mateusz; Yang, H.-Y. Karen; Zweibel, Ellen, E-mail: mateuszr@umich.edu, E-mail: hsyang@astro.umd.edu, E-mail: zweibel@astro.wisc.edu

2017-01-10

Galactic outflows play an important role in galactic evolution. Despite their importance, a detailed understanding of the physical mechanisms responsible for the driving of these winds is lacking. In an effort to gain more insight into the nature of these flows, we perform global three-dimensional magnetohydrodynamical simulations of an isolated Milky Way-size starburst galaxy. We focus on the dynamical role of cosmic rays (CRs) injected by supernovae, and specifically on the impact of the streaming and anisotropic diffusion of CRs along the magnetic fields. We find that these microphysical effects can have a significant effect on the wind launching andmore » mass loading factors, depending on the details of the plasma physics. Due to the CR streaming instability, CRs propagating in the interstellar medium scatter on self-excited Alfvén waves and couple to the gas. When the wave growth due to the streaming instability is inhibited by some damping process, such as turbulent damping, the coupling of CRs to the gas is weaker and their effective propagation speed faster than the Alfvén speed. Alternatively, CRs could scatter from “extrinsic turbulence” that is driven by another mechanism. We demonstrate that the presence of moderately super-Alfvénic CR streaming enhances the efficiency of galactic wind driving. Cosmic rays stream away from denser regions near the galactic disk along partially ordered magnetic fields and in the process accelerate more tenuous gas away from the galaxy. For CR acceleration efficiencies broadly consistent with the observational constraints, CRs reduce the galactic star formation rates and significantly aid in launching galactic winds.« less

RR LYRAE ATMOSPHERICS: WRINKLES OLD AND NEW. A PREVIEW

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

Preston, George W., E-mail: gwp@obs.carnegiescience.ed

I report some results of an echelle spectroscopic survey of RR Lyrae stars begun in 2006 that I presented in my Henry Norris Lecture of 2010 January 4. Topics include (1) atmospheric velocity gradients, (2) phase-dependent envelope turbulence as it relates to Peterson's discoveries of axial rotation on the horizontal branch and to Stothers' explanation of the Blazhko effect, (3) the three apparitions of hydrogen emission during a pulsation cycle, (4) the occurrence of He I lines in emission and absorption, (5) detection of He II emission and metallic line doubling in Blazhko stars, and finally (6) speculation about whatmore » helium observations of RR Lyrae stars in omega Centauri might tell us about the putative helium populations and the horizontal branch of that strange globular cluster.« less

The age of the galactic disk

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

Sandage, A.

The galactic disk is a dissipative structure and must, therefore be younger than the halo if galaxy formation generally proceeds by collapse. Just how much younger the oldest stars in the galactic disk are than the oldest halo stars remains an open question. A fast collapse (on a time scale no longer than the rotation period of the extended protogalaxy) permits an age gap of the order of approximately 10 to the 9th power years. A slow collapse, governed by the cooling rate of the partially pressure supported falling gas that formed into what is now the thick stellar disk,more » permits a longer age gap, claimed by some to be as long as 6 Gyr. Early methods of age dating the oldest components of the disk contain implicit assumptions concerning the details of the age-metallicity relation for stars in the solar neighborhood. The discovery that this relation for open clusters outside the solar circle is different that in the solar neighborhood (Geisler 1987), complicates the earlier arguments. The oldest stars in the galactic disk are at least as old as NGC 188. The new data by Janes on NGC 6791, shown first at this conference, suggest a disk age of at least 12.5 Gyr, as do data near the main sequence termination point of metal rich, high proper motion stars of low orbital eccentricity. Hence, a case can still be made that the oldest part of the galactic thick disk is similar in age to the halo globular clusters, if their ages are the same as 47 Tuc.« less

3. CASTIRON BOLSTER MARKED 'B & O RR CO. 1866' ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

3. CAST-IRON BOLSTER MARKED 'B & O RR CO. 1866' PROTECTING DOORWAY TO MACHINE SHOP. - Baltimore & Ohio Railroad, Martinsburg Machine Shop, West Side of Tuscarora Creek Opposite East End of Race Street, Martinsburg, Berkeley County, WV

SMM detection of diffuse Galactic 511 keV annihilation radiation

NASA Technical Reports Server (NTRS)

Share, G. H.; Kinzer, R. L.; Kurfess, J. D.; Messina, D. C.; Purcell, W. R.

1988-01-01

Observations of the 511 keV annihilation line from the vicinity of the Galactic center from October to February for 1980/1981, 1981/1982, 1982/1983, 1984/1985, and 1985/1986 are presented. The measurements were made with the gamma-ray spectrometer on the SMM. The design of the instrument and some of its properties used in the analysis are described, and the methods used for accumulating, fitting, and analyzing the data are outlined. It is shown how the Galactic 511 keV line was separated from the intense and variable background observed in orbit. The SMM observations are compared with previous measurements of annihilation radiation from the Galactic center region, and the astrophysical implications are discussed. It is argued that most of the measurements made to date suggest the presence of an extended Galactic source of annihilation radiation.

Galactic supernova remnant candidates discovered by THOR

NASA Astrophysics Data System (ADS)

Anderson, L. D.; Wang, Y.; Bihr, S.; Rugel, M.; Beuther, H.; Bigiel, F.; Churchwell, E.; Glover, S. C. O.; Goodman, A. A.; Henning, Th.; Heyer, M.; Klessen, R. S.; Linz, H.; Longmore, S. N.; Menten, K. M.; Ott, J.; Roy, N.; Soler, J. D.; Stil, J. M.; Urquhart, J. S.

2017-09-01

Context. There is a considerable deficiency in the number of known supernova remnants (SNRs) in the Galaxy compared to that expected. This deficiency is thought to be caused by a lack of sensitive radio continuum data. Searches for extended low-surface brightness radio sources may find new Galactic SNRs, but confusion with the much larger population of H II regions makes identifying such features challenging. SNRs can, however, be separated from H II regions using their significantly lower mid-infrared (MIR) to radio continuum intensity ratios. Aims: Our goal is to find missing SNR candidates in the Galactic disk by locating extended radio continuum sources that lack MIR counterparts. Methods: We use the combination of high-resolution 1-2 GHz continuum data from The HI, OH, Recombination line survey of the Milky Way (THOR) and lower-resolution VLA 1.4 GHz Galactic Plane Survey (VGPS) continuum data, together with MIR data from the Spitzer GLIMPSE, Spitzer MIPSGAL, and WISE surveys to identify SNR candidates. To ensure that the candidates are not being confused with H II regions, we exclude radio continuum sources from the WISE Catalog of Galactic H II Regions, which contains all known and candidate H II regions in the Galaxy. Results: We locate 76 new Galactic SNR candidates in the THOR and VGPS combined survey area of 67.4° > ℓ > 17.5°, | b | ≤ 1.25° and measure the radio flux density for 52 previously-known SNRs. The candidate SNRs have a similar spatial distribution to the known SNRs, although we note a large number of new candidates near ℓ ≃ 30°, the tangent point of the Scutum spiral arm. The candidates are on average smaller in angle compared to the known regions, 6.4' ± 4.7' versus 11.0' ± 7.8', and have lower integrated flux densities. Conclusions: The THOR survey shows that sensitive radio continuum data can discover a large number of SNR candidates, and that these candidates can be efficiently identified using the combination of radio and

Uptake, tissue distribution and accumulation of microcystin-RR in Corydoras paleatus, Jenynsia multidentata and Odontesthes bonariensis. A field and laboratory study.

PubMed

Cazenave, Jimena; Wunderlin, Daniel Alberto; de Los Angeles Bistoni, María; Amé, María Valeria; Krause, Eberhard; Pflugmacher, Stephan; Wiegand, Claudia

2005-10-15

The uptake and accumulation of microcystin-RR (MC-RR) in fish was investigated under laboratory conditions and in wild fish. Jenynsia multidentata and Corydoras paleatus were exposed for 24h to 50mug/L MC-RR dissolved in water. After exposure, liver, gill, brain, intestine, gall bladder, blood and muscle were analyzed for MC-RR by HPLC and analysis confirmed by LC-ESI-TOF-MS spectrometry. Furthermore, wild individuals of Odontesthes bonariensis were sampled from the eutrophic, cyanobacteria-containing San Roque reservoir, and analyzed for the presence of MC-RR in liver, gill, intestine, and muscle. MC-RR was found in liver, gills, and muscle of all exposed and wild fish, while in C. paleatus MC-RR was also present in the intestine. Moreover, we found presence of MC-RR in brain of J. multidentata. Results indicate that MC-RR uptake might occur at two different organs: intestine and gills, through either feeding (including drinking) or respiratory activities. This suggests that MC-RR is taken into the blood stream after absorption, and distributed to different tissues. The liver showed the major bioaccumulation of MC-RR in both experimentally exposed and wild individuals, with muscle of wild fish showing relative high amounts of this toxin in comparison with those exposed in the laboratory; though MC-RR was present in muscle of fish exposed for 24h. The amount of MC-RR in muscle of O. bonariensis exceeded the value suggested by WHO to be safe, thus causing a health risk to persons consuming fish as a result of chronic exposure to microcystin. Gills also showed bioaccumulation of MC-RR, raising questions on the mechanism involved in the possible uptake of MC-RR through gills as well as on its accumulation in this organ. Although MC-LR has been reported in brain of fish, this is the first report confirming the presence of MC-RR in this organ, which means that both toxins are able to cross the blood-brain barrier. These findings also raise questions on the probable

The galactic gamma-ray distribution: Implications for galactic structure and the radial cosmic ray gradient

NASA Technical Reports Server (NTRS)

Harding, A. K.; Stecker, F. W.

1984-01-01

The radial distribution of gamma ray emissivity in the Galaxy was derived from flux longitude profiles, using both the final SAS-2 results and the recently corrected COS-B results and analyzing the northern and southern galactic regions separately. The recent CO surveys of the Southern Hemisphere, were used in conjunction with the Northern Hemisphere data, to derive the radial distribution of cosmic rays on both sides of the galactic plane. In addition to the 5 kpc ring, there is evidence from the radial asymmetry for spiral features which are consistent with those derived from the distribution of bright HII regions. Positive evidence was also found for a strong increase in the cosmic ray flux in the inner Galaxy, particularly in the 5 kpc region in both halves of the plane.

Orbits of Selected Globular Clusters in the Galactic Bulge

NASA Astrophysics Data System (ADS)

Pérez-Villegas, A.; Rossi, L.; Ortolani, S.; Casotto, S.; Barbuy, B.; Bica, E.

2018-05-01

We present orbit analysis for a sample of eight inner bulge globular clusters, together with one reference halo object. We used proper motion values derived from long time base CCD data. Orbits are integrated in both an axisymmetric model and a model including the Galactic bar potential. The inclusion of the bar proved to be essential for the description of the dynamical behaviour of the clusters. We use the Monte Carlo scheme to construct the initial conditions for each cluster, taking into account the uncertainties in the kinematical data and distances. The sample clusters show typically maximum height to the Galactic plane below 1.5 kpc, and develop rather eccentric orbits. Seven of the bulge sample clusters share the orbital properties of the bar/bulge, having perigalactic and apogalatic distances, and maximum vertical excursion from the Galactic plane inside the bar region. NGC 6540 instead shows a completely different orbital behaviour, having a dynamical signature of the thick disc. Both prograde and prograde-retrograde orbits with respect to the direction of the Galactic rotation were revealed, which might characterise a chaotic behaviour.

Gamma-ray spectroscopy: The diffuse galactic glow

NASA Technical Reports Server (NTRS)

Hartmann, Dieter H.

1991-01-01

The goal of this project is the development of a numerical code that provides statistical models of the sky distribution of gamma-ray lines due to the production of radioactive isotopes by ongoing Galactic nucleosynthesis. We are particularly interested in quasi-steady emission from novae, supernovae, and stellar winds, but continuum radiation and transient sources must also be considered. We have made significant progress during the first half period of this project and expect the timely completion of a code that can be applied to Oriented Scintillation Spectrometer Experiment (OSSE) Galactic plane survey data.

A compact ECG R-R interval, respiration and activity recording system.

PubMed

Yoshimura, Takahiro; Yonezawa, Yoshiharu; Maki, Hiromichi; Ogawa, Hidekuni; Hahn, Allen W; Thayer, Julian F; Caldwell, W Morton

2003-01-01

An ECG R-R interval, respiration and activity recording system has been developed for monitoring variability of heart rate and respiratory frequency during daily life. The recording system employs a variable gain instrumentation amplifier, an accelerometer, a low power 8-bit single-chip microcomputer and a 1024 KB EEPROM. It is constructed on three ECG chest electrodes. The R-R interval and respiration are detected from the ECG. Activity during walking and running is calculated from an accelerator. The detected data are stored in an EEPROM and after recording, are downloaded to a desktop computer for analysis.

Galactic Supernova Remnant Candidates Discovered by THOR

NASA Astrophysics Data System (ADS)

Anderson, Loren; Wang, Yuan; Bihr, Simon; Rugel, Michael; Beuther, Henrik; THOR Team

2018-01-01

There is a considerable deficiency in the number of known supernova remnants (SNRs) in the Galaxy compared to that expected. Searches for extended low-surface brightness radio sources may find new Galactic SNRs, but confusion with the much larger population of HII regions makes identifying such features challenging. SNRs can, however, be separated from HII regions using their significantly lower mid-infrared (MIR) to radio continuum intensity ratios. We use the combination of high-resolution 1-2 GHz continuum data from The HI, OH, Recombination line survey of the Milky Way (THOR) and lower-resolution VLA 1.4 GHz Galactic Plane Survey (VGPS) continuum data, together with MIR data from the Spitzer GLIMPSE, Spitzer MIPSGAL, and WISE surveys to identify SNR candidates. To ensure that the candidates are not being confused with HII regions, we exclude radio continuum sources from the WISE Catalog of Galactic HII Regions, which contains all known and candidate H II regions in the Galaxy. We locate 76 new Galactic SNR candidates in the THOR and VGPS combined survey area of 67.4deg>l>17.5deg, |b|<1.25deg and measure the radio flux density for 52 previously-known SNRs. The candidate SNRs have a similar spatial distribution to the known SNRs, although we note a large number of new candidates near l=30deg, the tangent point of the Scutum spiral arm. The candidates are on average smaller in angle compared to the known regions, 6.4'+/-4.7' versus 11.0'+/-7.8', and have lower integrated flux densities. If the 76 candidates are confirmed as true SNRs, for example using radio polarization measurements or by deriving radio spectral indices, this would more than double the number of known Galactic SNRs in the survey area. This large increase would still, however, leave a discrepancy between the known and expected SNR populations of about a factor of two.

Does the Galactic Bulge Have Fewer Planets?

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2016-12-01

The Milky Ways dense central bulge is a very different environment than the surrounding galactic disk in which we live. Do the differences affect the ability of planets to form in the bulge?Exploring Galactic PlanetsSchematic illustrating how gravitational microlensing by an extrasolar planet works. [NASA]Planet formation is a complex process with many aspects that we dont yet understand. Do environmental properties like host star metallicity, the density of nearby stars, or the intensity of the ambient radiation field affect the ability of planets to form? To answer these questions, we will ultimately need to search for planets around stars in a large variety of different environments in our galaxy.One way to detect recently formed, distant planets is by gravitational microlensing. In this process, light from a distant source star is bent by a lens star that is briefly located between us and the source. As the Earth moves, this momentary alignment causes a blip in the sources light curve that we can detect and planets hosted by the lens star can cause an additional observable bump.Artists impression of the Milky Way galaxy. The central bulge is much denserthan the surroundingdisk. [ESO/NASA/JPL-Caltech/M. Kornmesser/R. Hurt]Relative AbundancesMost source stars reside in the galactic bulge, so microlensing events can probe planetary systems at any distance between the Earth and the galactic bulge. This means that planet detections from microlensing could potentially be used to measure the relative abundances of exoplanets in different parts of our galaxy.A team of scientists led by Matthew Penny, a Sagan postdoctoral fellow at Ohio State University, set out to do just that. The group considered a sample of 31 exoplanetary systems detected by microlensing and asked the following question: are the planet abundances in the galactic bulge and the galactic disk the same?A Paucity of PlanetsTo answer this question, Penny and collaborators derived the expected

A Speeding Binary in the Galactic Halo

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2016-04-01

The recent discovery of a hyper-velocity binary star system in the halo of the Milky Way poses a mystery: how was this system accelerated to its high speed?Accelerating StarsUnlike the uniform motion in the Galactic disk, stars in the Milky Ways halo exhibit a huge diversity of orbits that are usually tilted relative to the disk and have a variety of speeds. One type of halo star, so-called hyper-velocity stars, travel with speeds that can approach the escape velocity of the Galaxy.How do these hyper-velocity stars come about? Assuming they form in the Galactic disk, there are multiple proposed scenarios through which they could be accelerated and injected into the halo, such as:Ejection after a close encounter with the supermassive black hole at the Galactic centerEjection due to a nearby supernova explosionEjection as the result of a dynamical interaction in a dense stellar population.Further observations of hyper-velocity stars are necessary to identify the mechanism responsible for their acceleration.J1211s SurpriseModels of J1211s orbit show it did not originate from the Galactic center (black dot). The solar symbol shows the position of the Sun and the star shows the current position of J1211. The bottom two panels show two depictions(x-y plane and r-z plane) of estimated orbits of J1211 over the past 10 Gyr. [Nmeth et al. 2016]To this end, a team of scientists led by Pter Nmeth (Friedrich Alexander University, Erlangen-Nrnberg) recently studied the candidate halo hyper-velocity star SDSS J121150.27+143716.2. The scientists obtained spectroscopy of J1211 using spectrographs at the Keck Telescope in Hawaii and ESOs Very Large Telescope in Chile. To their surprise, they discovered the signature of a companion in the spectra: J1211 is actually a binary!Nmeth and collaborators found that J1211, located roughly 18,000 light-years away, is moving at a rapid ~570 km/s relative to the galactic rest frame. The binary system consists of a hot (30,600 K) subdwarf and a

RcRR1, a Rosa canina type-A response regulator gene, is involved in cytokinin-modulated rhizoid organogenesis.

PubMed

Gao, Bin; Fan, Lusheng; Li, Xingxing; Yang, Huifang; Liu, Fengluan; Wang, Ling; Xi, Lin; Ma, Nan; Zhao, Liangjun

2013-01-01

In vitro, a new protocol of plant regeneration in rose was achieved via protocorm-like bodies (PLBs) induced from the root-like organs named rhizoids that developed from leaf explants. The development of rhizoids is a critical stage for efficient regeneration, which is triggered by exogenous auxin. However, the role of cytokinin in the control of organogenesis in rose is as yet uncharacterized. The aim of this study was to elucidate the molecular mechanism of cytokinin-modulated rhizoid formation in Rosa canina. Here, we found that cytokinin is a key regulator in the formation of rhizoids. Treatment with cytokinin reduced callus activity and significantly inhibited rhizoid formation in Rosa canina. We further isolated the full-length cDNA of a type-A response regulator gene of cytokinin signaling, RcRR1, from which the deduced amino acid sequence contained the conserved DDK motif. Gene expression analysis revealed that RcRR1 was differentially expressed during rhizoid formation and its expression level was rapidly up-regulated by cytokinin. In addition, the functionality of RcRR1 was tested in Arabidopsis. RcRR1 was found to be localized to the nucleus in GFP-RcRR1 transgenic plants and overexpression of RcRR1 resulted in increased primary root length and lateral root density. More importantly, RcRR1 overexpression transgenic plants also showed reduced sensitivity to cytokinin during root growth; auxin distribution and the expression of auxin efflux carriers PIN genes were altered in RcRR1 overexpression plants. Taken together, these results demonstrate that RcRR1 is a functional type-A response regulator which is involved in cytokinin-regulated rhizoid formation in Rosa canina.

RcRR1, a Rosa canina Type-A Response Regulator Gene, Is Involved in Cytokinin-Modulated Rhizoid Organogenesis

PubMed Central

Li, Xingxing; Yang, Huifang; Liu, Fengluan; Wang, Ling; Xi, Lin; Ma, Nan; Zhao, Liangjun

2013-01-01

In vitro, a new protocol of plant regeneration in rose was achieved via protocorm-like bodies (PLBs) induced from the root-like organs named rhizoids that developed from leaf explants. The development of rhizoids is a critical stage for efficient regeneration, which is triggered by exogenous auxin. However, the role of cytokinin in the control of organogenesis in rose is as yet uncharacterized. The aim of this study was to elucidate the molecular mechanism of cytokinin-modulated rhizoid formation in Rosa canina. Here, we found that cytokinin is a key regulator in the formation of rhizoids. Treatment with cytokinin reduced callus activity and significantly inhibited rhizoid formation in Rosa canina. We further isolated the full-length cDNA of a type-A response regulator gene of cytokinin signaling, RcRR1, from which the deduced amino acid sequence contained the conserved DDK motif. Gene expression analysis revealed that RcRR1 was differentially expressed during rhizoid formation and its expression level was rapidly up-regulated by cytokinin. In addition, the functionality of RcRR1 was tested in Arabidopsis. RcRR1 was found to be localized to the nucleus in GFP-RcRR1 transgenic plants and overexpression of RcRR1 resulted in increased primary root length and lateral root density. More importantly, RcRR1 overexpression transgenic plants also showed reduced sensitivity to cytokinin during root growth; auxin distribution and the expression of auxin efflux carriers PIN genes were altered in RcRR1 overexpression plants. Taken together, these results demonstrate that RcRR1 is a functional type-A response regulator which is involved in cytokinin-regulated rhizoid formation in Rosa canina. PMID:24009713

RR Lyrae variables in M33: two new fields and an analysis of the galaxy's population

NASA Astrophysics Data System (ADS)

Tanakul, Nahathai; Yang, Soung-Chul; Sarajedini, Ata

2017-06-01

We present a re-analysis of M33 RR Lyrae variables in four different fields: two inner disc fields and two outer disc fields. These are located at 8.5, 8.7, 36 and 46 arcmin from the centre of M33, respectively. We identify 48 new RR Lyrae variable stars and refine the light-curve properties of 51 previously identified variables. From the light curves, we calculate reddenings and metallicities for each star. Using data in this paper and previously published material, we are able to construct a radial density profile for the RR Lyrae stars in M33. This profile, when plotted in log space, has a slope of ˜-2.0 ± 0.15 which agrees with the radial distribution of halo stars in the Milky Way and M31. This suggests that the majority of M33 RR Lyrae variables observed so far belong to the halo. We also examine the RR Lyrae specific frequency and absolute magnitude relation in M33 and find good agreement with previous studies.

HEAO 1 measurements of the galactic ridge

NASA Technical Reports Server (NTRS)

Worrall, D. M.; Marshall, F. E.; Boldt, E. A.; Swank, J. H.

1981-01-01

The HEAO A2 experiment data was systematically searched for unresolved galactic disc emission. Although there were suggestions of non-uniformities in the emission, the data were consistent with a disc of half-thickness 241 + 22 pc and surface emissivity (2-10 keV) at galactic radius R(kpc) of 2.2 10 to the minus 7th power exp(-R/3.5) erg/sq cm to the (-2)power/s (R 7.8 kpc). giving a luminosity of approximately 4.4 10 to the 37th power erg S to the (-1) power. If the model is extrapolated to radii less than 7.8 kpc, the unresolved disc emission is approximately 1.4 10 to the 38th power erg S to the (-1) power (2-10 keV) i.e., a few percent of the luminosity of the galaxy in resolved sources. the disc emission has a spectrum which is significantly softer than that of the high galactic latitude diffuse X-ray background and it is most probably of discrete source origin.

Galactic civilizations - Population dynamics and interstellar diffusion

NASA Technical Reports Server (NTRS)

Newman, W. I.; Sagan, C.

1981-01-01

A model is developed of the interstellar diffusion of galactic civilizations which takes into account the population dynamics of such civilizations. The problem is formulated in terms of potential theory, with a family of nonlinear partial differential and difference equations specifying population growth and diffusion for an organism with advantageous genes that undergoes random dispersal while increasing in population locally, and a population at zero population growth. In the case of nonlinear diffusion with growth and saturation, it is found that the colonization wavefront from the nearest independently arisen galactic civilization can have reached the earth only if its lifetime exceeds 2.6 million years, or 20 million years if discretization can be neglected. For zero population growth, the corresponding lifetime is 13 billion years. It is concluded that the earth is uncolonized not because interstellar spacefaring civilizations are rare, but because there are too many worlds to be colonized in the plausible colonization lifetime of nearby civilizations, and that there exist no very old galactic civilizations with a consistent policy of the conquest of inhabited worlds.

Vertical Shear of the Galactic Interstellar Medium

NASA Technical Reports Server (NTRS)

Benjamin, Robert A.

2000-01-01

The detection of UV absorption, 21 cm, H alpha and other diffuse optical emission lines from gas up to ten kiloparsecs above the plane of the Milky Way and other galaxies provides the first, opportunity to probe the rotational properties of the ionized "atmospheres" of galaxies. This rotation has implications for our understanding of the Galactic gravitational potential, angular momentum transport in the Galactic disk, and the maintenance of a Galactic dynamo. The available evidence indicates that gas rotates nearly cylindrically up to a few kiloparsecs. This is in contrast to the expectation that there should be a significant gradient in rotation speed as a function of height assuming a reasonable mass model for the Galaxy. For example, for a vertical cut at galactocentric radius R = 5 kpc in NGC 891 by Rand, the rotation speed is observed to drop by approximately 30 kilometers per second from z = 1 to 5 kpc and is expected to drop by 80 kilometers per second. Magnetic tension forces may resolve this discrepancy. Other possibilities will be examined in the near future.

Resonance Trapping in the Galactic Disc and Halo and its Relation with Moving Groups

NASA Astrophysics Data System (ADS)

Pichardo, Barbara; Moreno, Edmundo; william, schuster B.

2015-08-01

With the use of a detailed Milky Way nonaxisymmetric potential, observationally and dynamically constrained, the eects of the bar and the spiral arms in the Galaxy are studied in the disc and in the stellar halo. Especially the trapping of stars in the disk and Galactic halo by resonances on the Galactic plane created by the Galactic bar has been analysed in detail. To this purpose, a new method is presented to delineate the trapping regions using empirical diagrams of some orbital properties obtained in the Galactic potential. In these diagrams we plot in the inertial Galactic frame a characteristic orbital energy versus a characteristic orbital angular momentum, or versus the orbital Jacobi constant in the reference frame of the bar, when this is the only nonaxisymmetric component in the Galactic potential. With these diagrams some trapping regions are obtained in the disc and halo using a sample of disc stars and halo stars in the solar neighborhood. We compute several families of periodic orbits on the Galactic plane, some associated with this resonant trapping. In particular, we nd that the trapping eect of these resonances on the Galactic plane can extend some kpc from this plane, trapping stars in the Galactic halo. The purpose of our analysis is to investigate if the trapping regions contain some known moving groups in our Galaxy. We have applied our method to the Kapteyn group, a moving group in the halo, and we have found that this group appears not to be associated with a particular resonance on the Galactic plane.

Galactic fly-bys: New source of lithium production

NASA Astrophysics Data System (ADS)

Prodanović, Tijana; Bogdanović, Tamara; Urošević, Dejan

2013-05-01

Observations of low-metallicity halo stars have revealed a puzzling result: the abundance of Li7 in these stars is at least three times lower than their predicted primordial abundance. It is unclear whether the cause of this disagreement is a lack of understanding of lithium destruction mechanisms in stars or the non-standard physics behind the big bang nucleosynthesis (BBN). Uncertainties related to the destruction of lithium in stars can be circumvented if lithium abundance is measured in the “pristine” gas of the low metallicity systems. The first measurement in one such system, the small magellanic cloud (SMC), was found to be at the level of the pure expected primordial value, but is on the other hand, just barely consistent with the expected galactic abundance for the system at the SMC metallicity, where important lithium quantity was also produced in interactions of galactic cosmic rays and presents an addition to the already present primordial abundance. Because of the importance of the SMC lithium measurement for the resolution of the lithium problem, we here draw attention to the possibility of another post-BBN production channel of lithium, which could present an important addition to the observed SMC lithium abundance. Besides standard galactic cosmic rays, additional post-BBN production of lithium might come from cosmic rays accelerated in galaxy-galaxy interactions. This might be important for a system such is the SMC, which has experienced galaxy harassment in its history. Within a simplified but illustrative framework we demonstrate that large-scale tidal shocks from a few galactic fly-bys can possibly produce lithium in amounts comparable to those expected from the interactions of galactic cosmic-rays produced in supernovae over the entire history of a system. In case of the SMC, we find that only two such fly-bys could possibly account for as much lithium as the standard, galactic cosmic ray production channel. However, adding any a new

Implications of the IRAS data for galactic gamma ray astronomy and EGRET

NASA Technical Reports Server (NTRS)

Stecker, Floyd W.

1990-01-01

Using the results of gamma-ray, millimeter wave and far surveys of the galaxy, logically consistent picture of the large scale distribution of galactic gas and cosmic rays was derived, tied to the overall processes of stellar birth and destruction on a galactic scale. Using the results of the IRAS far-infrared survey of te galaxy, the large scale radial distributions of galactic far-infrared emission independently was obtained for both the Northern and Southern Hemisphere sides of the Galaxy. The dominant feature in these distributions was found to be a broad peak coincident with the 5 kpc molecular gas cloud ring. Evidence was found for spiral arm features. Strong correlations are evident between the large scale galactic distributions of far-infrared emission, gamma-ray emission and total CO emission. There is particularly tight correlation between the distribution of warm molecular clouds and far-infrared emission on a galactic scale. The 5 kpc ring was evident in existing galactic gamma-ray data. The extent to which the more detailed spiral arm features are evident in the more resolved EGRET (Energetic Gamma-Ray Experimental Telescope) data will help to determine more precisely the propagation characteristics of cosmic rays.

Differential detoxification and antioxidant response in diverse organs of Corydoras paleatus experimentally exposed to microcystin-RR.

PubMed

Cazenave, Jimena; Bistoni, María de Los Angeles; Pesce, Silvia Fabiana; Wunderlin, Daniel Alberto

2006-01-05

We assessed changes in activities of both detoxification and antioxidant enzymes as well as lipid peroxidation levels in liver, gill, intestine and brain of Corydoras paleatus exposed to dissolved microcystin-RR (MC-RR). Fish were captured at an unpolluted area, transported to the laboratory, and acclimated previous to experiments. Exposures were carried out using MC-RR at 0.5, 2, 5 and 10 microg L(-1). After exposures for 24h, fish were sacrificed and dissected separating liver, gills, intestine and brain of each fish. Organs were used for enzyme extractions, evaluating both antioxidant and detoxification systems through the assay of glutathione reductase (GR), guaiacol peroxidase (POD), glutathione peroxidase (GPx), catalase (CAT) as well as glutathione S-transferase (GST). Additionally, thiobarbaturic acid (TBA) method was used to evaluate the peroxidation of lipids (LPO). GST was inhibited in all studied organs at most MC-RR concentrations used. Activities of GR, POD and GPx were enhanced in liver at 2 microg L(-1), but inhibited in gills at all tested concentrations. CAT activity was enhanced in liver at all studied concentrations. Antioxidant response in liver is activated at low toxin concentrations, followed by a drop at the highest MC-RR levels. On the contrary, detoxification activity is inhibited in liver and brain in a dose-dependent way. On the other hand, MC-RR (>or=2 microg L(-1)) induced LPO in brain of exposed fish, but not in other organs. This finding becomes to this organ in one of the most severely affected. Results show that gills are also very affected, since both antioxidant and detoxification systems were inhibited in this tissue. Thus, inhibition of these defense systems could increase the uptake of different toxics through gills of fish exposed to dissolved MC-RR, leading to an increased health risk for fish. The different response observed on diverse organs exposed to MC-RR might be related to the uptake route as well as on

Evidence for accreted component in the Galactic discs

NASA Astrophysics Data System (ADS)

Xing, Q. F.; Zhao, G.

2018-06-01

We analyse the distribution of [Mg/Fe] abundance in the Galactic discs with F- and G-type dwarf stars selected from the Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST) archive. The sample stars are assigned into different stellar populations by using kinematic criteria. Our analysis reveals the chemical inhomogeneities in the Galactic thick disc. A few of metal-poor stars in the thick disc exhibit relatively low [Mg/Fe] abundance in respect to the standard thick-disc sample. The orbital eccentricities and maximum Galactocentric radii of low-α metal-poor stars are apparently greater than that of high-α thick-disc stars. The orbital parameters and chemical components of low-α stars in the thick disc suggest that they may have been formed in regions with low star formation rate that were located at large distances from the Galactic centre, such as infalling dwarf spheroidal galaxies.

The GALAH Survey and Galactic Archaeology in the Next Decade

NASA Astrophysics Data System (ADS)

Martell, S. L.

2016-10-01

The field of Galactic Archaeology aims to understand the origins and evolution of the stellar populations in the Milky Way, as a way to understand galaxy formation and evolution in general. The GALAH (Galactic Archaeology with HERMES) Survey is an ambitious Australian-led project to explore the Galactic history of star formation, chemical evolution, minor mergers and stellar migration. GALAH is using the HERMES spectrograph, a novel, highly multiplexed, four-channel high-resolution optical spectrograph, to collect high-quality R˜28,000 spectra for one million stars in the Milky Way. From these data we will determine stellar parameters, radial velocities and abundances for up to 29 elements per star, and carry out a thorough chemical tagging study of the nearby Galaxy. There are clear complementarities between GALAH and other ongoing and planned Galactic Archaeology surveys, and also with ancillary stellar data collected by major cosmological surveys. Combined, these data sets will provide a revolutionary view of the structure and history of the Milky Way.

The Observed Galactic Annihilation Line: Possible Signature of Accreting Small Mass Black Holes in the Galactic Center

NASA Technical Reports Server (NTRS)

Titarchuk, Lev; Chardonnet, Pascal

2006-01-01

Various balloon and satellite observatories have revealed what appears to be an extended source of 0.511 MeV annihilation radiation with flux of approx. 10(exp -3) photons/sq cm/s centered on the Galactic Center. Positrons from radioactive products of stellar explosions can account for a significant fraction of the emission. We discuss an additional source for this emission: namely e(+)e(-) pairs produced when X-rays generated from the approx. 2.6 x 10(exp 6) solar mass Galactic Center Black Hole interact with approx. 10 MeV temperature blackbody emission from 10(exp 17) g black holes within 10(exp 14-l5) cm of the center. The number of such Small Mass Black Holes (SMMBHs) can account for the production of the 10(exp 42) e(+)/s that produces the observed annihilation in the inner Galaxy when transport effects are taken into account. We consider the possibility for confirming the presence of these SMMBHs in the Galactic Center region with future generations of gamma-ray instruments if a blackbody like emission of approx. 10 MeV temperature would be detected by them. Small Mass Black Hole can be a potential candidate for dark (invisible) matter hal

Near-infrared variability study of the central 2.3 arcmin × 2.3 arcmin of the Galactic Centre - I. Catalogue of variable sources

NASA Astrophysics Data System (ADS)

Dong, Hui; Schödel, Rainer; Williams, Benjamin F.; Nogueras-Lara, Francisco; Gallego-Cano, Eulalia; Gallego-Calvente, Teresa; Wang, Q. Daniel; Morris, Mark R.; Do, Tuan; Ghez, Andrea

2017-09-01

We used 4-yr baseline Hubble Space Telescope/Wide Field Camera 3 IR observations of the Galactic Centre in the F153M band (1.53 μm) to identify variable stars in the central ∼2.3 arcmin × 2.3 arcmin field. We classified 3845 long-term (periods from months to years) and 76 short-term (periods of a few days or less) variables among a total sample of 33 070 stars. For 36 of the latter ones, we also derived their periods (<3 d). Our catalogue not only confirms bright long period variables and massive eclipsing binaries identified in previous works but also contains many newly recognized dim variable stars. For example, we found δ Scuti and RR Lyrae stars towards the Galactic Centre for the first time, as well as one BL Her star (period < 1.3 d). We cross-correlated our catalogue with previous spectroscopic studies and found that 319 variables have well-defined stellar types, such as Wolf-Rayet, OB main sequence, supergiants and asymptotic giant branch stars. We used colours and magnitudes to infer the probable variable types for those stars without accurately measured periods or spectroscopic information. We conclude that the majority of unclassified variables could potentially be eclipsing/ellipsoidal binaries and Type II Cepheids. Our source catalogue will be valuable for future studies aimed at constraining the distance, star formation history and massive binary fraction of the Milky Way nuclear star cluster.

Galactic Tidal Shocks Effects in Globular Clusters

NASA Astrophysics Data System (ADS)

Cruz, F.; Aguilar, L.

2001-07-01

We present results of a set of N--Body simulations of 105--particle King models in the presence of a realistic Galactic tidal field. Tidal effects over a cluster are dominated by two processes, differentiated by the way they produc e mass loss in the system. The first one is the Roche lobe overflow, which depend s directly on the ratio of cluster to the Roche lobe size. The second process is tidal heating, produced by the time varying part of the Galactic tide, which injects energy directly on the orbits of the stars inside the cluster.

The structure and content of the galaxy and galactic gamma rays

NASA Technical Reports Server (NTRS)

Fichtel, C. E. (Editor); Stecker, F. W. (Editor)

1977-01-01

Gamma radiation investigations by COS-B and SAS-2 satellite are reported. Data from CO surveys of the galaxy and the galactic distribution of pulsars are analyzed. Theories of galactic gamma ray emission are explored.

VizieR Online Data Catalog: SWASP catalogue of RR Lyrae stars (Greer+, 2017)

NASA Astrophysics Data System (ADS)

Greer, P. A.; Payne, S. G.; Norton, A. J.; Maxted, P. F. L.; Smalley, B.; West, P. J.; Wheatley, R. G.; Kolb, U. C.

2017-07-01

The SuperWASP RR Lyrae catalogue contains 4963 RRab type RR Lyrae objects from the SuperWASP archive. Each entry includes the unique SWASP identifier, pulsation period in days, pulsation amplitude in mags, median light curve amplitude in mags, the corresponding GCVS name, and corresponding SSS/CRTS names, where known. The SWASP blazhko candidate catalogue contains 1324 rows of Blazhko periods for 983 unique objects from the SWASP RRab catalogue. (2 data files).

Response of Haloalkaliphilic Archaeon Natronococcus Jeotgali RR17 to Hypergravity

NASA Astrophysics Data System (ADS)

Thombre, Rebecca S.; Bhalerao, Aniruddha R.; Shinde, Vinaya D.; Dhar, Sunil Kumar; Shouche, Yogesh S.

2017-06-01

The survival of archaeabacteria in extreme inhabitable environments on earth that challenge organismic survival is ubiquitously known. However, the studies related to the effect of hypergravity on the growth and proliferation of archaea are unprecedented. The survival of organisms in hypergravity and rocks in addition to resistance to cosmic radiations, pressure and other extremities is imperative to study the possibilities of microbial travel between planets and endurance in hyperaccelerative forces faced during ejection of rocks from planets. The current investigation highlights the growth of an extremophilic archaeon isolated from a rocky substrate in hypergravity environment. The haloalkaliphilic archaeon, Natronococcus jeotgali RR17 was isolated from an Indian laterite rock, submerged in the Arabian sea lining Coastal Maharashtra, India. The endolithic haloarchaeon was subjected to hypergravity from 56 - 893 X gusing acceleration generated by centrifugal rotation. The cells of N. jeotgali RR17 proliferated and demonstrated good growth in hypergravity (223 X g). This is the first report on isolation of endolithic haloarchaeon N. jeotgali RR17 from an Indian laterite rock and its ability to proliferate in hypergravity. The present study demonstrates the ability of microbial life to survive and proliferate in hypergravity. Thus the inability of organismic growth in hypergravity may no longer be a limitation for astrobiology studies related to habitability of substellar objects, brown dwarfs and other planetary bodies in the universe besides planet earth.

Implications of the IRAS data for galactic gamma-ray astronomy and EGRET

NASA Technical Reports Server (NTRS)

Stecker, F. W.

1990-01-01

Using the results of gamma-ray, millimeter wave and far infrared surveys of the galaxy, one can derive a logically consistent picture of the large scale distribution of galactic gas and cosmic rays, one tied to the overall processes of stellar birth and destruction on a galactic scale. Using the results of the IRAS far-infrared survey of the galaxy, the large scale radial distribution of galactic far-infrared emission were obtained independently for both the Northern and Southern Hemisphere sides of the Galaxy. It was found that the dominant feature in these distributions to be a broad peak coincident with the 5 kpc molecular gas cloud ring. Also found was evidence of spiral arm features. Strong correlations are evident between the large scale galactic distributions of far infrared emission, gamma-ray emission and total CO emission. There is a particularly tight correlation between the distribution of warm molecular clouds and far-infrared emission on a galactic scale.

Molecular clouds and galactic spiral structure

NASA Technical Reports Server (NTRS)

Dame, T. M.

1984-01-01

Galactic CO line emission at 115 GHz was surveyed in order to study the distribution of molecular clouds in the inner galaxy. Comparison of this survey with similar H1 data reveals a detailed correlation with the most intense 21 cm features. To each of the classical 21 cm H1 spiral arms of the inner galaxy there corresponds a CO molecular arm which is generally more clearly defined and of higher contrast. A simple model is devised for the galactic distribution of molecular clouds. The modeling results suggest that molecular clouds are essentially transient objects, existing for 15 to 40 million years after their formation in a spiral arm, and are largely confined to spiral features about 300 pc wide.

Gravitational lensing of active galactic nuclei.

PubMed Central

Hewitt, J N

1995-01-01

Most of the known cases of strong gravitational lensing involve multiple imaging of an active galactic nucleus. The properties of lensed active galactic nuclei make them promising systems for astrophysical applications of gravitational lensing; in particular, they show structure on scales of milliseconds of arc to tens of seconds of arc, they are variable, and they are polarized. More than 20 cases of strong gravitational lenses are now known, and about half of them are radio sources. High-resolution radio imaging is making possible the development of well-constrained lens models. Variability studies at radio and optical wavelengths are beginning to yield results of astrophysical interest, such as an independent measure of the distance scale and limits on source sizes. PMID:11607613

Gravitational lensing of active galactic nuclei.

PubMed

Hewitt, J N

1995-12-05

Most of the known cases of strong gravitational lensing involve multiple imaging of an active galactic nucleus. The properties of lensed active galactic nuclei make them promising systems for astrophysical applications of gravitational lensing; in particular, they show structure on scales of milliseconds of arc to tens of seconds of arc, they are variable, and they are polarized. More than 20 cases of strong gravitational lenses are now known, and about half of them are radio sources. High-resolution radio imaging is making possible the development of well-constrained lens models. Variability studies at radio and optical wavelengths are beginning to yield results of astrophysical interest, such as an independent measure of the distance scale and limits on source sizes.

Evaluation of Galactic Cosmic Ray Models

NASA Technical Reports Server (NTRS)

Adams, James H., Jr.; Heiblim, Samuel; Malott, Christopher

2009-01-01

Models of the galactic cosmic ray spectra have been tested by comparing their predictions to an evaluated database containing more than 380 measured cosmic ray spectra extending from 1960 to the present.

Galactic Cosmic Rays: From Earth to Sources

NASA Technical Reports Server (NTRS)

Brandt, Theresa J.

2012-01-01

For nearly 100 years we have known that cosmic rays come from outer space, yet proof of their origin, as well as a comprehensive understanding of their acceleration, remains elusive. Direct detection of high energy (up to 10(exp 15)eV), charged nuclei with experiments such as the balloon-born, antarctic Trans-Iron Galactic Element Recorder (TIGER) have provided insight into these mysteries through measurements of cosmic ray abundances. The abundance of these rare elements with respect to certain intrinsic properties suggests that cosmic rays include a component of massive star ejecta. Supernovae and their remnants (SNe & SNRs), often occurring at the end of a massive star's life or in an environment including massive star material, are one of the most likely candidates for sources accelerating galactic comic ray nuclei up to the requisite high energies. The Fermi Gamma-ray Space Telescope Large Area Detector (Fermi LAT) has improved our understanding of such sources by widening the window of observable energies and thus into potential sources' energetic processes. In combination with multiwavelength observations, we are now better able to constrain particle populations (often hadron-dominated at GeV energies) and environmental conditions, such as the magnetic field strength. The SNR CTB 37A is one such source which could contribute to the observed galactic cosmic rays. By assembling populations of SNRs, we will be able to more definitively define their contribution to the observed galactic cosmic rays, as well as better understand SNRs themselves. Such multimessenger studies will thus illuminate the long-standing cosmic ray mysteries, shedding light on potential sources, acceleration mechanisms, and cosmic ray propagation.

[Primary Study on Predicting the Termination of Paroxysmal Atrial Fibrillation Based on a Novel RdR RR Intervals Scatter Plot].

PubMed

Lu, Hongwei; Zhang, Chenxi; Sun, Ying; Hao, Zhidong; Wang, Chunfang; Tian, Jiajia

2015-08-01

Predicting the termination of paroxysmal atrial fibrillation (AF) may provide a signal to decide whether there is a need to intervene the AF timely. We proposed a novel RdR RR intervals scatter plot in our study. The abscissa of the RdR scatter plot was set to RR intervals and the ordinate was set as the difference between successive RR intervals. The RdR scatter plot includes information of RR intervals and difference between successive RR intervals, which captures more heart rate variability (HRV) information. By RdR scatter plot analysis of one minute RR intervals for 50 segments with non-terminating AF and immediately terminating AF, it was found that the points in RdR scatter plot of non-terminating AF were more decentralized than the ones of immediately terminating AF. By dividing the RdR scatter plot into uniform grids and counting the number of non-empty grids, non-terminating AF and immediately terminating AF segments were differentiated. By utilizing 49 RR intervals, for 20 segments of learning set, 17 segments were correctly detected, and for 30 segments of test set, 20 segments were detected. While utilizing 66 RR intervals, for 18 segments of learning set, 16 segments were correctly detected, and for 28 segments of test set, 20 segments were detected. The results demonstrated that during the last one minute before the termination of paroxysmal AF, the variance of the RR intervals and the difference of the neighboring two RR intervals became smaller. The termination of paroxysmal AF could be successfully predicted by utilizing the RdR scatter plot, while the predicting accuracy should be further improved.

77 FR 1009 - Airworthiness Directives; Rolls-Royce plc (RR) RB211-524 Series Turbofan Engines

Federal Register 2010, 2011, 2012, 2013, 2014

2012-01-09

... Field Repair Scheme FRS5367/B, and A mandatory terminating action to the repetitive inspections to be... Repaired Using RR Field Repair Scheme FRS5367/B Borescope-inspect combustion liner head sections previously repaired using RR Field Repair Scheme FRS5367/B. Use paragraphs 3.A.(1) through 3.A.(5) of the...

RR Lyrae, Delta Scuti, SX Phoenicis stars and Baade-Wesselink method. I - Photometric and radial velocity measurements of four field stars - RR Cet, DX Del, BS AQR and DY Peg

NASA Astrophysics Data System (ADS)

Meylan, G.; Burki, G.; Rufener, F.; Mayor, M.; Burnet, M.; Ischi, E.

1986-04-01

Simultaneous measurements in the Geneva seven-color photometry and in radial velocities with the spectrophotometer CORAVEL for two RR Lyrae, one Delta Scuti and one SX Phoenicis field star were obtained in order to apply the Baade-Wesselink method to these kinds of variable stars. As a first step, the data regarding the RR Cet, DX Del, BS Aqr, and DY Peg are presented. The target of this study will consist in determining the physical parameters (temperature, gravity, metal content, mass, luminosity) and distances of these stars.

The absolute magnitudes of RR Lyraes from HIPPARCOS parallaxes and proper motions

NASA Astrophysics Data System (ADS)

Fernley, J.; Barnes, T. G.; Skillen, I.; Hawley, S. L.; Hanley, C. J.; Evans, D. W.; Solano, E.; Garrido, R.

1998-02-01

We have used HIPPARCOS proper motions and the method of Statistical Parallax to estimate the absolute magnitude of RR Lyrae stars. In addition we used the HIPPARCOS parallax of RR Lyrae itself to determine it's absolute magnitude. These two results are in excellent agreement with each other and give a zero-point for the RR Lyrae M_v,[Fe/H] relation of 0.77+/-0.15 at [Fe/H]=-1.53. This zero-point is in good agreement with that obtained recently by several groups using Baade-Wesselink methods which, averaged over the results from the different groups, gives M_v = 0.73+/-0.14 at [Fe/H]=-1.53. Taking the HIPPARCOS based zero-point and a value of 0.18+/-0.03 for the slope of the M_v,[Fe/H] relation from the literature we find firstly, the distance modulus of the LMC is 18.26+/-0.15 and secondly, the mean age of the Globular Clusters is 17.4+/-3.0 GYrs. These values are compared with recent estimates based on other "standard candles" that have also been calibrated with HIPPARCOS data. It is clear that, in addition to astrophysical problems, there are also problems in the application of HIPPARCOS data that are not yet fully understood. Table 1, which contains the basic data for the RR Lyraes, is available only at CDS. It may be retrieved via anonymous FTP at cdsarc.u-strasbg.fr (130.79.128.5) or via the Web at http://cdsweb.u-strasbg.fr/Abstract.html

VizieR Online Data Catalog: Mid-infrared study of RR Lyrae stars (Gavrilchenko+, 2014)

NASA Astrophysics Data System (ADS)

Gavrilchenko, T.; Klein, C. R.; Bloom, J. S.; Richards, J. W.

2015-02-01

The first goal was to find a large sample of WISE-observed RR Lyrae stars. A data base of previously identified RR Lyrae stars was created, combining information from General Catalogue of Variable Stars (GCVS), All Sky Automated Survey (ASAS), SIMBAD, VizieR, and individual papers. For many of the sources in this data base the only available data were the coordinates and RR Lyrae classification. When provided, information about the period, distance, subclass, and magnitude for several different wavebands was also stored. If a single source appeared in multiple surveys or papers, information from all relevant surveys was included, with markers indicating contradicting measurements between surveys. The resulting data base contains about 17000 sources, of which about 5000 sources have documented V-band periods. (3 data files).

The H.E.S.S. Galactic plane survey

NASA Astrophysics Data System (ADS)

H. E. S. S. Collaboration; Abdalla, H.; Abramowski, A.; Aharonian, F.; Benkhali, F. Ait; Angüner, E. O.; Arakawa, M.; Arrieta, M.; Aubert, P.; Backes, M.; Balzer, A.; Barnard, M.; Becherini, Y.; Tjus, J. Becker; Berge, D.; Bernhard, S.; Bernlöhr, K.; Blackwell, R.; Böttcher, M.; Boisson, C.; Bolmont, J.; Bonnefoy, S.; Bordas, P.; Bregeon, J.; Brun, F.; Brun, P.; Bryan, M.; Büchele, M.; Bulik, T.; Capasso, M.; Carrigan, S.; Caroff, S.; Carosi, A.; Casanova, S.; Cerruti, M.; Chakraborty, N.; Chaves, R. C. G.; Chen, A.; Chevalier, J.; Colafrancesco, S.; Condon, B.; Conrad, J.; Davids, I. D.; Decock, J.; Deil, C.; Devin, J.; deWilt, P.; Dirson, L.; Djannati-Ataï, A.; Domainko, W.; Donath, A.; Drury, L. O.'C.; Dutson, K.; Dyks, J.; Edwards, T.; Egberts, K.; Eger, P.; Emery, G.; Ernenwein, J.-P.; Eschbach, S.; Farnier, C.; Fegan, S.; Fernandes, M. V.; Fiasson, A.; Fontaine, G.; Förster, A.; Funk, S.; Füßling, M.; Gabici, S.; Gallant, Y. A.; Garrigoux, T.; Gast, H.; Gaté, F.; Giavitto, G.; Giebels, B.; Glawion, D.; Glicenstein, J. F.; Gottschall, D.; Grondin, M.-H.; Hahn, J.; Haupt, M.; Hawkes, J.; Heinzelmann, G.; Henri, G.; Hermann, G.; Hinton, J. A.; Hofmann, W.; Hoischen, C.; Holch, T. L.; Holler, M.; Horns, D.; Ivascenko, A.; Iwasaki, H.; Jacholkowska, A.; Jamrozy, M.; Jankowsky, D.; Jankowsky, F.; Jingo, M.; Jouvin, L.; Jung-Richardt, I.; Kastendieck, M. A.; Katarzyński, K.; Katsuragawa, M.; Katz, U.; Kerszberg, D.; Khangulyan, D.; Khélifi, B.; King, J.; Klepser, S.; Klochkov, D.; Kluźniak, W.; Komin, Nu.; Kosack, K.; Krakau, S.; Kraus, M.; Krüger, P. P.; Laffon, H.; Lamanna, G.; Lau, J.; Lees, J.-P.; Lefaucheur, J.; Lemière, A.; Lemoine-Goumard, M.; Lenain, J.-P.; Leser, E.; Lohse, T.; Lorentz, M.; Liu, R.; López-Coto, R.; Lypova, I.; Marandon, V.; Malyshev, D.; Marcowith, A.; Mariaud, C.; Marx, R.; Maurin, G.; Maxted, N.; Mayer, M.; Meintjes, P. J.; Meyer, M.; Mitchell, A. M. W.; Moderski, R.; Mohamed, M.; Mohrmann, L.; Morå, K.; Moulin, E.; Murach, T.; Nakashima, S.; de Naurois, M.; Ndiyavala, H.; Niederwanger, F.; Niemiec, J.; Oakes, L.; O'Brien, P.; Odaka, H.; Ohm, S.; Ostrowski, M.; Oya, I.; Padovani, M.; Panter, M.; Parsons, R. D.; Paz Arribas, M.; Pekeur, N. W.; Pelletier, G.; Perennes, C.; Petrucci, P.-O.; Peyaud, B.; Piel, Q.; Pita, S.; Poireau, V.; Poon, H.; Prokhorov, D.; Prokoph, H.; Pühlhofer, G.; Punch, M.; Quirrenbach, A.; Raab, S.; Rauth, R.; Reimer, A.; Reimer, O.; Renaud, M.; de los Reyes, R.; Rieger, F.; Rinchiuso, L.; Romoli, C.; Rowell, G.; Rudak, B.; Rulten, C. B.; Safi-Harb, S.; Sahakian, V.; Saito, S.; Sanchez, D. A.; Santangelo, A.; Sasaki, M.; Schandri, M.; Schlickeiser, R.; Schüssler, F.; Schulz, A.; Schwanke, U.; Schwemmer, S.; Seglar-Arroyo, M.; Settimo, M.; Seyffert, A. S.; Shafi, N.; Shilon, I.; Shiningayamwe, K.; Simoni, R.; Sol, H.; Spanier, F.; Spir-Jacob, M.; Stawarz, Ł.; Steenkamp, R.; Stegmann, C.; Steppa, C.; Sushch, I.; Takahashi, T.; Tavernet, J.-P.; Tavernier, T.; Taylor, A. M.; Terrier, R.; Tibaldo, L.; Tiziani, D.; Tluczykont, M.; Trichard, C.; Tsirou, M.; Tsuji, N.; Tuffs, R.; Uchiyama, Y.; van der Walt, D. J.; van Eldik, C.; van Rensburg, C.; van Soelen, B.; Vasileiadis, G.; Veh, J.; Venter, C.; Viana, A.; Vincent, P.; Vink, J.; Voisin, F.; Völk, H. J.; Vuillaume, T.; Wadiasingh, Z.; Wagner, S. J.; Wagner, P.; Wagner, R. M.; White, R.; Wierzcholska, A.; Willmann, P.; Wörnlein, A.; Wouters, D.; Yang, R.; Zaborov, D.; Zacharias, M.; Zanin, R.; Zdziarski, A. A.; Zech, A.; Zefi, F.; Ziegler, A.; Zorn, J.; Żywucka, N.

2018-04-01

We present the results of the most comprehensive survey of the Galactic plane in very high-energy (VHE) γ-rays, including a public release of Galactic sky maps, a catalog of VHE sources, and the discovery of 16 new sources of VHE γ-rays. The High Energy Spectroscopic System (H.E.S.S.) Galactic plane survey (HGPS) was a decade-long observation program carried out by the H.E.S.S. I array of Cherenkov telescopes in Namibia from 2004 to 2013. The observations amount to nearly 2700 h of quality-selected data, covering the Galactic plane at longitudes from ℓ = 250° to 65° and latitudes |b|≤ 3°. In addition to the unprecedented spatial coverage, the HGPS also features a relatively high angular resolution (0.08° ≈ 5 arcmin mean point spread function 68% containment radius), sensitivity (≲1.5% Crab flux for point-like sources), and energy range (0.2-100 TeV). We constructed a catalog of VHE γ-ray sources from the HGPS data set with a systematic procedure for both source detection and characterization of morphology and spectrum. We present this likelihood-based method in detail, including the introduction of a model component to account for unresolved, large-scale emission along the Galactic plane. In total, the resulting HGPS catalog contains 78 VHE sources, of which 14 are not reanalyzed here, for example, due to their complex morphology, namely shell-like sources and the Galactic center region. Where possible, we provide a firm identification of the VHE source or plausible associations with sources in other astronomical catalogs. We also studied the characteristics of the VHE sources with source parameter distributions. 16 new sources were previously unknown or unpublished, and we individually discuss their identifications or possible associations. We firmly identified 31 sources as pulsar wind nebulae (PWNe), supernova remnants (SNRs), composite SNRs, or gamma-ray binaries. Among the 47 sources not yet identified, most of them (36) have possible

Propagation of Galactic cosmic rays: the influence of anisotropic diffusion

NASA Astrophysics Data System (ADS)

AL-Zetoun, A.; Achterberg, A.

2018-06-01

We consider the anisotropic diffusion of cosmic rays in the large-scale Galactic magnetic field, where diffusion along the field and diffusion across the field proceeds at different rates. To calculate this diffusion, we use stochastic differential equations to describe the cosmic ray propagation, solving these numerically. The Galactic magnetic field is described using the Jansson-Farrar model for the Galactic magnetic field. In this paper, we study the influence of perpendicular diffusion on the residence time of cosmic rays in the Galaxy. This provides an estimate for the influence of anisotropic diffusion on the residence time and the amount of matter (grammage) that a typical cosmic ray traverses during its residence in the Galaxy.

The Galactic O-Star Catalog (GOSC) and the Galactic O-Star Spectroscopic Survey (GOSSS): current status

NASA Astrophysics Data System (ADS)

Maíz Apellániz, J.; Alonso Moragón, A.; Ortiz de Zárate Alcarazo, L.; The Gosss Team

2017-03-01

We present the updates of the Galactic O-Star Catalog (GOSC) that we have undertaken in the last two years: new spectral types, more objects, additional information, and coordination with CDS. We also present updates for the Galactic O-Star Spectroscopic Survey (GOSSS). A new paper (GOSSS-III) has been published and ˜ 1000 targets have been observed since 2014. Four new setups have been added to our lineup and for two of them we have already obtained over 100 spectra: with OSIRIS at the 10.4 m GTC we are observing northern dim stars and with FRODOspec at the 2.0 m Liverpool Telescope we are observing northern bright stars. Finally, we also make available new versions of MGB, the spectral classification tool associated with the project, and of the GOSSS grid of spectroscopic standards.

Chicago, Burlington, & Quincy R.R car works aurora, ILL. Photocopy ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Chicago, Burlington, & Quincy R.R car works aurora, ILL. Photocopy of an undated lithograph based on an ambrotype by D.C. Pratt, C. 1857 - Chicago, Burlington & Quincy Railroad, Roundhouse & Shops, Broadway & Spring Streets, Aurora, Kane County, IL

A study of ultraviolet absorption lines through the complete Galactic halo by the analysis of HST faint object spectrograph spectra of active Galactic nuclei, 1

NASA Technical Reports Server (NTRS)

Burks, Geoffrey S.; Bartko, Frank; Shull, J. Michael; Stocke, John T.; Sachs, Elise R.; Burbidge, E. Margaret; Cohen, Ross D.; Junkkarinen, Vesa T.; Harms, Richard J.; Massa, Derck

1994-01-01

The ultraviolet (1150 - 2850 A) spectra of a number of active galactic nuclei (AGNs) observed with the Hubble Space Telescope (HST) Faint Object Spectrograph (FOS) have been used to study the properties of the Galactic halo. The objects that served as probes are 3C 273, PKS 0454-220, Pg 1211+143, CSO 251, Ton 951, and PG 1351+640. The equivalent widths of certain interstellar ions have been measured, with special attention paid to the C IV/C II and Si IV/Si II ratios. These ratios have been intercompared, and the highest values are found in the direction of 3C 273, where C IV/C II = 1.2 and Si IV/Si II greater than 1. These high ratios may be due to a nearby supernova remnant, rather than to ionized gas higher up in the Galactic halo. Our data give some support to the notion that QSO metal-line systems may arise from intervening galaxies which contain high supernova rates, galactic fountains, and turbulent mixing layers.

Period changes of 7 bright RR Lyrae variables included in the BAV standard program.

NASA Astrophysics Data System (ADS)

Wunder, E.

1995-11-01

On the basis of 1578 times of maxima historical and present period changes of the RR Lyrae stars SW And, SW Aqr, AA Aql, X Ari, RS Boo, RR Cet and XZ Cyg are analysed. In tables the period jumps and the quadratic terms of the elements are quantified and timed; elements are given to describe the historical O-C-curves; instant elements are listed to support nowadays observations.

Period Change Similarities Among the RR Lyrae Variables in Oosterhoff I and Oosterhoff II Globular Systems

NASA Astrophysics Data System (ADS)

Kunder, Andrea; Walker, Alistair; Stetson, Peter B.; Bono, Giuseppe; Nemec, James M.; de Propris, Roberto; Monelli, Matteo; Cassisi, Santi; Andreuzzi, Gloria; Dall'Ora, Massimo; Di Cecco, Alessandra; Zoccali, Manuela

2011-01-01

We present period change rates (dP/dt) for 42 RR Lyrae variables in the globular cluster IC 4499. Despite clear evidence of these period increases or decreases, the observed period change rates are an order of magnitude larger than predicted from theoretical models of this cluster. We find that there is a preference for increasing periods, a phenomenon observed in most RR Lyrae stars in Milky Way globular clusters. The period change rates as a function of position in the period-amplitude plane are used to examine possible evolutionary effects in OoI clusters, OoII clusters, field RR Lyrae stars, and the mixed-population cluster ω Centauri. It is found that there is no correlation between the period change rate and the typical definition of Oosterhoff groups. If the RR Lyrae period changes correspond with evolutionary effects, this would be in contrast to the hypothesis that RR Lyrae variables in OoII systems are evolved horizontal-branch stars that spent their zero-age horizontal-branch phase on the blue side of the instability strip. This may suggest that age may not be the primary explanation for the Oosterhoff types. Based in part on observations made with the European Southern Observatory telescopes obtained from the ESO/ST-ECF Science Archive Facility.

The black hole at the Galactic Center: Observations and models

NASA Astrophysics Data System (ADS)

Zakharov, Alexander F.

One of the most interesting astronomical objects is the Galactic Center. It is a subject of intensive astronomical observations in different spectral bands in recent years. We concentrate our discussion on a theoretical analysis of observational data of bright stars in the IR-band obtained with large telescopes. We also discuss the importance of VLBI observations of bright structures which could characterize the shadow at the Galactic Center. If we adopt general relativity (GR), there are a number of theoretical models for the Galactic Center, such as a cluster of neutron stars, boson stars, neutrino balls, etc. Some of these models were rejected or the range of their parameters is significantly constrained with consequent observations and theoretical analysis. In recent years, a number of alternative theories of gravity have been proposed because there are dark matter (DM) and dark energy (DE) problems. An alternative theory of gravity may be considered as one possible solution for such problems. Some of these theories have black hole solutions, while other theories have no such solutions. There are attempts to describe the Galactic Center with alternative theories of gravity and in this case one can constrain parameters of such theories with observational data for the Galactic Center. In particular, theories of massive gravity are intensively developing and theorists have overcome pathologies presented in the initial versions of these theories. In theories of massive gravity, a graviton is massive in contrast with GR where a graviton is massless. Now these theories are considered as an alternative to GR. For example, the LIGO-Virgo collaboration obtained the graviton mass constraint of about 1.2 × 10‑22 eV in their first publication about the discovery of the first gravitational wave detection event that resulted of the merger of two massive black holes. Surprisingly, one could obtain a consistent and comparable constraint of graviton mass at a level around mg

Exploring the crowded central region of ten Galactic globular clusters using EMCCDs. Variable star searches and new discoveries

NASA Astrophysics Data System (ADS)

Figuera Jaimes, R.; Bramich, D. M.; Skottfelt, J.; Kains, N.; Jørgensen, U. G.; Horne, K.; Dominik, M.; Alsubai, K. A.; Bozza, V.; Calchi Novati, S.; Ciceri, S.; D'Ago, G.; Galianni, P.; Gu, S.-H.; Harpsøe, K. B. W.; Haugbølle, T.; Hinse, T. C.; Hundertmark, M.; Juncher, D.; Korhonen, H.; Mancini, L.; Popovas, A.; Rabus, M.; Rahvar, S.; Scarpetta, G.; Schmidt, R. W.; Snodgrass, C.; Southworth, J.; Starkey, D.; Street, R. A.; Surdej, J.; Wang, X.-B.; Wertz, O.

2016-04-01

Aims: We aim to obtain time-series photometry of the very crowded central regions of Galactic globular clusters; to obtain better angular resolution thanhas been previously achieved with conventional CCDs on ground-based telescopes; and to complete, or improve, the census of the variable star population in those stellar systems. Methods: Images were taken using the Danish 1.54-m Telescope at the ESO observatory at La Silla in Chile. The telescope was equipped with an electron-multiplying CCD, and the short-exposure-time images obtained (ten images per second) were stacked using the shift-and-add technique to produce the normal-exposure-time images (minutes). Photometry was performed via difference image analysis. Automatic detection of variable stars in the field was attempted. Results: The light curves of 12 541 stars in the cores of ten globular clusters were statistically analysed to automatically extract the variable stars. We obtained light curves for 31 previously known variable stars (3 long-period irregular, 2 semi-regular, 20 RR Lyrae, 1 SX Phoenicis, 3 cataclysmic variables, 1 W Ursae Majoris-type and 1 unclassified) and we discovered 30 new variables (16 long-period irregular, 7 semi-regular, 4 RR Lyrae, 1 SX Phoenicis and 2 unclassified). Fluxes and photometric measurements for these stars are available in electronic form through the Strasbourg astronomical Data Center. Based on data collected by the MiNDSTEp team with the Danish 1.54m telescope at ESO's La Silla observatory in Chile.Full Table 1 is only available at CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/588/A128

Unveiling the Hybrid Genome Structure of Escherichia coli RR1 (HB101 RecA+)

PubMed Central

Jeong, Haeyoung; Sim, Young Mi; Kim, Hyun Ju; Lee, Sang Jun

2017-01-01

There have been extensive genome sequencing studies for Escherichia coli strains, particularly for pathogenic isolates, because fast determination of pathogenic potential and/or drug resistance and their propagation routes is crucial. For laboratory E. coli strains, however, genome sequence information is limited except for several well-known strains. We determined the complete genome sequence of laboratory E. coli strain RR1 (HB101 RecA+), which has long been used as a general cloning host. A hybrid genome sequence of K-12 MG1655 and B BL21(DE3) was constructed based on the initial mapping of Illumina HiSeq reads to each reference, and iterative rounds of read mapping, variant detection, and consensus extraction were carried out. Finally, PCR and Sanger sequencing-based finishing were applied to resolve non-single nucleotide variant regions with aberrant read depths and breakpoints, most of them resulting from prophages and insertion sequence transpositions that are not present in the reference genome sequence. We found that 96.9% of the RR1 genome is derived from K-12, and identified exact crossover junctions between K-12 and B genomic fragments. However, because RR1 has experienced a series of genetic manipulations since branching from the common ancestor, it has a set of mutations different from those found in K-12 MG1655. As well as identifying all known genotypes of RR1 on the basis of genomic context, we found novel mutations. Our results extend current knowledge of the genotype of RR1 and its relatives, and provide insights into the pedigree, genomic background, and physiology of common laboratory strains. PMID:28421066

VizieR Online Data Catalog: OGLE II. VI photometry of Galactic Bulge (Udalski+, 2002)

NASA Astrophysics Data System (ADS)

Udalski, A.; Szymanski, M.; Kubiak, M.; Pietrzynski, G.; Soszynski, I.; Wozniak, P.; Zebrun, K.; Szewczyk, O.; Wyrzykowski, L.

2003-09-01

We present the VI photometric maps of the Galactic bulge. They contain VI photometry and astrometry of about 30 million stars from 49 fields of 0.225 square degree each in the Galactic center region. The data were collected during the second phase of the OGLE microlensing project. We discuss the accuracy of data and present color-magnitude diagrams of selected fields observed by OGLE in the Galactic bulge. The VI maps of the Galactic bulge are accessible electronically for the astronomical community from the OGLE Internet archive (2 data files).

Photocopy of floor plan of the C.B. & Q. R.R ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Photocopy of floor plan of the C.B. & Q. R.R roundhouse and locomotive shops. June 1980. - Chicago, Burlington & Quincy Railroad, Roundhouse & Shops, Broadway & Spring Streets, Aurora, Kane County, IL

Dust and molecules in extra-galactic planetary nebulae

NASA Astrophysics Data System (ADS)

Garcia-Hernandez, Domingo Aníbal

2015-08-01

Extra-galactic planetary nebulae (PNe) permit the study of dust and molecules in metallicity environments other than the Galaxy. Their known distances lower the number of free parameters in the observations vs. models comparison, providing strong constraints on the gas-phase and solid-state astrochemistry models. Observations of PNe in the Galaxy and other Local Group galaxies such as the Magellanic Clouds (MC) provide evidence that metallicity affects the production of dust as well as the formation of complex organic molecules and inorganic solid-state compounds in their circumstellar envelopes. In particular, the lower metallicity MC environments seem to be less favorable to dust production and the frequency of carbonaceous dust features and complex fullerene molecules is generally higher with decreasing metallicity. Here, I present an observational review of the dust and molecular content in extra-galactic PNe as compared to their higher metallicity Galactic counterparts. A special attention is given to the level of dust processing and the formation of complex organic molecules (e.g., polycyclic aromatic hydrocarbons, fullerenes, and graphene precursors) depending on metallicity.

CA II K-line metallicity indicator for field RR Lyrae stars

NASA Astrophysics Data System (ADS)

Clementini, Gisella; Tosi, Monica; Merighi, Roberto

In order to check and, possibly, improve the Preston's Delta S calibration scale, CCD spectra have been obtained for 25 field RR Lyrae variables. Eleven of the program stars have values of (Fe/H) derived by Butler and Deming (1979) from the Fe II lines' strength. For them we find that the equivalent width of the Ca II K line is extremely well correlated to the (Fe/H) values, the best fit relation being: (Fe/H) = 0.43W(K) - 2.75 where W(K) is the equivalent width of the K line. We conclude that the use of the K line equivalent width is at present the best method to derive the (Fe/H) abundance of the RR Lyrae stars.

Does electromagnetic radiation accelerate galactic cosmic rays

NASA Technical Reports Server (NTRS)

Eichler, D.

1977-01-01

The 'reactor' theories of Tsytovich and collaborators (1973) of cosmic-ray acceleration by electromagnetic radiation are examined in the context of galactic cosmic rays. It is shown that any isotropic synchrotron or Compton reactors with reasonable astrophysical parameters can yield particles with a maximum relativistic factor of only about 10,000. If they are to produce particles with higher relativistic factors, the losses due to inverse Compton scattering of the electromagnetic radiation in them outweigh the acceleration, and this violates the assumptions of the theory. This is a critical restriction in the context of galactic cosmic rays, which have a power-law spectrum extending up to a relativistic factor of 1 million.

The Clusters AgeS Experiment (CASE). Variable stars in the field of the globular cluster NGC 362

NASA Astrophysics Data System (ADS)

Rozyczka, M.; Thompson, I. B.; Narloch, W.; Pych, W.; Schwarzenberg-Czerny, A.

2016-09-01

The field of the globular cluster NGC 362 was monitored between 1997 and 2015 in a search for variable stars. BV light curves were obtained for 151 periodic or likely periodic variable stars, over a hundred of which are new detections. Twelve newly detected variable stars are proper-motion members of the cluster: two SX Phe and two RR Lyr pulsators, one contact binary, three detached or semi-detached eclipsing binaries, and four spotted variable stars. The most interesting objects among these are the binary blue straggler V20 with an asymmetric light curve, and the 8.1 d semidetached binary V24 located on the red giant branch of NGC 362, which is a Chandra X-ray source. We also provide substantial new data for 24 previously known variable stars.

Chemical Composition of Galactic Disk Stars

NASA Astrophysics Data System (ADS)

Mishenina, T. V.; Basak, N. Yu.; Gorbaneva, T. I.; Soubiran, C.; Kovtyukh, V. V.

Abundances of Na, Al, Ca, in the stars of galactic disks are obtained. The separation of thin and stars on cinematic criterion was made early. The behavior of chemical element abundances with metallicity for studied stars was presented.

The Cluster AgeS Experiment (CASE). Variable Stars in the Field of the Globular Cluster M22

NASA Astrophysics Data System (ADS)

Rozyczka, M.; Thompson, I. B.; Pych, W.; Narloch, W.; Poleski, R.; Schwarzenberg-Czerny, A.

2017-09-01

The field of the globular cluster M22 (NGC 6656) was monitored between 2000 and 2008 in a search for variable stars. BV light curves were obtained for 359 periodic, likely periodic, and long-term variables, 238 of which are new detections. 39 newly detected variables, and 63 previously known ones are members or likely members of the cluster, including 20 SX Phe, 10 RRab and 16 RRc type pulsators, one BL Her type pulsator, 21 contact binaries, and 9 detached or semi-detached eclipsing binaries. The most interesting among the identified objects are V112 - a bright multimode SX Phe pulsator, V125 - a β Lyr type binary on the blue horizontal branch, V129 - a blue/yellow straggler with a W UMa-like light curve, located halfway between the extreme horizontal branch and red giant branch, and V134 - an extreme horizontal branch object with P=2.33 d and a nearly sinusoidal light curve. All four of them are proper motion members of the cluster. Among nonmembers, a P=2.83 d detached eclipsing binary hosting a δ Sct type pulsator was found, and a peculiar P=0.93 d binary with ellipsoidal modulation and narrow minimum in the middle of one of the descending shoulders of the sinusoid. We also collected substantial new data for previously known variables. In particular we revise the statistics of the occurrence of the Blazhko effect in RR Lyr type variables of M22.

New constraints on all flavor Galactic diffuse neutrino emission with the ANTARES telescope

NASA Astrophysics Data System (ADS)

Albert, A.; André, M.; Anghinolfi, M.; Anton, G.; Ardid, M.; Aubert, J.-J.; Avgitas, T.; Baret, B.; Barrios-Martí, J.; Basa, S.; Belhorma, B.; Bertin, V.; Biagi, S.; Bormuth, R.; Bourret, S.; Bouwhuis, M. C.; Bruijn, R.; Brunner, J.; Busto, J.; Capone, A.; Caramete, L.; Carr, J.; Celli, S.; Cherkaoui El Moursli, R.; Chiarusi, T.; Circella, M.; Coelho, J. A. B.; Coleiro, A.; Coniglione, R.; Costantini, H.; Coyle, P.; Creusot, A.; Díaz, A. F.; Deschamps, A.; de Bonis, G.; Distefano, C.; di Palma, I.; Domi, A.; Donzaud, C.; Dornic, D.; Drouhin, D.; Eberl, T.; El Bojaddaini, I.; El Khayati, N.; Elsässer, D.; Enzenhöfer, A.; Ettahiri, A.; Fassi, F.; Felis, I.; Fusco, L. A.; Galatà, S.; Gay, P.; Giordano, V.; Glotin, H.; Grégoire, T.; Gracia Ruiz, R.; Graf, K.; Hallmann, S.; van Haren, H.; Heijboer, A. J.; Hello, Y.; Hernández-Rey, J. J.; Hößl, J.; Hofestädt, J.; Hugon, C.; Illuminati, G.; James, C. W.; de Jong, M.; Jongen, M.; Kadler, M.; Kalekin, O.; Katz, U.; Kießling, D.; Kouchner, A.; Kreter, M.; Kreykenbohm, I.; Kulikovskiy, V.; Lachaud, C.; Lahmann, R.; Lefèvre, D.; Leonora, E.; Lotze, M.; Loucatos, S.; Marcelin, M.; Margiotta, A.; Marinelli, A.; Martínez-Mora, J. A.; Mele, R.; Melis, K.; Michael, T.; Migliozzi, P.; Moussa, A.; Navas, S.; Nezri, E.; Organokov, M.; Pǎvǎlaş, G. E.; Pellegrino, C.; Perrina, C.; Piattelli, P.; Popa, V.; Pradier, T.; Quinn, L.; Racca, C.; Riccobene, G.; Sánchez-Losa, A.; Saldaña, M.; Salvadori, I.; Samtleben, D. F. E.; Sanguineti, M.; Sapienza, P.; Schüssler, F.; Sieger, C.; Spurio, M.; Stolarczyk, Th.; Taiuti, M.; Tayalati, Y.; Trovato, A.; Turpin, D.; Tönnis, C.; Vallage, B.; van Elewyck, V.; Versari, F.; Vivolo, D.; Vizzoca, A.; Wilms, J.; Zornoza, J. D.; Zúñiga, J.; Gaggero, D.; Grasso, D.; ANTARES Collaboration

2017-09-01

The flux of very high-energy neutrinos produced in our Galaxy by the interaction of accelerated cosmic rays with the interstellar medium is not yet determined. The characterization of this flux will shed light on Galactic accelerator features, gas distribution morphology and Galactic cosmic ray transport. The central Galactic plane can be the site of an enhanced neutrino production, thus leading to anisotropies in the extraterrestrial neutrino signal as measured by the IceCube Collaboration. The ANTARES neutrino telescope, located in the Mediterranean Sea, offers a favorable view of this part of the sky, thereby allowing for a contribution to the determination of this flux. The expected diffuse Galactic neutrino emission can be obtained, linking a model of generation and propagation of cosmic rays with the morphology of the gas distribution in the Milky Way. In this paper, the so-called "gamma model" introduced recently to explain the high-energy gamma-ray diffuse Galactic emission is assumed as reference. The neutrino flux predicted by the "gamma model" depends on the assumed primary cosmic ray spectrum cutoff. Considering a radially dependent diffusion coefficient, this proposed scenario is able to account for the local cosmic ray measurements, as well as for the Galactic gamma-ray observations. Nine years of ANTARES data are used in this work to search for a possible Galactic contribution according to this scenario. All flavor neutrino interactions are considered. No excess of events is observed, and an upper limit is set on the neutrino flux of 1.1 (1.2) times the prediction of the "gamma model," assuming the primary cosmic ray spectrum cutoff at 5 (50) PeV. This limit excludes the diffuse Galactic neutrino emission as the major cause of the "spectral anomaly" between the two hemispheres measured by IceCube.

A polarized fast radio burst at low Galactic latitude

NASA Astrophysics Data System (ADS)

Petroff, E.; Burke-Spolaor, S.; Keane, E. F.; McLaughlin, M. A.; Miller, R.; Andreoni, I.; Bailes, M.; Barr, E. D.; Bernard, S. R.; Bhandari, S.; Bhat, N. D. R.; Burgay, M.; Caleb, M.; Champion, D.; Chandra, P.; Cooke, J.; Dhillon, V. S.; Farnes, J. S.; Hardy, L. K.; Jaroenjittichai, P.; Johnston, S.; Kasliwal, M.; Kramer, M.; Littlefair, S. P.; Macquart, J. P.; Mickaliger, M.; Possenti, A.; Pritchard, T.; Ravi, V.; Rest, A.; Rowlinson, A.; Sawangwit, U.; Stappers, B.; Sullivan, M.; Tiburzi, C.; van Straten, W.; ANTARES Collaboration; Albert, A.; André, M.; Anghinolfi, M.; Anton, G.; Ardid, M.; Aubert, J.-J.; Avgitas, T.; Baret, B.; Barrios-Martí, J.; Basa, S.; Bertin, V.; Biagi, S.; Bormuth, R.; Bourret, S.; Bouwhuis, M. C.; Bruijn, R.; Brunner, J.; Busto, J.; Capone, A.; Caramete, L.; Carr, J.; Celli, S.; Chiarusi, T.; Circella, M.; Coelho, J. A. B.; Coleiro, A.; Coniglione, R.; Costantini, H.; Coyle, P.; Creusot, A.; Deschamps, A.; de Bonis, G.; Distefano, C.; di Palma, I.; Donzaud, C.; Dornic, D.; Drouhin, D.; Eberl, T.; El Bojaddaini, I.; Elsässer, D.; Enzenhöfer, A.; Felis, I.; Fusco, L. A.; Galatà, S.; Gay, P.; Geißelsöder, S.; Geyer, K.; Giordano, V.; Gleixner, A.; Glotin, H.; Grégoire, T.; Gracia-Ruiz, R.; Graf, K.; Hallmann, S.; van Haren, H.; Heijboer, A. J.; Hello, Y.; Hernández-Rey, J. J.; Hößl, J.; Hofestädt, J.; Hugon, C.; Illuminati, G.; James, C. W.; de Jong, M.; Jongen, M.; Kadler, M.; Kalekin, O.; Katz, U.; Kießling, D.; Kouchner, A.; Kreter, M.; Kreykenbohm, I.; Kulikovskiy, V.; Lachaud, C.; Lahmann, R.; Lefèvre, D.; Leonora, E.; Lotze, M.; Loucatos, S.; Marcelin, M.; Margiotta, A.; Marinelli, A.; Martínez-Mora, J. A.; Mathieu, A.; Mele, R.; Melis, K.; Michael, T.; Migliozzi, P.; Moussa, A.; Mueller, C.; Nezri, E.; Pǎvǎlaş, G. E.; Pellegrino, C.; Perrina, C.; Piattelli, P.; Popa, V.; Pradier, T.; Quinn, L.; Racca, C.; Riccobene, G.; Roensch, K.; Sánchez-Losa, A.; Saldaña, M.; Salvadori, I.; Samtleben, D. F. E.; Sanguineti, M.; Sapienza, P.; Schnabel, J.; Seitz, T.; Sieger, C.; Spurio, M.; Stolarczyk, Th.; Taiuti, M.; Tayalati, Y.; Trovato, A.; Tselengidou, M.; Turpin, D.; Tönnis, C.; Vallage, B.; Vallée, C.; van Elewyck, V.; Vivolo, D.; Vizzoca, A.; Wagner, S.; Wilms, J.; Zornoza, J. D.; Zúñiga, J.; H.E.S.S. Collaboration; Abdalla, H.; Abramowski, A.; Aharonian, F.; Ait Benkhali, F.; Akhperjanian, A. G.; Andersson, T.; Angüner, E. O.; Arrieta, M.; Aubert, P.; Backes, M.; Balzer, A.; Barnard, M.; Becherini, Y.; Tjus, J. Becker; Berge, D.; Bernhard, S.; Bernlöhr, K.; Blackwell, R.; Böttcher, M.; Boisson, C.; Bolmont, J.; Bordas, P.; Bregeon, J.; Brun, F.; Brun, P.; Bryan, M.; Bulik, T.; Capasso, M.; Casanova, S.; Cerruti, M.; Chakraborty, N.; Chalme-Calvet, R.; Chaves, R. C. G.; Chen, A.; Chevalier, J.; Chrétien, M.; Colafrancesco, S.; Cologna, G.; Condon, B.; Conrad, J.; Cui, Y.; Davids, I. D.; Decock, J.; Degrange, B.; Deil, C.; Devin, J.; Dewilt, P.; Dirson, L.; Djannati-Ataï, A.; Domainko, W.; Donath, A.; Drury, L. O'c.; Dubus, G.; Dutson, K.; Dyks, J.; Edwards, T.; Egberts, K.; Eger, P.; Ernenwein, J.-P.; Eschbach, S.; Farnier, C.; Fegan, S.; Fernandes, M. V.; Fiasson, A.; Fontaine, G.; Förster, A.; Funk, S.; Füßling, M.; Gabici, S.; Gajdus, M.; Gallant, Y. A.; Garrigoux, T.; Giavitto, G.; Giebels, B.; Glicenstein, J. F.; Gottschall, D.; Goyal, A.; Grondin, M.-H.; Hadasch, D.; Hahn, J.; Haupt, M.; Hawkes, J.; Heinzelmann, G.; Henri, G.; Hermann, G.; Hervet, O.; Hinton, J. A.; Hofmann, W.; Hoischen, C.; Holler, M.; Horns, D.; Ivascenko, A.; Jacholkowska, A.; Jamrozy, M.; Janiak, M.; Jankowsky, D.; Jankowsky, F.; Jingo, M.; Jogler, T.; Jouvin, L.; Jung-Richardt, I.; Kastendieck, M. A.; Katarzyński, K.; Kerszberg, D.; Khélifi, B.; Kieffer, M.; King, J.; Klepser, S.; Klochkov, D.; Kluźniak, W.; Kolitzus, D.; Komin, Nu.; Kosack, K.; Krakau, S.; Kraus, M.; Krayzel, F.; Krüger, P. P.; Laffon, H.; Lamanna, G.; Lau, J.; Lees, J.-P.; Lefaucheur, J.; Lefranc, V.; Lemière, A.; Lemoine-Goumard, M.; Lenain, J.-P.; Leser, E.; Lohse, T.; Lorentz, M.; Liu, R.; López-Coto, R.; Lypova, I.; Marandon, V.; Marcowith, A.; Mariaud, C.; Marx, R.; Maurin, G.; Maxted, N.; Mayer, M.; Meintjes, P. J.; Meyer, M.; Mitchell, A. M. W.; Moderski, R.; Mohamed, M.; Mohrmann, L.; Morâ, K.; Moulin, E.; Murach, T.; de Naurois, M.; Niederwanger, F.; Niemiec, J.; Oakes, L.; O'Brien, P.; Odaka, H.; Öttl, S.; Ohm, S.; Ostrowski, M.; Oya, I.; Padovani, M.; Panter, M.; Parsons, R. D.; Pekeur, N. W.; Pelletier, G.; Perennes, C.; Petrucci, P.-O.; Peyaud, B.; Piel, Q.; Pita, S.; Poon, H.; Prokhorov, D.; Prokoph, H.; Pühlhofer, G.; Punch, M.; Quirrenbach, A.; Raab, S.; Reimer, A.; Reimer, O.; Renaud, M.; Reyes, R. De Los; Rieger, F.; Romoli, C.; Rosier-Lees, S.; Rowell, G.; Rudak, B.; Rulten, C. B.; Sahakian, V.; Salek, D.; Sanchez, D. A.; Santangelo, A.; Sasaki, M.; Schlickeiser, R.; Schulz, A.; Schüssler, F.; Schwanke, U.; Schwemmer, S.; Settimo, M.; Seyffert, A. S.; Shafi, N.; Shilon, I.; Simoni, R.; Sol, H.; Spanier, F.; Spengler, G.; Spies, F.; Stawarz, Ł.; Steenkamp, R.; Stegmann, C.; Stinzing, F.; Stycz, K.; Sushch, I.; Tavernet, J.-P.; Tavernier, T.; Taylor, A. M.; Terrier, R.; Tibaldo, L.; Tiziani, D.; Tluczykont, M.; Trichard, C.; Tuffs, R.; Uchiyama, Y.; Walt, D. J. Van Der; van Eldik, C.; van Rensburg, C.; van Soelen, B.; Vasileiadis, G.; Veh, J.; Venter, C.; Viana, A.; Vincent, P.; Vink, J.; Voisin, F.; Völk, H. J.; Vuillaume, T.; Wadiasingh, Z.; Wagner, S. J.; Wagner, P.; Wagner, R. M.; White, R.; Wierzcholska, A.; Willmann, P.; Wörnlein, A.; Wouters, D.; Yang, R.; Zabalza, V.; Zaborov, D.; Zacharias, M.; Zanin, R.; Zdziarski, A. A.; Zech, A.; Zefi, F.; Ziegler, A.; Żywucka, N.

2017-08-01

We report on the discovery of a new fast radio burst (FRB), FRB 150215, with the Parkes radio telescope on 2015 February 15. The burst was detected in real time with a dispersion measure (DM) of 1105.6 ± 0.8 pc cm-3, a pulse duration of 2.8^{+1.2}_{-0.5} ms, and a measured peak flux density assuming that the burst was at beam centre of 0.7^{+0.2}_{-0.1} Jy. The FRB originated at a Galactic longitude and latitude of 24.66°, 5.28° and 25° away from the Galactic Center. The burst was found to be 43 ± 5 per cent linearly polarized with a rotation measure (RM) in the range -9 < RM < 12 rad m-2 (95 per cent confidence level), consistent with zero. The burst was followed up with 11 telescopes to search for radio, optical, X-ray, γ-ray and neutrino emission. Neither transient nor variable emission was found to be associated with the burst and no repeat pulses have been observed in 17.25 h of observing. The sightline to the burst is close to the Galactic plane and the observed physical properties of FRB 150215 demonstrate the existence of sight lines of anomalously low RM for a given electron column density. The Galactic RM foreground may approach a null value due to magnetic field reversals along the line of sight, a decreased total electron column density from the Milky Way, or some combination of these effects. A lower Galactic DM contribution might explain why this burst was detectable whereas previous searches at low latitude have had lower detection rates than those out of the plane.

A Green Bank Telescope Survey of Large Galactic H II Regions

NASA Astrophysics Data System (ADS)

Anderson, L. D.; Armentrout, W. P.; Luisi, Matteo; Bania, T. M.; Balser, Dana S.; Wenger, Trey V.

2018-02-01

As part of our ongoing H II Region Discovery Survey (HRDS), we report the Green Bank Telescope detection of 148 new angularly large Galactic H II regions in radio recombination line (RRL) emission. Our targets are located at a declination of δ > -45^\\circ , which corresponds to 266^\\circ > {\\ell }> -20^\\circ at b=0^\\circ . All sources were selected from the Wide-field Infrared Survey Explorer Catalog of Galactic H II Regions, and have infrared angular diameters ≥slant 260\\prime\\prime . The Galactic distribution of these “large” H II regions is similar to that of the previously known sample of Galactic H II regions. The large H II region RRL line width and peak line intensity distributions are skewed toward lower values, compared with that of previous HRDS surveys. We discover seven sources with extremely narrow RRLs < 10 {km} {{{s}}}-1. If half the line width is due to turbulence, these seven sources have thermal plasma temperatures < 1100 {{K}}. These temperatures are lower than any measured for Galactic H II regions, and the narrow-line components may arise instead from partially ionized zones in the H II region photodissociation regions. We discover G039.515+00.511, one of the most luminous H II regions in the Galaxy. We also detect the RRL emission from three H II regions with diameters > 100 {pc}, making them some of the physically largest known H II regions in the Galaxy. This survey completes the HRDS H II region census in the Northern sky, where we have discovered 887 H II regions and more than doubled the size of the previously known census of Galactic H II regions.

Gamma-ray Monitoring of Active Galactic Nuclei with HAWC

NASA Astrophysics Data System (ADS)

Lauer, Robert; HAWC Collaboration

2016-03-01

Active Galactic Nuclei (AGN) are extra-galactic sources that can exhibit extreme flux variability over a wide range of wavelengths. TeV gamma rays have been observed from about 60 AGN and can help to diagnose emission models and to study cosmic features like extra-galactic background light or inter-galactic magnetic fields. The High Altitude Water Cherenkov (HAWC) observatory is a new extensive air shower array that can complement the pointed TeV observations of imaging air Cherenkov telescopes. HAWC is optimized for studying gamma rays with energies between 100 GeV and 100 TeV and has an instantaneous field of view of ~2 sr and a duty cycle >95% that allow us to scan 2/3 of the sky every day. By performing an unbiased monitoring of TeV emissions of AGN over most of the northern and part of the southern sky, HAWC can provide crucial information and trigger follow-up observations in collaborations with pointed TeV instruments. Furthermore, HAWC coverage of AGN is complementary to that provided by the Fermi satellite at lower energies. In this contribution, we will present HAWC flux light curves of TeV gamma rays from various sources, notably the bright AGN Markarian 421 and Markarian 501, and highlight recent results from multi-wavelengths and multi-instrument studies.

Evaluating Galactic Cosmic Ray Environment Models Using RaD-X Flight Data

NASA Technical Reports Server (NTRS)

Norman, R. B.; Mertens, C. J.; Slaba, T. C.

2016-01-01

Galactic cosmic rays enter Earth's atmosphere after interacting with the geomagnetic field. The primary galactic cosmic rays spectrum is fundamentally changed as it interacts with Earth's atmosphere through nuclear and atomic interactions. At points deeper in the atmosphere, such as at airline altitudes, the radiation environment is a combination of the primary galactic cosmic rays and the secondary particles produced through nuclear interactions. The RaD-X balloon experiment measured the atmospheric radiation environment above 20 km during 2 days in September 2015. These experimental measurements were used to validate and quantify uncertainty in physics-based models used to calculate exposure levels for commercial aviation. In this paper, the Badhwar-O'Neill 2014, the International Organization for Standardization 15390, and the German Aerospace Company galactic cosmic ray environment models are used as input into the same radiation transport code to predict and compare dosimetric quantities to RaD-X measurements. In general, the various model results match the measured tissue equivalent dose well, with results generated by the German Aerospace Center galactic cosmic ray environment model providing the best comparison. For dose equivalent and dose measured in silicon, however, the models were compared less favorably to the measurements.

Probing the Galactic Structure of the Milky Way with H II Regions

NASA Astrophysics Data System (ADS)

Red, Wesley Alexander; Wenger, Trey V.; Balser, Dana; Anderson, Loren; Bania, Thomas

2018-01-01

Mapping the structure of the Milky Way is challenging since we reside within the Galactic disk and distances are difficult to determine. Elemental abundances provide important constraints on theories of the formation and evolution of the Milky Way. HII regions are the brightest objects in the Galaxy at radio wavelengths and are detected across the entire Galactic disk. We use the Jansky Very Large Array (VLA) to observe the radio recombination line (RRL) and continuum emission of 120 Galactic HII regions located across the Galactic disk. In thermal equilibrium, metal abundances are expected to set the nebular electron temperature with high abundances producing low temperatures. We derive the metallicity of HII regions using an empirical relation between an HII region's radio recombination line-to-continuum ratio and nebular metallicity. Here we focus on a subset of 20 HII regions from our sample that have been well studied with the Green Bank Telescope (GBT) to test our data reduction pipeline and analysis methods. Our goal is to expand this study to the Southern skies with the Australia Telescope Compact Array and create a metallicity map of the entire Galactic disk.

Gaia Data Release 1. Testing parallaxes with local Cepheids and RR Lyrae stars

NASA Astrophysics Data System (ADS)

Gaia Collaboration; Clementini, G.; Eyer, L.; Ripepi, V.; Marconi, M.; Muraveva, T.; Garofalo, A.; Sarro, L. M.; Palmer, M.; Luri, X.; Molinaro, R.; Rimoldini, L.; Szabados, L.; Musella, I.; Anderson, R. I.; Prusti, T.; de Bruijne, J. H. J.; Brown, A. G. A.; Vallenari, A.; Babusiaux, C.; Bailer-Jones, C. A. L.; Bastian, U.; Biermann, M.; Evans, D. W.; Jansen, F.; Jordi, C.; Klioner, S. A.; Lammers, U.; Lindegren, L.; Mignard, F.; Panem, C.; Pourbaix, D.; Randich, S.; Sartoretti, P.; Siddiqui, H. I.; Soubiran, C.; Valette, V.; van Leeuwen, F.; Walton, N. A.; Aerts, C.; Arenou, F.; Cropper, M.; Drimmel, R.; Høg, E.; Katz, D.; Lattanzi, M. G.; O'Mullane, W.; Grebel, E. K.; Holland, A. D.; Huc, C.; Passot, X.; Perryman, M.; Bramante, L.; Cacciari, C.; Castañeda, J.; Chaoul, L.; Cheek, N.; De Angeli, F.; Fabricius, C.; Guerra, R.; Hernández, J.; Jean-Antoine-Piccolo, A.; Masana, E.; Messineo, R.; Mowlavi, N.; Nienartowicz, K.; Ordóñez-Blanco, D.; Panuzzo, P.; Portell, J.; Richards, P. J.; Riello, M.; Seabroke, G. M.; Tanga, P.; Thévenin, F.; Torra, J.; Els, S. G.; Gracia-Abril, G.; Comoretto, G.; Garcia-Reinaldos, M.; Lock, T.; Mercier, E.; Altmann, M.; Andrae, R.; Astraatmadja, T. L.; Bellas-Velidis, I.; Benson, K.; Berthier, J.; Blomme, R.; Busso, G.; Carry, B.; Cellino, A.; Cowell, S.; Creevey, O.; Cuypers, J.; Davidson, M.; De Ridder, J.; de Torres, A.; Delchambre, L.; Dell'Oro, A.; Ducourant, C.; Frémat, Y.; García-Torres, M.; Gosset, E.; Halbwachs, J.-L.; Hambly, N. C.; Harrison, D. L.; Hauser, M.; Hestroffer, D.; Hodgkin, S. T.; Huckle, H. E.; Hutton, A.; Jasniewicz, G.; Jordan, S.; Kontizas, M.; Korn, A. J.; Lanzafame, A. C.; Manteiga, M.; Moitinho, A.; Muinonen, K.; Osinde, J.; Pancino, E.; Pauwels, T.; Petit, J.-M.; Recio-Blanco, A.; Robin, A. C.; Siopis, C.; Smith, M.; Smith, K. W.; Sozzetti, A.; Thuillot, W.; van Reeven, W.; Viala, Y.; Abbas, U.; Abreu Aramburu, A.; Accart, S.; Aguado, J. J.; Allan, P. M.; Allasia, W.; Altavilla, G.; Álvarez, M. A.; Alves, J.; Andrei, A. H.; Anglada Varela, E.; Antiche, E.; Antoja, T.; Antón, S.; Arcay, B.; Bach, N.; Baker, S. G.; Balaguer-Núñez, L.; Barache, C.; Barata, C.; Barbier, A.; Barblan, F.; Barrado y Navascués, D.; Barros, M.; Barstow, M. A.; Becciani, U.; Bellazzini, M.; Bello García, A.; Belokurov, V.; Bendjoya, P.; Berihuete, A.; Bianchi, L.; Bienaymé, O.; Billebaud, F.; Blagorodnova, N.; Blanco-Cuaresma, S.; Boch, T.; Bombrun, A.; Borrachero, R.; Bouquillon, S.; Bourda, G.; Bragaglia, A.; Breddels, M. A.; Brouillet, N.; Brüsemeister, T.; Bucciarelli, B.; Burgess, P.; Burgon, R.; Burlacu, A.; Busonero, D.; Buzzi, R.; Caffau, E.; Cambras, J.; Campbell, H.; Cancelliere, R.; Cantat-Gaudin, T.; Carlucci, T.; Carrasco, J. M.; Castellani, M.; Charlot, P.; Charnas, J.; Chiavassa, A.; Clotet, M.; Cocozza, G.; Collins, R. S.; Costigan, G.; Crifo, F.; Cross, N. J. G.; Crosta, M.; Crowley, C.; Dafonte, C.; Damerdji, Y.; Dapergolas, A.; David, P.; David, M.; De Cat, P.; de Felice, F.; de Laverny, P.; De Luise, F.; De March, R.; de Souza, R.; Debosscher, J.; del Pozo, E.; Delbo, M.; Delgado, A.; Delgado, H. E.; Di Matteo, P.; Diakite, S.; Distefano, E.; Dolding, C.; Dos Anjos, S.; Drazinos, P.; Durán, J.; Dzigan, Y.; Edvardsson, B.; Enke, H.; Evans, N. W.; Eynard Bontemps, G.; Fabre, C.; Fabrizio, M.; Falcão, A. J.; Farràs Casas, M.; Federici, L.; Fedorets, G.; Fernández-Hernández, J.; Fernique, P.; Fienga, A.; Figueras, F.; Filippi, F.; Findeisen, K.; Fonti, A.; Fouesneau, M.; Fraile, E.; Fraser, M.; Fuchs, J.; Gai, M.; Galleti, S.; Galluccio, L.; Garabato, D.; García-Sedano, F.; Garralda, N.; Gavras, P.; Gerssen, J.; Geyer, R.; Gilmore, G.; Girona, S.; Giuffrida, G.; Gomes, M.; González-Marcos, A.; González-Núñez, J.; González-Vidal, J. J.; Granvik, M.; Guerrier, A.; Guillout, P.; Guiraud, J.; Gúrpide, A.; Gutiérrez-Sánchez, R.; Guy, L. P.; Haigron, R.; Hatzidimitriou, D.; Haywood, M.; Heiter, U.; Helmi, A.; Hobbs, D.; Hofmann, W.; Holl, B.; Holland, G.; Hunt, J. A. S.; Hypki, A.; Icardi, V.; Irwin, M.; Jevardat de Fombelle, G.; Jofré, P.; Jonker, P. G.; Jorissen, A.; Julbe, F.; Karampelas, A.; Kochoska, A.; Kohley, R.; Kolenberg, K.; Kontizas, E.; Koposov, S. E.; Kordopatis, G.; Koubsky, P.; Krone-Martins, A.; Kudryashova, M.; Bachchan, R. K.; Lacoste-Seris, F.; Lanza, A. F.; Lavigne, J.-B.; Le Poncin-Lafitte, C.; Lebreton, Y.; Lebzelter, T.; Leccia, S.; Leclerc, N.; Lecoeur-Taibi, I.; Lemaitre, V.; Lenhardt, H.; Leroux, F.; Liao, S.; Licata, E.; Lindstrøm, H. E. P.; Lister, T. A.; Livanou, E.; Lobel, A.; Löffler, W.; López, M.; Lorenz, D.; MacDonald, I.; Magalhães Fernandes, T.; Managau, S.; Mann, R. G.; Mantelet, G.; Marchal, O.; Marchant, J. M.; Marinoni, S.; Marrese, P. M.; Marschalkó, G.; Marshall, D. J.; Martín-Fleitas, J. M.; Martino, M.; Mary, N.; Matijevič, G.; McMillan, P. J.; Messina, S.; Michalik, D.; Millar, N. R.; Miranda, B. M. H.; Molina, D.; Molinaro, M.; Molnár, L.; Moniez, M.; Montegriffo, P.; Mor, R.; Mora, A.; Morbidelli, R.; Morel, T.; Morgenthaler, S.; Morris, D.; Mulone, A. F.; Narbonne, J.; Nelemans, G.; Nicastro, L.; Noval, L.; Ordénovic, C.; Ordieres-Meré, J.; Osborne, P.; Pagani, C.; Pagano, I.; Pailler, F.; Palacin, H.; Palaversa, L.; Parsons, P.; Pecoraro, M.; Pedrosa, R.; Pentikäinen, H.; Pichon, B.; Piersimoni, A. M.; Pineau, F.-X.; Plachy, E.; Plum, G.; Poujoulet, E.; Prša, A.; Pulone, L.; Ragaini, S.; Rago, S.; Rambaux, N.; Ramos-Lerate, M.; Ranalli, P.; Rauw, G.; Read, A.; Regibo, S.; Reylé, C.; Ribeiro, R. A.; Riva, A.; Rixon, G.; Roelens, M.; Romero-Gómez, M.; Rowell, N.; Royer, F.; Ruiz-Dern, L.; Sadowski, G.; Sagristà Sellés, T.; Sahlmann, J.; Salgado, J.; Salguero, E.; Sarasso, M.; Savietto, H.; Schultheis, M.; Sciacca, E.; Segol, M.; Segovia, J. C.; Segransan, D.; Shih, I.-C.; Smareglia, R.; Smart, R. L.; Solano, E.; Solitro, F.; Sordo, R.; Soria Nieto, S.; Souchay, J.; Spagna, A.; Spoto, F.; Stampa, U.; Steele, I. A.; Steidelmüller, H.; Stephenson, C. A.; Stoev, H.; Suess, F. F.; Süveges, M.; Surdej, J.; Szegedi-Elek, E.; Tapiador, D.; Taris, F.; Tauran, G.; Taylor, M. B.; Teixeira, R.; Terrett, D.; Tingley, B.; Trager, S. C.; Turon, C.; Ulla, A.; Utrilla, E.; Valentini, G.; van Elteren, A.; Van Hemelryck, E.; van Leeuwen, M.; Varadi, M.; Vecchiato, A.; Veljanoski, J.; Via, T.; Vicente, D.; Vogt, S.; Voss, H.; Votruba, V.; Voutsinas, S.; Walmsley, G.; Weiler, M.; Weingrill, K.; Wevers, T.; Wyrzykowski, Ł.; Yoldas, A.; Žerjal, M.; Zucker, S.; Zurbach, C.; Zwitter, T.; Alecu, A.; Allen, M.; Allende Prieto, C.; Amorim, A.; Anglada-Escudé, G.; Arsenijevic, V.; Azaz, S.; Balm, P.; Beck, M.; Bernstein, H.-H.; Bigot, L.; Bijaoui, A.; Blasco, C.; Bonfigli, M.; Bono, G.; Boudreault, S.; Bressan, A.; Brown, S.; Brunet, P.-M.; Bunclark, P.; Buonanno, R.; Butkevich, A. G.; Carret, C.; Carrion, C.; Chemin, L.; Chéreau, F.; Corcione, L.; Darmigny, E.; de Boer, K. S.; de Teodoro, P.; de Zeeuw, P. T.; Delle Luche, C.; Domingues, C. D.; Dubath, P.; Fodor, F.; Frézouls, B.; Fries, A.; Fustes, D.; Fyfe, D.; Gallardo, E.; Gallegos, J.; Gardiol, D.; Gebran, M.; Gomboc, A.; Gómez, A.; Grux, E.; Gueguen, A.; Heyrovsky, A.; Hoar, J.; Iannicola, G.; Isasi Parache, Y.; Janotto, A.-M.; Joliet, E.; Jonckheere, A.; Keil, R.; Kim, D.-W.; Klagyivik, P.; Klar, J.; Knude, J.; Kochukhov, O.; Kolka, I.; Kos, J.; Kutka, A.; Lainey, V.; LeBouquin, D.; Liu, C.; Loreggia, D.; Makarov, V. V.; Marseille, M. G.; Martayan, C.; Martinez-Rubi, O.; Massart, B.; Meynadier, F.; Mignot, S.; Munari, U.; Nguyen, A.-T.; Nordlander, T.; O'Flaherty, K. S.; Ocvirk, P.; Olias Sanz, A.; Ortiz, P.; Osorio, J.; Oszkiewicz, D.; Ouzounis, A.; Park, P.; Pasquato, E.; Peltzer, C.; Peralta, J.; Péturaud, F.; Pieniluoma, T.; Pigozzi, E.; Poels, J.; Prat, G.; Prod'homme, T.; Raison, F.; Rebordao, J. M.; Risquez, D.; Rocca-Volmerange, B.; Rosen, S.; Ruiz-Fuertes, M. I.; Russo, F.; Serraller Vizcaino, I.; Short, A.; Siebert, A.; Silva, H.; Sinachopoulos, D.; Slezak, E.; Soffel, M.; Sosnowska, D.; Straižys, V.; ter Linden, M.; Terrell, D.; Theil, S.; Tiede, C.; Troisi, L.; Tsalmantza, P.; Tur, D.; Vaccari, M.; Vachier, F.; Valles, P.; Van Hamme, W.; Veltz, L.; Virtanen, J.; Wallut, J.-M.; Wichmann, R.; Wilkinson, M. I.; Ziaeepour, H.; Zschocke, S.

2017-09-01

Context. Parallaxes for 331 classical Cepheids, 31 Type II Cepheids, and 364 RR Lyrae stars in common between Gaia and the Hipparcos and Tycho-2 catalogues are published in Gaia Data Release 1 (DR1) as part of the Tycho-Gaia Astrometric Solution (TGAS). Aims: In order to test these first parallax measurements of the primary standard candles of the cosmological distance ladder, which involve astrometry collected by Gaia during the initial 14 months of science operation, we compared them with literature estimates and derived new period-luminosity (PL), period-Wesenheit (PW) relations for classical and Type II Cepheids and infrared PL, PL-metallicity (PLZ), and optical luminosity-metallicity (MV-[Fe/H]) relations for the RR Lyrae stars, with zero points based on TGAS. Methods: Classical Cepheids were carefully selected in order to discard known or suspected binary systems. The final sample comprises 102 fundamental mode pulsators with periods ranging from 1.68 to 51.66 days (of which 33 with σϖ/ϖ< 0.5). The Type II Cepheids include a total of 26 W Virginis and BL Herculis stars spanning the period range from 1.16 to 30.00 days (of which only 7 with σϖ/ϖ< 0.5). The RR Lyrae stars include 200 sources with pulsation period ranging from 0.27 to 0.80 days (of which 112 with σϖ/ϖ< 0.5). The new relations were computed using multi-band (V,I,J,Ks) photometry and spectroscopic metal abundances available in the literature, and by applying three alternative approaches: (I) linear least-squares fitting of the absolute magnitudes inferred from direct transformation of the TGAS parallaxes; (II) adopting astrometry-based luminosities; and (III) using a Bayesian fitting approach. The last two methods work in parallax space where parallaxes are used directly, thus maintaining symmetrical errors and allowing negative parallaxes to be used. The TGAS-based PL,PW,PLZ, and MV- [Fe/H] relations are discussed by comparing the distance to the Large Magellanic Cloud provided by

Galactic Spiral Shocks with Thermal Instability in Vertically Stratified Galactic Disks

NASA Astrophysics Data System (ADS)

Kim, Chang-Goo; Kim, Woong-Tae; Ostriker, Eve C.

2010-09-01

Galactic spiral shocks are dominant morphological features and believed to be responsible for substructure formation within spiral arms in disk galaxies. They can also contribute a substantial amount of kinetic energy to the interstellar gas by tapping the (differential) rotational motion. We use numerical hydrodynamic simulations to investigate dynamics and structure of spiral shocks with thermal instability (TI) in vertically stratified galactic disks, focusing on environmental conditions (of heating and the galactic potential) similar to the Solar neighborhood. We initially consider an isothermal disk in vertical hydrostatic equilibrium and let it evolve subject to interstellar cooling and heating as well as a stellar spiral potential. Due to TI, a disk with surface density Σ0 >= 6.7 M sun pc-2 rapidly turns to a thin dense slab near the midplane sandwiched between layers of rarefied gas. The imposed spiral potential leads to a vertically curved shock that exhibits strong flapping motions in the plane perpendicular to the arm. The overall flow structure at saturation is comprised of the arm, postshock expansion zone, and interarm regions that occupy typically 10%, 20%, and 70% of the arm-to-arm distance, in which the gas resides for 15%, 30%, and 55% of the arm-to-arm crossing time, respectively. The flows are characterized by transitions from rarefied to dense phases at the shock and from dense to rarefied phases in the postshock expansion zone, although gas with too-large postshock-density does not undergo this return phase transition, instead forming dense condensations. If self-gravity is omitted, the shock flapping drives random motions in the gas, but only up to ~2-3 km s-1 in the in-plane direction and less than 2 km s-1 in the vertical direction. Time-averaged shock profiles show that the spiral arms in stratified disks are broader and less dense compared to those in unstratified models, and that the vertical density distribution is overall consistent

PIPER and Polarized Galactic Foregrounds

NASA Technical Reports Server (NTRS)

Chuss, David

2009-01-01

In addition to probing inflationary cosmology, PIPER will measure the polarized dust emission from the Galaxy. PIPER will be capable of full (I,0,U,V) measurement over four frequency bands ' These measurements will provide insight into the physics of dust grains and a probe of the Galactic magnetic field on large and intermediate scales.

Special Features of Galactic Dynamics

NASA Astrophysics Data System (ADS)

Efthymiopoulos, Christos; Voglis, Nikos; Kalapotharakos, Constantinos

This is an introductory article to some basic notions and currently open problems of galactic dynamics. The focus is on topics mostly relevant to the so-called `new methods' of celestial mechanics or Hamiltonian dynamics, as applied to the ellipsoidal components of galaxies, i.e., to the elliptical galaxies and to the dark halos and bulges of disk galaxies. Traditional topics such as Jeans theorem, the role of a `third integral' of motion, Nekhoroshev theory, violent relaxation, and the statistical mechanics of collisionless stellar systems are first discussed. The emphasis is on modern extrapolations of these old topics. Recent results from orbital and global dynamical studies of galaxies are then shortly reviewed. The role of various families of orbits in supporting self-consistency, as well as the role of chaos in galaxies, are stressed. A description is then given of the main numerical techniques of integration of the N-body problem in the framework of stellar dynamics and of the results obtained via N-Body experiments. A final topic is the secular evolution and self-organization of galactic systems.

The Bolocam Galactic Plane Survey

NASA Technical Reports Server (NTRS)

Glenn, Jason; Aguirre, James; Bally, John; Battersby, Cara; Bradley, Eric Todd; Cyganowski, Claudia; Dowell, Darren; Drosback, Meredith; Dunham, Miranda K.; Evans, Neal J., II;

An Update on the Status of RR Lyrae Research - Report of the RRL2015 Meeting (October, Hungary) (Abstract)

NASA Astrophysics Data System (ADS)

Kolenberg, K.

2016-06-01

(Abstract only) In October 2015 we organized the first international meeting focused on RR Lyrae research, with the goal to discuss recent developments and future RR Lyrae plans. The Scientific rationale is the following:

High-resolution spectrum of the Galactic center

NASA Technical Reports Server (NTRS)

Mahoney, W. A.; Ling, J. C.; Wheaton, W. A.

1993-01-01

Recent observations of the Galactic center region indicate the presence of a narrow gamma-ray line feature at 170 keV, and theoretical speculations suggest it may result from Compton backscattering of the 511 keV annihilation radiation. The high-resolution gamma-ray spectrometer on HEAO 3 observed the Galactic center in the fall of 1979 and in the spring of 1980. In view of the recent developments, the HEAO data were re-examined to search for this new feature and to look for possible correlations with the 511 keV line emisison. No evidence for such Compton backscattered radiation was found and the derived upper limits for emission in a line feature near 170 keV were well below previously reported fluxes, indicating possible time variability.

The Galactic Spaceship Tour Challenge

ERIC Educational Resources Information Center

Engel, Bill; Schmidt, Diane

2004-01-01

A science fiction problem was placed before the students, they had to plan a profitable trip for Galactic spaceship tour and for which group of five students was made to solve the problem, which would encourage cooperative efforts, and different people in the group could work on different aspects. An important part of this problem is that students…

The Milky Way, the Galactic halo, and the Halos of Galaxies

NASA Astrophysics Data System (ADS)

Gerhard, Ortwin

2015-08-01

The Milky Way, "our" Galaxy, is currently the subject of intense study with many ground-based surveys, in anticipation of upcoming results from the GAIA mission. From this work we have been learning about the full three-dimensional structure of the Galactic box/peanut bulge, the distribution of stars in the bar and disk, and the many streams in the Galactic halo. The data tell us that most of the Galactic bulge formed from the disk, and that a large fraction of the Galactic halo has been accreted from outside. Similarly, in many external galaxy halos there is now evidence for tidal streams and accretion of satellites. To see these features requires exquisite data - mostly very deep photometry, but some halo substructures have also been found with kinematic data. These observations illustrate how galaxy halos are still growing, and sometimes can be used to "time" the accretion events. In comparison with cosmological simulations, the structure of galaxy halos gives us a vivid illustration of the hierarchical nature of our Universe.

HI Clouds Near the Galactic Center: Possible Tracers of the Nuclear Wind

NASA Astrophysics Data System (ADS)

Lockman, Felix J.; McClure-Griffiths, Naomi; DiTeodoro, Enrico

2017-01-01

We have used the Green Bank Telescope to discover more than one hundred neutral hydrogen clouds that appear to be embedded in the Fermi Bubble -- the Milky Way’s nuclear wind. With the other members of this population that were previously found with the Australia Telescope Compact Array, we now have a sample of about 200 such clouds. They are identified by their peculiar velocities. The cloud kinematics show no trace of Galactic rotation or association with the Galactic bar. Near longitude zero the clouds can have values of VLSR = +-200 km/s. No clouds have been detected with |VLSR| > 350 km/s. The clouds are concentrated toward the Galactic plane, but some are still found to |b|=10 degrees, or z > 1 kpc at the Galactic Center, where the current surveys end. These clouds are important tracers of conditions in the nuclear wind of the Milky Way.

DHIGLS: DRAO H I Intermediate Galactic Latitude Survey

NASA Astrophysics Data System (ADS)

Blagrave, K.; Martin, P. G.; Joncas, G.; Kothes, R.; Stil, J. M.; Miville-Deschênes, M. A.; Lockman, Felix J.; Taylor, A. R.

2017-01-01

Observations of Galactic H I gas for seven targeted regions at intermediate Galactic latitude are presented at 1\\prime angular resolution using data from the DRAO Synthesis Telescope (ST) and the Green Bank Telescope (GBT). The DHIGLS data are the most extensive arcminute-resolution measurements of the diffuse atomic interstellar medium beyond those in the Galactic plane. The acquisition, reduction, calibration, and mosaicking of the DRAO ST data and the cross calibration and incorporation of the short-spacing information from the GBT are described. The high quality of the resulting DHIGLS products enables a variety of new studies in directions of low Galactic column density. We analyze the angular power spectra of maps of the integrated H I emission (column density) from the data cubes for several distinct velocity ranges. In fitting power-spectrum models based on a power law, but including the effects of the synthesized beam and noise at high spatial frequencies, we find exponents ranging from -2.5 to -3.0. Power spectra of maps of the centroid velocity for these components give similar results. These exponents are interpreted as being representative of the three-dimensional density and velocity fields of the atomic gas, respectively. We find evidence for dramatic changes in the H I structures in channel maps over even small changes in velocity. This narrow line emission has counterparts in absorption spectra against bright background radio sources, quantifying that the gas is cold and dense and can be identified as the cold neutral medium phase. Fully reduced DHIGLS H I data cubes and other data products are available at www.cita.utoronto.ca/DHIGLS.

The age of the Galactic disk - Inflow, chemical evolution, astration, and radioactivity

NASA Technical Reports Server (NTRS)

Clayton, Donald D.

1989-01-01

Theoretical models of Galactic evolution and observational data on the age of the Galaxy are compared, with a focus on recent results. Topics addressed include the infall of material and its effects on the age-metallicity relation, the distribution of metallicity, the present gas fraction and metallicity, and the age spectrum of interstellar nuclei; the chemical evolution of the solar neighborhood; the key results of nuclear cosmochronology; and astration effects on Galactic age. It is found that both nuclear cosmochronology and detailed stellar and Galactic evolution models tend to support an age of 12-16 Gyr.

The Optical Gravitational Lensing Experiment. BVI Maps of Dense Stellar Regions. III. The Galactic Bulge

NASA Astrophysics Data System (ADS)

Udalski, A.; Szymanski, M.; Kubiak, M.; Pietrzynski, G.; Soszynski, I.; Wozniak, P.; Zebrun, K.; Szewczyk, O.; Wyrzykowski, L.

2002-09-01

We present the VI photometric maps of the Galactic bulge. They contain VI photometry and astrometry of about 30 million stars from 49 fields of 0.225 square degree each in the Galactic center region. The data were collected during the second phase of the OGLE microlensing project. We discuss the accuracy of data and present color-magnitude diagrams of selected fields observed by OGLE in the Galactic bulge. The VI maps of the Galactic bulge are accessible electronically for the astronomical community from the OGLE Internet archive.

Galactic Forces Rule the Dynamics of Milky Way Dwarf Galaxies

NASA Astrophysics Data System (ADS)

Hammer, Francois; Yang, Yanbin; Arenou, Frederic; Babusiaux, Carine; Wang, Jianling; Puech, Mathieu; Flores, Hector

2018-06-01

Dwarf galaxies populating the Galactic halo are assumed to host the largest fractions of dark matter, as calculated from their velocity dispersions. Their major axes are preferentially aligned with the Vast Polar Structure (VPOS) that is perpendicular to the Galactic disk, and we find their velocity gradients aligned as well. This finding results in a probability of random occurrence for the VPOS as low as ∼10‑5. It suggests that tidal forces exerted by the Milky Way are distorting dwarf galaxies. Here we demonstrate on the basis of the impulse approximation that the Galactic gravitational acceleration induces the dwarf line-of-sight velocity dispersion, which is also evidenced by strong dependences between both quantities. Since this result is valid for any dwarf mass value, it implies that dark matter estimates in Milky Way dwarfs cannot be deduced from the product of their radius to the square of their line-of-sight velocity dispersion. This questions the high dark matter fractions reported for these evanescent systems, and the universally adopted total-to-stellar mass relationship in the dwarf regime. It suggests that many dwarfs are at their first passage and are dissolving into the Galactic halo. This gives rise to a promising method to estimate the Milky Way total mass profile at large distances.

Interstellar Scattering Towards the Galactic Center as Probed by OH/IR Stars

NASA Technical Reports Server (NTRS)

Vanlangevelde, Huib Jan; Frail, Dale A.; Cordes, James M.; Diamond, Philip J.

1992-01-01

Angular broadening measurements are reported of 20 OH/IR stars near the galactic center. This class of sources is known to have bright, intrinsically compact (less than or equal to 20 mas) maser components within their circumstellar shells. VLBA antennas and the VLA were used to perform a MKII spectral line VLBI experiment. The rapid drop in correlated flux with increasing baseline, especially for sources closest to the galactic center, is attributed to interstellar scattering. Angular diameters were measured for 13 of our sources. Lower limits were obtained for the remaining seven. With the data, together with additional data taken from the literature, the distribution was determined of interstellar scattering toward the galactic center. A region was found of pronounced scattering nearly centered on SgrA*. Two interpretations are considered for the enhanced scattering. One hypothesis is that the scattering is due to a clump of enhanced turbulence, such as those that lie along lines of sight to other known objects, that has no physical relationship to the galactic center. The other model considers the location of the enhanced scattering to arise in the galactic center itself. The physical implications of the models yield information on the nature of interstellar scattering.

Taking the Galactic Exoplanet Census with K2

NASA Astrophysics Data System (ADS)

Christiansen, Jessie; CHAI (California/Hawaii/Arizona/Indiana) K2 Follow-up Consortium

2016-06-01

The NASA Kepler mission was designed and executed with the goal of measuring planet occurrence rates. The stellar sample, the science pipeline, and the planet candidate sample have all been chosen and characterised with an eye to generating uniform, robust statistical measurements. The subsequent K2 mission, however, has been much more open to all science goals, and subsequently the target selection, planet candidate generation and catalogue assembly have been substantially more ad hoc. Here we discuss the pathway forward to using the Galactic latitude coverage of K2 to begin the Galactic exoplanet census that will be continued by the NASA TESS mission.

50 CFR 680.5 - Recordkeeping and reporting (R&R).

Code of Federal Regulations, 2011 CFR

2011-10-01

... 50 Wildlife and Fisheries 11 2011-10-01 2011-10-01 false Recordkeeping and reporting (R&R). 680.5... information is true, correct, and complete to the best of his or her knowledge and belief. (5) Submittal. The..., 2005, as amended at 70 FR 33395, June 8, 2005; 70 FR 75421, Dec. 20, 2005; 73 FR 76189, Dec. 15, 2008...

50 CFR 680.5 - Recordkeeping and reporting (R&R).

Code of Federal Regulations, 2014 CFR

2014-10-01

... 50 Wildlife and Fisheries 13 2014-10-01 2014-10-01 false Recordkeeping and reporting (R&R). 680.5... information is true, correct, and complete to the best of his or her knowledge and belief. (5) Submittal. The..., 2005, as amended at 70 FR 33395, June 8, 2005; 70 FR 75421, Dec. 20, 2005; 73 FR 76189, Dec. 15, 2008...

50 CFR 680.5 - Recordkeeping and reporting (R&R).

Code of Federal Regulations, 2013 CFR

2013-10-01

... 50 Wildlife and Fisheries 13 2013-10-01 2013-10-01 false Recordkeeping and reporting (R&R). 680.5... information is true, correct, and complete to the best of his or her knowledge and belief. (5) Submittal. The..., 2005, as amended at 70 FR 33395, June 8, 2005; 70 FR 75421, Dec. 20, 2005; 73 FR 76189, Dec. 15, 2008...

50 CFR 680.5 - Recordkeeping and reporting (R&R).

Code of Federal Regulations, 2012 CFR

2012-10-01

... 50 Wildlife and Fisheries 13 2012-10-01 2012-10-01 false Recordkeeping and reporting (R&R). 680.5... information is true, correct, and complete to the best of his or her knowledge and belief. (5) Submittal. The..., 2005, as amended at 70 FR 33395, June 8, 2005; 70 FR 75421, Dec. 20, 2005; 73 FR 76189, Dec. 15, 2008...

50 CFR 680.5 - Recordkeeping and reporting (R&R).

Code of Federal Regulations, 2010 CFR

2010-10-01

... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Recordkeeping and reporting (R&R). 680.5... information is true, correct, and complete to the best of his or her knowledge and belief. (5) Submittal. The..., 2005, as amended at 70 FR 33395, June 8, 2005; 70 FR 75421, Dec. 20, 2005; 73 FR 76189, Dec. 15, 2008...

The relationship between the galactic matter distribution, cosmic ray dynamics, and gamma ray production

NASA Technical Reports Server (NTRS)

Kniffen, D. A.; Fichtel, C. E.; Thompson, D. J.

1976-01-01

Theoretical considerations and analysis of the results of gamma ray astronomy suggest that the galactic cosmic rays are dynamically coupled to the interstellar matter through the magnetic fields, and hence the cosmic ray density should be enhanced where the matter density is greatest on the scale of galactic arms. This concept has been explored in a galactic model using recent 21 cm radio observations of the neutral hydrogen and 2.6 mm observations of carbon monoxide, which is considered to be a tracer of molecular hydrogen. The model assumes: (1) cosmic rays are galactic and not universal; (2) on the scale of galactic arms, the cosmic ray column (surface) density is proportional to the total interstellar gas column density; (3) the cosmic ray scale height is significantly larger than the scale height of the matter; and (4) ours is a spiral galaxy characterized by an arm to interarm density ratio of about 3:1.

IRAS and the Boston University Arecibo Galactic H I Survey: A catalog of cloud properties

NASA Technical Reports Server (NTRS)

Bania, Thomas M.

1992-01-01

The Infrared Astronomy Satellite (IRAS) Galactic Plane Surface Brightness Images were used to identify infrared emission associated with cool, diffuse H I clouds detected by the Boston University-Arecibo Galactic H I Survey. These clouds are associated with galactic star clusters, H II regions, and molecular clouds. Using emission-absorption experiments toward galactic H II regions, we determined the H I properties of cool H I clouds seen in absorption against the thermal continuum, including their kinematic distances. Correlations were then made between IRAS sources and these H II regions, thus some of the spatial confusion associated with the IRAS fields near the galactic plane was resolved since the distances to these sources was known. Because we can also correlate the BU-Arecibo clouds with existing CO surveys, these results will allow us to determine the intrinsic properties of the gas (neutral and ionized atomic as well as molecular) and dust for interstellar clouds in the inner galaxy. For the IRAS-identified H II region sample, we have established the far infrared (FIR) luminosities and galactic distribution of these sources.

Galactic Winds and Intragroup Medium Energetics

NASA Technical Reports Server (NTRS)

Dupke, Renato; Lloyd-Davies, Ed; Bregman, Joel

2004-01-01

The main objective of this proposal was to study the metallicity distribution of HCG 97 with the goals of determining the SN Type enrichment, the strength of galactic winds and how it impacts on the evolution of cluster's ICM within the framework of hierarchical formation scenarios.

Measurements of hadronic B decays to excited-charm mesons, observation of a new charm resonance and construction of a silicon vertex detector for CLEO II.V

NASA Astrophysics Data System (ADS)

Nelson, Timothy Knight

We describe measurements of the branching ratios B(B --->D*+p- p-total) =(29.2+/-4.5+/-3.8+/-3.1) ×10-4 B(B- --> D*+p- p -non- res)=( 9.7+/-3.6+/-1.5+/-1.9)× 10- 4 B(B---> D1(2420) 0p-) B(D1( 2420)0--> D*+p- )= (6.9+1.8-1.4 +/-1.1+/-0.4)× 10-4 B(B---> D01( j= / )p- ) B(D01 (j= /) -->D* +p-) = ( 10.6+/-1.9+/-1.7+/-2.3)× 10-4 B(B---> D*2( 2460)0p- )B(D *2( 2460)0--> D*+p- )= (3.1+/- 0.84+/-0.46+/-0.28)×10 -4, using data collected by the CLEO II detector. These measurements provide the first observation of the D01(j=/) with a mass and width of 2.461<lyr>+0.053lyr>>- 0.049lyr>GeV and 290<lyr>+110lyr>> - 91lyr>MeV respectively. The mixing angles between the partial waves and strong phase shifts among the resonances are also measured assuming one possible parameterization of the amplitude. A method allowing full reconstruction of the signal without reconstruction of the D meson in the final state is used. The measurements are extracted using an four-dimensional, unbinned, maximum- likelihood fit to the distributions of the D*+p- mass and the decay angles. The primary element of the CLEO II.V upgrade was the installation of a three-layer Silicon Vertexing Detector. The design and construction of this detector are described in detail.

SPI measurements of Galactic 26Al

NASA Astrophysics Data System (ADS)

Diehl, R.; Knödlseder, J.; Lichti, G. G.; Kretschmer, K.; Schanne, S.; Schönfelder, V.; Strong, A. W.; von Kienlin, A.; Weidenspointner, G.; Winkler, C.; Wunderer, C.

2003-11-01

The precision measurement of the 1809 keV gamma-ray line from Galactic 26Al is one of the goals of the SPI spectrometer on INTEGRAL with its Ge detector camera. We aim for determination of the detailed shape of this gamma-ray line, and its variation for different source regions along the plane of the Galaxy. Data from the first part of the core program observations of the first mission year have been inspected. A clear detection of the 26Al line at =~ 5-7 sigma significance demonstrates that SPI will deepen 26Al studies. The line intensity is consistent with expectations from previous experiments, and the line appears narrower than the 5.4 keV FWHM reported by GRIS, more consistent with RHESSI's recent value. Only preliminary statements can be made at this time, however, due to the multi-component background underlying the signal at =~ 40 times higher intensity than the signal from Galactic 26Al.

The fuelling of active galactic nuclei

NASA Technical Reports Server (NTRS)

Shlosman, Isaac; Begelman, Mitchell C.; Frank, Julian

1990-01-01

Accretion mechanisms for powering the central engines of active galactic nuclei (AGN) and possible sources of fuel are reviewed. It is a argued that the interstellar matter in the main body of the host galaxy is channeled toward the center, and the problem of angular momentum transport is addressed. Thin accretion disks are not a viable means of delivering fuel to luminous AGN on scales much larger than a parsec because of the long inflow time and effects of self-gravity. There are also serious obstacles to maintaining and regulating geometrically thick, hot accretion flows. The role of nonaxisymmetric perturbations of the gravitational potential on galactic scales and their triggers is emphasized. A unified model is outlined for fueling AGN, in which the inflow on large scales is driven by gravitational torques, and on small scales forms a mildly self-gravitating disk of clouds with inflow driven by magnetic torques or cloud-cloud collisions.

Testing Intermittence of the Galactic Star Formation History along with the Infall Model

NASA Astrophysics Data System (ADS)

Takeuchi, Tsutomu T.; Hirashita, Hiroyuki

2000-09-01

We analyze the star formation history (SFH) of the Galactic disk by using an infall model. Based on the observed SFH of the Galactic disk, we first determine the timescale of the gas infall into the Galactic disk (tin) and that of the gas consumption to form stars (tsf). Since each of the two timescales does not prove to be determined independently from the SFH, we first fix tsf. Then, tin is determined so that we minimize χ2. Consequently, we choose three parameter sets: [tsf (Gyr),tin (Gyr)]=(6.0, 23), (11, 12), and (15, 9.0), where we set the Galactic age as 15 Gyr. All of the three cases predict almost identical star formation history. Next, we test the intermittence (or variability) of the star formation rate (SFR) along with the smooth SFH suggested from the infall model. The large value of the χ2 statistic supports the violent time variation of the SFH. If we interpret the observed SFH with smooth and variable components, the amplitude of the variable component is comparable to the smooth component. Thus, intermittent SFH of the Galactic disk is strongly suggested. We also examined the metallicity distribution of G dwarfs. We found that the true parameter set lies between [tsf (Gyr),tin (Gyr)]=(6, 23) and (11, 12), though we need a more sophisticated model including the process of metal enrichment within the Galactic halo.

Elucidation of kinematical and dynamical structure of the Galactic bulge

NASA Astrophysics Data System (ADS)

Yano, T.; Gouda, N.; Ueda, H.; Koyama, H.; Kan-ya, Y.; Taruya, A.

2008-07-01

Future space mission of astrometric satellite, GAIA and JASMINE (Japan Astrometry Satellite Mission for Infrared Exploration), will produce astrometric parameter, such as positions, parallaxes, and proper motions of stars in the Galactic bulge. Then kinematical information will be obtained in the future. Accordingly it is expected that our understanding of the dynamical structure will be greatly improved. Therefore it is important to make a method to construct a kinematical and dynamical structure of the Galactic bulge immediately.

Radiation protection issues in galactic cosmic ray risk assessment.

PubMed

Sinclair, W K

1994-01-01

Radiation protection involves the limitation of exposure to below threshold doses for direct (or deterministic) effects and a knowledge of the risk of stochastic effects after low doses. The principal stochastic risk associated with low dose rate galactic cosmic rays is the increased risk of cancer. Estimates of this risk depend on two factors (a) estimates of cancer risk for low-LET radiation and (b) values of the appropriate radiation weighting factors, WR, for the high-LET radiations of galactic cosmic rays. Both factors are subject to considerable uncertainty. The low-LET cancer risk derived from the late effects of the atomic bombs is vulnerable to a number of uncertainties including especially that from projection in time, and from extrapolation from high to low dose rate. Nevertheless, recent low dose studies of workers and others tend to confirm these estimates. WR, relies on biological effects studied mainly in non-human systems. Additional laboratory studies could reduce the uncertainties in WR and thus produce a more confident estimate of the overall risk of galactic cosmic rays.

Searches for point sources in the Galactic Center region

NASA Astrophysics Data System (ADS)

di Mauro, Mattia; Fermi-LAT Collaboration

2017-01-01

Several groups have demonstrated the existence of an excess in the gamma-ray emission around the Galactic Center (GC) with respect to the predictions from a variety of Galactic Interstellar Emission Models (GIEMs) and point source catalogs. The origin of this excess, peaked at a few GeV, is still under debate. A possible interpretation is that it comes from a population of unresolved Millisecond Pulsars (MSPs) in the Galactic bulge. We investigate the detection of point sources in the GC region using new tools which the Fermi-LAT Collaboration is developing in the context of searches for Dark Matter (DM) signals. These new tools perform very fast scans iteratively testing for additional point sources at each of the pixels of the region of interest. We show also how to discriminate between point sources and structural residuals from the GIEM. We apply these methods to the GC region considering different GIEMs and testing the DM and MSPs intepretations for the GC excess. Additionally, we create a list of promising MSP candidates that could represent the brightest sources of a MSP bulge population.

Radiation protection issues in galactic cosmic ray risk assessment

NASA Technical Reports Server (NTRS)

Sinclair, W. K.

1994-01-01

Radiation protection involves the limitation of exposure to below threshold doses for direct (or deterministic) effects and a knowledge of the risk of stochastic effects after low doses. The principal stochastic risk associated with low dose rate galactic cosmic rays is the increased risk of cancer. Estimates of this risk depend on two factors (a) estimates of cancer risk for low-LET radiation and (b) values of the appropriate radiation weighting factors, WR, for the high-LET radiations of galactic cosmic rays. Both factors are subject to considerable uncertainty. The low-LET cancer risk derived from the late effects of the atomic bombs is vulnerable to a number of uncertainties including especially that from projection in time, and from extrapolation from high to low dose rate. Nevertheless, recent low dose studies of workers and others tend to confirm these estimates. WR, relies on biological effects studied mainly in non-human systems. Additional laboratory studies could reduce the uncertainties in WR and thus produce a more confident estimate of the overall risk of galactic cosmic rays.

Evaluation of the i3 Scale-up of Reading Recovery: Year One Report, 2011-12. RR-76

ERIC Educational Resources Information Center

May, Henry; Gray, Abigail; Gillespie, Jessica N.; Sirinides, Philip; Sam, Cecile; Goldsworthy, Heather; Armijo, Michael; Tognatta, Namrata

2013-01-01

Reading Recovery (RR) is a short-term early intervention designed to help the lowest-achieving readers in first grade reach average levels of classroom performance in literacy. Students identified to receive Reading Recovery meet individually with a specially trained Reading Recovery (RR) teacher every school day for 30-minute lessons over a…

Diffuse X-ray sky in the Galactic center

NASA Astrophysics Data System (ADS)

Koyama, Katsuji

2018-01-01

The Galactic diffuse X-ray emission (GDXE) in the Milky Way Galaxy is spatially and spectrally decomposed into the Galactic center X-ray emission (GCXE), the Galactic ridge X-ray emission (GRXE), and the Galactic bulge X-ray emission (GBXE). The X-ray spectra of the GDXE are characterized by the strong K-shell lines of the highly ionized atoms, and the brightest lines are the K-shell transition (principal quantum number transition of n = 2 → 1) of neutral iron (Fe I-Kα), He-like iron (Fe XXV-Heα), and He-like sulfur (S XV-Heα). Accordingly, the GDXE is composed of a high-temperature plasma of ˜7 keV (HTP) and a low-temperature plasma of ˜1 keV, which emit the Fe XXV-Heα and S XV-Heα lines, respectively. The Fe I-Kα line is emitted from nearly neutral irons, and hence the third component of the GDXE is a cool gas (CG). The Fe I-Kα distribution in the GCXE region is clumpy (Fe I-Kα clump), associated with giant molecular cloud (MC) complexes (Sagittarius A, B, C, D, and E) in the central molecular zone. The origin of the Fe I-Kα clumps is the fluorescence and Thomson scattering from the MCs irradiated by past big flares of the supermassive black hole Sagittarius A*. The scale heights and equivalent widths of the Fe I-Kα, Fe XXV-Heα, and Fe XXVI-Lyα (n = 2 → 1 transition of H-like iron) lines are different among the GCXE, GBXE, and GRXE. Therefore, their structures and origins are separately examined. This paper gives an overview of the research history and the present understandings of the GDXE, while in particular focusing on the origin of the HTP and CG in the GCXE.

Introduction to Galactic Chemical Evolution

NASA Astrophysics Data System (ADS)

Matteucci, Francesca

2016-04-01

In this lecture I will introduce the concept of galactic chemical evolution, namely the study of how and where the chemical elements formed and how they were distributed in the stars and gas in galaxies. The main ingredients to build models of galactic chemical evolution will be described. They include: initial conditions, star formation history, stellar nucleosynthesis and gas flows in and out of galaxies. Then some simple analytical models and their solutions will be discussed together with the main criticisms associated to them. The yield per stellar generation will be defined and the hypothesis of instantaneous recycling approximation will be critically discussed. Detailed numerical models of chemical evolution of galaxies of different morphological type, able to follow the time evolution of the abundances of single elements, will be discussed and their predictions will be compared to observational data. The comparisons will include stellar abundances as well as interstellar medium ones, measured in galaxies. I will show how, from these comparisons, one can derive important constraints on stellar nucleosynthesis and galaxy formation mechanisms. Most of the concepts described in this lecture can be found in the monograph by Matteucci (2012).

Exact axially symmetric galactic dynamos

NASA Astrophysics Data System (ADS)

Henriksen, R. N.; Woodfinden, A.; Irwin, J. A.

2018-05-01

We give a selection of exact dynamos in axial symmetry on a galactic scale. These include some steady examples, at least one of which is wholly analytic in terms of simple functions and has been discussed elsewhere. Most solutions are found in terms of special functions, such as associated Lagrange or hypergeometric functions. They may be considered exact in the sense that they are known to any desired accuracy in principle. The new aspect developed here is to present scale-invariant solutions with zero resistivity that are self-similar in time. The time dependence is either a power law or an exponential factor, but since the geometry of the solution is self-similar in time we do not need to fix a time to study it. Several examples are discussed. Our results demonstrate (without the need to invoke any other mechanisms) X-shaped magnetic fields and (axially symmetric) magnetic spiral arms (both of which are well observed and documented) and predict reversing rotation measures in galaxy haloes (now observed in the CHANG-ES sample) as well as the fact that planar magnetic spirals are lifted into the galactic halo.

The Physical Nature of the Circum-Galactic Medium

NASA Astrophysics Data System (ADS)

Faucher-Giguere, Claude-Andre

The installation of the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope (HST) as part of its last servicing mission has revolutionized the study of gas in and around galaxies through the study of ultra-violet (UV) diagnostics. These diagnostics are enabling studies of gas flows in and out of low-redshift, evolved galaxies that are not feasible from the ground. Despite the great observational advances made possible with COS, it is necessary to complement the high-quality spectra with theoretical modeling sufficiently accurate for robust and complete physical interpretation so that the full scientific potential of the mission can be realized. The clear correlation between O VI absorption in galactic halos and the specific star formation rate of central galaxies revealed by COS, in particular, highlights the close connection between circum-galactic gas and galaxies. It is now also appreciated that the gaseous halos of galaxies contain a total mass and a mass in metals that are at least comparable to (and likely significantly greater than) the total and metal masses in the interstellar medium of galaxies. The circum-galactic medium (CGM) is thus intimately related to galaxy evolution, including the transformation of blue star-forming disks into red passive ellipticals. However, the physical origin of observed galaxy-halo gas correlations and of halo gas in general is presently not understood. We will model the CGM of low-redshift galaxies probed by HST observations with cosmological simulations of unprecedented resolution and with much more physically predictive models of star formation and stellar and black hole feedback than previously available. Our simulations will also employ a numerical solver that resolves all the main historical differences between grid- and particle-based hydrodynamical codes. Importantly, we will process all of our simulations with radiative transfer calculations to faithfully map the simulations to observable quantities, a

Mapping the Tidal Destruction of the Hercules Dwarf: A Wide-field DECam Imaging Search for RR Lyrae Stars

NASA Astrophysics Data System (ADS)

Garling, Christopher; Willman, Beth; Sand, David J.; Hargis, Jonathan; Crnojević, Denija; Bechtol, Keith; Carlin, Jeffrey L.; Strader, Jay; Zou, Hu; Zhou, Xu; Nie, Jundan; Zhang, Tianmeng; Zhou, Zhimin; Peng, Xiyan

2018-01-01

We investigate the hypothesized tidal disruption of the Hercules ultra-faint dwarf galaxy (UFD). Previous tidal disruption studies of the Hercules UFD have been hindered by the high degree of foreground contamination in the direction of the dwarf. We bypass this issue by using RR Lyrae stars, which are standard candles with a very low field-volume density at the distance of Hercules. We use wide-field imaging from the Dark Energy Camera on CTIO to identify candidate RR Lyrae stars, supplemented with observations taken in coordination with the Beijing–Arizona Sky Survey on the Bok Telescope. Combining color, magnitude, and light-curve information, we identify three new RR Lyrae stars associated with Hercules. All three of these new RR Lyrae stars lie outside its published tidal radius. When considered with the nine RR Lyrae stars already known within the tidal radius, these results suggest that a substantial fraction of Hercules’ stellar content has been stripped. With this degree of tidal disruption, Hercules is an interesting case between a visibly disrupted dwarf (such as the Sagittarius dwarf spheroidal galaxy) and one in dynamic equilibrium. The degree of disruption also shows that we must be more careful with the ways we determine object membership when estimating dwarf masses in the future. One of the three discovered RR Lyrae stars sits along the minor axis of Hercules, but over two tidal radii away. This type of debris is consistent with recent models that suggest Hercules’ orbit is aligned with its minor axis.

North Galactic Plane Structure with IPHAS Be Stars.

NASA Astrophysics Data System (ADS)

Gkouvelis, L.; Fabregat, J.; IPHAS Consortium

2016-11-01

Our goal is to investigate the spiral structure of the Northern Galactic plane using as tracers the classical Be stars detected by INT Photometric Hα Survey (IPHAS). IPHAS scans the 29oGalactic disk in the anticenter direction.

Galaxy IC 3639 with Obscured Active Galactic Nucleus

NASA Image and Video Library

2017-01-07

IC 3639, a galaxy with an active galactic nucleus, is seen in this image combining data from the Hubble Space Telescope and the European Southern Observatory. This galaxy contains an example of a supermassive black hole hidden by gas and dust. Researchers analyzed NuSTAR data from this object and compared them with previous observations from NASA's Chandra X-Ray Observatory and the Japanese-led Suzaku satellite. The findings from NuSTAR, which is more sensitive to higher energy X-rays than these observatories, confirm the nature of IC 3639 as an active galactic nucleus that is heavily obscured, and intrinsically much brighter than observed. http://photojournal.jpl.nasa.gov/catalog/PIA21087

FERMI BUBBLES AND BUBBLE-LIKE EMISSION FROM THE GALACTIC PLANE

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

De Boer, Wim; Weber, Markus, E-mail: wim.de.boer@kit.edu, E-mail: markus.weber2@kit.edu

2014-10-10

The diffuse gamma-ray sky revealed ''bubbles'' of emission above and below the Galactic plane, symmetric around the center of the Milky Way, with a height of 10 kpc in both directions. At present, there is no convincing explanation for the origin. To understand the role of the Galactic center, one has to study the bubble spectrum inside the disk, a region that has been excluded from previous analyses because of the large foreground. From a novel template fit, which allows a simultaneous determination of the signal and foreground in any direction, we find that bubble-like emission is not only found inmore » the halo, but in the Galactic plane as well, with a width in latitude coinciding with the molecular clouds. The longitude distribution has a width corresponding to the Galactic bar with an additional contribution from the Scutum-Centaurus arm. The energy spectrum of the bubbles coincides with the predicted contribution from CRs trapped in sources (SCRs). Also, the energetics fits well. Hence, we conclude that the bubble-like emission has a hadronic origin that arises from SCRs, and the bubbles in the halo arise from hadronic interactions in advected gas. Evidence for advection is provided by the ROSAT X-rays of hot gas in the bubble region.« less

Role of Turbulent Damping in Cosmic Ray Galactic Winds

NASA Astrophysics Data System (ADS)

Holguin, Francisco; Ruszkowski, Mateusz; Lazarian, Alex; Yang, H. Y. Karen

2018-06-01

Large-scale galactic winds driven by stellar feedback are one phenomenon that influences the dynamical and chemical evolution of a galaxy, pushing and redistributing material throughout the interstellar medium (ISM) and galactic halo. A detailed understanding of the exact physical mechanisms responsible for these winds is lacking. Non-thermal feedback from galactic cosmic rays (CR), high-energy charged particles accelerated in supernovae and young stars, can impact the efficiency in accelerating the wind. In the self-confinement model, CR stream along magnetic field lines at the Alfven speed due to scattering off self-excited Aflv{é}n waves. However, magneto-hydrodynamic (MHD) turbulence stirred up by stellar feedback dissipates these confining waves, allowing CR to be super Aflvenic. Previous simulations relying on a simplified model of transport have shown that super-Alfv{é}nic streaming of CRs can launch a stronger wind. We perform three-dimensional MHD simulations of a section of a galactic disk, including CR streaming dependent on the local environment, using a realistic model of turbulent dissipation of Alfven waves presented in Lazarian (2016). In this implementation, the CR streaming speed can be super Alfv{é}nic depending on local conditions. We compare results for Alfv{é}nic and locally determined streaming, and find that gas/CR distributions and instantaneous mass loading factor of the wind are different depending on the level of turbulence.Lazarian, A. “Damping of Alfven waves by turbulence and its consequences: from cosmic-ray streaming to launching winds.” ApJ. Vol. 833, Num. 2. (2016).

Detection of Another Molecular Bubble in the Galactic Center

NASA Astrophysics Data System (ADS)

Tsujimoto, Shiho; Oka, Tomoharu; Takekawa, Shunya; Yamada, Masaya; Tokuyama, Sekito; Iwata, Yuhei; Roll, Justin A.

2018-04-01

The l=-1\\buildrel{\\circ}\\over{.} 2 region in the Galactic center has a high CO J = 3–2/J = 1–0 intensity ratio and extremely broad velocity width. This paper reports the detection of five expanding shells in the l=-1\\buildrel{\\circ}\\over{.} 2 region based on the CO J = 1–0, 13CO J = 1–0, CO J = 3–2, and SiO J = 8–7 line data sets obtained with the Nobeyama Radio Observatory 45 m telescope and James Clerk Maxwell Telescope. The kinetic energy and expansion time of the expanding shells are estimated to be {10}48.3{--50.8} erg and {10}4.7{--5.0} yr, respectively. The origin of these expanding shells is discussed. The total kinetic energy of 1051 erg and the typical expansion time of ∼105 yr correspond to multiple supernova explosions at a rate of 10‑5–10‑4 yr‑1. This indicates that the l=-1\\buildrel{\\circ}\\over{.} 2 region may be a molecular bubble associated with an embedded massive star cluster, although the absence of an infrared counterpart makes this interpretation somewhat controversial. The expansion time of the shells increases as the Galactic longitude decreases, suggesting that the massive star cluster is moving from Galactic west to east with respect to the interacting molecular gas. We propose a model wherein the cluster is moving along the innermost x 1 orbit and the interacting gas collides with it from the Galactic eastern side.

Understanding EROS2 observations toward the spiral arms within a classical Galactic model framework

NASA Astrophysics Data System (ADS)

Moniez, M.; Sajadian, S.; Karami, M.; Rahvar, S.; Ansari, R.

2017-08-01

Aims: EROS (Expérience de Recherche d'Objets Sombres) has searched for microlensing toward four directions in the Galactic plane away from the Galactic center. The interpretation of the catalog optical depth is complicated by the spread of the source distance distribution. We compare the EROS microlensing observations with Galactic models (including the Besançon model), tuned to fit the EROS source catalogs, and take into account all observational data such as the microlensing optical depth, the Einstein crossing durations, and the color and magnitude distributions of the catalogued stars. Methods: We simulated EROS-like source catalogs using the HIgh-Precision PARallax COllecting Satellite (Hipparcos) database, the Galactic mass distribution, and an interstellar extinction table. Taking into account the EROS star detection efficiency, we were able to produce simulated color-magnitude diagrams that fit the observed diagrams. This allows us to estimate average microlensing optical depths and event durations that are directly comparable with the measured values. Results: Both the Besançon model and our Galactic model allow us to fully understand the EROS color-magnitude data. The average optical depths and mean event durations calculated from these models are in reasonable agreement with the observations. Varying the Galactic structure parameters through simulation, we were also able to deduce contraints on the kinematics of the disk, the disk stellar mass function (at a few kpc distance from the Sun), and the maximum contribution of a thick disk of compact objects in the Galactic plane (Mthick< 5 - 7 × 1010M⊙ at 95%, depending on the model). We also show that the microlensing data toward one of our monitored directions are significantly sensitive to the Galactic bar parameters, although much larger statistics are needed to provide competitive constraints. Conclusions: Our simulation gives a better understanding of the lens and source spatial distributions in

Planck 2015 results. XXVIII. The Planck Catalogue of Galactic cold clumps

NASA Astrophysics Data System (ADS)

Planck Collaboration; Ade, P. A. R.; Aghanim, N.; Arnaud, M.; Ashdown, M.; Aumont, J.; Baccigalupi, C.; Banday, A. J.; Barreiro, R. B.; Bartolo, N.; Battaner, E.; Benabed, K.; Benoît, A.; Benoit-Lévy, A.; Bernard, J.-P.; Bersanelli, M.; Bielewicz, P.; Bonaldi, A.; Bonavera, L.; Bond, J. R.; Borrill, J.; Bouchet, F. R.; Boulanger, F.; Bucher, M.; Burigana, C.; Butler, R. C.; Calabrese, E.; Catalano, A.; Chamballu, A.; Chiang, H. C.; Christensen, P. R.; Clements, D. L.; Colombi, S.; Colombo, L. P. L.; Combet, C.; Couchot, F.; Coulais, A.; Crill, B. P.; Curto, A.; Cuttaia, F.; Danese, L.; Davies, R. D.; Davis, R. J.; de Bernardis, P.; de Rosa, A.; de Zotti, G.; Delabrouille, J.; Désert, F.-X.; Dickinson, C.; Diego, J. M.; Dole, H.; Donzelli, S.; Doré, O.; Douspis, M.; Ducout, A.; Dupac, X.; Efstathiou, G.; Elsner, F.; Enßlin, T. A.; Eriksen, H. K.; Falgarone, E.; Fergusson, J.; Finelli, F.; Forni, O.; Frailis, M.; Fraisse, A. A.; Franceschi, E.; Frejsel, A.; Galeotta, S.; Galli, S.; Ganga, K.; Giard, M.; Giraud-Héraud, Y.; Gjerløw, E.; González-Nuevo, J.; Górski, K. M.; Gratton, S.; Gregorio, A.; Gruppuso, A.; Gudmundsson, J. E.; Hansen, F. K.; Hanson, D.; Harrison, D. L.; Helou, G.; Henrot-Versillé, S.; Hernández-Monteagudo, C.; Herranz, D.; Hildebrandt, S. R.; Hivon, E.; Hobson, M.; Holmes, W. A.; Hornstrup, A.; Hovest, W.; Huffenberger, K. M.; Hurier, G.; Jaffe, A. H.; Jaffe, T. R.; Jones, W. C.; Juvela, M.; Keihänen, E.; Keskitalo, R.; Kisner, T. S.; Knoche, J.; Kunz, M.; Kurki-Suonio, H.; Lagache, G.; Lamarre, J.-M.; Lasenby, A.; Lattanzi, M.; Lawrence, C. R.; Leonardi, R.; Lesgourgues, J.; Levrier, F.; Liguori, M.; Lilje, P. B.; Linden-Vørnle, M.; López-Caniego, M.; Lubin, P. M.; Macías-Pérez, J. F.; Maggio, G.; Maino, D.; Mandolesi, N.; Mangilli, A.; Marshall, D. J.; Martin, P. G.; Martínez-González, E.; Masi, S.; Matarrese, S.; Mazzotta, P.; McGehee, P.; Melchiorri, A.; Mendes, L.; Mennella, A.; Migliaccio, M.; Mitra, S.; Miville-Deschênes, M.-A.; Moneti, A.; Montier, L.; Morgante, G.; Mortlock, D.; Moss, A.; Munshi, D.; Murphy, J. A.; Naselsky, P.; Nati, F.; Natoli, P.; Netterfield, C. B.; Nørgaard-Nielsen, H. U.; Noviello, F.; Novikov, D.; Novikov, I.; Oxborrow, C. A.; Paci, F.; Pagano, L.; Pajot, F.; Paladini, R.; Paoletti, D.; Pasian, F.; Patanchon, G.; Pearson, T. J.; Pelkonen, V.-M.; Perdereau, O.; Perotto, L.; Perrotta, F.; Pettorino, V.; Piacentini, F.; Piat, M.; Pierpaoli, E.; Pietrobon, D.; Plaszczynski, S.; Pointecouteau, E.; Polenta, G.; Pratt, G. W.; Prézeau, G.; Prunet, S.; Puget, J.-L.; Rachen, J. P.; Reach, W. T.; Rebolo, R.; Reinecke, M.; Remazeilles, M.; Renault, C.; Renzi, A.; Ristorcelli, I.; Rocha, G.; Rosset, C.; Rossetti, M.; Roudier, G.; Rubiño-Martín, J. A.; Rusholme, B.; Sandri, M.; Santos, D.; Savelainen, M.; Savini, G.; Scott, D.; Seiffert, M. D.; Shellard, E. P. S.; Spencer, L. D.; Stolyarov, V.; Sudiwala, R.; Sunyaev, R.; Sutton, D.; Suur-Uski, A.-S.; Sygnet, J.-F.; Tauber, J. A.; Terenzi, L.; Toffolatti, L.; Tomasi, M.; Tristram, M.; Tucci, M.; Tuovinen, J.; Umana, G.; Valenziano, L.; Valiviita, J.; Van Tent, B.; Vielva, P.; Villa, F.; Wade, L. A.; Wandelt, B. D.; Wehus, I. K.; Yvon, D.; Zacchei, A.; Zonca, A.

2016-09-01

We present the Planck Catalogue of Galactic Cold Clumps (PGCC), an all-sky catalogue of Galactic cold clump candidates detected by Planck. This catalogue is the full version of the Early Cold Core (ECC) catalogue, which was made available in 2011 with the Early Release Compact Source Catalogue (ERCSC) and which contained 915 high signal-to-noise sources. It is based on the Planck 48-month mission data that are currently being released to the astronomical community. The PGCC catalogue is an observational catalogue consisting exclusively of Galactic cold sources. The three highest Planck bands (857, 454, and 353 GHz) have been combined with IRAS data at 3 THz to perform a multi-frequency detection of sources colder than their local environment. After rejection of possible extragalactic contaminants, the PGCC catalogue contains 13188 Galactic sources spread across the whole sky, I.e., from the Galactic plane to high latitudes, following the spatial distribution of the main molecular cloud complexes. The median temperature of PGCC sources lies between 13 and 14.5 K, depending on the quality of the flux density measurements, with a temperature ranging from 5.8 to 20 K after removing the sources with the top 1% highest temperature estimates. Using seven independent methods, reliable distance estimates have been obtained for 5574 sources, which allows us to derive their physical properties such as their mass, physical size, mean density, and luminosity.The PGCC sources are located mainly in the solar neighbourhood, but also up to a distance of 10.5 kpc in the direction of the Galactic centre, and range from low-mass cores to large molecular clouds. Because of this diversity and because the PGCC catalogue contains sources in very different environments, the catalogue is useful for investigating the evolution from molecular clouds to cores. Finally, it also includes 54 additional sources located in the Small and Large Magellanic Clouds.

Planck 2015 results: XXVIII. The Planck Catalogue of Galactic cold clumps

DOE PAGES

Ade, P. A. R.; Aghanim, N.; Arnaud, M.; ...

2016-09-20

Here, we present the Planck Catalogue of Galactic Cold Clumps (PGCC), an all-sky catalogue of Galactic cold clump candidates detected by Planck. This catalogue is the full version of the Early Cold Core (ECC) catalogue, which was made available in 2011 with the Early Release Compact Source Catalogue (ERCSC) and which contained 915 high signal-to-noise sources. It is based on the Planck 48-month mission data that are currently being released to the astronomical community. The PGCC catalogue is an observational catalogue consisting exclusively of Galactic cold sources. The three highest Planck bands (857, 454, and 353 GHz) have been combinedmore » with IRAS data at 3 THz to perform a multi-frequency detection of sources colder than their local environment. After rejection of possible extragalactic contaminants, the PGCC catalogue contains 13188 Galactic sources spread across the whole sky, i.e., from the Galactic plane to high latitudes, following the spatial distribution of the main molecular cloud complexes. The median temperature of PGCC sources lies between 13 and 14.5 K, depending on the quality of the flux density measurements, with a temperature ranging from 5.8 to 20 K after removing the sources with the top 1% highest temperature estimates. Using seven independent methods, reliable distance estimates have been obtained for 5574 sources, which allows us to derive their physical properties such as their mass, physical size, mean density, and luminosity.The PGCC sources are located mainly in the solar neighbourhood, but also up to a distance of 10.5 kpc in the direction of the Galactic centre, and range from low-mass cores to large molecular clouds. Because of this diversity and because the PGCC catalogue contains sources in very different environments, the catalogue is useful for investigating the evolution from molecular clouds to cores. Finally, it also includes 54 additional sources located in the Small and Large Magellanic Clouds.« less

WISEGAL. WISE for the Galactic Plane

NASA Astrophysics Data System (ADS)

Noriega-Crespo, Alberto

There is truly a community effort to study on a global scale the properties of the Milky Way, like its structure, its star formation and interstellar medium, and to use this knowledge to create accurate templates to understand the properties of extragalactic systems. A testimony of this effort are the multi-wavelength surveys of the Galactic Plane that have been recently carried out or are underway from both the ground (e.g. IPHAS, ATLASGAL, JCMT Galactic Plane Survey) or space (GLIMPSE, MIPSGAL, HiGAL). Adding to this wealth of data is the recent release of approximately 57 percent of the whole sky by the Wide-field Infrared Survey Explorer (WISE) team of their high angular resolution and sensitive mid-IR (3.4, 4.6, 12 and 22 micron) images and point source catalogs, encompassing nearly three quarters of the Galactic Plane, including the less studied regions of the Outer Galaxy. The WISE Atlas Images are spectacular, but to take full advantage of them, they need to be transformed from their default Data Number (DN) units into absolute surface brightness calibrated units. Furthermore, to mitigate the contamination effect of the point sources on the extended/diffuse emission, we will remove them and create residual images. This processing will enable a wide range of science projects using the Atlas Images, where measuring the spectral energy distribution of the extended emission is crucial. In this project we propose to transform the W3 (12 micron) and W4 (22 micron) images of the Galactic Plane, in particular of the Outer Galaxy where WISE provides an unique data set, into a background-calibrated, point-source subtracted images using IRIS (DIRBE IRAS Calibrated data). This transformation will allow us to carry out research projects on Massive star formation, the properties of dust in the diffuse ISM, the three dimensional distribution of the dust emission in the Galaxy and the mid/far infrared properties of Supernova Remnants, among others, and to perform a

Evolution of Supernova Remnants Near the Galactic Center

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

Yalinewich, A.; Piran, T.; Sari, R.

Supernovae near the Galactic center (GC) evolve differently from regular Galactic supernovae. This is mainly due to the environment into which the supernova remnants (SNRs) propagate. SNRs near the GC propagate into a wind swept environment with a velocity directed away from the GC, and a graded density profile. This causes these SNRs to be non-spherical, and to evolve faster than their Galactic counterparts. We develop an analytic theory for the evolution of explosions within a stellar wind, and verify it using a hydrodynamic code. We show that such explosions can evolve in one of three possible morphologies. Using thesemore » results we discuss the association between the two SNRs (SGR East and SGR A’s bipolar radio/X-ray lobes) and the two neutron stars (the Cannonball and SGR J1745-2900) near the GC. We show that, given the morphologies of the SNR and positions of the neutron stars, the only possible association is between SGR A’s bipolar radio/X-ray lobes and SGR J1745-2900. If a compact object was created in the explosion of SGR East, it remains undetected, and the SNR of the supernova that created the Cannonball has already disappeared.« less

Einstein Observations of Galactic supernova remnants

NASA Technical Reports Server (NTRS)

Seward, Frederick D.

1990-01-01

This paper summarizes the observations of Galactic supernova remnants with the imaging detectors of the Einstein Observatory. X-ray surface brightness contours of 47 remnants are shown together with gray-scale pictures. Count rates for these remnants have been derived and are listed for the HRI, IPC, and MPC detectors.

A Disk Origin for the Monoceros Ring and A13 Stellar Overdensities

NASA Astrophysics Data System (ADS)

Sheffield, Allyson A.; Price-Whelan, Adrian M.; Tzanidakis, Anastasios; Johnston, Kathryn V.; Laporte, Chervin F. P.; Sesar, Branimir

2018-02-01

The Monoceros Ring (also known as the Galactic Anticenter Stellar Structure) and A13 are stellar overdensities at estimated heliocentric distances of d ∼ 11 kpc and 15 kpc observed at low Galactic latitudes toward the anticenter of our Galaxy. While these overdensities were initially thought to be remnants of a tidally disrupted satellite galaxy, an alternate scenario is that they are composed of stars from the Milky Way (MW) disk kicked out to their current location due to interactions between a satellite galaxy and the disk. To test this scenario, we study the stellar populations of the Monoceros Ring and A13 by measuring the number of RR Lyrae and M giant stars associated with these overdensities. We obtain low-resolution spectroscopy for RR Lyrae stars in the two structures and measure radial velocities to compare with previously measured velocities for M giant stars in the regions of the Monoceros Ring and A13, to assess the fraction of RR Lyrae to M giant stars (f RR:MG) in A13 and Mon/GASS. We perform velocity modeling on 153 RR Lyrae stars (116 in the Monoceros Ring and 37 in A13) and find that both structures have very low f RR:MG. The results support a scenario in which stars in A13 and Mon/GASS formed in the MW disk. We discuss a possible association between Mon/GASS, A13, and the Triangulum-Andromeda overdensity based on their similar velocity distributions and f RR:MG.

Active galactic nucleus outflows in galaxy discs

NASA Astrophysics Data System (ADS)

Hartwig, Tilman; Volonteri, Marta; Dashyan, Gohar

2018-05-01

Galactic outflows, driven by active galactic nuclei (AGNs), play a crucial role in galaxy formation and in the self-regulated growth of supermassive black holes (BHs). AGN feedback couples to and affects gas, rather than stars, and in many, if not most, gas-rich galaxies cold gas is rotationally supported and settles in a disc. We present a 2D analytical model for AGN-driven outflows in a gaseous disc and demonstrate the main improvements, compared to existing 1D solutions. We find significant differences for the outflow dynamics and wind efficiency. The outflow is energy-driven due to inefficient cooling up to a certain AGN luminosity (˜1043 erg s-1 in our fiducial model), above which the outflow remains momentum-driven in the disc up to galactic scales. We reproduce results of 3D simulations that gas is preferentially ejected perpendicular to the disc and find that the fraction of ejected interstellar medium is lower than in 1D models. The recovery time of gas in the disc, defined as the free-fall time from the radius to which the AGN pushes the ISM at most, is remarkably short, of the order 1 Myr. This indicates that AGN-driven winds cannot suppress BH growth for long. Without the inclusion of supernova feedback, we find a scaling of the BH mass with the halo velocity dispersion of MBH ∝ σ4.8.

The population of planetary nebulae near the Galactic Centre: chemical abundances

NASA Astrophysics Data System (ADS)

Mollá, M.; Cavichia, O.; Costa, R. D. D.; Maciel, W. J.

2017-10-01

In this work, we report physical parameters and abundances derived for a sample of 15 high extinction planetary nebulae located in the inner 2° of the Galactic bulge, based on low dispersion spectroscopy secured at the SOAR telescope using the Goodman spectrograph. The new data allow us to extend our database including older, weaker objects that are at the faint end of the planetary nebulae luminosity function. The data provide chemical compositions for PNe located in this region of the bulge to explore the chemical enrichment history of the central region of the Galactic bulge. The results show that the abundances of our sample are skewed to higher metallicities than previous data in the outer regions of the bulge. This can indicate a faster chemical enrichment taking place at the Galactic centre.

FUSE Observations of Galactic and LMC Novae in Outburst

NASA Technical Reports Server (NTRS)

Huschildt, P. H.

2001-01-01

This document is a collection of five abstracts from papers written on the 'FUSE Observations of Galactic and LMC Novae in Outburst'. The titles are the following: (1) Analyzing FUSE Observations of Galactic and LMC Novae; (2) Detailed NLTE Model Atmospheres for Novae during Outburst: Modeling Optical and Ultraviolet Observations for Nova LMC 1988; (3) Numerical Solution of the Expanding Stellar Atmosphere Problem; (4) A Non-LTE Line-Blanketed Expanding Atmosphere Model for A-supergiant Alpha Cygni; and (5) Non-LTE Model Atmosphere Analysis of the Early Ultraviolet Spectra of Nova Andromedae 1986. A list of journal publications is also included.

Unusual Metals in Galactic Center Stars

NASA Astrophysics Data System (ADS)

Hensley, Kerry

2018-03-01

Far from the galactic suburbs where the Sun resides, a cluster of stars in the nucleus of the Milky Way orbits a supermassive black hole. Can chemical abundance measurements help us understand the formation history of the galactic center nuclear star cluster?Studying Stellar PopulationsMetallicity distributions for stars in the inner two degrees of the Milky Way (blue) and the central parsec (orange). [Do et al. 2018]While many galaxies host nuclear star clusters, most are too distant for us to study in detail; only in the Milky Way can we resolve individual stars within one parsec of a supermassive black hole. The nucleus of our galaxy is an exotic and dangerous place, and its not yet clear how these stars came to be where they are were they siphoned off from other parts of the galaxy, or did they form in place, in an environment rocked by tidal forces?Studying the chemical abundances of stars provides a way to separate distinct stellar populations and discern when and where these stars formed. Previous studies using medium-resolution spectroscopy have revealed that many stars within the central parsec of our galaxy have very high metallicities possibly higher than any other region of the Milky Way. Can high-resolution spectroscopy tell us more about this unusual population of stars?Spectral Lines on DisplayTuan Do (University of California, Los Angeles, Galactic Center Group) and collaborators performed high-resolution spectroscopic observations of two late-type giant starslocated half a parsec from the Milky Ways supermassive black hole.Comparison of the observed spectra of the two galactic center stars (black) with synthetic spectra with low (blue) and high (orange) [Sc/Fe] values. Click to enlarge. [Do et al. 2018]In order to constrain the metallicities of these stars, Do and collaborators compared the observed spectra to a grid of synthetic spectra and used a spectral synthesis technique to determine the abundances of individual elements. They found that

Ground-based photometry for 42 Kepler-field RR Lyrae stars

NASA Astrophysics Data System (ADS)

Jeon, Young-Beom; Ngeow, Chow-Choong; Nemec, James M.

2014-02-01

Follow-up (U)BVRI photometric observations have been carried out for 42 RR Lyrae stars in the Kepler field. The new magnitude and color information will complement the available extensive high-precision Kepler photometry and recent spectroscopic results. The photometric observations were made with the following telescopes: 1-m and 41-cm telescopes of Lulin Observatory (Taiwan), 81-cm telescope of Tenagra Observatory (Arizona, USA), 1-m telescope at the Mt. Lemmon Optical Astronomy Observatory (LOAO, Arizona, USA), 1.8-m and 15-cm telescopes at the Bohyunsan Optical Astronomy Observatory (BOAO, Korea) and 61-cm telescope at the Sobaeksan Optical Astronomy Observatory (SOAO, Korea). The observations span from 2010 to 2013, with ~200 to ~600 data points per light curve. Preliminary results of the Korean observations were presented at the 5th KASC workshop in Hungary. In this work, we analyze all observations. These observations permit the construction of full light curves for these RR Lyrae stars and can be used to derive multi-filter Fourier parameters.

Constraints on Galactic Neutrino Emission with Seven Years of IceCube Data

NASA Astrophysics Data System (ADS)

Aartsen, M. G.; Ackermann, M.; Adams, J.; Aguilar, J. A.; Ahlers, M.; Ahrens, M.; Samarai, I. Al; Altmann, D.; Andeen, K.; Anderson, T.; Ansseau, I.; Anton, G.; Argüelles, C.; Auffenberg, J.; Axani, S.; Bagherpour, H.; Bai, X.; Barron, J. P.; Barwick, S. W.; Baum, V.; Bay, R.; Beatty, J. J.; Becker Tjus, J.; Becker, K.-H.; BenZvi, S.; Berley, D.; Bernardini, E.; Besson, D. Z.; Binder, G.; Bindig, D.; Blaufuss, E.; Blot, S.; Bohm, C.; Börner, M.; Bos, F.; Bose, D.; Böser, S.; Botner, O.; Bourbeau, J.; Bradascio, F.; Braun, J.; Brayeur, L.; Brenzke, M.; Bretz, H.-P.; Bron, S.; Burgman, A.; Carver, T.; Casey, J.; Casier, M.; Cheung, E.; Chirkin, D.; Christov, A.; Clark, K.; Classen, L.; Coenders, S.; Collin, G. H.; Conrad, J. M.; Cowen, D. F.; Cross, R.; Day, M.; de André, J. P. A. M.; De Clercq, C.; DeLaunay, J. J.; Dembinski, H.; De Ridder, S.; Desiati, P.; de Vries, K. D.; de Wasseige, G.; de With, M.; DeYoung, T.; Díaz-Vélez, J. C.; di Lorenzo, V.; Dujmovic, H.; Dumm, J. P.; Dunkman, M.; Eberhardt, B.; Ehrhardt, T.; Eichmann, B.; Eller, P.; Evenson, P. A.; Fahey, S.; Fazely, A. R.; Felde, J.; Filimonov, K.; Finley, C.; Flis, S.; Franckowiak, A.; Friedman, E.; Fuchs, T.; Gaisser, T. K.; Gallagher, J.; Gerhardt, L.; Ghorbani, K.; Giang, W.; Glauch, T.; Glüsenkamp, T.; Goldschmidt, A.; Gonzalez, J. G.; Grant, D.; Griffith, Z.; Haack, C.; Hallgren, A.; Halzen, F.; Hanson, K.; Hebecker, D.; Heereman, D.; Helbing, K.; Hellauer, R.; Hickford, S.; Hignight, J.; Hill, G. C.; Hoffman, K. D.; Hoffmann, R.; Hokanson-Fasig, B.; Hoshina, K.; Huang, F.; Huber, M.; Hultqvist, K.; In, S.; Ishihara, A.; Jacobi, E.; Japaridze, G. S.; Jeong, M.; Jero, K.; Jones, B. J. P.; Kalacynski, P.; Kang, W.; Kappes, A.; Karg, T.; Karle, A.; Katz, U.; Kauer, M.; Keivani, A.; Kelley, J. L.; Kheirandish, A.; Kim, J.; Kim, M.; Kintscher, T.; Kiryluk, J.; Kittler, T.; Klein, S. R.; Kohnen, G.; Koirala, R.; Kolanoski, H.; Köpke, L.; Kopper, C.; Kopper, S.; Koschinsky, J. P.; Koskinen, D. J.; Kowalski, M.; Krings, K.; Kroll, M.; Krückl, G.; Kunnen, J.; Kunwar, S.; Kurahashi, N.; Kuwabara, T.; Kyriacou, A.; Labare, M.; Lanfranchi, J. L.; Larson, M. J.; Lauber, F.; Lennarz, D.; Lesiak-Bzdak, M.; Leuermann, M.; Liu, Q. R.; Lu, L.; Lünemann, J.; Luszczak, W.; Madsen, J.; Maggi, G.; Mahn, K. B. M.; Mancina, S.; Maruyama, R.; Mase, K.; Maunu, R.; McNally, F.; Meagher, K.; Medici, M.; Meier, M.; Menne, T.; Merino, G.; Meures, T.; Miarecki, S.; Micallef, J.; Momenté, G.; Montaruli, T.; Moore, R. W.; Moulai, M.; Nahnhauer, R.; Nakarmi, P.; Naumann, U.; Neer, G.; Niederhausen, H.; Nowicki, S. C.; Nygren, D. R.; Obertacke Pollmann, A.; Olivas, A.; O'Murchadha, A.; Palczewski, T.; Pandya, H.; Pankova, D. V.; Peiffer, P.; Pepper, J. A.; Pérez de los Heros, C.; Pieloth, D.; Pinat, E.; Plum, M.; Price, P. B.; Przybylski, G. T.; Raab, C.; Rädel, L.; Rameez, M.; Rawlins, K.; Reimann, R.; Relethford, B.; Relich, M.; Resconi, E.; Rhode, W.; Richman, M.; Robertson, S.; Rongen, M.; Rott, C.; Ruhe, T.; Ryckbosch, D.; Rysewyk, D.; Sälzer, T.; Sanchez Herrera, S. E.; Sandrock, A.; Sandroos, J.; Sarkar, S.; Sarkar, S.; Satalecka, K.; Schlunder, P.; Schmidt, T.; Schneider, A.; Schoenen, S.; Schöneberg, S.; Schumacher, L.; Seckel, D.; Seunarine, S.; Soldin, D.; Song, M.; Spiczak, G. M.; Spiering, C.; Stachurska, J.; Stanev, T.; Stasik, A.; Stettner, J.; Steuer, A.; Stezelberger, T.; Stokstad, R. G.; Stößl, A.; Strotjohann, N. L.; Sullivan, G. W.; Sutherland, M.; Taboada, I.; Tatar, J.; Tenholt, F.; Ter-Antonyan, S.; Terliuk, A.; Tešić, G.; Tilav, S.; Toale, P. A.; Tobin, M. N.; Toscano, S.; Tosi, D.; Tselengidou, M.; Tung, C. F.; Turcati, A.; Turley, C. F.; Ty, B.; Unger, E.; Usner, M.; Vandenbroucke, J.; Van Driessche, W.; van Eijndhoven, N.; Vanheule, S.; van Santen, J.; Vehring, M.; Vogel, E.; Vraeghe, M.; Walck, C.; Wallace, A.; Wallraff, M.; Wandler, F. D.; Wandkowsky, N.; Waza, A.; Weaver, C.; Weiss, M. J.; Wendt, C.; Westerhoff, S.; Whelan, B. J.; Wickmann, S.; Wiebe, K.; Wiebusch, C. H.; Wille, L.; Williams, D. R.; Wills, L.; Wolf, M.; Wood, J.; Wood, T. R.; Woolsey, E.; Woschnagg, K.; Xu, D. L.; Xu, X. W.; Xu, Y.; Yanez, J. P.; Yodh, G.; Yoshida, S.; Yuan, T.; Zoll, M.; IceCube Collaboration

2017-11-01

The origins of high-energy astrophysical neutrinos remain a mystery despite extensive searches for their sources. We present constraints from seven years of IceCube Neutrino Observatory muon data on the neutrino flux coming from the Galactic plane. This flux is expected from cosmic-ray interactions with the interstellar medium or near localized sources. Two methods were developed to test for a spatially extended flux from the entire plane, both of which are maximum likelihood fits but with different signal and background modeling techniques. We consider three templates for Galactic neutrino emission based primarily on gamma-ray observations and models that cover a wide range of possibilities. Based on these templates and in the benchmark case of an unbroken {E}-2.5 power-law energy spectrum, we set 90% confidence level upper limits, constraining the possible Galactic contribution to the diffuse neutrino flux to be relatively small, less than 14% of the flux reported in Aartsen et al. above 1 TeV. A stacking method is also used to test catalogs of known high-energy Galactic gamma-ray sources.

Finding evolved stars in the inner Galactic disk with Gaia

NASA Astrophysics Data System (ADS)

Quiroga-Nuñez, L. H.; van Langevelde, H. J.; Pihlström, Y. M.; Sjouwerman, L. O.; Brown, A. G. A.

2018-04-01

The Bulge Asymmetries and Dynamical Evolution (BAaDE) survey will provide positions and line-of-sight velocities of ~20, 000 evolved, maser bearing stars in the Galactic plane. Although this Galactic region is affected by optical extinction, BAaDE targets may have Gaia cross-matches, eventually providing additional stellar information. In an initial attempt to cross-match BAaDE targets with Gaia, we have found more than 5,000 candidates. Of these, we may expect half to show SiO emission, which will allow us to obtain velocity information. The cross-match is being refined to avoid false positives using different criteria based on distance analysis, flux variability, and color assessment in the mid- and near-IR. Once the cross-matches can be confirmed, we will have a unique sample to characterize the stellar population of evolved stars in the Galactic bulge, which can be considered fossils of the Milky Way formation.

Ordinary Dark Matter versus Mysterious Dark Matter in Galactic Rotation

NASA Astrophysics Data System (ADS)

Gallo, C. F.; Feng, James

2008-04-01

To theoretically describe the measured rotational velocity curves of spiral galaxies, there are two different approaches and conclusions. (1) ORDINARY DARK MATTER. We assume Newtonian gravity/dynamics and successfully find (via computer) mass distributions in bulge/disk configurations that duplicate the measured rotational velocities. There is ordinary dark matter within the galactic disk towards the cooler periphery which has lower emissivity/opacity. There are no mysteries in this scenario based on verified physics. (2) MYSTERIOUS DARK MATTER. Others INaccurately assume the galactic mass distributions follow the measured light distributions, and then the measured rotational velocity curves are NOT duplicated. To alleviate this discrepancy, speculations are invoked re ``Massive Peripheral Spherical Halos of Mysterious Dark Matter.'' But NO matter has been detected in this UNtenable Halo configuration. Many UNverified ``Mysteries'' are invoked as necessary and convenient. CONCLUSION. The first approach utilizing Newtonian gravity/dynamics and searching for the ordinary mass distributions within the galactic disk simulates reality and agrees with data.

Query Storage and Relay in Research Root (LACREND RR)

DTIC Science & Technology

2017-05-30

QUERY STORAGE AND RELAY IN RESEARCH ROOT (LACREND-RR) UNIVERSITY OF SOUTHERN CALIFORNIA MAY 2017 FINAL TECHNICAL REPORT APPROVED FOR PUBLIC ...exempt from public affairs security and policy review in accordance with SAF/AQR memorandum dated 10 Dec 08 and AFRL/CA policy clarification...memorandum dated 16 Jan 09. This report is available to the general public , including foreign nationals. Copies may be obtained from the Defense Technical

The Formation and Evolution of Galactic Disks with APOGEE and the Gaia Survey

NASA Astrophysics Data System (ADS)

Li, Chengdong; Zhao, Gang; Zhai, Meng; Jia, Yunpeng

2018-06-01

We explore the structure and evolutionary history of Galactic disks with Apache Point Observatory Galactic Evolution Experiment data release 13 (DR13 hereafter) and Gaia Tycho-Gaia Astrometric Solution data. We use the [α/M] ratio to allocate stars into particular Galactic components to elucidate the chemical and dynamical properties of the thin and thick disks. The spatial motions of the sample stars are obtained in Galactic Cartesian and cylindrical coordinates. We analyze the abundance trends and metallicity and [α/M] gradients of the thick and thin disks. We confirm the existence of metal-weak thick-disk stars in Galactic disks. A kinematical method is used to select the thin- and thick-disk stars for comparison. We calculate the scale length and scale height of the kinematically and chemically selected thick and thin disks based on the axisymmetric Jeans equation. We conclude that the scale length of the thick disk is approximately equal to that of the thin disk via a kinematical approach. For the chemical selection, this disparity is about 1 kpc. Finally, we get the stellar orbital parameters and try to unveil the formation scenario of the thick disk. We conclude that the gas-rich merger and radial migration are more reasonable formation scenarios for the thick disk.

VizieR Online Data Catalog: Type II Cepheid and RR Lyrae variables (Feast+, 2008)

NASA Astrophysics Data System (ADS)

Feast, M. W.; Laney, C. D.; Kinman, T. D.; van Leeuwen, F.; Whitelock, P. A.

2008-10-01

Infrared and optical absolute magnitudes are derived for the type II Cepheids kappa Pav and VY Pyx using revised Hipparcos parallaxes and for kappa Pav, V553 Cen and SW Tau from pulsational parallaxes. Revised Hipparcos and HST parallaxes for RR Lyrae agree satisfactorily and are combined in deriving absolute magnitudes. Phase-corrected J, H and Ks mags are given for 142 Hipparcos RR Lyraes based on Two-Micron All-Sky Survey observations. Pulsation and trigonometrical parallaxes for classical Cepheids are compared to establish the best value for the projection factor (p) used in pulsational analyses. (3 data files).

Sagittarius A* as an origin of the Galactic PeV cosmic rays?

NASA Astrophysics Data System (ADS)

Fujita, Yutaka; Murase, Kohta; Kimura, Shigeo S.

2017-04-01

Supernova remnants (SNRs) have commonly been considered as a source of the observed PeV cosmic rays (CRs) or a Galactic PeV particle accelerator ("Pevatron"). In this work, we study Sagittarius A* (Sgr A*), which is the low-luminosity active galactic nucleus of the Milky Way Galaxy, as another possible canditate of the Pevatron, because it sometimes became very active in the past. We assume that a large number of PeV CRs were injected by Sgr A* at the outburst about 107 yr ago when the Fermi bubbles were created. We constrain the diffusion coefficient for the CRs in the Galactic halo on the condition that the CRs have arrived on the Earth by now, while a fairly large fraction of them have escaped from the halo. Based on a diffusion-halo model, we solve a diffusion equation for the CRs and compare the results with the CR spectrum on the Earth. The observed small anisotropy of the arrival directions of CRs may be explained if the diffusion coefficient in the Galactic disk is smaller than that in the halo. Our model predicts that a boron-to-carbon ratio should be energy-independent around the knee, where the CRs from Sgr A* become dominant. It is unlikely that the spectrum of the CRs accelerated at the outburst is represented by a power-law similar to the one for those responsible for the gamma-ray emission from the central molecular zone (CMZ) around the Galactic center.

Reconfinement and loss of stability in jets from active galactic nuclei

NASA Astrophysics Data System (ADS)

Gourgouliatos, Konstantinos N.; Komissarov, Serguei S.

2018-02-01

Jets powered by active galactic nuclei appear impressively stable compared with their terrestrial and laboratory counterparts—they can be traced from their origin to distances exceeding their injection radius by up to a billion times1,2. However, some less energetic jets get disrupted and lose their coherence on the scale of their host galaxy1,3. Quite remarkably, on the same scale, these jets are expected to become confined by the thermal pressure of the intra-galactic gas2. Motivated by these observations, we have started a systematic study of active galactic nuclei jets undergoing reconfinement via computer simulations. Here, we show that in the case of unmagnetized relativistic jets, the reconfinement is accompanied by the development of an instability and transition to a turbulent state. During their initial growth, the perturbations have a highly organized streamwise-oriented structure, indicating that it is not the Kelvin-Helmholtz instability, the instability which has been the main focus of the jet stability studies so far4,5. Instead, it is closely related to the centrifugal instability6. This instability is likely to be behind the division of active galactic nuclei jets into two morphological types in the Fanaroff-Riley classification7.

TEV GAMMA-RAY OBSERVATIONS OF THE GALACTIC CENTER RIDGE BY VERITAS

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

Archer, A.; Buckley, J. H.; Bugaev, V.

2016-04-20

The Galactic Center ridge has been observed extensively in the past by both GeV and TeV gamma-ray instruments revealing a wealth of structure, including a diffuse component and the point sources G0.9+0.1 (a composite supernova remnant) and Sgr A* (believed to be associated with the supermassive black hole located at the center of our Galaxy). Previous very high energy (VHE) gamma-ray observations with the H.E.S.S. experiment have also detected an extended TeV gamma-ray component along the Galactic plane in the >300 GeV gamma-ray regime. Here we report on observations of the Galactic Center ridge from 2010 to 2014 by themore » VERITAS telescope array in the >2 TeV energy range. From these observations we (1) provide improved measurements of the differential energy spectrum for Sgr A* in the >2 TeV gamma-ray regime, (2) provide a detection in the >2 TeV gamma-ray emission from the composite SNR G0.9+0.1 and an improved determination of its multi-TeV gamma-ray energy spectrum, and (3) report on the detection of VER J1746-289, a localized enhancement of >2 TeV gamma-ray emission along the Galactic plane.« less

Diffuse Gamma Rays Galactic and Extragalactic Diffuse Emission

NASA Technical Reports Server (NTRS)

Moskalenko, Igor V.; Strong, Andrew W.; Reimer, Olaf

2004-01-01

Diffuse gamma rays consist of several components: truly diffuse emission from the interstellar medium, the extragalactic background, whose origin is not firmly established yet, and the contribution from unresolved and faint Galactic point sources. One approach to unravel these components is to study the diffuse emission from the interstellar medium, which traces the interactions of high energy particles with interstellar gas and radiation fields. Because of its origin such emission is potentially able to reveal much about the sources and propagation of cosmic rays. The extragalactic background, if reliably determined, can be used in cosmological and blazar studies. Studying the derived average spectrum of faint Galactic sources may be able to give a clue to the nature of the emitting objects.

Galactic Hearts of Glass

NASA Technical Reports Server (NTRS)

2006-01-01

[figure removed for brevity, see original site] Click on image for larger graph

This artist's concept shows delicate greenish crystals sprinkled throughout the violent core of a pair of colliding galaxies. The white spots represent a thriving population of stars of all sizes and ages. NASA's Spitzer Space Telescope detected more than 20 bright and dusty galactic mergers like the one depicted here, all teeming with the tiny gem-like crystals.

When galaxies collide, they trigger the birth of large numbers of massive stars. Astronomers believe these blazing hot stars act like furnaces to produce silicate crystals in the same way that glass is made from sand. The stars probably shed the crystals as they age, and as they blow apart in supernovae explosions.

At the same time the crystals are being churned out, they are also being destroyed. Fast-moving particles from supernova blasts easily convert silicates crystals back to their amorphous, or shapeless, form.

How is Spitzer seeing the crystals if they are rapidly disappearing? Astronomers say that, for a short period of time at the beginning of galactic mergers, massive stars might be producing silicate crystals faster than they are eliminating them. When our own galaxy merges with the Andromeda galaxy in a few billion years, a similar burst of massive stars and silicate crystals might occur.

Crystal Storm in Distant Galaxy The graph (see inset above) of infrared data from NASA's Spitzer Space Telescope tells astronomers that a distant galaxy called IRAS 08752+3915 is experiencing a storm of tiny crystals made up of silicates. The crystals are similar to the glass-like grains of sand found on Earth's many beaches.

The data were taken by Spitzer's infrared spectrograph, which splits light open to reveal its rainbow-like components. The resulting spectrum shown here reveals the signatures of both crystalline (green) and non-crystalline (brown) silicates.

Spitzer detected the same

The black hole at the Galactic Center: observations and models in a nutshell

NASA Astrophysics Data System (ADS)

Zakharov, Alexander

2017-12-01

The Galactic Center (Sgr A*) is a peculiar place in our Galaxy (Milky Way). Our Solar system is located at a distance around 8 kpc from the Galactic Center (GC). There were a number of different including exotic ones such as boson stars, fermion balls, neutrino balls, a cluster of neutron stars. Some of these models are significantly constrained with consequent observations and now supermassive black hole with mass around 4 × 106 M ⊙ is the preferable model for GC. Moreover, one can test alternative theories of gravity with observations of bright stars near the Galactic Center and and observations of bright structures near the black hole at the Galactic Center to reconstruct shadow structure around the black hole with current and future observational VLBI facilities such as the Event Horizon Telescope. In particular, we got a graviton mass constraint which is comparable and consistent with constraints obtained recently by the LIGO-Virgo collaboration.

Research on the Solid State Fermentation of Jerusalem Artichoke Pomace for Producing R,R-2,3-Butanediol by Paenibacillus polymyxa ZJ-9.

PubMed

Cao, Can; Zhang, Li; Gao, Jian; Xu, Hong; Xue, Feng; Huang, Weiwei; Li, Yan

2017-06-01

R,R-2,3-butanediol (R,R-2,3-BD) was produced by Paenibacillus polymyxa ZJ-9, which was capable of utilizing inulin without previous hydrolysis. The Jerusalem artichoke pomace (JAP) derived from the conversion of Jerusalem artichoke powder into inulin extract, which was usually used for biorefinery by submerged fermentation (SMF), was utilized in solid state fermentation (SSF) to produce R,R-2,3-BD. In this study, the fermentation parameters of SSF were optimized and determined in flasks. A novel bioreactor was designed and assembled for the laboratory scale-up of SSF, with a maximum yield of R,R-2,3-BD (67.90 g/kg (JAP)). This result is a 36.3% improvement compared with the flasks. Based on the same bath of Jerusalem artichoke powder, the total output of R,R-2,3-BD increased by 38.8% for the SSF of JAP combined with the SMF of inulin extraction. Overall, the utilization of JAP for R,R-2,3-BD production was beneficial to the comprehensive utilization of Jerusalem artichoke tuber.

The QUEST RR Lyrae Survey. II. The Halo Overdensities in the First Catalog

NASA Astrophysics Data System (ADS)

Vivas, A. Katherina; Zinn, Robert

2006-08-01

The first catalog of the RR Lyrae stars (RRLSs) in the Galactic halo by the Quasar Equatorial Survey Team (QUEST) has been searched for significant overdensities that may be debris from disrupted dwarf galaxies or globular clusters. These RRLSs are contained in a band ~2.3d wide in declination that spans ~165° in right ascension and lie ~4 to ~60 kpc from the Sun. Away from the major overdensities, the distribution of these stars is adequately fitted by a smooth halo model, in which the flattening of the halo decreases with increasing galactocentric distance (as reported by Preston et al.). This model was used to estimate the ``background'' of RRLSs on which the halo overdensities are overlaid. A procedure was developed for recognizing groups of stars that constitute significant overdensities with respect to this background. To test this procedure, a Monte Carlo routine was used to make artificial RRLS surveys that follow the smooth halo model but with Poisson-distributed noise in the numbers of RRLSs and, within limits, random variations in the positions and magnitudes of the artificial stars. The 104 artificial surveys created by this routine were examined for significant groups in exactly the same way as the QUEST survey. These calculations provided estimates of the frequencies with which random fluctuations produce significant groups. In the QUEST survey there are six significant overdensities that contain six or more stars and several smaller ones. The small ones and possibly one or two of the larger ones may be artifacts of statistical fluctuations, and they need to be confirmed by measurements of radial velocity and/or proper motion. The most prominent groups are the northern stream from the Sagittarius dwarf spheroidal galaxy and a large group in Virgo, formerly known as the ``12.4 hr clump,'' which Duffau and coworkers have recently shown to contain a stellar stream (the Virgo stellar stream). Two other groups lie in the direction of the Monoceros stream

THE BOLOCAM GALACTIC PLANE SURVEY. VIII. A MID-INFRARED KINEMATIC DISTANCE DISCRIMINATION METHOD

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

Ellsworth-Bowers, Timothy P.; Glenn, Jason; Battersby, Cara

2013-06-10

We present a new distance estimation method for dust-continuum-identified molecular cloud clumps. Recent (sub-)millimeter Galactic plane surveys have cataloged tens of thousands of these objects, plausible precursors to stellar clusters, but detailed study of their physical properties requires robust distance determinations. We derive Bayesian distance probability density functions (DPDFs) for 770 objects from the Bolocam Galactic Plane Survey in the Galactic longitude range 7. Degree-Sign 5 {<=} l {<=} 65 Degree-Sign . The DPDF formalism is based on kinematic distances, and uses any number of external data sets to place prior distance probabilities to resolve the kinematic distance ambiguity (KDA)more » for objects in the inner Galaxy. We present here priors related to the mid-infrared absorption of dust in dense molecular regions and the distribution of molecular gas in the Galactic disk. By assuming a numerical model of Galactic mid-infrared emission and simple radiative transfer, we match the morphology of (sub-)millimeter thermal dust emission with mid-infrared absorption to compute a prior DPDF for distance discrimination. Selecting objects first from (sub-)millimeter source catalogs avoids a bias towards the darkest infrared dark clouds (IRDCs) and extends the range of heliocentric distance probed by mid-infrared extinction and includes lower-contrast sources. We derive well-constrained KDA resolutions for 618 molecular cloud clumps, with approximately 15% placed at or beyond the tangent distance. Objects with mid-infrared contrast sufficient to be cataloged as IRDCs are generally placed at the near kinematic distance. Distance comparisons with Galactic Ring Survey KDA resolutions yield a 92% agreement. A face-on view of the Milky Way using resolved distances reveals sections of the Sagittarius and Scutum-Centaurus Arms. This KDA-resolution method for large catalogs of sources through the combination of (sub-)millimeter and mid-infrared observations of

Galactic X-ray emission from pulsars

NASA Technical Reports Server (NTRS)

Harding, A. K.

1981-01-01

The contribution of pulsars to the gamma-ray flux from the galactic plane is examined using data from the most recent pulsar surveys. It is assumed that pulsar gamma-rays are produced by curvature radiation from relativistic particles above the polar cap and attenuated by pair production in the strong magnetic and electric fields. Assuming that all pulsars produce gamma-rays in this way, their luminosities can be predicted as a function of period and magnetic field strength. Using the distribution of pulsars in the galaxy as determined from data on 328 pulsars detected in three surveys, the local gamma-ray production spectrum, the longitude profile, and the latitude profile of pulsar gamma-ray flux are calculated. The largest sources of uncertainty in the size of the pulsar contribution are the value of the mean interstellar electron density, the turnover in the pulsar radio luminosity function, and the average pulsar magnetic field strength. A present estimate is that pulsars contribute from 15 to 20 % of the total flux of gamma-rays from the galactic plane.

The Galactic Magnetic Field as Viewed from the VLA

NASA Astrophysics Data System (ADS)

van Eck, Cameron; Brown, Jo-Anne

2009-05-01

Interstellar magnetic fields play critical roles in many astrophysical processes. Yet despite their importance, our knowledge about magnetic fields in our Galaxy remains limited. For the field within the Milky Way much of what we do know comes from radio astronomy, through observations of polarization and Faraday rotation measures (RMs) of extragalactic sources and pulsars. A high angular density of RM measurements in several critical areas of the Galaxy is needed to clarify the Galactic magnetic field structure. Understanding the overall structure of the magnetic field will subsequently help us determine the origin and evolution of the field. In an effort to determine the overall structure of the field, Sun et al. (2008) produced 3 models of the Galactic magnetic field based on RM measurements available at the time. These models made distinct predictions for RMs in a region of the inner Galaxy at low Galactic latitude. Using observations made with the Very Large Array (VLA), we have determined RMs for sources in this critical region. In this talk we will present the results of our study and show how the RMs strongly support the ASS+RING model.

A relationship between galactic cosmic radiation and tree rings.

PubMed

Dengel, Sigrid; Aeby, Dominik; Grace, John

2009-11-01

Here, we investigated the interannual variation in the growth rings formed by Sitka spruce (Picea sitchensis) trees in northern Britain (55 degrees N, 3 degrees W) over the period 1961-2005 in an attempt to disentangle the influence of atmospheric variables acting at different times of year. Annual growth rings, measured along the north radius of freshly cut (frozen) tree discs and climatological data recorded at an adjacent site were used in the study. Correlations were based on Pearson product-moment correlation coefficients between the annual growth anomaly and these climatic and atmospheric factors. Rather weak correlations between these variables and growth were found. However, there was a consistent and statistically significant relationship between growth of the trees and the flux density of galactic cosmic radiation. Moreover, there was an underlying periodicity in growth, with four minima since 1961, resembling the period cycle of galactic cosmic radiation. * We discuss the hypotheses that might explain this correlation: the tendency of galactic cosmic radiation to produce cloud condensation nuclei, which in turn increases the diffuse component of solar radiation, and thus increases the photosynthesis of the forest canopy.

Flux-limited sample of Galactic carbon stars

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

Claussen, M.J.; Kleinmann, S.G.; Joyce, R.R.

Published observational data (including IRAS observations) for a flux-limited sample of 215 Galactic carbon stars (CSs) selected from the 2-micron sky survey of Neugebauer and Leighton (1969) are compiled in extensive tables and graphs and analyzed statistically. The sample is found to penetrate a volume of radius 1.5 kpc, and the local CS space density and surface density are calculated as log rho0 (per cu kpc) = 2.0 + or - 0.4 and log N (per sq kpc) = 1.6 + or - 0.2, respectively. The total Galactic mass-return rate from these CSs is estimated as 0.013 solar mass/yr, implyingmore » a time scale of 0.1-1 Myr for the CS evolutionary phase and a mass of 1.2-1.6 solar mass for the (probably F-type) main-seqence progenitors of CSs. 81 references.« less

Galactic Cosmic Rays in the Outer Heliosphere

NASA Technical Reports Server (NTRS)

Florinski, V.; Washimi, H.; Pogorelov, N. V.; Adams, J. H.

2010-01-01

We report a next generation model of galactic cosmic ray (GCR) transport in the three dimensional heliosphere. Our model is based on an accurate three-dimensional representation of the heliospheric interface. This representation is obtained by taking into account the interaction between partially ionized, magnetized plasma flows of the solar wind and the local interstellar medium. Our model reveals that after entering the heliosphere GCRs are stored in the heliosheath for several years. The preferred GCR entry locations are near the nose of the heliopause and at high latitudes. Low-energy (hundreds of MeV) galactic ions observed in the heliosheath have spent, on average, a longer time in the solar wind than those observed in the inner heliosphere, which would explain their cooled-off spectra at these energies. We also discuss radial gradients in the heliosheath and the implications for future Voyager observations

Monitoring the Galactic - Search for Hard X-Ray Transients

NASA Astrophysics Data System (ADS)

Marshall, Francis

Hard X-ray transients with fluxs from ~1 to ~30 mCrab are a common feature of the galactic plane with apparent concentrations in specific regions of the plane. Concentrations in the Scutum and Carina fields probably indicate an enhancement of Be X-ray binaries along the tangent direction of two spiral arms. The frequency of outbursts suggest that at any one time 1 or 2 transients are active in the Scutum field alone. We propose weekly scans of the galactic plane to understand this population of sources. The scans will also monitor about 50 already known sources with better spectral information than available with the ASM.

An Electron-positron Jet Model for the Galactic Center

NASA Technical Reports Server (NTRS)

Burns, M. L.

1983-01-01

High energy observations of the galactic center on the subparsec scale seem to be consistent with electron-positron production in the form of relativistic jets. These jets could be produced by an approximately 1,000,000 solar mass black hole dynamo transportating pairs away from the massive core. An electromagnetic cascade shower would develop first from ambient soft protons and then nonlinearly; the shower using itself as a scattering medium. This is suited to producing, cooling and transporting pairs to the observed annihilation region. It is possible the center of our galaxy is a miniature version of more powerful active galactic nuclei that exhibit jet activity.

An electron-positron jet model for the Galactic center

NASA Technical Reports Server (NTRS)

Burns, M. L.

1983-01-01

High energy observations of the galactic center on the subparsec scale seem to be consistent with electron-positron production in the form of relativistic jets. These jets could be produced by an approximately 1,000,000 solar mass black hole dynamo transporting pairs away from the massive core. An electomagnetic cascade shower would develop first from ambient soft protons and then nonlinearly, the shower using itself as a scattering medium. This is suited to producing, cooling and transporting pairs to the observed annihilation region. It is possible the center of our galaxy is a miniature version of more powerful active galactic nuclei that exhibit jet activity.

An electron-positron jet model for the Galactic center

NASA Astrophysics Data System (ADS)

Burns, M. L.

1983-07-01

High energy observations of the galactic center on the subparsec scale seem to be consistent with electron-positron production in the form of relativistic jets. These jets could be produced by an approximately 1,000,000 solar mass black hole dynamo transporting pairs away from the massive core. An electomagnetic cascade shower would develop first from ambient soft protons and then nonlinearly, the shower using itself as a scattering medium. This is suited to producing, cooling and transporting pairs to the observed annihilation region. It is possible the center of our galaxy is a miniature version of more powerful active galactic nuclei that exhibit jet activity.

An electron-positron jet model for the galactic center

NASA Astrophysics Data System (ADS)

Burns, M. L.

1983-03-01

High energy observations of the galactic center on the subparsec scale seem to be consistent with electron-positron production in the form of relativistic jets. These jets could be produced by an approximately 1,000,000 solar mass black hole dynamo transportating pairs away from the massive core. An electromagnetic cascade shower would develop first from ambient soft protons and then nonlinearly; the shower using itself as a scattering medium. This is suited to producing, cooling and transporting pairs to the observed annihilation region. It is possible the center of our galaxy is a miniature version of more powerful active galactic nuclei that exhibit jet activity.

Fast dynamos, cosmic rays, and the Galactic magnetic field

NASA Technical Reports Server (NTRS)

Parker, E. N.

1992-01-01

It is suggested here that the dynamo believed to be responsible for the magnetic field of the Galaxy is a fast dynamo due to the dynamical reconnection of the azimuthal field of the Galaxy as the field is deformed by the instability of the gaseous disk and the rapid inflation of magnetic lobes by the cosmic-ray gas to form the Galactic halo. The reconnection of adjacent lobes carries out both the alpha effect and field dissipation essential for the existence of the Galactic alpha-omega dynamo. The azimuthal field is generated primarily in the gaseous disk, while the alpha effect is carried out in the halo.

The K2 Galactic Archaeology Program Data Release. I. Asteroseismic Results from Campaign 1

NASA Astrophysics Data System (ADS)

Stello, Dennis; Zinn, Joel; Elsworth, Yvonne; Garcia, Rafael A.; Kallinger, Thomas; Mathur, Savita; Mosser, Benoit; Sharma, Sanjib; Chaplin, William J.; Davies, Guy; Huber, Daniel; Jones, Caitlin D.; Miglio, Andrea; Silva Aguirre, Victor

2017-01-01

NASA's K2 mission is observing tens of thousands of stars along the ecliptic, providing data suitable for large-scale asteroseismic analyses to inform galactic archaeology studies. Its first campaign covered a field near the north Galactic cap, a region never covered before by large asteroseismic-ensemble investigations, and was therefore of particular interest for exploring this part of our Galaxy. Here we report the asteroseismic analysis of all stars selected by the K2 Galactic Archaeology Program during the mission's “north Galactic cap” campaign 1. Our consolidated analysis uses six independent methods to measure the global seismic properties, in particular the large frequency separation and the frequency of maximum power. From the full target sample of 8630 stars we find about 1200 oscillating red giants, a number comparable with estimates from galactic synthesis modeling. Thus, as a valuable by-product we find roughly 7500 stars to be dwarfs, which provide a sample well suited for galactic exoplanet occurrence studies because they originate from our simple and easily reproducible selection function. In addition, to facilitate the full potential of the data set for galactic archaeology, we assess the detection completeness of our sample of oscillating red giants. We find that the sample is at least nearly complete for stars with 40 ≲ {ν }\\max /μHz ≲ 270 and {ν }\\max ,{detect}< 2.6× {10}6\\cdot {2}-{\\text{Kp}} μHz. There is a detection bias against helium core burning stars with {ν }\\max ˜ 30 μHz, affecting the number of measurements of {{Δ }}ν and possibly also {ν }\\max . Although we can detect oscillations down to {\\text{Kp}} = 15, our campaign 1 sample lacks enough faint giants to assess the detection completeness for stars fainter than {\\text{Kp}} ˜ 14.5.

The crystal structure of the AhRR-ARNT heterodimer reveals the structural basis of the repression of AhR-mediated transcription.

PubMed

Sakurai, Shunya; Shimizu, Toshiyuki; Ohto, Umeharu

2017-10-27

2,3,7,8-Tetrachlorodibenzo- p -dioxin and related compounds are extraordinarily potent environmental toxic pollutants. Most of the 2,3,7,8-tetrachlorodibenzo- p -dioxin toxicities are mediated by aryl hydrocarbon receptor (AhR), a ligand-dependent transcription factor belonging to the basic helix-loop-helix (bHLH) Per-ARNT-Sim (PAS) family. Upon ligand binding, AhR forms a heterodimer with AhR nuclear translocator (ARNT) and induces the expression of genes involved in various biological responses. One of the genes induced by AhR encodes AhR repressor (AhRR), which also forms a heterodimer with ARNT and represses the activation of AhR-dependent transcription. The control of AhR activation is critical for managing AhR-mediated diseases, but the mechanisms by which AhRR represses AhR activation remain poorly understood, because of the lack of structural information. Here, we determined the structure of the AhRR-ARNT heterodimer by X-ray crystallography, which revealed an asymmetric intertwined domain organization presenting structural features that are both conserved and distinct among bHLH-PAS family members. The structures of AhRR-ARNT and AhR-ARNT were similar in the bHLH-PAS-A region, whereas the PAS-B of ARNT in the AhRR-ARNT complex exhibited a different domain arrangement in this family reported so far. The structure clearly disclosed that AhRR competitively represses AhR binding to ARNT and target DNA and further suggested the existence of an AhRR-ARNT-specific repression mechanism. This study provides a structural basis for understanding the mechanism by which AhRR represses AhR-mediated gene transcription. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

A Search for New Galactic Magnetars in Archival Chandra and XMM-Newton Observations

NASA Astrophysics Data System (ADS)

Muno, M. P.; Gaensler, B. M.; Nechita, A.; Miller, J. M.; Slane, P. O.

2008-06-01

We present constraints on the number of Galactic magnetars, which we have established by searching for sources with periodic variability in 506 archival Chandra observations and 441 archival XMM-Newton observations of the Galactic plane (| b| < 5°). Our search revealed four sources with periodic variability on timescales of 200-5000 s, all of which are probably accreting white dwarfs. We identify 7 of 12 known Galactic magnetars, but find no new examples with periods between 5 and 20 s. We convert this nondetection into limits on the total number of Galactic magnetars by computing the fraction of the young Galactic stellar population that our survey covered. We find that easily detectable magnetars, modeled after persistent anomalous X-ray pulsars (e.g., with LX = 1035 ergs s-1 [0.5-10.0 keV] and Arms = 12% ), could have been identified in ≈5% of the Galactic spiral arms by mass. If we assume that three previously known examples randomly fall within our survey, then there are 59+ 92-32 in the Galaxy. Barely detectable magnetars (LX = 3 × 1033 ergs s-1 and Arms = 15% ) could have been identified throughout ≈0.4% of the spiral arms. The lack of new examples implies that <540 exist in the Galaxy (90% confidence). Similar constraints are found by considering the detectability of transient magnetars in outburst. For assumed lifetimes of 104 yr, the birth rate of magnetars is between 0.003 and 0.06 yr-1. Therefore, the birth rate of magnetars is at least 10% of that for normal radio pulsars, and could exceed that value, unless transient magnetars are active for gtrsim105 yr.

HST/COS OBSERVATIONS OF GALACTIC HIGH-VELOCITY CLOUDS: FOUR ACTIVE GALACTIC NUCLEUS SIGHT LINES THROUGH COMPLEX C

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

Shull, J. Michael; Stevans, Matthew; Danforth, Charles

2011-10-01

We report ultraviolet spectra of Galactic high-velocity clouds (HVCs) in Complex C, taken by the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope (HST), together with new 21 cm spectra from the Green Bank Telescope. The wide spectral coverage and higher signal-to-noise ratio, compared to previous HST spectra, provide better velocity definition of the HVC absorption, additional ionization species (including high ions), and improved abundances in this halo gas. Complex C has a metallicity of 10%-30% solar and a wide range of ions, suggesting dynamical and thermal interactions with hot gas in the Galactic halo. Spectra in the COSmore » medium-resolution G130M (1133-1468 A) and G160M (1383-1796 A) gratings detect ultraviolet absorption lines from eight elements in low-ionization states (O I, N I, C II, S II, Si II, Al II, Fe II, P II) and three elements in intermediate- and high-ionization states (Si III, Si IV, C IV, N V). Our four active galactic nucleus sight lines toward Mrk 817, Mrk 290, Mrk 876, and PG 1259+593 have high-velocity H I and O VI column densities, log N{sub Hi}= 19.39-20.05 and log N{sub Ovi}= 13.58-14.10, with substantial amounts of kinematically associated photoionized gas. The high-ion abundance ratios are consistent with cooling interfaces between photoionized and collisionally ionized gas: N(C IV)/N(O VI) {approx} 0.3-0.5, N(Si IV)/N(O VI) {approx} 0.05-0.11, N(N V)/N(O VI) {approx} 0.07-0.13, and N(Si IV)/N(Si III) {approx}0.2.« less

The Galactic Bulge Radial Velocity/Abundance Assay

NASA Astrophysics Data System (ADS)

Rich, R. M.

2012-08-01

The Bulge Radial Velocity Assay (BRAVA) measured radial velocities for ˜ 9500 late-type giants in the Galactic bulge, predominantly from -10° < l < +10° and -2° < b < -10°. The project has discovered that the bulge exhibits cylindrical rotation characteristic of bars, and two studies of dynamics (Shen et al. 2010; Wang et al. 2012 MNRAS sub.) find that bar models- either N-body formed from an instability in a preexisting disk, or a self-consistent model- can account for the observed kinematics. Studies of the Plaut field at (l,b) = 0°, -8° show that alpha enhancement is found in bulge giants even 1 kpc from the nucleus. New infrared studies extending to within 0.25° = 35 pc of the Galactic Center find no iron or alpha gradient from Baade's Window (l,b) = 0.9°, -3.9° to our innermost field, in contrast to the marked gradient observed in the outer bulge. We consider the case of the remarkable globular cluster Terzan 5, which has a strongly bimodal iron and rm [α/Fe] within its members, and we consider evidence pro and con that the bulge was assembled from dissolved clusters. The Subaru telescope has the potential to contribute to study of the Galactic bulge, especially using the Hyper Superime-Cam and planned spectroscopic modes, as well as the high resolution spectrograph. The planned Jasmine satellite series may deliver a comprehensive survey of distances and proper motions of bulge stars, and insight into the origin and importance of the X-shaped bulge.

77 FR 13483 - Airworthiness Directives; Rolls-Royce plc (RR) Turbofan Engines

Federal Register 2010, 2011, 2012, 2013, 2014

2012-03-07

... Directives; Rolls-Royce plc (RR) Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ACTION... service information identified in this AD, contact Rolls-Royce plc, Corporate Communications, P.O. Box 31...), or, have Rolls-Royce plc revise Alert Service Bulletin (ASB) No. RB.211-72-AF964 to remove the...

76 FR 65136 - Airworthiness Directives; Rolls-Royce plc (RR) Turbofan Engines

Federal Register 2010, 2011, 2012, 2013, 2014

2011-10-20

... Airworthiness Directives; Rolls-Royce plc (RR) Turbofan Engines AGENCY: Federal Aviation Administration (FAA... information identified in this AD, contact Rolls-Royce plc, Corporate Communications, P.O. Box 31, Derby...-166679 (76 FR 24793, May 3, 2011), and adding the following new AD: Rolls-Royce plc: Docket No. FAA-2010...

Galactic Cosmic-ray Transport in the Global Heliosphere: A Four-Dimensional Stochastic Model

NASA Astrophysics Data System (ADS)

Florinski, V.

2009-04-01

We study galactic cosmic-ray transport in the outer heliosphere and heliosheath using a newly developed transport model based on stochastic integration of the phase-space trajectories of Parker's equation. The model employs backward integration of the diffusion-convection transport equation using Ito calculus and is four-dimensional in space+momentum. We apply the model to the problem of galactic proton transport in the heliosphere during a negative solar minimum. Model results are compared with the Voyager measurements of galactic proton radial gradients and spectra in the heliosheath. We show that the heliosheath is not as efficient in diverting cosmic rays during solar minima as predicted by earlier two-dimensional models.

Search for Gamma-Ray Emission from Galactic Novae using Fermi-LAT Pass 8

NASA Astrophysics Data System (ADS)

Buson, Sara; Franckowiak, Anna; Cheung, Teddy; Jean, Pierre; Fermi-LAT Collaboration

2016-01-01

Recently Galactic novae have been identified as a new class of GeV gamma-ray emitters, with 6 detected so far with the Fermi Large Area Telescope (Fermi-LAT) data. Based on optical observations we have compiled a catalog of ~70 Galactic novae, which peak (in optical) during the operations of the Fermi mission. Based on the properties of known gamma-ray novae we developed a search procedure that we apply to all novae in the catalog to detect these slow transient sources or set flux upper limits using the Fermi-LAT Pass 8 data set. This is the first time a large sample of Galactic novae has been uniformly studied.

A Low-metallicity Molecular Cloud in the Lower Galactic Halo

NASA Astrophysics Data System (ADS)

Hernandez, Audra K.; Wakker, Bart P.; Benjamin, Robert A.; French, David; Kerp, Juergen; Lockman, Felix J.; O'Toole, Simon; Winkel, Benjamin

2013-11-01

We find evidence for the impact of infalling, low-metallicity gas on the Galactic disk. This is based on FUV absorption line spectra, 21 cm emission line spectra, and far-infrared (FIR) mapping to estimate the abundance and physical properties of IV21 (IVC135+54-45), a galactic intermediate-velocity molecular cloud that lies ~300 pc above the disk. The metallicity of IV21 was estimated using observations toward the subdwarf B star PG1144+615, located at a projected distance of 16 pc from the cloud's densest core, by measuring ion and H I column densities for comparison with known solar abundances. Despite the cloud's bright FIR emission and large column densities of molecular gas as traced by CO, we find that it has a sub-solar metallicity of log (Z/Z ⊙) = -0.43 ± 0.12 dex. IV21 is thus the first known sub-solar metallicity cloud in the solar neighborhood. In contrast, most intermediate-velocity clouds (IVC) have near-solar metallicities and are believed to originate in the Galactic Fountain. The cloud's low metallicity is also atypical for Galactic molecular clouds, especially in light of the bright FIR emission which suggest a substantial dust content. The measured I 100 μm/N(H I) ratio is a factor of three below the average found in high latitude H I clouds within the solar neighborhood. We argue that IV21 represents the impact of an infalling, low-metallicity high-velocity cloud that is mixing with disk gas in the lower Galactic halo. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from MAST at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program No. 12275. The Green Bank Telescope is part of the National Radio Astronomy Observatory which is a Facility of the National Science Foundation, operated by Associated Universities, Inc.

MOCCA-SURVEY Database I: Galactic Globular Clusters Harbouring a Black Hole Subsystem

NASA Astrophysics Data System (ADS)

Askar, Abbas; Sedda, Manuel Arca; Giersz, Mirek

2018-05-01

There have been increasing theoretical speculations and observational indications that certain globular clusters (GCs) could contain a sizeable population of stellar mass black holes (BHs). In this paper, we shortlist at least 29 Galactic GCs that could be hosting a subsystem of BHs (BHS). In a companion paper, we analysed results from a wide array of GC models (simulated with the MOCCA code for cluster simulations) that retained few tens to several hundreds of BHs at 12 Gyr and showed that the properties of the BHS in those GCs correlate with the GC's observable properties. Building on those results, we use available observational properties of 140 Galactic GCs to identify 29 GCs that could potentially be harbouring up to a few hundreds of BHs. Utilizing observational properties and theoretical scaling relations, we estimate the density, size and mass of the BHS in these GCs. We also calculate the total number of BHs and the fraction of BHs contained in a binary system for our shortlisted Galactic GCs. Additionally, we mention other Galactic GCs that could also contain significant number of single BHs or BHs in binary systems.

A 1420 MHz Catalog of Compact Sources in the Northern Galactic Plane

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

Taylor, A. R.; Leahy, D. A.; Sunstrum, C.

We present a catalog of compact sources of radio emission at 1420 MHz in the northern Galactic plane from the Canadian Galactic Plane Survey. The catalog contains 72,758 compact sources with an angular size less than 3′ within the Galactic longitude range 52° <  ℓ  < 192° down to a 5 σ detection level of ∼1.2 mJy. Linear polarization properties are included for 12,368 sources with signals greater than 4 σ{sub QU} in the Canadian Galactic Plane Survey (CGPS) Stokes Q and U images at the position of the total intensity peak. We compare CGPS flux densities with cataloged flux densities in themore » Northern VLA Sky Survey catalog for 10,897 isolated unresolved sources with CGPS flux density greater than 4 mJy to search for sources that show variable flux density on timescales of several years. We identify 146 candidate variables that exhibit high fractional variations between the two surveys. In addition, we identify 13 candidate transient sources that have CGPS flux density above 10 mJy but are not detected in the Northern VLA Sky Survey.« less

Chandra Deep X-ray Observation of a Typical Galactic Plane Region and Near-Infrared Identification

NASA Technical Reports Server (NTRS)

Ebisawa, K.; Tsujimoto, M.; Paizis, A.; Hamaguichi, K.; Bamba, A.; Cutri, R.; Kaneda, H.; Maeda, Y.; Sato, G.; Senda, A.

2004-01-01

Using the Chandra Advanced CCD Imaging Spectrometer Imaging array (ACIS-I), we have carried out a deep hard X-ray observation of the Galactic plane region at (l,b) approx. (28.5 deg,0.0 deg), where no discrete X-ray source has been reported previously. We have detected 274 new point X-ray sources (4 sigma confidence) as well as strong Galactic diffuse emission within two partidly overlapping ACIS-I fields (approx. 250 sq arcmin in total). The point source sensitivity was approx. 3 x 10(exp -15)ergs/s/sq cm in the hard X-ray band (2-10 keV and approx. 2 x 10(exp -16) ergs/s/sq cm in the soft band (0.5-2 keV). Sum of all the detected point source fluxes account for only approx. 10 % of the total X-ray fluxes in the field of view. In order to explain the total X-ray fluxes by a superposition of fainter point sources, an extremely rapid increase of the source population is required below our sensitivity limit, which is hardly reconciled with any source distribution in the Galactic plane. Therefore, we conclude that X-ray emission from the Galactic plane has truly diffuse origin. Only 26 point sources were detected both in the soft and hard bands, indicating that there are two distinct classes of the X-ray sources distinguished by the spectral hardness ratio. Surface number density of the hard sources is only slightly higher than observed at the high Galactic latitude regions, strongly suggesting that majority of the hard X-ray sources are active galaxies seen through the Galactic plane. Following the Chandra observation, we have performed a near-infrared (NIR) survey with SOFI at ESO/NTT to identify these new X-ray sources. Since the Galactic plane is opaque in NIR, we did not see the background extragalactic sources in NIR. In fact, only 22 % of the hard sources had NIR counterparts which are most likely to be Galactic origin. Composite X-ray energy spectrum of those hard X-ray sources having NIR counterparts exhibits a narrow approx. 6.7 keV iron emission line, which

The Milky Way, the Galactic Halo, and the Halos of Galaxies

NASA Astrophysics Data System (ADS)

Gerhard, Ortwin

2016-08-01

The Milky Way, ``our'' Galaxy, is currently the subject of intense study with many ground-based surveys, in anticipation of upcoming results from the Gaia mission. From this work we have been learning about the full three-dimensional structure of the Galactic box/peanut bulge, the distribution of stars in the bar and disk, and the many streams and substructures in the Galactic halo. The data indicate that a large fraction of the Galactic halo has been accreted from outside. Similarly, in many external galaxy halos there is now evidence for tidal streams and accretion of satellites. To study these features requires exquisite, deep photometry and spectroscopy. These observations illustrate how galaxy halos are still growing, and sometimes can be used to ``time'' the accretion events. In comparison with cosmological simulations, the structure of galaxy halos gives us a vivid illustration of the hierarchical nature of our Universe.

A Discovery of a Compact High Velocity Cloud-Galactic Supershell System

NASA Astrophysics Data System (ADS)

Park, Geumsook; Koo, Bon-Chul; Kang, Ji-hyun; Gibson, Steven J.; Peek, Joshua Eli Goldston; Douglas, Kevin A.; Korpela, Eric J.; Heiles, Carl E.

2017-01-01

High velocity clouds (HVCs) are neutral hydrogen (HI) gas clouds having very different radial velocities from those of the Galactic disk material. While some large HVC complexes are known to be gas streams tidally stripped from satellite galaxies of the Milky Way, there are relatively isolated and small angular-sized HVCs, so called “compact HVCs (CHVCs)”, the origin of which remains controversial. There are about 300 known CHVCs in the Milky Way, and many of them show a head-tail structure, implying a ram pressure interaction with the diffuse Galactic halo gas. It is, however, not clear whether CHVCs are completely dissipated in the Galactic halo to feed the multi-phase circumgalactic medium or they can survive their trip through the halo and collide with the Galactic disk. The colliding CHVCs may leave a gigantic trail in the disk, and it had been suggested that some of HI supershells that require ≧ 3 x 1052 erg may be produced by the collision of such HVCs.Here we report the detection of a kiloparsec (kpc)-size supershell in the outskirts of the Milky Way with the compact HVC 040+01-282 (hereafter, CHVC040) at its geometrical center using the “Inner-Galaxy Arecibo L-band Feed Array” HI 21 cm survey data. The morphological and physical properties of both objects suggest that CHVC040, which is either a fragment of a nearby disrupted galaxy or a cloud that originated from an intergalactic accreting flow, collided with the disk ˜5 Myr ago to form the supershell. Our results show that some compact HVCs can survive their trip through the Galactic halo and inject energy and momentum into the Milky Way disk.

TeV Gamma Rays From Galactic Center Pulsars

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

Hooper, Dan; Cholis, Ilias; Linden, Tim

Measurements of the nearby pulsars Geminga and B0656+14 by the HAWC and Milagro telescopes have revealed the presence of bright TeV-emitting halos surrounding these objects. If young and middle-aged pulsars near the Galactic Center transfer a similar fraction of their energy into TeV photons, then these sources could dominate the emission that is observed by HESS and other ground-based telescopes from the innermost ~10^2 parsecs of the Milky Way. In particular, both the spectral shape and the angular extent of this emission is consistent with TeV halos produced by a population of pulsars. The overall flux of this emission requiresmore » a birth rate of ~100-1000 neutron stars per Myr near the Galactic Center, in good agreement with recent estimates.« less

Detecting dark matter with imploding pulsars in the galactic center.

PubMed

Bramante, Joseph; Linden, Tim

2014-11-07

The paucity of old millisecond pulsars observed at the galactic center of the Milky Way could be the result of dark matter accumulating in and destroying neutron stars. In regions of high dark matter density, dark matter clumped in a pulsar can exceed the Schwarzschild limit and collapse into a natal black hole which destroys the pulsar. We examine what dark matter models are consistent with this hypothesis and find regions of parameter space where dark matter accumulation can significantly degrade the neutron star population within the galactic center while remaining consistent with observations of old millisecond pulsars in globular clusters and near the solar position. We identify what dark matter couplings and masses might cause a young pulsar at the galactic center to unexpectedly extinguish. Finally, we find that pulsar collapse age scales inversely with the dark matter density and linearly with the dark matter velocity dispersion. This implies that maximum pulsar age is spatially dependent on position within the dark matter halo of the Milky Way. In turn, this pulsar age spatial dependence will be dark matter model dependent.

Observing the Next Galactic Supernova with the NOvA Detectors

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

Vasel, Justin A.; Sheshukov, Andrey; Habig, Alec

The next galactic core-collapse supernova will deliver a wealth of neutrinos which for the first time we are well-situated to measure. These explosions produce neutrinos with energies between 10 and 100 MeV over a period of tens of seconds. Galactic supernovae are relatively rare events, occurring with a frequency of just a few per century. It is therefore essential that all neutrino detectors capable of detecting these neutrinos are ready to trigger on this signal when it occurs. This poster describes a data-driven trigger which is designed to detect the neutrino signal from a galactic core-collapse supernova with the NOvAmore » detectors. The trigger analyzes 5ms blocks of detector activity and applies background rejection algorithms to detect the signal time structure over the background. This background reduction is an essential part of the process, as the NOvA detectors are designed to detect neutrinos from Fermilab's NuMI beam which have an average energy of 2GeV--well above the average energy of supernova neutrinos.« less

A High Resolution View of Galactic Centers: Arp 220 and M31

NASA Astrophysics Data System (ADS)

Lockhart, Kelly E.

The centers of galaxy are small in size and yet incredibly complex. They play host to supermassive black holes and nuclear star clusters (NSCs) and are subject to large gas inows, nuclear starbursts, and active galactic nuclear (AGN) activity. They can also be the launching site for large-scale galactic outows. However, though these systems are quite important to galactic evolution, observations are quite difficult due to their small size. Using high spatial resolution narrowband imaging with HST/WFC3 of Arp 220, a latestage galaxy merger, I discover an ionized gas bubble feature ( r = 600 pc) just off the nucleus. The bubble is aligned with both the western nucleus and with the large-scale galactic outflow. Using energetics arguments, I link the bubble with a young, obscured AGN or with an intense nuclear starburst. Given its alignment along the large-scale outflow axis, I argue that the bubble presents evidence for a link between the galactic center and the large-scale outflow. I also present new observations of the NSC in M31, the closest large spiral galaxy to our own. Using the OSIRIS near-infrared integral field spectrograph (IFS) on Keck, I map the kinematics of the old stellar population in the eccentric disk of the NSC. I compare the observations to models to derive a precession speed of the disk of 0+/-5 km s-1 pc-1 , and hence confirm that winds from the old stellar population may be the source of gas needed to form the young stellar population in the NSC. Studies of galactic centers are dependent on high spatial resolution observations. In particular, IFSs are ideal instruments for these studies as they provide two-dimensional spectroscopy of the field of view, enabling 2D kinematic studies. I report on work to characterize and improve the data reduction pipeline of the OSIRIS IFS, and discuss implications for future generations of IFS instrumentation.

The Ties that Bind? Galactic Magnetic Fields and Ram Pressure Stripping

NASA Astrophysics Data System (ADS)

Tonnesen, Stephanie; Stone, James

2014-11-01

One process affecting gas-rich cluster galaxies is ram pressure stripping (RPS), i.e., the removal of galactic gas through direct interaction with the intracluster medium (ICM). Galactic magnetic fields may have an important impact on the stripping rate and tail structure. We run the first magnetohydrodynamic (MHD) simulations of RPS that include a galactic magnetic field, using 159 pc resolution throughout our entire domain in order to resolve mixing throughout the tail. We find very little difference in the total amount of gas removed from the unmagnetized and magnetized galaxies, although a magnetic field with a radial component will initially accelerate stripped gas more quickly. In general, we find that magnetic fields in the disk lead to slower velocities in the stripped gas near the disk and faster velocities farther from the disk. We also find that magnetic fields in the galactic gas lead to larger unmixed structures in the tail. Finally, we discuss whether ram pressure stripped tails can magnetize the ICM. We find that the total magnetic energy density grows as the tail lengthens, likely through turbulence. There are μG-strength fields in the tail in all of our MHD runs, which survive to at least 100 kpc from the disk (the edge of our simulated region), indicating that the area-filling factor of magnetized tails in a cluster could be large.

The Galactic HII Region Luminosity Function at Infrared and Radio Wavelengths

NASA Astrophysics Data System (ADS)

Mascoop, Joshua; Anderson, Loren; Sandor Makai, Zoltan; Armentrout, William Paul

2018-01-01

HII regions are the clearest indicators of ongoing high-mass star formation. The HII region luminosity function (LF) therefore probes present global star formation properties, and its shape has been related to HII region properties and galaxy Hubble types. Most HII region LF studies to date have been conducted in external galaxies; due to observational difficulties, there have been relatively few studies of the Milky Way HII region LF. Using ~600 HII regions from the WISE Catalog of Galactic HII Regions, we examine the Galactic LF in the first quadrant. Our high-resolution view of Galactic star formation regions allows us to separate nearby sources, and our sample is complete for all HII regions ionized by single O9.5 stars.We analyze the Galactic LF at six infrared wavelengths - where the emission is due to dust - and also at 20 cm, where the emission is from ionized gas. All LFs have a similar shape, showing that infrared LFs can be used in place of ionized gas tracers. All LFs can be described by a single power law with an index of approximately -2, in agreement with previous studes. We find no compelling evidence of a break or "knee" in the LF. Moreover, we see no significant variation in the form of the LF as a function of heliocentric distance, HII region size, or Galactocentric radius.

A Search for Galactic Red Supergiant Variables Beyond the Solar Circle

NASA Astrophysics Data System (ADS)

Alves, David; MacConnell, Jack; Wing, Robert; Bond, Howard E.; Zurek, David; Hoard, Donald W.

2000-02-01

The Galactic rotation curve outside of the Solar circle is particularly difficult to ascertain, yet of critical importance for characterizing the distribution of mass in the Galaxy. We propose to identify a new and large sample of stellar kinematic tracers beyond the Solar circle, in the form of red supergiant variables (RSVs; spectral type M0-M5, luminosity class Ia-Ib). RSVs are ideal tracers of the heavily extincted outer Galactic disk, because (1) they are the intrinsically most luminous Pop I standard candles in the near-infrared, (2) they are more common than the classically employed Cepheids, and (3) they exhibit a period-luminosity relation of comparable precision to that of Cepheids. With the CTIO 0.9m in queue mode, we will derive the pulsation periods of our RSV candidates, allowing us to identify the most distant RSVs for further study. In addition, follow- up observations to obtain accurate, phase-weighted (``(gamma)'') radial velocities (a prerequisite for determining the Galactic rotation curve with RSVs) cannot be planned without period information. We have preselected RSV candidates from a catalog of ~1500 red supergiants in the Galactic plane, originally identified on objective-prism plates. Spectral types and luminosity classes have been determined from 8-color Wing photometry and medium-resolution spectra. The pulsation periods are expected to be 100 to 1000 days, and thus we request long-term status.

The ties that bind? Galactic magnetic fields and ram pressure stripping

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

Tonnesen, Stephanie; Stone, James, E-mail: stonnes@astro.princeton.edu, E-mail: jstone@astro.princeton.edu

One process affecting gas-rich cluster galaxies is ram pressure stripping (RPS), i.e., the removal of galactic gas through direct interaction with the intracluster medium (ICM). Galactic magnetic fields may have an important impact on the stripping rate and tail structure. We run the first magnetohydrodynamic (MHD) simulations of RPS that include a galactic magnetic field, using 159 pc resolution throughout our entire domain in order to resolve mixing throughout the tail. We find very little difference in the total amount of gas removed from the unmagnetized and magnetized galaxies, although a magnetic field with a radial component will initially acceleratemore » stripped gas more quickly. In general, we find that magnetic fields in the disk lead to slower velocities in the stripped gas near the disk and faster velocities farther from the disk. We also find that magnetic fields in the galactic gas lead to larger unmixed structures in the tail. Finally, we discuss whether ram pressure stripped tails can magnetize the ICM. We find that the total magnetic energy density grows as the tail lengthens, likely through turbulence. There are μG-strength fields in the tail in all of our MHD runs, which survive to at least 100 kpc from the disk (the edge of our simulated region), indicating that the area-filling factor of magnetized tails in a cluster could be large.« less

Gala: A Python package for galactic dynamics

NASA Astrophysics Data System (ADS)

Price-Whelan, Adrian M.

2017-10-01

Gala is an Astropy-affiliated Python package for galactic dynamics. Python enables wrapping low-level languages (e.g., C) for speed without losing flexibility or ease-of-use in the user-interface. The API for Gala was designed to provide a class-based and user-friendly interface to fast (C or Cython-optimized) implementations of common operations such as gravitational potential and force evaluation, orbit integration, dynamical transformations, and chaos indicators for nonlinear dynamics. Gala also relies heavily on and interfaces well with the implementations of physical units and astronomical coordinate systems in the Astropy package (astropy.units and astropy.coordinates). Gala was designed to be used by both astronomical researchers and by students in courses on gravitational dynamics or astronomy. It has already been used in a number of scientific publications and has also been used in graduate courses on Galactic dynamics to, e.g., provide interactive visualizations of textbook material.

GSFC Contributions to the NATO X-ray Astronomy Institute, Erice, July 1979. [X-ray spectra of supernova remants, galactic X-ray sources, active galactic nuclei, and clusters of galaxies

NASA Technical Reports Server (NTRS)

Holt, S. S.; Mushotzky, R. F.

1979-01-01

An overview of X-ray astronomical spectroscopy in general is presented and results obtained by HEAO 1 and 2 as well as earlier spacecraft are examined. Particular emphasis is given to the spectra of supernova remnants; galactic binary X-ray sources, cataclysmic variables, bulges, pulsars, and stars; the active nuclei of Seyfert 1 galaxy, BL Lac, and quasars; the diffuse X-ray background; and galactic clusters.

NuSTAR results from the Galactic Center - diffuse emission

NASA Astrophysics Data System (ADS)

Hailey, Charles

2016-03-01

The Nuclear Spectroscopic Telescope Array (NuSTAR) was launched in June 2012. It carried the first true, hard X-ray (>~10 keV-79 keV) focusing telescopes into orbit. Its twin telescopes provide 10 times better angular resolution and 100 times better sensitivity than previously obtainable in the hard X-ray band. Consequently NuSTAR is able to resolve faint diffuse structures whose hard X-rays offer insight into some of the most energetic processes in the Galactic Center. One of the surprising discoveries that NuSTAR made in the Galactic Center is the central hard X-ray emission (CHXE). The CHXE is a diffuse emission detected from ~10 keV to beyond 50 keV in X-ray energy, and extending spatially over a region ~8 parsecs x ~4 parsecs in and out of the plane of the galaxy respectively, and centered on the supermassive black hole Sgr A*. The CHXE was speculated to be due to a large population of unresolved black hole X-ray binaries, millisecond pulsars (MSP), a class of highly magnetized white dwarf binaries called intermediate polars, or to particle outflows from Sgr A*. The presence of an unexpectedly large population of MSP in the Galactic Center would be particularly interesting, since MSP emitting at higher energies and over a much larger region have been posited to be the origin of the gamma-ray emission that is also ascribed to dark matter annihilation in the galaxy. In addition, the connection of the CHXE to the ~9000 unidentified X-ray sources in the central the the ~100 pc detected by the Chandra Observatory, to the soft X-ray emission detected by the Chandra and XMM/Newton observatories in the Galactic Center, and to the hard X-ray emission detected by both the RXTE and INTEGRAL observatories in the Galactic Ridge, is unclear. I review these results and present recent NuSTAR observations that potentially resolve the origin of the CHXE and point to a unified origin for all these X-ray emissions. Two other noteworthy classes of diffuse structures in the

Constraining the Galactic structure parameters with the XSTPS-GAC and SDSS photometric surveys

NASA Astrophysics Data System (ADS)

Chen, B.-Q.; Liu, X.-W.; Yuan, H.-B.; Robin, A. C.; Huang, Y.; Xiang, M.-S.; Wang, C.; Ren, J.-J.; Tian, Z.-J.; Zhang, H.-W.

2017-01-01

Photometric data from the Xuyi Schmidt Telescope Photometric Survey of the Galactic Anticentre (XSTPS-GAC) and the Sloan Digital Sky Survey (SDSS) are used to derive the global structure parameters of the smooth components of the Milky Way. The data, which cover nearly 11 000 deg2 sky area and the full range of Galactic latitude, allow us to construct a globally representative Galactic model. The number density distribution of Galactic halo stars is fitted with an oblate spheroid that decays by power law. The best fitting yields an axis ratio and a power-law index κ = 0.65 and p = 2.79, respectively. The r-band differential star counts of three dwarf samples are then fitted with a Galactic model. The best-fitting model yielded by a Markov Chain Monte Carlo analysis has thin and thick disc scale heights and lengths of H1 = 322 pc and L1 = 2343 pc, H2 = 794 pc and L2 = 3638 pc, a local thick-to-thin disc density ratio of f2 = 11 per cent, and a local density ratio of the oblate halo to the thin disc of fh = 0.16 per cent. The measured star count distribution, which is in good agreement with the above model for most of the sky area, shows a number of statistically significant large-scale overdensities, including some of the previously known substructures, such as the Virgo overdensity and the so-called `north near structure', and a new feature between 150° < l < 240° and -1° < b < -5°, at an estimated distance between 1.0 and 1.5 kpc. The Galactic North-South asymmetry in the anticentre is even stronger than previously thought.

X-Ray Processing of ChaMPlane Fields: Methods and Initial Results for Selected Anti-Galactic Center Fields

NASA Astrophysics Data System (ADS)

Hong, JaeSub; van den Berg, Maureen; Schlegel, Eric M.; Grindlay, Jonathan E.; Koenig, Xavier; Laycock, Silas; Zhao, Ping

2005-12-01

We describe the X-ray analysis procedure of the ongoing Chandra Multiwavelength Plane (ChaMPlane) Survey and report the initial results from the analysis of 15 selected anti-Galactic center observations (90degGalactic sources but also of general use: optimum photometry in crowded fields using advanced techniques for overlapping sources, rigorous astrometry and 95% error circles for combining X-ray images or matching to optical/IR images, and application of quantile analysis for spectral analysis of faint sources. We apply these techniques to 15 anti-Galactic center observations (of 14 distinct fields), in which we have detected 921 X-ray point sources. We present logN-logS distributions and quantile analysis to show that in the hard band (2-8 keV) active galactic nuclei dominate the sources. Complete analysis of all ChaMPlane anti-Galactic center fields will be given in a subsequent paper, followed by papers on sources in the Galactic center and bulge regions.

Impact of Distance Determinations on Galactic Structure. I. Young and Intermediate-Age Tracers

NASA Astrophysics Data System (ADS)

Matsunaga, Noriyuki; Bono, Giuseppe; Chen, Xiaodian; de Grijs, Richard; Inno, Laura; Nishiyama, Shogo

2018-06-01

Here we discuss impacts of distance determinations on the Galactic disk traced by relatively young objects. The Galactic disk, ˜40 kpc in diameter, is a cross-road of studies on the methods of measuring distances, interstellar extinction, evolution of galaxies, and other subjects of interest in astronomy. A proper treatment of interstellar extinction is, for example, crucial for estimating distances to stars in the disk outside the small range of the solar neighborhood. We'll review the current status of relevant studies and discuss some new approaches to the extinction law. When the extinction law is reasonably constrained, distance indicators found in today and future surveys are telling us stellar distribution and more throughout the Galactic disk. Among several useful distance indicators, the focus of this review is Cepheids and open clusters (especially contact binaries in clusters). These tracers are particularly useful for addressing the metallicity gradient of the Galactic disk, an important feature for which comparison between observations and theoretical models can reveal the evolution of the disk.

Galactic Evolution

NASA Astrophysics Data System (ADS)

Brekke, Stewart

2013-04-01

All galaxies began as spiral galaxies. The early universe began with sets of two or more pre-galactic arms orbiting each other. As gravitational attraction between the arms took effect, the fore-sections of the arms tangentially collided forming spiral galaxies when they attached with the orbital motion of the arms being converted to the rotational motion of the newly formed spiral galaxies or (Iφ)arm1+ (Iφ)arm2+ ...+ (Iφ)armn= (Iφ)galaxy. If the centripetal force on the arms is more than the gravitational force on the arms, the spiral galaxy remains a spiral galaxy i.e. mv^2/r>=Gmarmmgalaxy/r^2. If the galaxy is slowly rotating, the spiral arms collapse into the body of the galaxy because the gravitational force is greater than the centripetal force on the arms and an elliptical galaxy is formed i.e. mv^2/r < Gmarmsmgalaxy/r^2.

16. The Baltimore & Ohio R.R System, Division BaltimoreEast, Bridge ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

16. The Baltimore & Ohio R.R System, Division Baltimore-East, Bridge No 13-A, Branch Philadelphia. Baltimore: Office of Engineer of Bridges, 1945. Copy of drawing located at the Baltimore County Department of Public Works, Towson, Maryland. - Allender Road Bridge, Spanning CSX Transportation railroad tracks at Allender Road, White Marsh, Baltimore County, MD

Detection of extended galactic sources with an underwater neutrino telescope

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

Leisos, A.; Tsirigotis, A. G.; Tzamarias, S. E.

2014-11-18

In this study we investigate the discovery capability of a Very Large Volume Neutrino Telescope to Galactic extended sources. We focus on the brightest HESS gamma rays sources which are considered also as very high energy neutrino emitters. We use the unbinned method taking into account both the spatial and the energy distribution of high energy neutrinos and we investigate parts of the Galactic plane where nearby potential neutrino emitters form neutrino source clusters. Neutrino source clusters as well as isolated neutrino sources are combined to estimate the observation period for 5 sigma discovery of neutrino signals from these objects.

The Galactic Magnetic Field and Ultra-High Energy Cosmic Rays

NASA Astrophysics Data System (ADS)

Urban, Federico R.

The Galactic Magnetic Field is a peeving and importune screen between Ultra-High Energy Cosmic Rays and us cosmologists, engaged in the combat to unveil their properties and origin, as it deviates their paths towards the Earth in unpredictable ways. I will, in this order: briefly review the available field models on the market; explain a little trick which allows one to obtain cosmic rays deflection variances without even knowing what the (random) GMF model is; and argue that there is a lack of anisotropy in the large scales cosmic rays signal, which the Galactic field can do nothing about.

Crystallography of rare galactic honeycomb structure near supernova 1987a

NASA Technical Reports Server (NTRS)

Noever, David A.

1994-01-01

Near supernova 1987a, the rare honeycomb structure of 20-30 galactic bubbles measures 30 x 90 light years. Its remarkable regularity in bubble size suggests a single-event origin which may correlate with the nearby supernova. To test the honeycomb's regularity in shape and size, the formalism of statistical crystallography is developed here for bubble sideness. The standard size-shape relations (Lewis's law, Desch's law, and Aboav-Weaire's law) govern area, perimeter and nearest neighbor shapes. Taken together, they predict a highly non-equilibrium structure for the galactic honeycomb which evolves as a bimodal shape distribution without dominant bubble perimeter energy.

Photographic photometry of RR Lyrae variables in the globular cluster M15

NASA Astrophysics Data System (ADS)

Bingham, E. A.; Cacciari, C.; Dickens, R. J.; Pecci, F. F.

1984-08-01

Light curves in B and V bands are presented for 56 RR Lyrae variables in the Oosterhoff Group II globular cluster M15. Correlations between light curves parameters are obtained and their significance is discussed. An accurate assessment of the sources of error in the period-color relation has permitted the prediction of the range of masses among the variables with a dispersion of about 0.025 solar mass. The period color relation was used to derive a mass-to-light ratio of -1.92 (+ or - 0.03). The luminosity observed in M15 implies an age a few billion years less than current estimates. The morphology of the SG tracks indicates that many of the RR Lyraes in M15 begin their horizontal evolution within the instability strip, spending much longer in the center of the strip than M3-like clusters which evolve more rapidly bluewards across the strip.

Exploring the Dust Content of Galactic Winds with MIPS

NASA Astrophysics Data System (ADS)

Martin, Crystal; Engelbracht, Charles; Gordon, Karl

2005-06-01

This program explores the dust content of galactic winds. Nearly half of all stars in the universe probably form in a starburst event, where high concentrations of supernova explosions drive galactic-scale gaseous outflows. In nearby starburst galaxies, winds have been mapped at radio, optical, and X-ray frequencies revealing bipolar lobes of hot gas laced with cooler filaments bubbling out of the host galaxy. Most of the outflowing material is entrained interstellar gas, so it will remain quite dusty unless the grains are destroyed. Dusty winds have significant implications for the circulation of heavy elements in galaxies, the dust content of the intergalactic medium, and the acceleration of gaseous outflows. GALEX images of scattered ultraviolet light from galactic winds now provide compelling evidence for the survival of some grains. MIPS photometry of starburst winds at 24, 70, and 160 microns can, in principle, measure the dust temperature providing accurate estimates of the amount of dust (e.g. Engelbracht et al. 2004). To date, however, most MIPS observations of starburst galaxies are far too shallow to detect thermal emission from halo dust. The requested observations would provide the most sensitive observations currently possible for a sample of starburst galaxies, selected to span the full range of starburst luminosity and spatial geometry in the local universe.

The Dusty Galactic Center as Seen by SCUBA-2

NASA Astrophysics Data System (ADS)

Parsons, H.; Dempsey, J. T.; Thomas, H. S.; Berry, D.; Currie, M. J.; Friberg, P.; Wouterloot, J. G. A.; Chrysostomou, A.; Graves, S.; Tilanus, R. P. J.; Bell, G. S.; Rawlings, M. G.

2018-02-01

We present new JCMT SCUBA-2 observations of the Galactic Center region from 355^\\circ < l< 5^\\circ and b< +/- 1^\\circ , covering 10 × 2 square degrees along the Galactic Plane to a depth of 43 mJy beam‑1 at 850 μm and 360 mJy beam‑1 at 450 μm. We describe the mapping strategy and reduction method used. We present 12CO(3-2) observations of selected regions in the field. We derive the molecular-line conversion factors (mJy beam‑1 per K km s‑1) at 850 and 450 μm, which are then used to obtain the amount of contamination in the continuum maps due to 12CO(3-2) emission in the 850 μm band. Toward the fields where the CO contamination has been accounted for, we present an 850 μm CO-corrected compact source catalog. Finally, we look for possible physical trends in the CO contamination with respect to column density, mass, and concentration. No trends were seen in the data despite the recognition of three contributors to CO contamination: opacity, shocks, and temperature, which would be expected to relate to physical conditions. These SCUBA-2 Galactic Center data and catalog are available via https://doi.org/10.11570/17.0009.

Discovery of carbon-rich Miras in the Galactic bulge

NASA Astrophysics Data System (ADS)

Matsunaga, Noriyuki; Menzies, John W.; Feast, Michael W.; Whitelock, Patricia A.; Onozato, Hiroki; Barway, Sudhanshu; Aydi, Elias

2017-08-01

Only one carbon-rich (C-rich, hereinafter) Mira variable has so far been suggested as a member of the Galactic bulge and this is in a symbiotic system. Here we describe a method for selecting C-rich candidates from an infrared colour-colour diagram, (J - Ks) versus ([9] - [18]). Follow-up low-resolution spectroscopy resulted in the detection of eight C-rich Mira variables from a sample of 36 candidates towards the Galactic bulge. Our near-infrared photometry indicates that two of these, including the known symbiotic, are closer than the main body of the bulge while a third is a known foreground object. Of the five bulge members, one shows He I and [O II] emission and is possibly another symbiotic star. Our method is useful for identifying rare C-rich stars in the Galactic bulge and elsewhere. The age of these C-rich stars and the evolutionary process which produced them remain uncertain. They could be old and the products of either binary mass transfer or mergers, I.e. the descendants of blue stragglers, but we cannot rule out the possibility that they belong to a small in situ population of metal-poor intermediate age (<5 Gyr) stars in the bulge or that they have been accreted from a dwarf galaxy.

Modulating terrestrial impacts from Oort cloud comets by the adiabatically changing galactic tides

NASA Astrophysics Data System (ADS)

Matese, J. J.; Whitman, P. G.; Innanen, K. A.; Valtonen, M. J.

Time modulation of the flux of new Jupiter-dominated Oort cloud comets is the subject of interest here. The major perturbation of these comets during the present epoch is due to the tidal field of the relatively smooth distribution of matter in the galactic disk. A secondary source of the near-parabolic comet flux are stars penetrating the inner Oort cloud and providing impulses that create brief comet showers. Substantial stellar-induced showers occur approximately every 100 m.y. Less frequent (but stronger) impulses due to giant molecular clouds can also perturb comets from the inner cloud. These occur on timescales of approximately equal to 500 m.y. In contrast to these infrequent stochastic shower phenomena is the continuously varying tidal-induced flux due to the galaxy. As the Sun orbits the galactic center it undergoes quasiharmonic motion about the galactic midplane, which is superimposed on the small eccentricity, near-Keplerian motion in the plane having epicycle period approximately equal to 150 m.y. In the process the galactic tidal field on the Sun/cloud system will vary causing a modulation of the observable Oort cloud flux. We have created a model of the galactic matter distribution as it affects the solar motion over a time interval ranging from 300 m.y. in the past to 100 m.y. into the future. As constraints on the disk's compact dark matter component we require consistency with the following: (1) the observed galactic rotation curve, (2) today's flux distribution of new comets, (3) the studies of K-giant distributions, and (4) the periodicity found in the terrestrial cratering record. The adiabatically varying galactic tidal torque is then determined and used to predict the time dependence of the flux. We find that a model in which approximately half the disk matter is compact is consistent with these constraints. Under such circumstances the peak-to-trough flux variation will be approx. equal to 5:1 with a full width of 9 m.y. This variability

Galactic City at the Edge of the Universe

NASA Image and Video Library

2011-01-12

Astronomers have discovered a massive cluster of young galaxies forming in the distant universe. The growing galactic metropolis is known as COSMOS-AzTEC3. This image was taken Japan Subaru telescope atop Mauna Kea in Hawaii.

Investigation of gamma rays from the galactic center

NASA Technical Reports Server (NTRS)

Helmken, H. F.

1973-01-01

Data from Argentine balloon flights made to investigate gamma ray emission from the galactic center are summarized. Data are also summarized from a Palestine, Texas balloon flight to measure gamma rays from NP 0532 and Crab Nebulae.

ASTE Surveys of Galactic Star-Forming Regions

NASA Astrophysics Data System (ADS)

Kohno, Kotaro

2008-05-01

We report some recent highlights on the observational studies of Galactic star formation based on surveys using the Atacama Submillimeter Telescope Experiment (ASTE), a new 10 m telescope in the Atacama desert in northern Chile (Kohno et al., 2008, ApSS, 313, 279). The highlights will include (1) a large scale CO(3-2) imaging survey of the Galactic Center, unveiling the presence of numerous compact high velocity clouds with high CO(3-2)/CO(1-0) ratios as a "fossil” of the recent burst of star formation in the Galactic Center region (Oka et al., 2007, PASJ, 59, 15; Nagai et al., 2007, PASJ, 59, 25; Tanaka et al., 2007, PASJ, 59, 323), (2) a large scale CO(3-2) imaging survey of the Sgr arm and inter-am regions, revealing the distinct difference on the morphology and physical property of molecular gas between the arm and inter-arm regions for the first time (Sawada, Koda, et al., in prep.), and (3) a wide area 1.1 mm imaging survey of Southern low mass star-forming regions such as Chamaeleon and Lupus molecular clouds using the bolometer camera AzTEC (Wilson et al., 2008, MNRAS, in press) mounted on ASTE, yielding detections of starless cores with a very low mass detection limist down to 0.1 solar masses (Hiramatsu, Tsukagoshi, Kawabe et al., in prep.). Related topics on the massive star-forming regions in very nearby galaxies such as LMC (Minamidani et al., 2008, ApJS, in press) and M 33 (Tosaki et al., 2007, ApJ, 664, L27; Onodera et al., in prep.; Komugi et al., in prep.) will also be reviewed.

Millisecond Pulsars and the Galactic Center Excess

NASA Astrophysics Data System (ADS)

Gonthier, Peter L.; Koh, Yew-Meng; Kust Harding, Alice; Ferrara, Elizabeth C.

2017-08-01

Various groups including the Fermi team have confirmed the spectrum of the gamma- ray excess in the Galactic Center (GCE). While some authors interpret the GCE as evidence for the annihilation of dark matter (DM), others have pointed out that the GCE spectrum is nearly identical to the average spectrum of Fermi millisecond pul- sars (MSP). Assuming the Galactic Center (GC) is populated by a yet unobserved source of MSPs that has similar properties to that of MSPs in the Galactic Disk (GD), we present results of a population synthesis of MSPs from the GC. We establish parameters of various models implemented in the simulation code by matching characteristics of 54 detected Fermi MSPs in the first point source catalog and 92 detected radio MSPs in a select group of thirteen radio surveys and targeting a birth rate of 45 MSPs per mega-year. As a check of our simulation, we find excellent agreement with the estimated numbers of MSPs in eight globular clusters. In order to reproduce the gamma-ray spectrum of the GCE, we need to populate the GC with 10,000 MSPs having a Navarro-Frenk-White distribution suggested by the halo density of DM. It may be possible for Fermi to detect some of these MSPs in the near future; the simulation also predicts that many GC MSPs have radio fluxes S1400above 10 �μJy observable by future pointed radio observations. We express our gratitude for the generous support of the National Science Foundation (RUI: AST-1009731), Fermi Guest Investigator Program and the NASA Astrophysics Theory and Fundamental Program (NNX09AQ71G).

Galactic conformity measured in semi-analytic models

NASA Astrophysics Data System (ADS)

Lacerna, I.; Contreras, S.; González, R. E.; Padilla, N.; Gonzalez-Perez, V.

2018-03-01

We study the correlation between the specific star formation rate of central galaxies and neighbour galaxies, also known as `galactic conformity', out to 20 h^{-1} {Mpc} using three semi-analytic models (SAMs, one from L-GALAXIES and other two from GALFORM). The aim is to establish whether SAMs are able to show galactic conformity using different models and selection criteria. In all the models, when the selection of primary galaxies is based on an isolation criterion in real space, the mean fraction of quenched (Q) galaxies around Q primary galaxies is higher than that around star-forming primary galaxies of the same stellar mass. The overall signal of conformity decreases when we remove satellites selected as primary galaxies, but the effect is much stronger in GALFORM models compared with the L-GALAXIES model. We find this difference is partially explained by the fact that in GALFORM once a galaxy becomes a satellite remains as such, whereas satellites can become centrals at a later time in L-GALAXIES. The signal of conformity decreases down to 60 per cent in the L-GALAXIES model after removing central galaxies that were ejected from their host halo in the past. Galactic conformity is also influenced by primary galaxies at fixed stellar mass that reside in dark matter haloes of different masses. Finally, we explore a proxy of conformity between distinct haloes. In this case, the conformity is weak beyond ˜3 h^{-1} {Mpc} (<3 per cent in L-GALAXIES, <1-2 per cent in GALFORM models). Therefore, it seems difficult that conformity is directly related with a long-range effect.

PERIOD–COLOR AND AMPLITUDE–COLOR RELATIONS AT MAXIMUM AND MINIMUM LIGHT FOR RR LYRAE STARS IN THE SDSS STRIPE 82 REGION

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

Ngeow, Chow-Choong; Kanbur, Shashi M.; Schrecengost, Zachariah

Investigation of period–color (PC) and amplitude–color (AC) relations at the maximum and minimum light can be used to probe the interaction of the hydrogen ionization front (HIF) with the photosphere and the radiation hydrodynamics of the outer envelopes of Cepheids and RR Lyraes. For example, theoretical calculations indicated that such interactions would occur at minimum light for RR Lyrae and result in a flatter PC relation. In the past, the PC and AC relations have been investigated by using either the ( V − R ){sub MACHO} or ( V − I ) colors. In this work, we extend previousmore » work to other bands by analyzing the RR Lyraes in the Sloan Digital Sky Survey Stripe 82 Region. Multi-epoch data are available for RR Lyraes located within the footprint of the Stripe 82 Region in five ( ugriz ) bands. We present the PC and AC relations at maximum and minimum light in four colors: ( u − g ){sub 0}, ( g − r ){sub 0}, ( r − i ){sub 0}, and ( i − z ){sub 0}, after they are corrected for extinction. We found that the PC and AC relations for this sample of RR Lyraes show a complex nature in the form of flat, linear or quadratic relations. Furthermore, the PC relations at minimum light for fundamental mode RR Lyrae stars are separated according to the Oosterhoff type, especially in the ( g − r ){sub 0} and ( r − i ){sub 0} colors. If only considering the results from linear regressions, our results are quantitatively consistent with the theory of HIF-photosphere interaction for both fundamental and first overtone RR Lyraes.« less

The Apache Point Observatory Galactic Evolution Experiment (APOGEE) and its successor, APOGEE-2

NASA Astrophysics Data System (ADS)

Majewski, S. R.; APOGEE Team; APOGEE-2 Team

2016-09-01

The Apache Point Observatory Galactic Evolution Experiment (APOGEE) of Sloan Digital Sky Survey III (SDSS-III) has produced a large catalog of high resolution ({R = 22 500}), high quality (S/N > 100), infrared (H-band) spectra for stars throughout all stellar populations of the Milky Way, including in regions veiled by significant dust opacity. APOGEE's half million spectra collected on > 163 000 unique stars, with time series information via repeat visits to each star, are being applied to numerous problems in stellar populations, Galactic astronomy, and stellar astrophysics. From among the early results of the APOGEE project - which span from measurements of Galactic dynamics, to multi-element chemical maps of the disk and bulge, new views of the interstellar medium, explorations of stellar companions, the chemistry of star clusters, and the discovery of rare stellar species - I highlight a few results that demonstrate APOGEE's unique ability to sample and characterize the Galactic disk and bulge. Plans are now under way for an even more ambitious successor to APOGEE: the six-year, dual-hemisphere APOGEE-2 project. Both phases of APOGEE feature a strong focus on targets having asteroseismological measurements from either Kepler or {CoRoT}, from which it is possible to derive relatively precise stellar ages. The combined APOGEE and APOGEE-2 databases of stellar chemistry, dynamics and ages constitute an unusually comprehensive, systematic and homogeneous resource for constraining models of Galactic evolution.

Consistency between the luminosity function of resolved millisecond pulsars and the galactic center excess

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

Ploeg, Harrison; Gordon, Chris; Crocker, Roland

Fermi Large Area Telescope data reveal an excess of GeV gamma rays from the direction of the Galactic Center and bulge. Several explanations have been proposed for this excess including an unresolved population of millisecond pulsars (MSPs) and self-annihilating dark matter. It has been claimed that a key discriminant for or against the MSP explanation can be extracted from the properties of the luminosity function describing this source population. Specifically, is the luminosity function of the putative MSPs in the Galactic Center consistent with that characterizing the resolved MSPs in the Galactic disk? To investigate this we have used amore » Bayesian Markov Chain Monte Carlo to evaluate the posterior distribution of the parameters of the MSP luminosity function describing both resolved MSPs and the Galactic Center excess. At variance with some other claims, our analysis reveals that, within current uncertainties, both data sets can be well fit with the same luminosity function.« less

High-Energy Radiation from a Model of Quasars, Active Galactic Nuclei, and the Galactic Center with Magnetic Monopoles

NASA Astrophysics Data System (ADS)

Peng, Qiu-he; Chou, Chih-kang

2001-04-01

The fact that magnetic monopoles may catalyze nucleon decay (the Rubakov-Callan [RC] effect) as predicated by the grand unified theory of particle physics is invoked as the energy source of quasars and active galactic nuclei. Recent study of this model revealed that the radius of the supermassive object (SMO) located at the Galactic center is much larger than its Schwarzschild radius. We propose that this SMOs could be the source of high-energy gamma-ray radiation, although the emitted radiation may be mainly concentrated in the infrared. The surface temperature of the SMO at the Galactic center is taken as 121 K, inferred from the observed maximum of the flux spectrum of Sgr A* at the near infrared (1×1013 Hz); the radius of the SMO is about 8.1×1015 cm or 1.1×104RS (RS is the Schwarzschild radius). The mass of the SMO is derived from the observed total luminosity of Sgr A* (1×1037 ergs s-1) as 2.5×106 Msolar. Strong gamma-ray radiation with energy higher than 0.5 MeV may be emitted from the SMO. The flux of positrons emitted from the SMO is estimated to be 6.5×1042e+ s-1. The content parameter of magnetic monopoles ξ≡[(Nm/NB)/1.9×10- 25](<σβ>/10-27) also may be deduced from observations to be 230. Taking the cross section of the RC effect as 1×10-27 cm2, the strength of the radial magnetic field at the surface of the SMO is estimated to be 20-100 G. Our model also can predict the production of extreme ultra-high-energy cosmic rays.

Galactic Structure: A Constructivist Approach to Teaching Astronomy.

ERIC Educational Resources Information Center

Domenech, Antonio; Casasus, Elena

1991-01-01

An astrophysics course based on the constructivist approach to science teaching is described. The study of galactic structure is given as an example. Direct experiences and observations, representative-symbolic language, organized knowledge, and formal strategies are emphasized. (KR)

Aging and cardiovascular complexity: effect of the length of RR tachograms

PubMed Central

Nagaraj, Nithin

2016-01-01

As we age, our hearts undergo changes that result in a reduction in complexity of physiological interactions between different control mechanisms. This results in a potential risk of cardiovascular diseases which are the number one cause of death globally. Since cardiac signals are nonstationary and nonlinear in nature, complexity measures are better suited to handle such data. In this study, three complexity measures are used, namely Lempel–Ziv complexity (LZ), Sample Entropy (SampEn) and Effort-To-Compress (ETC). We determined the minimum length of RR tachogram required for characterizing complexity of healthy young and healthy old hearts. All the three measures indicated significantly lower complexity values for older subjects than younger ones. However, the minimum length of heart-beat interval data needed differs for the three measures, with LZ and ETC needing as low as 10 samples, whereas SampEn requires at least 80 samples. Our study indicates that complexity measures such as LZ and ETC are good candidates for the analysis of cardiovascular dynamics since they are able to work with very short RR tachograms. PMID:27957395

Testing the Bose-Einstein Condensate dark matter model at galactic cluster scale

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

Harko, Tiberiu; Liang, Pengxiang; Liang, Shi-Dong

The possibility that dark matter may be in the form of a Bose-Einstein Condensate (BEC) has been extensively explored at galactic scale. In particular, good fits for the galactic rotations curves have been obtained, and upper limits for the dark matter particle mass and scattering length have been estimated. In the present paper we extend the investigation of the properties of the BEC dark matter to the galactic cluster scale, involving dark matter dominated astrophysical systems formed of thousands of galaxies each. By considering that one of the major components of a galactic cluster, the intra-cluster hot gas, is describedmore » by King's β-model, and that both intra-cluster gas and dark matter are in hydrostatic equilibrium, bound by the same total mass profile, we derive the mass and density profiles of the BEC dark matter. In our analysis we consider several theoretical models, corresponding to isothermal hot gas and zero temperature BEC dark matter, non-isothermal gas and zero temperature dark matter, and isothermal gas and finite temperature BEC, respectively. The properties of the finite temperature BEC dark matter cluster are investigated in detail numerically. We compare our theoretical results with the observational data of 106 galactic clusters. Using a least-squares fitting, as well as the observational results for the dark matter self-interaction cross section, we obtain some upper bounds for the mass and scattering length of the dark matter particle. Our results suggest that the mass of the dark matter particle is of the order of μ eV, while the scattering length has values in the range of 10{sup −7} fm.« less

Transient Events in Archival Very Large Array Observations of the Galactic Center

NASA Astrophysics Data System (ADS)

Chiti, Anirudh; Chatterjee, Shami; Wharton, Robert; Cordes, James; Lazio, T. Joseph W.; Kaplan, David L.; Bower, Geoffrey C.; Croft, Steve

2016-12-01

The Galactic center has some of the highest stellar densities in the Galaxy and a range of interstellar scattering properties, which may aid in the detection of new radio-selected transient events. Here, we describe a search for radio transients in the Galactic center, using over 200 hr of archival data from the Very Large Array at 5 and 8.4 GHz. Every observation of Sgr A* from 1985 to 2005 has been searched using an automated processing and detection pipeline sensitive to transients with timescales between 30 s and 5 minutes with a typical detection threshold of ˜100 mJy. Eight possible candidates pass tests to filter false-positives from radio-frequency interference, calibration errors, and imaging artifacts. Two events are identified as promising candidates based on the smoothness of their light curves. Despite the high quality of their light curves, these detections remain suspect due to evidence of incomplete subtraction of the complex structure in the Galactic center, and apparent contingency of one detection on reduction routines. Events of this intensity (˜100 mJy) and duration (˜100 s) are not obviously associated with known astrophysical sources, and no counterparts are found in data at other wavelengths. We consider potential sources, including Galactic center pulsars, dwarf stars, sources like GCRT J1745-3009, and bursts from X-ray binaries. None can fully explain the observed transients, suggesting either a new astrophysical source or a subtle imaging artifact. More sensitive multiwavelength studies are necessary to characterize these events, which, if real, occur with a rate of {14}-12+32 {{hr}}-1 {\\deg }-2 in the Galactic center.

Dynamics of the CMZ - Giant Magnetic Loops Connection in the Galactic Center

NASA Astrophysics Data System (ADS)

Langer, William

2012-10-01

Understanding the mass transfer and dynamics among the Galactic Center, the disk, and the halo of the Milky Way is fundamental to the study of the evolution of galaxies and star formation. Several giant molecular loops (GML), detected in CO maps of the Galactic Center, are likely the result of the magnetic Parker instability. We have new evidence of a possible dynamical connection between these loops and the Central Molecular Zone (CMZ) from a sparse [CII] sampling from our Herschel Open Time Key Project GOT C+. The CMZ-GML region is dynamically active and is likely to have a significant ionized component. However, we have no information on the distribution and dynamics of the ionized gas. The fine-structure lines of [NII] are key probes of the warm ionized medium (WIM) and along with the [CII] can isolate the different ionization components. We have a Herschel OT2 Priority 1 program to map the GML and the CMZ-GML connection in [CII] in more detail. However, we did not propose needed [NII] observations due to an incomplete analysis of our limited GOT C+ data at the time. Here we propose to observe with the SOFIA/GREAT instrument, [NII] in the CMZ-GML interface region using the L1b band, and serendipitously CO (16-15) using band L2. With this data, combined with our Herschel HIFI [CII], Mopra 12CO (1-0) and 13CO (1-0), and HI, we will characterize these important ISM components and their motions in these Galactic Center features. These observations of the nearest such regions of galactic center activity, also have bearing on the dynamics of other galactic nuclei.

The Diffuse Radiation Field at High Galactic Latitudes

NASA Astrophysics Data System (ADS)

Akshaya, M. S.; Murthy, Jayant; Ravichandran, S.; Henry, R. C.; Overduin, James

2018-05-01

We have used GALEX observations of the north and south Galactic poles to study the diffuse ultraviolet background at locations where the Galactic light is expected to be at a minimum. We find offsets of 230–290 photon units in the far-UV (1531 Å) and 480–580 photon units in the near-UV (2361 Å). Of this, approximately 120 photon units can be ascribed to dust-scattered light and another 110 photon units (190 in the near-UV) to extragalactic radiation. The remaining radiation is, as yet, unidentified and amounts to 120–180 photon units in the far-UV and 300–400 photon units in the near-UV. We find that molecular hydrogen fluorescence contributes to the far-UV when the 100 μm surface brightness is greater than 1.08 MJy sr‑1.

Deciphering the Dipole Anisotropy of Galactic Cosmic Rays.

PubMed

Ahlers, Markus

2016-10-07

Recent measurements of the dipole anisotropy in the arrival directions of Galactic cosmic rays (CRs) indicate a strong energy dependence of the dipole amplitude and phase in the TeV-PeV range. We argue here that these observations can be well understood within standard diffusion theory as a combined effect of (i) one or more local sources at Galactic longitude 120°≲l≲300° dominating the CR gradient below 0.1-0.3 PeV, (ii) the presence of a strong ordered magnetic field in our local environment, (iii) the relative motion of the solar system, and (iv) the limited reconstruction capabilities of ground-based observatories. We show that an excellent candidate of the local CR source responsible for the dipole anisotropy at 1-100 TeV is the Vela supernova remnant.

The origin of the diffuse galactic IR/submm emission: Revisited after IRAS

NASA Technical Reports Server (NTRS)

Cox, P.; Mezger, P. G.

1987-01-01

Balloon observations are compared with Infrared Astronomy Satellite observations. There was good agreement for the longitudinal profiles. However, the dust emission observed by IRAS, contrary to the balloon observations which show dust emission only within the absolute value of b is equal to or less than 3 degrees, extends all the way to the galactic pole. The model fits were repeated using more recent parameters for the distribution of interstellar matter in the galactic disk and central region. The IR luminosities are derived for the revised galactic distance scale of solar radius - 8.5 Kpc. A total IR luminosity of 1.2 E10 solar luminosity is obtained, which is about one third of the estimated stellar luminosity of the Galaxy. The dust emission spectrum lambdaI(sub lambda) attains it maximum at 100 microns. A secondary maximum in the dust emission spectrum occurs at 10 microns, which contains 15% of the total IR luminosity of the Galaxy. The galactic dust emission spectrum was compared with the dust emission spectra of external IRAS galaxies. The warm dust luminosity relates to the present OB star formation rate, while flux densities observed at longer submm wavelengths are dominated by cold dust emission and thus can be used to estimate gas masses.

The Planck Catalogue of Galactic Cold Clumps : Looking at the early stages of star-formation

NASA Astrophysics Data System (ADS)

Montier, Ludovic

2015-08-01

The Planck satellite has provided an unprecedented view of the submm sky, allowing us to search for the dust emission of Galactic cold sources. Combining Planck-HFI all-sky maps in the high frequency channels with the IRAS map at 100um, we built the Planck catalogue of Galactic Cold Clumps (PGCC, Planck 2015 results XXVIII 2015), counting 13188 sources distributed over the whole sky, and following mainly the Galactic structures at low and intermediate latitudes. This is the first all-sky catalogue of Galactic cold sources obtained with a single instrument at this resolution and sensitivity, which opens a new window on star-formation processes in our Galaxy.I will briefly describe the colour detection method used to extract the Galactic cold sources, i.e., the Cold Core Colour Detection Tool (CoCoCoDeT, Montier et al. 2010), and its application to the Planck data. I will discuss the statistical distribution of the properties of the PGCC sources (in terms of dust temperature, distance, mass, density and luminosity), which illustrates that the PGCC catalogue spans a large variety of environments and objects, from molecular clouds to cold cores, and covers various stages of evolution. The Planck catalogue is a very powerful tool to study the formation and the evolution of prestellar objects and star-forming regions.I will finally present an overview of the Herschel Key Program Galactic Cold Cores (PI. M.Juvela), which allowed us to follow-up about 350 Planck Galactic Cold Clumps, in various stages of evolution and environments. With this program, the nature and the composition of the 5' Planck sources have been revealed at a sub-arcmin resolution, showing very different configurations, such as starless cold cores or multiple Young Stellar objects still embedded in their cold envelope.

Expectations for high energy diffuse galactic neutrinos for different cosmic ray distributions

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

Pagliaroli, Giulia; Evoli, Carmelo; Villante, Francesco Lorenzo, E-mail: giulia.pagliaroli@gssi.infn.it, E-mail: carmelo.evoli@gssi.infn.it, E-mail: francesco.villante@lngs.infn.it

2016-11-01

The interaction of cosmic rays with the gas contained in our Galaxy is a guaranteed source of diffuse high energy neutrinos. We provide expectations for this component by considering different assumptions for the cosmic ray distribution in the Galaxy which are intended to cover the large uncertainty in cosmic ray propagation models. We calculate the angular dependence of the diffuse galactic neutrino flux and the corresponding rate of High Energy Starting Events in IceCube by including the effect of detector angular resolution. Moreover we discuss the possibility to discriminate the galactic component from an isotropic astrophysical flux. We show thatmore » a statistically significant excess of events from the galactic plane in present IceCube data would disfavour models in which the cosmic ray density is uniform , thus bringing relevant information on the cosmic ray radial distribution.« less

PREFACE: Galactic Center Workshop 2006

NASA Astrophysics Data System (ADS)

Schödel, Rainer; Bower, Geoffrey C.; Muno, Michael P.; Nayakshin, Sergei; Ott, Thomas

2006-12-01

We are pleased to present the proceedings from the Galactic Center Workshop 2006—From the Center of the Milky Way to Nearby Low-Luminosity Galactic Nuclei. The conference took place in the Physikzentrum, Bad Honnef, Germany, on 18 to 22 April 2006. It is the third workshop of this kind, following the Galactic Center Workshops held 1998 in Tucson, Arizona, and 2002 in Kona, Hawaii. The center of the Milky Way is the only galactic nucleus of a fairly common spiral galaxy that can be observed in great detail. With a distance of roughly 8 kpc, the resolution that can currently be achieved is of the order 40 mpc/8000 AU in the X-ray domain, 2 mpc/400 AU in the near-infrared, and 0.01 mpc/1 AU with VLBI in the millimeter domain. This is two to three orders of magnitude better than for any comparable nearby galaxy, making thus the center of the Milky Way thetemplate object for the general physical interpretation of the phenomena that can be observed in galactic nuclei. We recommend the summary article News from the year 2006 Galactic Centre workshopby Mark Morris and Sergei Nayakshin—who also gave the summary talk of the conference—to the reader in order to obtain a first, concise overview of the results presented at the workshop and some of the currently most exciting—and debated—developments in recent GC research. While the workshops held in 1998 and 2002 were dedicated solely to the center of the Milky Way, the field of view was widened in Bad Honnef to include nearby low-luminosity nuclei. This new feature followed the realization that not only the GC serves as a template for understanding extragalactic nuclei, but that the latter can also provide the context and broader statistical base for understanding the center of our Milky Way. This concerns especially the accretion and emission processes related to the Sagittarius A*, the manifestation of the super massive black hole in the GC, but also the surprising observation of great numbers of massive, young

Contributions of tidal lung inflation to human R-R interval and arterial pressure fluctuations

NASA Technical Reports Server (NTRS)

Koh, J.; Brown, T. E.; Beightol, L. A.; Eckberg, D. L.

1998-01-01

We studied the effects of mechanical lung inflation on respiratory frequency R-R interval and arterial pressure fluctuations in nine healthy young adults undergoing elective orthopedic surgery. We conducted this research to define the contribution of pulmonary and thoracic stretch receptor input to respiratory sinus arrhythmia. We compared fast Fourier transform spectral power during three modes of ventilation: (1) spontaneous, frequency-controlled (0.25 Hz) breathing, (2) intermittent positive pressure ventilation (0.25 Hz, with a tidal volume of 8 ml/kg) and (3) high frequency jet ventilation (5.0 Hz, 2.5 kg/cm2), after sedation and vecuronium paralysis. Mean R-R intervals, arterial pressures and arterial blood gas levels were comparable during all three breathing conditions. Respiratory frequency systolic pressure spectral power was comparable during spontaneous breathing and conventional mechanical ventilation, but was significantly reduced during high frequency jet ventilation (P < 0.05). Respiratory frequency R-R interval spectral power (used as an index of respiratory sinus arrhythmia) declined dramatically with sedation and muscle paralysis (P < 0.05), but was greater during conventional mechanical, than high frequency jet ventilation (P < 0.05). These results suggest that although phasic inputs from pulmonary and thoracic stretch receptors make a statistically significant contribution to respiratory sinus arrhythmia, that contribution is small.

Blowing in the Milky Way Wind: Neutral Hydrogen Clouds Tracing the Galactic Nuclear Outflow

NASA Astrophysics Data System (ADS)

Di Teodoro, Enrico M.; McClure-Griffiths, N. M.; Lockman, Felix J.; Denbo, Sara R.; Endsley, Ryan; Ford, H. Alyson; Harrington, Kevin

2018-03-01

We present the results of a new sensitive survey of neutral hydrogen above and below the Galactic Center with the Green Bank Telescope. The observations extend up to Galactic latitude | b| < 10^\\circ with an effective angular resolution of 9.‧5 and an average rms brightness temperature noise of 40 mK in a 1 {km} {{{s}}}-1 channel. The survey reveals the existence of a population of anomalous high-velocity clouds extending up to heights of about 1.5 kpc from the Galactic plane and showing no signature of Galactic rotation. These clouds have local standard of rest velocities | {V}LSR}| ≲ 360 {km} {{{s}}}-1, and assuming a Galactic Center origin, they have sizes of a few tens of parsec and neutral hydrogen masses spanning 10{--}{10}5 {M}ȯ . Accounting for selection effects, the cloud population is symmetric in longitude, latitude, and V LSR. We model the cloud kinematics in terms of an outflow expanding from the Galactic Center and find the population consistent with being material moving with radial velocity {V}{{w}}≃ 330 {km} {{{s}}}-1 distributed throughout a bicone with opening angle α > 140^\\circ . This simple model implies an outflow luminosity {L}{{w}}> 3× {10}40 erg s‑1 over the past 10 Myr, consistent with star formation feedback in the inner region of the Milky Way, with a cold gas mass-loss rate ≲ 0.1 {{M}ȯ {yr}}-1. These clouds may represent the cold gas component accelerated in the nuclear wind driven by our Galaxy, although some of the derived properties challenge current theoretical models of the entrainment process.

Galactic Bulge Giants: Probing Stellar and Galactic Evolution. 1. Catalogue of Spitzer IRAC and MIPS Sources (PREPRINT)

NASA Technical Reports Server (NTRS)

Uttenthaler, Stefan; Stute, Matthias; Sahai, Raghvendra; Blommaert, Joris A.; Schultheis, Mathias; Kraemer, Kathleen E.; Groenewegen, Martin A.; Price, Stephan D.

2010-01-01

Aims. We aim at measuring mass-loss rates and the luminosities of a statistically large sample of Galactic bulge stars at several galactocentric radii. The sensitivity of previous infrared surveys of the bulge has been rather limited, thus fundamental questions for late stellar evolution, such as the stage at which substantial mass-loss begins on the red giant branch and its dependence on fundamental stellar properties, remain unanswered. We aim at providing evidence and answers to these questions. Methods. To this end, we observed seven 15 15 arcmin2 fields in the nuclear bulge and its vicinity with unprecedented sensitivity using the IRAC and MIPS imaging instruments on-board the Spitzer Space Telescope. In each of the fields, tens of thousands of point sources were detected. Results. In the first paper based on this data set, we present the observations, data reduction, the final catalogue of sources, and a detailed comparison to previous mid-IR surveys of the Galactic bulge, as well as to theoretical isochrones. We find in general good agreement with other surveys and the isochrones, supporting the high quality of our catalogue.

Galactic archaeology in action space

NASA Astrophysics Data System (ADS)

Sanderson, Robyn

2009-05-01

Working in action space offers an instructive alternative view of the process of hierarchical assembly in galaxies, but performing the necessary canonical transformation formally requires both complete phase space information of a stellar population and knowledge of the correct galactic potential, neither of which is generally available. I use the approximate-action method pioneered by MacMillan and Binney (2008) to examine the remnant of a late-time merger in M31, which was modeled by Fardal et al. (2007).

Observing globular cluster RR Lyraes with the BYU West Mountain Observatory

NASA Astrophysics Data System (ADS)

Jeffery, E. J.; Joner, M. D.; Walton, R. S.

2016-05-01

We have utilized the 0.9-meter telescope of the Brigham Young University West Mountain Observatory to secure data on six northern hemi- sphere globular clusters. Here we present observations of RR Lyrae stars located in these clusters. We compare light curves produced using both DAOPHOT and ISIS software packages. Light curve fitting is done with FITLC.

The Half RR Rule: A Poor Rule of Thumb and Not a Risk Assessment Tool for QT Interval Prolongation.

PubMed

Berling, Ingrid; Isbister, Geoffrey K

2015-10-01

Measuring the QT interval on an electrocardiogram (ECG) is integral to risk assessment of Torsade de Pointes (TdP). This study aimed to investigate the accuracy of the 1/2 RR rule as a risk assessment tool for drug-induced TdP, comparing it to the QT nomogram, Bazett's corrected QT (QTcB), and Fridericia's corrected QT (QTcF). The authors calculated sensitivity and specificity of the 1/2 RR rule using a published data set of 129 cases of drug-induced TdP and 316 controls (noncardiotoxic overdoses), compared to the QT nomogram, QTcB > 500 msec and QTcF > 500 msec. To further determine the value of the 1/2 RR rule, its observed positive, and negative agreement were calculated when compared to the QT nomogram for determining an abnormal QT in eight samples of different drugs in overdose. The sensitivity and specificity of the 1/2 RR rule were 88% (95% confidence interval [CI] = 80% to 93%) and 53% (95% CI = 47% to 58%), respectively, compared to the QT nomogram (sensitivity = 97%, 95% CI = 92% to 99%; specificity = 99%, 95% CI = 97% to 100%). It was also less sensitive than QTcB > 500 msec and had a lower specificity than QTcB > 500 msec and QTcF > 500 msec. In drug overdose patients, the 1/2 RR rule had poor observed agreement averaging 41%, which was mainly due to poor positive agreement, except for amisulpride where there was good agreement. The 1/2 RR rule was not as sensitive as the QT nomogram or QTcB > 500 msec for drug-induced TdP. It had poor positive agreement in almost all overdose patients, resulting in over half of patients receiving unnecessary cardiac monitoring and repeat ECGs. © 2015 by the Society for Academic Emergency Medicine.

Galactic and extragalactic hydrogen in the X-ray spectra of Gamma Ray Bursts

NASA Astrophysics Data System (ADS)

Rácz, I. I.; Bagoly, Z.; Tóth, L. V.; Balázs, L. G.; Horváth, I.; Pintér, S.

2017-07-01

Two types of emission can be observed from gamma-ray bursts (GRBs): the prompt emission from the central engine which can be observed in gamma or X-ray (as a low energy tail) and the afterglow from the environment in X-ray and at shorter frequencies. We examined the Swift XRT spectra with the XSPEC software. The correct estimation of the galactic interstellar medium is very important because we observe the host emission together with the galactic hydrogen absorption. We found that the estimated intrinsic hydrogen column density and the X-ray flux depend heavily on the redshift and the galactic foreground hydrogen. We also found that the initial parameters of the iteration and the cosmological parameters did not have much effect on the fitting result.

Hot stars in young massive clusters: Mapping the current Galactic metallicity

NASA Astrophysics Data System (ADS)

de la Fuente, Diego; Najarro, Francisco; Davies, Ben; Trombley, Christine; Figer, Donald F.; Herrero, Artemio

2013-06-01

Young Massive Clusters (YMCs) with ages < 6 Myr are ideal tools for mapping the current chemical abundances in the Galactic disk for several reasons. First of all, the locations of these clusters can be known through spectrophotometric distances. Secondly, their young ages guarantee that these objects present the same chemical composition than the surrounding environment where they are recently born. Finally, the YMCs host very massive stars whose extreme luminosities allow to accomplish detailed spectroscopic analyses even in the most distant regions of the Milky Way. Our group has carried out ISAAC/VLT spectroscopic observations of hot massive stars belonging to several YMCs in different locations around the Galactic disk. As a result, high signal-to-noise, near-infrared spectra of dozens of blue massive stars (including many OB supergiants, Wolf-Rayet stars and a B hypergiant) have been obtained. These data are fully reduced, and NLTE spherical atmosphere modeling is in process. Several line diagnostics will be combined in order to calculate metal abundances accurately for each cluster. The diverse locations of the clusters will allow us to draw a two-dimensional chemical map of the Galactic disk for the first time. The study of the radial and azimuthal variations of elemental abundances will be crucial for understanding the chemical evolution of the Milky Way. Particularly, the ratio between Fe-peak and alpha elements will constitute a powerful tool to investigate the past stellar populations that originated the current Galactic chemistry.

Columbia/Einstein observations of galactic X-ray sources

NASA Technical Reports Server (NTRS)

Long, K. S.

1979-01-01

The imaging observations of galactic clusters are presented. These fall into three categories: pre-main-sequence stars in the Orion nebulae, isolated-main-and-post main-sequence stars, and supernova remnants SNR. In addition to SNR, approximately 30 sources were detected.

Resolving the structure of the Galactic foreground using Herschel measurements and the Kriging technique

NASA Astrophysics Data System (ADS)

Pinter, S.; Bagoly, Z.; Balázs, L. G.; Horvath, I.; Racz, I. I.; Zahorecz, S.; Tóth, L. V.

2018-05-01

Investigating the distant extragalactic Universe requires a subtraction of the Galactic foreground. One of the major difficulties deriving the fine structure of the galactic foreground is the embedded foreground and background point sources appearing in the given fields. It is especially so in the infrared. We report our study subtracting point sources from Herschel images with Kriging, an interpolation method where the interpolated values are modelled by a Gaussian process governed by prior covariances. Using the Kriging method on Herschel multi-wavelength observations the structure of the Galactic foreground can be studied with much higher resolution than previously, leading to a better foreground subtraction at the end.

Survey of the galactic disk from 1 = -150 deg to 1 = 82 deg in the submillimeter range

NASA Technical Reports Server (NTRS)

Caux, Emmanuel; Serra, Guy

1987-01-01

The first almost complete survey of the galactic disk from 1 = -150 deg to 1 = 82 deg in the submillimeter range (effective wavelength = 380 microns), performed with the AGLAE balloon-borne instrument modified to include a submillimeter channel, is reported. The instrumentation and observational procedures are described, as are the signal processing and calibration. The results are presented as a profile of the submillimeter brightness of the galactic disk displayed as a function of the galactic longitude. This profile exhibits diffuse emission all along the disk with bright peaks associated with resolved sources. The averaged galactic spectrum is in agreement with a temperature distribution of the interstellar cold dust.

Searching for fossil fragments of the Galactic bulge formation process

NASA Astrophysics Data System (ADS)

Ferraro, Francesco

2017-08-01

We have discovered that the stellar system Terzan5 (Ter5) in the Galactic bulge harbors stellar populations with very different IRON content (delta[Fe/H] 1 dex, Ferraro+09, Nature 462, 483) and AGES (12 Gyr and 4.5 Gyr for the sub-solar and super-solar metallicity populations, respectively, Ferraro+16, ApJ,828,75). This evidence demonstrates that Ter5 is not a globular cluster, and identifies it as (1) a site in the Galactic bulge where recent star formation occurred, and (2) the remnant of a massive system able to retain the iron-enriched gas ejected by violent supernova explosions. The striking chemical similarity between Ter5 and the bulge opens the fascinating possibility that we discovered the fossil remnant of a pristine massive structure that could have contributed to the Galactic bulge assembly.Prompted by this finding, here we propose to secure deep HST optical observations for the bulge stellar system Liller1, that shows a similar complexity as Ter5, with evidence of two stellar populations with different iron content. The immediate goal is to properly explore the main sequence turnoff region of the system for unveiling possible splits due to stellar populations of different ages. As demonstrated by our experience with Ter5, the requested HST observations, in combination with the K-band diffraction limited images that we already secured with GeMS-Gemini, are essential to achieve this goal.The project will allow us to establish if other fossil remnants of the bulge formation epoch do exist, thus probing that the merging of pre-evolved massive structures has been an important channel for the formation of the Galactic bulge.

Observational evidence of dust evolution in galactic extinction curves

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

Cecchi-Pestellini, Cesare; Casu, Silvia; Mulas, Giacomo

Although structural and optical properties of hydrogenated amorphous carbons are known to respond to varying physical conditions, most conventional extinction models are basically curve fits with modest predictive power. We compare an evolutionary model of the physical properties of carbonaceous grain mantles with their determination by homogeneously fitting observationally derived Galactic extinction curves with the same physically well-defined dust model. We find that a large sample of observed Galactic extinction curves are compatible with the evolutionary scenario underlying such a model, requiring physical conditions fully consistent with standard density, temperature, radiation field intensity, and average age of diffuse interstellar clouds.more » Hence, through the study of interstellar extinction we may, in principle, understand the evolutionary history of the diffuse interstellar clouds.« less

Problems in determining the surface density of the Galactic disk

NASA Technical Reports Server (NTRS)

Statler, Thomas S.

1989-01-01

A new method is presented for determining the local surface density of the Galactic disk from distance and velocity measurements of stars toward the Galactic poles. The procedure is fully three-dimensional, approximating the Galactic potential by a potential of Staeckel form and using the analytic third integral to treat the tilt and the change of shape of the velocity ellipsoid consistently. Applying the procedure to artificial data superficially resembling the K dwarf sample of Kuijken and Gilmore (1988, 1989), it is shown that the current best estimates of local disk surface density are uncertain by at least 30 percent. Of this, about 25 percent is due to the size of the velocity sample, about 15 percent comes from uncertainties in the rotation curve and the solar galactocentric distance, and about 10 percent from ignorance of the shape of the velocity distribution above z = 1 kpc, the errors adding in quadrature. Increasing the sample size by a factor of 3 will reduce the error to 20 percent. To achieve 10 percent accuracy, observations will be needed along other lines of sight to constrain the shape of the velocity ellipsoid.

Galactic cold cores. V. Dust opacity

NASA Astrophysics Data System (ADS)

Juvela, M.; Ristorcelli, I.; Marshall, D. J.; Montillaud, J.; Pelkonen, V.-M.; Ysard, N.; McGehee, P.; Paladini, R.; Pagani, L.; Malinen, J.; Rivera-Ingraham, A.; Lefèvre, C.; Tóth, L. V.; Montier, L. A.; Bernard, J.-P.; Martin, P.

2015-12-01

Context. The project Galactic Cold Cores has carried out Herschel photometric observations of interstellar clouds where the Planck satellite survey has located cold and compact clumps. The sources represent different stages of cloud evolution from starless clumps to protostellar cores and are located in different Galactic environments. Aims: We examine this sample of 116 Herschel fields to estimate the submillimetre dust opacity and to search for variations that might be attributed to the evolutionary stage of the sources or to environmental factors, including the location within the Galaxy. Methods: The submillimetre dust opacity was derived from Herschel data, and near-infrared observations of the reddening of background stars are converted into near-infrared optical depth. We investigated the systematic errors affecting these parameters and used modelling to correct for the expected biases. The ratio of 250 μm and J band opacities is correlated with the Galactic location and the star formation activity. We searched for local variations in the ratio τ(250 μm)/τ(J) using the correlation plots and opacity ratio maps. Results: We find a median ratio of τ(250 μm) /τ(J) = (1.6 ± 0.2) × 10-3, which is more than three times the mean value reported for the diffuse medium. Assuming an opacity spectral index β = 1.8 instead of β = 2.0, the value would be lower by ~ 30%. No significant systematic variation is detected with Galactocentric distance or with Galactic height. Examination of the τ(250 μm) /τ(J) maps reveals six fields with clear indications of a local increase of submillimetre opacity of up to τ(250 μm) /τ(J) ~ 4 × 10-3 towards the densest clumps. These are all nearby fields with spatially resolved clumps of high column density. Conclusions: We interpret the increase in the far-infrared opacity as a sign of grain growth in the densest and coldest regions of interstellar clouds. Planck (http://www.esa.int/Planck) is a project of the European

Demographics and Case Studies of Galactic Outflows in the Local Universe

NASA Astrophysics Data System (ADS)

Rupke, David

2017-07-01

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

The Origin of IRS 16: Dynamically Driven In-Spiral of a Dense Star Cluster to the Galactic Center?

NASA Astrophysics Data System (ADS)

Portegies Zwart, Simon F.; McMillan, Stephen L. W.; Gerhard, Ortwin

2003-08-01

We use direct N-body simulations to study the in-spiral and internal evolution of dense star clusters near the Galactic center. These clusters sink toward the center owing to dynamical friction with the stellar background and may go into core collapse before being disrupted by the Galactic tidal field. If a cluster reaches core collapse before disruption, its dense core, which has become rich in massive stars, survives to reach close to the Galactic center. When it eventually dissolves, the cluster deposits a disproportionate number of massive stars in the innermost parsec of the Galactic nucleus. Comparing the spatial distribution and kinematics of the massive stars with observations of IRS 16, a group of young He I stars near the Galactic center, we argue that this association may have formed in this way.

Clustering of Local Group Distances: Publication Bias or Correlated Measurements? V. Galactic Rotation Constants

NASA Astrophysics Data System (ADS)

de Grijs, Richard; Bono, Giuseppe

2017-10-01

As part of an extensive data mining effort, we have compiled a database of 162 Galactic rotation speed measurements at R 0 (the solar Galactocentric distance), {{{\\Theta }}}0. Published between 1927 and 2017 June, this represents the most comprehensive set of {{{\\Theta }}}0 values since the 1985 meta-analysis that led to the last revision of the International Astronomical Union’s recommended Galactic rotation constants. Although we do not find any compelling evidence for the presence of “publication bias” in recent decades, we find clear differences among the {{{\\Theta }}}0 values and the {{{\\Theta }}}0/{R}0 ratios resulting from the use of different tracer populations. Specifically, young tracers (including OB and supergiant stars, masers, Cepheid variables, H II regions, and young open clusters), as well as kinematic measurements of Sgr A* near the Galactic Center, imply a significantly larger Galactic rotation speed at the solar circle and a higher {{{\\Theta }}}0/{R}0 ratio (i.e., {{{\\Theta }}}0=247+/- 3 km s‑1 and {{{\\Theta }}}0/{R}0=29.81+/- 0.32 km s‑1 kpc‑1 statistical uncertainties only) than any of the tracers dominating the Galaxy’s mass budget (i.e., field stars and the H I/CO distributions). Using the latter to be most representative of the bulk of the Galaxy’s matter distribution, we arrive at an updated set of Galactic rotation constants,

RR Lyrae Variables in M31 and its satellites: an analysis of the galaxy's population

NASA Astrophysics Data System (ADS)

Tanakul, Nahathai; Sarajedini, Ata

2018-05-01

We present an analysis of M31 RR Lyrae stars in 6 different fields using archival imaging from the Hubble Space Telescope. Published data for M31, M33, and several M31 dwarf spheroidal galaxies are also used to study the global properties of RR Lyrae in these systems. From the properties of RR Lyrae stars, we found that the majority of M31 and M33 RRLs are of OoI while those in M31 dSphs are of Oosterhoff intermediate. The main parameter affecting these Oosterhoff types is likely to be metallicity. Metallicity also play a role in the lack of RRLs in the High Amplitude Short Period (HASP ,defined as those with P ≲ 0.48 and AV ≥ 0.75mag) variables in M31 dSphs. This difference in the properties of RRLs between their parent galaxy and satellites, as well as the lack of RRLs in the HASP region in dSphs can also be observed in the Milky Way. Therefore, systems like these dSphs are unlikely to be the main building blocks of the M31 and Milky Way halo.

INFLUENCE OF THE GALACTIC GRAVITATIONAL FIELD ON THE POSITIONAL ACCURACY OF EXTRAGALACTIC SOURCES

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

Larchenkova, Tatiana I.; Lutovinov, Alexander A.; Lyskova, Natalya S.

We investigate the influence of random variations of the Galactic gravitational field on the apparent celestial positions of extragalactic sources. The basic statistical characteristics of a stochastic process (first-order moments, an autocorrelation function and a power spectral density) are used to describe a light ray deflection in a gravitational field of randomly moving point masses as a function of the source coordinates. We map a 2D distribution of the standard deviation of the angular shifts in positions of distant sources (including reference sources of the International Celestial Reference Frame) with respect to their true positions. For different Galactic matter distributionsmore » the standard deviation of the offset angle can reach several tens of μ as (microarcsecond) toward the Galactic center, decreasing down to 4–6 μ as at high galactic latitudes. The conditional standard deviation (“jitter”) of 2.5 μ as is reached within 10 years at high galactic latitudes and within a few months toward the inner part of the Galaxy. The photometric microlensing events are not expected to be disturbed by astrometric random variations anywhere except the inner part of the Galaxy as the Einstein–Chvolson times are typically much shorter than the jittering timescale. While a jitter of a single reference source can be up to dozens of μ as over some reasonable observational time, using a sample of reference sources would reduce the error in relative astrometry. The obtained results can be used for estimating the physical upper limits on the time-dependent accuracy of astrometric measurements.« less

G306.3-0.9: A Newly Discovered Young Galactic Supernova Remnant

NASA Technical Reports Server (NTRS)

Reynolds, Mark T.; Loi, Syheh T.; Murphy, Tara; Miller, Jon M.; Maitra, Dipankar; Gueltekin, Kayhan; Gehrels, Neil; Kennea, Jamie A.; Siegel, Michael H.; Gelbord, Jonathan;

Coded-aperture imaging of the Galactic center region at gamma-ray energies

NASA Technical Reports Server (NTRS)

Cook, Walter R.; Grunsfeld, John M.; Heindl, William A.; Palmer, David M.; Prince, Thomas A.

1991-01-01

The first coded-aperture images of the Galactic center region at energies above 30 keV have revealed two strong gamma-ray sources. One source has been identified with the X-ray source IE 1740.7 - 2942, located 0.8 deg away from the nucleus. If this source is at the distance of the Galactic center, it is one of the most luminous objects in the galaxy at energies from 35 to 200 keV. The second source is consistent in location with the X-ray source GX 354 + 0 (MXB 1728-34). In addition, gamma-ray flux from the location of GX 1 + 4 was marginally detected at a level consistent with other post-1980 measurements. No significant hard X-ray or gamma-ray flux was detected from the direction of the Galactic nucleus or from the direction of the recently discovered gamma-ray source GRS 1758-258.

Planck 2013 results. XIII. Galactic CO emission

NASA Astrophysics Data System (ADS)

Planck Collaboration; Ade, P. A. R.; Aghanim, N.; Alves, M. I. R.; Armitage-Caplan, C.; Arnaud, M.; Ashdown, M.; Atrio-Barandela, F.; Aumont, J.; Baccigalupi, C.; Banday, A. J.; Barreiro, R. B.; Bartlett, J. G.; Battaner, E.; Benabed, K.; Benoît, A.; Benoit-Lévy, A.; Bernard, J.-P.; Bersanelli, M.; Bielewicz, P.; Bobin, J.; Bock, J. J.; Bonaldi, A.; Bond, J. R.; Borrill, J.; Bouchet, F. R.; Boulanger, F.; Bridges, M.; Bucher, M.; Burigana, C.; Butler, R. C.; Cardoso, J.-F.; Catalano, A.; Chamballu, A.; Chary, R.-R.; Chen, X.; Chiang, H. C.; Chiang, L.-Y.; Christensen, P. R.; Church, S.; Clements, D. L.; Colombi, S.; Colombo, L. P. L.; Combet, C.; Couchot, F.; Coulais, A.; Crill, B. P.; Curto, A.; Cuttaia, F.; Danese, L.; Davies, R. D.; de Bernardis, P.; de Rosa, A.; de Zotti, G.; Delabrouille, J.; Delouis, J.-M.; Dempsey, J. T.; Désert, F.-X.; Dickinson, C.; Diego, J. M.; Dole, H.; Donzelli, S.; Doré, O.; Douspis, M.; Dupac, X.; Efstathiou, G.; Enßlin, T. A.; Eriksen, H. K.; Falgarone, E.; Finelli, F.; Forni, O.; Frailis, M.; Franceschi, E.; Fukui, Y.; Galeotta, S.; Ganga, K.; Giard, M.; Giraud-Héraud, Y.; González-Nuevo, J.; Górski, K. M.; Gratton, S.; Gregorio, A.; Gruppuso, A.; Handa, T.; Hansen, F. K.; Hanson, D.; Harrison, D.; Henrot-Versillé, S.; Hernández-Monteagudo, C.; Herranz, D.; Hildebrandt, S. R.; Hily-Blant, P.; Hivon, E.; Hobson, M.; Holmes, W. A.; Hornstrup, A.; Hovest, W.; Huffenberger, K. M.; Hurier, G.; Jaffe, A. H.; Jaffe, T. R.; Jewell, J.; Jones, W. C.; Juvela, M.; Keihänen, E.; Keskitalo, R.; Kisner, T. S.; Knoche, J.; Knox, L.; Kunz, M.; Kurki-Suonio, H.; Lagache, G.; Lähteenmäki, A.; Lamarre, J.-M.; Lasenby, A.; Laureijs, R. J.; Lawrence, C. R.; Leonardi, R.; León-Tavares, J.; Lesgourgues, J.; Liguori, M.; Lilje, P. B.; Linden-Vørnle, M.; López-Caniego, M.; Lubin, P. M.; Macías-Pérez, J. F.; Maffei, B.; Mandolesi, N.; Maris, M.; Marshall, D. J.; Martin, P. G.; Martínez-González, E.; Masi, S.; Massardi, M.; Matarrese, S.; Matthai, F.; Mazzotta, P.; McGehee, P.; Melchiorri, A.; Mendes, L.; Mennella, A.; Migliaccio, M.; Mitra, S.; Miville-Deschênes, M.-A.; Moneti, A.; Montier, L.; Moore, T. J. T.; Morgante, G.; Morino, J.; Mortlock, D.; Munshi, D.; Murphy, J. A.; Nakajima, T.; Naselsky, P.; Nati, F.; Natoli, P.; Netterfield, C. B.; Nørgaard-Nielsen, H. U.; Noviello, F.; Novikov, D.; Novikov, I.; Okuda, T.; Osborne, S.; Oxborrow, C. A.; Paci, F.; Pagano, L.; Pajot, F.; Paladini, R.; Paoletti, D.; Pasian, F.; Patanchon, G.; Perdereau, O.; Perotto, L.; Perrotta, F.; Piacentini, F.; Piat, M.; Pierpaoli, E.; Pietrobon, D.; Plaszczynski, S.; Pointecouteau, E.; Polenta, G.; Ponthieu, N.; Popa, L.; Poutanen, T.; Pratt, G. W.; Prézeau, G.; Prunet, S.; Puget, J.-L.; Rachen, J. P.; Reach, W. T.; Rebolo, R.; Reinecke, M.; Remazeilles, M.; Renault, C.; Ricciardi, S.; Riller, T.; Ristorcelli, I.; Rocha, G.; Rosset, C.; Roudier, G.; Rowan-Robinson, M.; Rubiño-Martín, J. A.; Rusholme, B.; Sandri, M.; Santos, D.; Savini, G.; Scott, D.; Seiffert, M. D.; Shellard, E. P. S.; Spencer, L. D.; Starck, J.-L.; Stolyarov, V.; Stompor, R.; Sudiwala, R.; Sunyaev, R.; Sureau, F.; Sutton, D.; Suur-Uski, A.-S.; Sygnet, J.-F.; Tauber, J. A.; Tavagnacco, D.; Terenzi, L.; Thomas, H. S.; Toffolatti, L.; Tomasi, M.; Torii, K.; Tristram, M.; Tucci, M.; Tuovinen, J.; Umana, G.; Valenziano, L.; Valiviita, J.; Van Tent, B.; Vielva, P.; Villa, F.; Vittorio, N.; Wade, L. A.; Wandelt, B. D.; Wehus, I. K.; Yamamoto, H.; Yoda, T.; Yvon, D.; Zacchei, A.; Zonca, A.

2014-11-01

Rotational transition lines of CO play a major role in molecular radio astronomy as a mass tracer and in particular in the study of star formation and Galactic structure. Although a wealth of data exists for the Galactic plane and some well-known molecular clouds, there is no available high sensitivity all-sky survey of CO emission to date. Such all-sky surveys can be constructed using the Planck HFI data because the three lowest CO rotational transition lines at 115, 230 and 345 GHz significantly contribute to the signal of the 100, 217 and 353 GHz HFI channels, respectively. Two different component separation methods are used to extract the CO maps from Planck HFI data. The maps obtained are then compared to one another and to existing external CO surveys. From these quality checks the best CO maps, in terms of signal to noise ratio and/or residual contamination by other emission, are selected. Three different sets of velocity-integrated CO emission maps are produced with different trade-offs between signal-to-noise, angular resolution, and reliability. Maps for the CO J = 1 → 0, J = 2 → 1, and J = 3 → 2 rotational transitions are presented and described in detail. They are shown to be fully compatible with previous surveys of parts of the Galactic plane as well as with undersampled surveys of the high latitude sky. The Planck HFI velocity-integrated CO maps for the J = 1 → 0, J = 2 → 1, and J = 3 →2 rotational transitions provide an unprecedented all-sky CO view of the Galaxy. These maps are also of great interest to monitor potential CO contamination of the Planck studies of the cosmological microwave background.

Giant molecular filaments in the Milky Way. II. The fourth Galactic quadrant

NASA Astrophysics Data System (ADS)

Abreu-Vicente, J.; Ragan, S.; Kainulainen, J.; Henning, Th.; Beuther, H.; Johnston, K.

2016-05-01

Context. Filamentary structures are common morphological features of the cold, molecular interstellar medium (ISM). Recent studies have discovered massive, hundred-parsec-scale filaments that may be connected to the large-scale, Galactic spiral arm structure. Addressing the nature of these giant molecular filaments (GMFs) requires a census of their occurrence and properties. Aims: We perform a systematic search of GMFs in the fourth Galactic quadrant and determine their basic physical properties. Methods: We identify GMFs based on their dust extinction signatures in the near- and mid-infrared and the velocity structure probed by 13CO line emission. We use the 13CO line emission and ATLASGAL dust emission data to estimate the total and dense gas masses of the GMFs. We combine our sample with an earlier sample from literature and study the Galactic environment of the GMFs. Results: We identify nine GMFs in the fourth Galactic quadrant: six in the Centaurus spiral arm and three in inter-arm regions. Combining this sample with an earlier study using the same identification criteria in the first Galactic quadrant results in 16 GMFs, nine of which are located within spiral arms. The GMFs have sizes of 80-160 pc and 13CO-derived masses between 5-90 × 104M⊙. Their dense gas mass fractions are between 1.5-37%, which is higher in the GMFs connected to spiral arms. We also compare the different GMF-identification methods and find that emission and extinction-based techniques overlap only partially, thereby highlighting the need to use both to achieve a complete census. Table A.2 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/590/A131

Distribution of Si II in the Galactic center

NASA Technical Reports Server (NTRS)

Graf, P.; Herter, T.; Gull, G. E.; Houck, J. R.

1988-01-01

A map of the Galactic center region in the forbidden Si II 34.8-micron line is presented. The line emission arises from within the photodissociation region (PDR) associated with the neutral gas ring surrounding an ionized gas core confined within 2 pc of the Galactic center. Si II is a useful probe of the inner regions of the ring since it is always optically thin. The Si II data, when analyzed in conjunction with O I, C II, and molecular measurements, outlines the transition region between the PDR and the surrounding molecular cloud. The Si II emission is found to extend beyond that of the O II into the neutral gas ring. Although the interpretation is not unique, the data are consistent with a constant gas-phase abundance of silicon within the inner part of the PDR while the gaseous silicon is depleted by molecule formation in the transition region.

The Optical Gravitational Lensing Experiment Catalog of stellar proper motions in the OGLE-II Galactic bulge fields

NASA Astrophysics Data System (ADS)

Sumi, T.; Wu, X.; Udalski, A.; Szymański, M.; Kubiak, M.; Pietrzyński, G.; Soszyński, I.; Woźniak, P.; Zebruń, K.; Szewczyk, O.; Wyrzykowski, L.

2003-12-01

We present proper motion (μ ) catalogue of 5,078,188 stars in 49 Optical Gravitational Lensing Experiment II (OGLE-II) Galactic bulge fields, with the total area close to 11 square degrees. The proper motion measurements are based on 138 - 555 I-band images taken during four observing seasons: 1997-2000. The catalogue stars are in the magnitude range 11 < I < 18 mag. In particular, the catalogue includes Red Clump Giants (RCGs) and Red Giants in the Galactic Bulge, and main sequence stars in the Galactic disc. The proper motions up to μ = 500 mas yr -1 were measured with the mean accuracy of 0.8 ˜ 3.5 mas yr-1, depending on the brightness of a star. This catalogue may be useful for studying the kinematic of stars in the Galactic Bulge and the Galactic disk with Extinction maps in these fields which are construncted by using two-band photometry of RCGs.

A radio characterization of Galactic compact bubbles

NASA Astrophysics Data System (ADS)

Ingallinera, A.; Trigilio, C.; Umana, G.; Leto, P.; Noriega-Crespo, A.; Flagey, N.; Paladini, R.; Agliozzo, C.; Buemi, C. S.

2014-02-01

We report the radio observations of a subsample of the 428 Galactic compact bubbles discovered at 24 μm with the MIPSGAL survey. Pervasive through the entire Galactic plane, these objects are thought to be different kinds of evolved stars. The very large majority of the bubbles (˜70 per cent) are however not yet classified. We conducted radio observations with the Expanded Very Large Array at 6 and 20 cm in order to obtain the spectral index of 55 bubbles. We found that at least 70 per cent of the 31 bubbles for which we were effectively able to compute the spectral index (or its lower limit) are likely to be thermal emitters. We were also able to resolve some bubbles, obtaining that the size of the radio nebula is usually similar to the IR size, although our low resolution (with respect to IR images) did not allow further morphological studies. Comparisons between radio flux densities and IR archive data from Spitzer and IRAS suggest that at least three unclassified bubbles can be treated as planetary nebula candidates.

Rice University observations of the galactic center

NASA Technical Reports Server (NTRS)

Meegan, C. A.

1978-01-01

The most sensitive of the four balloon fight observations of the galactic center made by Rice University was conducted in 1974 from Rio Cuarto, Argentina at a float altitude of 4 mbar. The count rate spectrum of the observed background and the energy spectrum of the galactic center region are discussed. The detector used consists of a 6 inch Nal(T 1ambda) central detector collimated to approximately 15 deg FWHM by a Nal(T lamdba) anticoincidence shield. The shield in at least two interaction mean free paths thick at all gamma ray energies. The instrumental resolution is approximately 11% FWHM at 662 keV. Pulses from the central detector are analyzed by two 256 channel PHA's covering the energy range approximately 20 keV to approximately 12 MeV. The detector is equatorially mounted and pointed by command from the ground. Observations are made by measuring source and background alternately for 10 minute periods. Background is measured by rotating the detector 180 deg about the azimuthal axis.

On galactic origin of cosmic rays with energy up to 10(19) eV

NASA Technical Reports Server (NTRS)

Efimov, N. N.; Mikhailov, A. A.

1985-01-01

The experimental data on ultrahigh energy cosmic ray anisotropy are considered. In supposed models of galactic magnetic field the main characteristics of expected anisotropy are estimated and are compared with the experimental data. It is shown that particles with energy up to 10 to the 19th power eV are of galactic origin.

Magnetic monopole plasma oscillations and the survival of Galactic magnetic fields

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

Parker, E.N.

This paper explores the general nature of magnetic-monopole plasma oscillations as a theoretical possibility for the observed Galactic magnetic field in the presence of a high abundance of magnetic monopoles. The modification of the hydromagnetic induction equation by the monopole oscillations produces the half-velocity effect, in which the magnetic field is transported bodily with a velocity midway between the motion of the conducting fluid and the monopole plasma. Observational studies of the magnetic field in the Galaxy, and in other galaxies, exclude the half-velocity effect, indicating that the magnetic fields is not associated with monopole oscillations. In any case themore » phase mixing would destroy the oscillations in less than 100 Myr. The conclusion is that magnetic monopole oscillations do not play a significant role in the galactic magnetic fields. Hence the existence of galactic magnetic fields places a low limit on the monopole flux, so that their detection - if they exist at all - requires a collecting area at least as large as a football field. 47 references.« less

Quasars in the Galactic Anti-Center Area from LAMOST DR3

NASA Astrophysics Data System (ADS)

Huo, Zhi-Ying; Liu, Xiao-Wei; Shi, Jian-Rong; Xiang, Mao-Sheng; Huang, Yang; Yuan, Hai-Bo; Zhang, Jian-Nan; Zhang, Wei; Wang, Jian-Ling; Wu, Yu-Zhong; Cao, Zi-Huang; Zhang, Yong; Hou, Yong-Hui; Wang, Yue-Fei

2017-03-01

We present a sample of quasars discovered in an area near the Galactic Anti-Center covering 150^\\circ ≤ l≤ 210^\\circ and | b| ≤ 30^\\circ , based on LAMOST Data Release 3 (DR3). This sample contains 151 spectroscopically confirmed quasars. Among them 80 are newly discovered with LAMOST. All these quasars are very bright, with i magnitudes peaking around 17.5 mag. All the new quasars were discovered serendipitously from objects that were originally targeted with LAMOST as stars having bluer colors, except for a few candidates targeted as variable, young stellar objects. This bright quasar sample at low Galactic latitudes will help fill the gap in the spatial distribution of known quasars near the Galactic disk that are used to construct an astrometric reference frame for the purpose of accurate proper motion measurements that can be applied to, for example, Gaia. They are also excellent tracers to probe the kinematics and chemistry of the interstellar medium in the Milky Way disk and halo via absorption line spectroscopy.

Complex organic molecules in the Galactic Centre: the N-bearing family

NASA Astrophysics Data System (ADS)

Zeng, S.; Jiménez-Serra, I.; Rivilla, V. M.; Martín, S.; Martín-Pintado, J.; Requena-Torres, M. A.; Armijos-Abendaño, J.; Riquelme, D.; Aladro, R.

2018-05-01

We present an unbiased spectral line survey toward the Galactic Centre (GC) quiescent giant molecular cloud (QGMC), G+0.693 using the GBT and IRAM 30 telescopes. Our study highlights an extremely rich organic inventory of abundant amounts of nitrogen (N)-bearing species in a source without signatures of star formation. We report the detection of 17 N-bearing species in this source, of which 8 are complex organic molecules (COMs). A comparison of the derived abundances relative to H2 is made across various galactic and extragalactic environments. We conclude that the unique chemistry in this source is likely to be dominated by low-velocity shocks with X-rays/cosmic rays also playing an important role in the chemistry. Like previous findings obtained for O-bearing molecules, our results for N-bearing species suggest a more efficient hydrogenation of these species on dust grains in G+0.693 than in hot cores in the Galactic disk, as a consequence of the low dust temperatures coupled with energetic processing by X-ray/cosmic ray radiation in the GC.

A Modified Kinematic Model of Neutral and Ionized Gas in Galactic Center

NASA Astrophysics Data System (ADS)

Krishnarao, Dhanesh; Benjamin, Robert A.; Haffner, L. Matthew

2018-01-01

Gas near the center of the Milky Way is very complex across all phases (cold, warm, neutral, ionized, atomic, molecular, etc.) and shows strong observational evidence for warping, lopsided orientations and strongly non-circular kinematics. Historically, the kinematic complexities were modeled with many discrete features involved with expulsive phenomena near Galactic Center. However, much of the observed emission can be explained with a single unified and smooth density structure when geometrical and perspective effects are accounted for. Here we present a new model for a tilted, elliptical disk of gas within the inner 2 kpc of Galactic center based on the series of models following Burton & Liszt (1978 - 1992, Papers I- V). Machine learning techniques such as the Histogram of Oriented Gradients image correlation statistic are used to optimize the geometry and kinematics of neutral and ionized gas in 3D observational space (position,position, velocity). The model successfully predicts emission from neutral gas as seen by HI (Hi4Pi) and explains anomalous ionized gas features in H-Alpha emission (Wisconsin H-Alpha Mapper) and UV absorption lines (Hubble Space Telescope - Space Telescope Imaging Spectrograph). The modeled distribution of this tilted gas disk along with its kinematics of elliptical x1 orbits can reveal new insight about the Galactic Bar, star formation, and high-velocity gas near Galactic Center and its relation with the Fermi Bubble.

"D.L.&W. R.R. Profile for New Tunnel Through Bergen Hill" Plan ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

"D.L.&W. R.R. Profile for New Tunnel Through Bergen Hill" Plan Sheet. December 1, 1905. On file at New Jersey Transit Corporation Headquarters, Newark, New Jersey - Delaware, Lackawanna & Western Railroad, South Bergen Tunnel, Jersey City, Hudson County, NJ

The galactic distribution of carbon monoxide: An out-of-plane survey. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Cohen, R. S.

1978-01-01

Galactic CO line emission at 115 GHz has been surveyed. This survey confirms the finding that CO is concentrated in a ring. It provides a determination of the thickness of this molecular ring as a function of galactic radius and shows that CO is displaced from the conventional galactic plane. These results were arrived at by least-squares fitting the survey data to a circularly symmetric model of the Galaxy. A comparison of the CO and HI distributions shows that there are marked differences in the distributions of these species, both radially and out of the plane. A detailed discussion of the antenna characteristics, including the radiation pattern and pointing characteristics is presented.

Search for gamma-ray spectral modulations in Galactic pulsars

NASA Astrophysics Data System (ADS)

Majumdar, Jhilik; Calore, Francesca; Horns, Dieter

2018-04-01

Well-motivated extensions of the standard model predict ultra-light and fundamental pseudo-scalar particles (e.g., axions or axion-like particles: ALPs). Similarly to the Primakoff-effect for axions, ALPs can mix with photons and consequently be searched for in laboratory experiments and with astrophysical observations. Here, we search for energy-dependent modulations of high-energy gamma-ray spectra that are tell-tale signatures of photon-ALPs mixing. To this end, we analyze the data recorded with the Fermi-LAT from Galactic pulsars selected to have a line of sight crossing spiral arms at a large pitch angle. The large-scale Galactic magnetic field traces the shape of spiral arms, such that a sizable photon-ALP conversion probability is expected for the sources considered. For the nearby Vela pulsar, the energy spectrum is well described by a smooth model spectrum (a power-law with a sub-exponential cut-off) while for the six selected Galactic pulsars, a common fit of the ALPs parameters improves the goodness of fit in comparison to a smooth model spectrum with a significance of 4.6 σ. We determine the most-likely values for mass ma and coupling gaγγ to be ma=(3.6‑0.2 stat.+0.5 stat.± 0.2syst. ) neV and gaγγ=(2.3‑0.4stat.+0.3 stat.± 0.4syst.)× 10‑10 GeV‑1. In the error budget, we consider instrumental effects, scaling of the adopted Galactic magnetic field model (± 20 %), and uncertainties on the distance of individual sources. The best-fit parameters are by a factor of ≈ 3 larger than the current best limit on solar ALPs generation obtained with the CAST helioscope, although known modifications of the photon-ALP mixing in the high density solar environment could provide a plausible explanation for the apparent tension between the helioscope bound and the indication for photon-ALPs mixing reported here.

Black holes in binary stellar systems and galactic nuclei

NASA Astrophysics Data System (ADS)

Cherepashchuk, A. M.

2014-04-01

In the last 40 years, following pioneering papers by Ya B Zeldovich and E E Salpeter, in which a powerful energy release from nonspherical accretion of matter onto a black hole (BH) was predicted, many observational studies of black holes in the Universe have been carried out. To date, the masses of several dozen stellar-mass black holes (M_BH = (4{-}20) M_\\odot) in X-ray binary systems and of several hundred supermassive black holes (M_BH = (10^{6}{-}10^{10}) M_\\odot) in galactic nuclei have been measured. The estimated radii of these massive and compact objects do not exceed several gravitational radii. For about ten stellar-mass black holes and several dozen supermassive black holes, the values of the dimensionless angular momentum a_* have been estimated, which, in agreement with theoretical predictions, do not exceed the limiting value a_* = 0.998. A new field of astrophysics, so-called black hole demography, which studies the birth and growth of black holes and their evolutionary connection to other objects in the Universe, namely stars, galaxies, etc., is rapidly developing. In addition to supermassive black holes, massive stellar clusters are observed in galactic nuclei, and their evolution is distinct from that of supermassive black holes. The evolutionary relations between supermassive black holes in galactic centers and spheroidal stellar components (bulges) of galaxies, as well as dark-matter galactic haloes are brought out. The launch into Earth's orbit of the space radio interferometer RadioAstron opened up the real possibility of finally proving that numerous discovered massive and highly compact objects with properties very similar to those of black holes make up real black holes in the sense of Albert Einstein's General Relativity. Similar proofs of the existence of black holes in the Universe can be obtained by intercontinental radio interferometry at short wavelengths \\lambda \\lesssim 1 mm (the international program, Event Horizon Telescope).

[The influence of age and illness duration on cognitive impairment in aging patients with relapsing-remitting multiple sclerosis (RR-MS)].

PubMed

Leclercq, Eugénie; Cabaret, Maryline; Guilbert, Alma; Jougleux, Caroline; Vermersch, Patrick; Moroni, Christine

2014-09-01

The aim of this study was to dissociate age and duration of illness effects on cognitive impairment of patients with relapsing-remitting multiple sclerosis. Cognitive impairment among patients with multiple sclerosis (MS) is well known. However, few studies were devoted to assess the respective role of disease duration and age on cognitive functions in MS patients. Therefore, two studies were carried out on relapsing-remitting MS (RR-MS) patients using some tests of the BCcogSEP--a French test battery evaluating cognitive functions in MS. The cognitive deficits of RR-MS patients aged 50 years and over and whose symptoms had been present for more than 20 years were more severe than those of MS patients with a shorter illness duration (less than 10 years) or matched-age control participants. The more impaired cognitive functions were information-processing speed, episodic memory, verbal fluency and attention. On the other hand, cognitive performances of young RR-MS patients were similar to those of older RR-MS patients when all patients had the same illness duration (8 years in this study). Older patients even achieved better performance than younger ones on verbal fluency. This can be partly explained by the theory of cognitive reserve, as reported in previous cognitive aging studies. In RR-MS patients, the influence of illness duration seems to be a predominant factor in the development of cognitive impairment.

Extended Aperture Photometry of K2 RR Lyrae stars

NASA Astrophysics Data System (ADS)

Plachy, Emese; Klagyivik, Péter; Molnár, László; Sódor, Ádám; Szabó, Róbert

2017-10-01

We present the method of the Extended Aperture Photometry (EAP) that we applied on K2 RR Lyrae stars. Our aim is to minimize the instrumental variations of attitude control maneuvers by using apertures that cover the positional changes in the field of view thus contain the stars during the whole observation. We present example light curves that we compared to the light curves from the K2 Systematics Correction (K2SC) pipeline applied on the automated Single Aperture Photometry (SAP) and on the Pre-search Data Conditioning Simple Aperture Photometry (PDCSAP) data.

15. 'Southern Pacific R.R., One 236'0' Bet. End Pins S. ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

15. 'Southern Pacific R.R., One 236'-0' Bet. End Pins S. Tr. Thro'. Draw Bridge over Sacramento River at Tehama, The Phoenix Bridge Co., Phoenixville, Pa., Jan'y 19th 98, Dwg. 585.' - Southern Pacific Railroad Shasta Route, Bridge No. 210.52, Milepost 210.52, Tehama, Tehama County, CA

Mass Distributions Implying Flat Galactic Rotation Curves

ERIC Educational Resources Information Center

Keeports, David

2010-01-01

The rotational speeds of stars in the disc of a spiral galaxy are virtually independent of the distances of the stars from the centre of the galaxy. In common parlance, the stellar speed versus distance plot known as a galactic rotation curve is by observation typically nearly flat. This observation provides strong evidence that most galactic…

The DECam Plane Survey: Optical photometry of two billion objects in the southern Galactic plane

NASA Astrophysics Data System (ADS)

Schlafly, Edward; Green, Gregory M.; Lang, Dustin; Daylan, Tansu; Finkbeiner, Douglas; Lee, Albert; Meisner, Aaron; Schlegel, David; Valdes, Francisco

2018-01-01

The DECam Plane Survey is a five-band optical and near-infrared survey of the southern Galactic plane with the Dark Energy Camera at Cerro Tololo. The survey is designed to reach past the main-sequence turn-off at the distance of the Galactic center through a reddening E(B-V) of 1.5 mag. Typical single-exposure depths are 23.7, 22.8, 22.3, 21.9, and 21.0 mag in the grizY bands, with seeing around 1 arcsecond. The footprint covers the Galactic plane with |b| < 4°, 5° > l > -120°. The survey pipeline simultaneously solves for the positions and fluxes of tens of thousands of sources in each image, delivering positions and fluxes of roughly two billion stars with better than 10 mmag precision. Most of these objects are highly reddened and deep in the Galactic disk, probing the structure and properties of the Milky Way and its interstellar medium. The full survey is publicly available.

The Large Scale Structure of the Galactic Magnetic Field and High Energy Cosmic Ray Anisotropy

NASA Astrophysics Data System (ADS)

Alvarez-Muñiz, Jaime; Stanev, Todor

2006-10-01

Measurements of the magnetic field in our Galaxy are complex and usually difficult to interpret. A spiral regular field in the disk is favored by observations, however the number of field reversals is still under debate. Measurements of the parity of the field across the Galactic plane are also very difficult due to the presence of the disk field itself. In this work we demonstrate that cosmic ray protons in the energy range 1018 to 1019eV, if accelerated near the center of the Galaxy, are sensitive to the large scale structure of the Galactic Magnetic Field (GMF). In particular if the field is of even parity, and the spiral field is bi-symmetric (BSS), ultra high energy protons will predominantly come from the Southern Galactic hemisphere, and predominantly from the Northern Galactic hemisphere if the field is of even parity and axi-symmetric (ASS). There is no sensitivity to the BSS or ASS configurations if the field is of odd parity.

Fermi Large Area Telescope Measurements of the Diffuse Gamma-Ray Emission at Intermediate Galactic Latitudes

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

Abdo, A.A.; /Naval Research Lab, Wash., D.C.; Ackermann, M.

The diffuse galactic {gamma}-ray emission is produced by cosmic rays (CRs) interacting with the interstellar gas and radiation field. Measurements by the Energetic Gamma-Ray Experiment Telescope (EGRET) instrument on the Compton Gamma-Ray Observatory indicated excess {gamma}-ray emission {ge}1 GeV relative to diffuse galactic {gamma}-ray emission models consistent with directly measured CR spectra (the so-called 'EGRET GeV excess'). The Large Area Telescope (LAT) instrument on the Fermi Gamma-Ray Space Telescope has measured the diffuse {gamma}-ray emission with improved sensitivity and resolution compared to EGRET. We report on LAT measurements for energies 100 MeV to 10 GeV and galactic latitudes 10{sup o}more » {le} |b| {le} 20{sup o}. The LAT spectrum for this region of the sky is well reproduced by a diffuse galactic {gamma}-ray emission model that is consistent with local CR spectra and inconsistent with the EGRET GeV excess.« less

Fermi Large Area Telescope Measurements of the Diffuse Gamma-Ray Emission at Intermediate Galactic Latitudes

DOE PAGES

Abdo, A. A.; Ackermann, M.; Ajello, M.; ...

2009-12-16

We report that the diffuse galactic γ-ray emission is produced by cosmic rays (CRs) interacting with the interstellar gas and radiation field. Measurements by the Energetic Gamma-Ray Experiment Telescope (EGRET) instrument on the Compton Gamma-Ray Observatory indicated excess γ-ray emission ≳1 GeV relative to diffuse galactic γ-ray emission models consistent with directly measured CR spectra (the so-called “EGRET GeV excess”). The Large Area Telescope (LAT) instrument on the Fermi Gamma-Ray Space Telescope has measured the diffuse γ -ray emission with improved sensitivity and resolution compared to EGRET. We report on LAT measurements for energies 100 MeV to 10 GeV andmore » galactic latitudes 10° ≤ | b | ≤ 20°. Finally, the LAT spectrum for this region of the sky is well reproduced by a diffuse galactic γ-ray emission model that is consistent with local CR spectra and inconsistent with the EGRET GeV excess.« less

Fermi large area telescope measurements of the diffuse gamma-ray emission at intermediate galactic latitudes.

PubMed

Abdo, A A; Ackermann, M; Ajello, M; Anderson, B; Atwood, W B; Axelsson, M; Baldini, L; Ballet, J; Barbiellini, G; Bastieri, D; Baughman, B M; Bechtol, K; Bellazzini, R; Berenji, B; Blandford, R D; Bloom, E D; Bonamente, E; Borgland, A W; Bregeon, J; Brez, A; Brigida, M; Bruel, P; Burnett, T H; Caliandro, G A; Cameron, R A; Caraveo, P A; Casandjian, J M; Cecchi, C; Charles, E; Chekhtman, A; Cheung, C C; Chiang, J; Ciprini, S; Claus, R; Cohen-Tanugi, J; Conrad, J; Dereli, H; Dermer, C D; de Angelis, A; de Palma, F; Digel, S W; Di Bernardo, G; Dormody, M; do Couto e Silva, E; Drell, P S; Dubois, R; Dumora, D; Edmonds, Y; Farnier, C; Favuzzi, C; Fegan, S J; Focke, W B; Frailis, M; Fukazawa, Y; Funk, S; Fusco, P; Gaggero, D; Gargano, F; Gehrels, N; Germani, S; Giebels, B; Giglietto, N; Giordano, F; Glanzman, T; Godfrey, G; Grenier, I A; Grondin, M-H; Grove, J E; Guillemot, L; Guiriec, S; Hanabata, Y; Harding, A K; Hayashida, M; Hays, E; Hughes, R E; Jóhannesson, G; Johnson, A S; Johnson, R P; Johnson, T J; Johnson, W N; Kamae, T; Katagiri, H; Kataoka, J; Kawai, N; Kerr, M; Knödlseder, J; Kocian, M L; Kuehn, F; Kuss, M; Lande, J; Latronico, L; Longo, F; Loparco, F; Lott, B; Lovellette, M N; Lubrano, P; Madejski, G M; Makeev, A; Mazziotta, M N; McConville, W; McEnery, J E; Meurer, C; Michelson, P F; Mitthumsiri, W; Mizuno, T; Moiseev, A A; Monte, C; Monzani, M E; Morselli, A; Moskalenko, I V; Murgia, S; Nolan, P L; Nuss, E; Ohsugi, T; Okumura, A; Omodei, N; Orlando, E; Ormes, J F; Paneque, D; Panetta, J H; Parent, D; Pelassa, V; Pepe, M; Pesce-Rollins, M; Piron, F; Porter, T A; Rainò, S; Rando, R; Razzano, M; Reimer, A; Reimer, O; Reposeur, T; Ritz, S; Rodriguez, A Y; Roth, M; Ryde, F; Sadrozinski, H F-W; Sanchez, D; Sander, A; Saz Parkinson, P M; Scargle, J D; Sellerholm, A; Sgrò, C; Smith, D A; Smith, P D; Spandre, G; Spinelli, P; Starck, J-L; Stecker, F W; Striani, E; Strickman, M S; Strong, A W; Suson, D J; Tajima, H; Takahashi, H; Tanaka, T; Thayer, J B; Thayer, J G; Thompson, D J; Tibaldo, L; Torres, D F; Tosti, G; Tramacere, A; Uchiyama, Y; Usher, T L; Vasileiou, V; Vilchez, N; Vitale, V; Waite, A P; Wang, P; Winer, B L; Wood, K S; Ylinen, T; Ziegler, M

2009-12-18

The diffuse galactic gamma-ray emission is produced by cosmic rays (CRs) interacting with the interstellar gas and radiation field. Measurements by the Energetic Gamma-Ray Experiment Telescope (EGRET) instrument on the Compton Gamma-Ray Observatory indicated excess gamma-ray emission greater, > or approximately equal to 1 GeV relative to diffuse galactic gamma-ray emission models consistent with directly measured CR spectra (the so-called "EGRET GeV excess"). The Large Area Telescope (LAT) instrument on the Fermi Gamma-Ray Space Telescope has measured the diffuse gamma-ray emission with improved sensitivity and resolution compared to EGRET. We report on LAT measurements for energies 100 MeV to 10 GeV and galactic latitudes 10 degrees < or = |b| < or = 20 degrees. The LAT spectrum for this region of the sky is well reproduced by a diffuse galactic gamma-ray emission model that is consistent with local CR spectra and inconsistent with the EGRET GeV excess.

A new method of measuring centre-of-mass velocities of radially pulsating stars from high-resolution spectroscopy

NASA Astrophysics Data System (ADS)

Britavskiy, N.; Pancino, E.; Tsymbal, V.; Romano, D.; Fossati, L.

2018-03-01

We present a radial velocity analysis of 20 solar neighbourhood RR Lyrae and three Population II Cepheid variables. We obtained high-resolution, moderate-to-high signal-to-noise ratio spectra for most stars; these spectra covered different pulsation phases for each star. To estimate the gamma (centre-of-mass) velocities of the programme stars, we use two independent methods. The first, `classic' method is based on RR Lyrae radial velocity curve templates. The second method is based on the analysis of absorption-line profile asymmetry to determine both pulsational and gamma velocities. This second method is based on the least-squares deconvolution (LSD) technique applied to analyse the line asymmetry that occurs in the spectra. We obtain measurements of the pulsation component of the radial velocity with an accuracy of ±3.5 km s-1. The gamma velocity was determined with an accuracy of ±10 km s-1, even for those stars having a small number of spectra. The main advantage of this method is the possibility of obtaining an estimation of gamma velocity even from one spectroscopic observation with uncertain pulsation phase. A detailed investigation of LSD profile asymmetry shows that the projection factor p varies as a function of the pulsation phase - this is a key parameter, which converts observed spectral line radial velocity variations into photospheric pulsation velocities. As a by-product of our study, we present 41 densely spaced synthetic grids of LSD profile bisectors based on atmospheric models of RR Lyr covering all pulsation phases.

Light-curve Instabilities of β Lyrae Observed by the BRITE Satellites

NASA Astrophysics Data System (ADS)

Rucinski, Slavek M.; Pigulski, Andrzej; Popowicz, Adam; Kuschnig, Rainer; Kozłowski, Szymon; Moffat, Anthony F. J.; Pavlovski, Krešimir; Handler, Gerald; Pablo, H.; Wade, G. A.; Weiss, Werner W.; Zwintz, Konstanze

2018-07-01

Photometric instabilities of β Lyrae (β Lyr) were observed in 2016 by two red-filter BRITE satellites over more than 10 revolutions of the binary, with ∼100 minute sampling. Analysis of the time series shows that flares or fading events take place typically three to five times per binary orbit. The amplitudes of the disturbances (relative to the mean light curve, in units of the maximum out-of-eclipse light flux, f.u.) are characterized by a Gaussian distribution with σ = 0.0130 ± 0.0004 f.u. Most of the disturbances appear to be random, with a tendency to remain for one or a few orbital revolutions, sometimes changing from brightening to fading or the reverse. Phases just preceding the center of the deeper eclipse showed the most scatter while phases around the secondary eclipse were the quietest. This implies that the invisible companion is the most likely source of the instabilities. Wavelet transform analysis showed the domination of the variability scales at phase intervals 0.05–0.3 (0.65–4 days), with the shorter (longer) scales dominating in numbers (variability power) in this range. The series can be well described as a stochastic Gaussian process with the signal at short timescales showing a slightly stronger correlation than red noise. The signal decorrelation timescale, τ = (0.068 ± 0.018) in phase or (0.88 ± 0.23) days, appears to follow the same dependence on the accretor mass as that observed for active galactic nucleus and quasi-stellar object masses five to nine orders of magnitude larger than the β Lyr torus-hidden component.

Before the Bar: Kinematic Detection of a Spheroidal Metal-poor Bulge Component

NASA Astrophysics Data System (ADS)

Kunder, Andrea; Rich, R. M.; Koch, A.; Storm, J.; Nataf, D. M.; De Propris, R.; Walker, A. R.; Bono, G.; Johnson, C. I.; Shen, Juntai; Li, Z.-Y.

2016-04-01

We present 947 radial velocities of RR Lyrae variable stars in four fields located toward the Galactic bulge, observed within the data from the ongoing Bulge RR Lyrae Radial Velocity Assay (BRAVA-RR). We show that these RR Lyrae stars (RRLs) exhibit hot kinematics and null or negligible rotation and are therefore members of a separate population from the bar/pseudobulge that currently dominates the mass and luminosity of the inner Galaxy. Our RRLs predate these structures and have metallicities, kinematics, and spatial distribution that are consistent with a “classical” bulge, although we cannot yet completely rule out the possibility that they are the metal-poor tail of a more metal-rich ([{Fe}/{{H}}]˜ -1 dex) halo-bulge population. The complete catalog of radial velocities for the BRAVA-RR stars is also published electronically.

QT/RR relationship in patients after remote anterior myocardial infarction with left ventricular dysfunction and different types of ventricular arrhythmias.

PubMed

Szydlo, Krzysztof; Trusz-Gluza, Maria; Wita, Krystian; Filipecki, Artur; Orszulak, Witold; Urbanczyk, Dagmara; Krauze, Jolanta; Kolasa, Jaroslaw; Tabor, Zbigniew

2008-01-01

QT/RR relationship was found to be both rate-dependent and rate-independent, what suggests the influence of autonomic drive and other not-autonomic related factors on it. The steeper QT/RR slope in patients after acute myocardial infarction (MI) was described, but the relationship to ventricular arrhythmias is unknown. The purpose of this study was to calculate differences in QT/RR relationship in patients after remote anterior MI with left ventricular dysfunction and different types of ventricular arrhythmias. The cohort of 95 patients (age: 63 +/- 11 years, LVEF: 35 +/- 9%) with previous anterior MI (mean 1.1 years) was divided into two well-matched groups-50 patients without episodes of ventricular tachycardia (VT) or ventricular fibrillation (VF) (NoVT/VF: 39 males, 64 +/- 12 years, LVEF 37 +/- 8%) and 45 patients with VT and/or VF (all with ICD implanted) (VT/VF: 35 males, 62 +/- 10 years, LVEF 34 +/- 10%). No true antiarrhythmics were used. QT/RR slope was calculated from 24-hour Holter ECG for the entire recording (E), daytime (D) and nighttime (N) periods. Groups did not differ in basic clinical data (age, LVEF, treatment). QT/RR slopes were steeper in VT/VF than in NoVT/VF group in all analyzed periods: E - 0.195 +/- 0.03 versus 0.15 +/- 0.03 (P < 0.001), N - 0.190 +/- 0.03 versus 0.138 +/- 0.03 (P < 0.001) and D - 0.200 +/- 0.04 versus 0.152 +/- 0.03 (P < 0.001). No significant day-to-night differences were found in both groups. Steeper QT/RR slope and complete lack of day-to-night differences in VT/VF patients show inappropriate QT adaptation to the heart rate changes. The prognostic significance of this parameter needs prospective studies.

Serendipitous Discovery of RR Lyrae Stars in the Leo V Ultra-faint Galaxy

NASA Astrophysics Data System (ADS)

Medina, Gustavo E.; Muñoz, Ricardo R.; Vivas, A. Katherina; Förster, Francisco; Carlin, Jeffrey L.; Martinez, Jorge; Galbany, Lluis; González-Gaitán, Santiago; Hamuy, Mario; de Jaeger, Thomas; Maureira, Juan Carlos; San Martín, Jaime

2017-08-01

During the analysis of RR Lyrae stars (RRLs) discovered in the High Cadence Transient Survey (HiTS) taken with the Dark Energy Camera at the 4 m telescope at Cerro Tololo Inter-American Observatory, we found a group of three very distant, fundamental mode pulsator RR Lyrae (type ab). The location of these stars agrees with them belonging to the Leo V ultra-faint satellite galaxy, for which no variable stars have been reported to date. The heliocentric distance derived for Leo V based on these stars is 173 ± 5 kpc. The pulsational properties (amplitudes and periods) of these stars locate them within the locus of the Oosterhoff II group, similar to most other ultra-faint galaxies with known RRLs. This serendipitous discovery shows that distant RRLs may be used to search for unknown faint stellar systems in the outskirts of the Milky Way.

An application of Galactic parallax: the distance to the tidal stream GD-1

NASA Astrophysics Data System (ADS)

Eyre, Andy

2010-04-01

We assess the practicality of computing the distance to stellar streams in our Galaxy, using the method of Galactic parallax suggested by Eyre & Binney. We find that the uncertainty in Galactic parallax is dependent upon the specific geometry of the problem in question. In the case of the tidal stream GD-1, the problem geometry indicates that available proper-motion data, with individual accuracy ~4masyr-1, should allow estimation of its distance with about 50 per cent uncertainty. Proper motions accurate to ~1masyr-1, which are expected from the forthcoming Pan-STARRS PS-1 survey, will allow estimation of its distance to about 10 per cent uncertainty. Proper motions from the future Large Synoptic Survey Telescope (LSST) and Gaia projects will be more accurate still, and will allow the parallax for a stream 30 kpc distant to be measured with ~14 per cent uncertainty. We demonstrate the feasibility of the method and show that our uncertainty estimates are accurate by computing Galactic parallax using simulated data for the GD-1 stream. We also apply the method to actual data for the GD-1 stream, published by Koposov, Rix & Hogg. With the exception of one datum, the distances estimated using Galactic parallax match photometric estimates with less than 1 kpc discrepancy. The scatter in the distances recovered using Galactic parallax is very low, suggesting that the proper-motion uncertainty reported by Koposov et al. is in fact overestimated. We conclude that the GD-1 stream is (8 +/- 1)kpc distant, on a retrograde orbit inclined 37° to the plane, and that the visible portion of the stream is likely to be near pericentre.

Cosmic Ray Acceleration from Multiple Galactic Wind Shocks

NASA Astrophysics Data System (ADS)

Cotter, Cory; Bustard, Chad; Zweibel, Ellen

2018-01-01

Cosmic rays still have an unknown origin. Many mechanisms have been suggested for their acceleration including quasars, pulsars, magnetars, supernovae, supernova remnants, and galactic termination shocks. The source of acceleration may be a mixture of these and a different mixture in different energy regimes. Using numerical simulations, we investigate multiple shocks in galactic winds as potential cosmic rays sources. By having shocks closer to the parent galaxy, more particles may diffuse back to the disk instead of being blown out in the wind, as found in Bustard, Zweibel, and Cotter (2017, ApJ) and also Merten, Bustard, Zweibel, and Tjus (to be submitted to ApJ). Specifically, this flux of cosmic rays could contribute to the unexplained "shin" region between the well-known "knee" and "ankle" of the cosmic ray spectrum. We would like to acknowledge support from the National Science Foundation (NSF) Graduate Research Fellowship Program under grant No. DGE-125625 and NSF grant No. AST-1616037.

Results from the MACHO Galactic Pixel Lensing Search

NASA Astrophysics Data System (ADS)

Drake, Andrew J.; Minniti, Dante; Alcock, Charles; Allsman, Robyn A.; Alves, David; Axelrod, Tim S.; Becker, Andrew C.; Bennett, David; Cook, Kem H.; Freeman, Ken C.; Griest, Kim; Lehner, Matt; Marshall, Stuart; Peterson, Bruce; Pratt, Mark; Quinn, Peter; Rodgers, Alex; Stubbs, Chris; Sutherland, Will; Tomaney, Austin; Vandehei, Thor; Welch, Doug L.

The MACHO, EROS, OGLE and AGAPE collaborations have been studying nature of the galactic halo for a number of years using microlensing events. The MACHO group undertakes observations of the LMC, SMC and Galactic Bulge monitoring the light curves of millions of stars to detect microlensing. Most of these fields are crowded to the extent that all the monitored stars are blended. Such crowding makes the performance of accurate photometry difficult. We apply the new technique of Difference Image Analysis (DIA) on archival data to improve the photometry and increase both the detection sensitivity and effective search area. The application of this technique also allows us to detect so called `pixel lensing' events. These are microlensing events where the source star is only detectable during lensing. The detection of these events will allow us to make a large increase in the number of detected microlensing events. We present a light curve demonstrating the detection of a pixel lensing event with this technique.

Galactic binary science with the new LISA design

NASA Astrophysics Data System (ADS)

Cornish, Neil; Robson, Travis

2017-05-01

Building on the great success of the LISA Pathfinder mission, the outlines of a new LISA mission design were laid out at the 11th International LISA Symposium in Zurich. The revised design calls for three identical spacecraft forming an equilateral triangle with 2.5 million kilometer sides, and two laser links per side delivering full polarization sensitivity. With the demonstrated Pathfinder performance for the disturbance reduction system, and a well studied design for the laser metrology, it is anticipated that the new mission will have a sensitivity very close to the original LISA design. This implies that the mid-band performance, between 0.5 mHz and 3 mHz, will be limited by unresolved signals from compact binaries in our galaxy. Here we use the new LISA design to compute updated estimates for the galactic confusion noise, the number of resolvable galactic binaries, and the accuracy to which key parameters of these systems can be measured.

Interval ridge regression (iRR) as a fast and robust method for quantitative prediction and variable selection applied to edible oil adulteration.

PubMed

Jović, Ozren; Smrečki, Neven; Popović, Zora

2016-04-01

A novel quantitative prediction and variable selection method called interval ridge regression (iRR) is studied in this work. The method is performed on six data sets of FTIR, two data sets of UV-vis and one data set of DSC. The obtained results show that models built with ridge regression on optimal variables selected with iRR significantly outperfom models built with ridge regression on all variables in both calibration (6 out of 9 cases) and validation (2 out of 9 cases). In this study, iRR is also compared with interval partial least squares regression (iPLS). iRR outperfomed iPLS in validation (insignificantly in 6 out of 9 cases and significantly in one out of 9 cases for p<0.05). Also, iRR can be a fast alternative to iPLS, especially in case of unknown degree of complexity of analyzed system, i.e. if upper limit of number of latent variables is not easily estimated for iPLS. Adulteration of hempseed (H) oil, a well known health beneficial nutrient, is studied in this work by mixing it with cheap and widely used oils such as soybean (So) oil, rapeseed (R) oil and sunflower (Su) oil. Binary mixture sets of hempseed oil with these three oils (HSo, HR and HSu) and a ternary mixture set of H oil, R oil and Su oil (HRSu) were considered. The obtained accuracy indicates that using iRR on FTIR and UV-vis data, each particular oil can be very successfully quantified (in all 8 cases RMSEP<1.2%). This means that FTIR-ATR coupled with iRR can very rapidly and effectively determine the level of adulteration in the adulterated hempseed oil (R(2)>0.99). Copyright © 2015 Elsevier B.V. All rights reserved.

Trajectories of Cepheid variable stars in the Galactic nuclear bulge

NASA Astrophysics Data System (ADS)

Matsunaga, Noriyuki

2012-06-01

The central region of our Galaxy provides us with a good opportunity to study the evolution of galactic nuclei and bulges because we can observe various phenomena in detail at the proximity of 8 kpc. There is a hierarchical alignment of stellar systems with different sizes; from the extended bulge, the nuclear bulge, down to the compact cluster around the central supermassive blackhole. The nuclear bulge contains stars as young as a few Myr, and even hosts the ongoing star formation. These are in contrast to the more extended bulge which are dominated by old stars, 10Gyr. It is considered that the star formation in the nuclear bulge is caused by fresh gas provided from the inner disk. In this picture, the nuclear bulge plays an important role as the interface between the gas supplier, the inner disk, and the galactic nucleus. Kinematics of young stars in the nuclear bulge is important to discuss the star forming process and the gas circulation in the Galactic Center. We here propose spectroscopic observations of Cepheid variable stars, 25 Myr, which we recently discovered in the nuclear bulge. The spectra taken in this proposal will allow timely estimates of the systemic velocities of the variable stars.

Star formation across galactic environments

NASA Astrophysics Data System (ADS)

Young, Jason

I present here parallel investigations of star formation in typical and extreme galaxies. The typical galaxies are selected to be free of active galactic nuclei (AGN), while the extreme galaxies host quasars (the most luminous class of AGN). These two environments are each insightful in their own way; quasars are among the most violent objects in the universe, literally reshaping their host galaxies, while my sample of AGN-free star-forming galaxies ranges from systems larger than the Milky Way to small galaxies which are forming stars at unsustainably high rates. The current paradigm of galaxy formation and evolution suggests that extreme circumstances are key stepping stones in the assembly of galaxies like our Milky Way. To test this paradigm and fully explore its ramifications, this dual approach is needed. My sample of AGN-free galaxies is drawn from the KPNO International Spectroscopic Survey. This Halpha-selected, volume-limited survey was designed to detect star-forming galaxies without a bias toward continuum luminosity. This type of selection ensures that this sample is not biased toward galaxies that are large or nearby. My work studies the KISS galaxies in the mid- and far-infrared using photometry from the IRAC and MIPS instruments aboard the Spitzer Space Telescope. These infrared bands are particularly interesting for star formation studies because the ultraviolet light from young stars is reprocessed into thermal emission in the far-infrared (24mum MIPS) by dust and into vibrational transitions features in the mid-infrared (8.0mum IRAC) by polycyclic aromatic hydrocarbons (PAHs). The work I present here examines the efficiencies of PAH and thermal dust emission as tracers of star-formation rates over a wide range of galactic stellar masses. I find that the efficiency of PAH as a star-formation tracer varies with galactic stellar mass, while thermal dust has a highly variable efficiency that does not systematically depend on galactic stellar mass

On the RR Lyrae Stars in Globulars. IV. ω Centauri Optical UBVRI Photometry

NASA Astrophysics Data System (ADS)

Braga, V. F.; Stetson, P. B.; Bono, G.; Dall'Ora, M.; Ferraro, I.; Fiorentino, G.; Freyhammer, L. M.; Iannicola, G.; Marengo, M.; Neeley, J.; Valenti, E.; Buonanno, R.; Calamida, A.; Castellani, M.; da Silva, R.; Degl'Innocenti, S.; Di Cecco, A.; Fabrizio, M.; Freedman, W. L.; Giuffrida, G.; Lub, J.; Madore, B. F.; Marconi, M.; Marinoni, S.; Matsunaga, N.; Monelli, M.; Persson, S. E.; Piersimoni, A. M.; Pietrinferni, A.; Prada-Moroni, P.; Pulone, L.; Stellingwerf, R.; Tognelli, E.; Walker, A. R.

2016-12-01

New accurate and homogeneous optical UBVRI photometry has been obtained for variable stars in the Galactic globular cluster ω Cen (NGC 5139). We secured 8202 CCD images covering a time interval of 24 years and a sky area of 84 × 48 arcmin. The current data were complemented with data available in the literature and provided new, homogeneous pulsation parameters (mean magnitudes, luminosity amplitudes, periods) for 187 candidate ω Cen RR Lyrae (RRLs). Among them we have 101 RRc (first overtone) and 85 RRab (fundamental) variables, and a single candidate RRd (double-mode) variable. Candidate Blazhko RRLs show periods and colors that are intermediate between the RRc and RRab variables, suggesting that they are transitional objects. A comparison of the period distribution and the Bailey diagram indicates that RRLs in ω Cen show a long-period tail not present in typical Oosterhoff II (OoII) globulars. The RRLs in dwarf spheroidals and in ultra-faint dwarfs have properties between Oosterhoff intermediate and OoII clusters. Metallicity plays a key role in shaping the above evidence. These findings do not support the hypothesis that ω Cen is the core remnant of a spoiled dwarf galaxy. Using optical period-Wesenheit relations that are reddening-free and minimally dependent on metallicity we find a mean distance to ω Cen of 13.71 ± 0.08 ± 0.01 mag (semi-empirical and theoretical calibrations). Finally, we invert the I-band period-luminosity-metallicity relation to estimate individual RRLs’ metal abundances. The metallicity distribution agrees quite well with spectroscopic and photometric metallicity estimates available in the literature. Based in part on proprietary data and on data obtained from the ESO Science Archive Facility under multiple requests by the authors; and in part upon data distributed by the NOAO Science Archive. NOAO is operated by the Association of Universities for Research in Astronomy (AURA) under cooperative agreement with the National

COMPACT GALACTIC PLANETARY NEBULAE: AN HST /WFC3 MORPHOLOGICAL CATALOG, AND A STUDY OF THEIR ROLE IN THE GALAXY

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

Stanghellini, Letizia; Shaw, Richard A.; Villaver, Eva

We present the images of a Hubble Space Telescope ( HST /WFC3) snapshot program of angularly compact Galactic planetary nebulae (PNe), acquired with the aim of studying their size, evolutionary status, and morphology. PNe that are smaller than ∼4″ are underrepresented in most morphological studies, and today they are less well studied than their immediate evolutionary predecessors, the pre-planetary nebulae. The images have been acquired in the light of [O iii] λ 5007, which is commonly used to classify the PN morphology, in the UV continuum with the aim of detecting the central star unambiguously, and in the I -bandmore » to detect a cool stellar companion, if present. The sample of 51 confirmed PNe exhibits nearly the full range of primary morphological classes, with the distribution more heavily weighted toward bipolar PNe, but with the total of aspherical PNe almost identical to that of the general Galactic sample. A large range of microstructures is evident in our sample as well, with many nebulae displaying attached shells, halos, ansae, and internal structure in the form of arcs, rings, and spirals. Various aspherical structures in a few PNe, including detached arcs, suggest an interaction with the ISM. We studied the observed sample of compact Galactic PNe in the context of the general Galactic PN population, and explore whether their physical size, spatial distribution, reddening, radial metallicity gradient, and possible progenitors are peculiar within the population of Galactic PNe. We found that these compact Galactic PNe, which have been selected based on apparent dimensions, constitute a diverse Galactic PN population that is relatively uniformly distributed across the Galactic disk, including the outskirts of our Galaxy. This unique sample will be used in the future to probe the old Galactic disk population.« less

Galactic cosmic radiation exposure of pregnant aircrew members II

DOT National Transportation Integrated Search

2000-10-01

This report is an updated version of a previously published Technical Note in the journal Aviation, Space, and Environmental Medicine. The main change is that improved computer programs were used to estimate galactic cosmic radiation. The calculation...

Spectral Diagnostics of Galactic and Stellar X-Ray Emission from Charge Exchange Recombination

NASA Technical Reports Server (NTRS)

Wargelin, B.

2003-01-01

The proposed research uses the electron beam ion trap at the Lawrence Livermore National Laboratory to study the X-ray emission from charge-exchange recombination of highly charged ions with neutral gases. The resulting data fill a void in the existing experimental and theoretical data and are needed to explain all or part of the observed X-ray emission from the Galactic Ridge, solar and stellar winds, the Galactic Center, supernova ejecta, and photoionized nebulae.

Resolving Star Formation, Multiphase ISM Structure, and Wind Driving with MHD and RHD Models of Galactic Disks

NASA Astrophysics Data System (ADS)

Ostriker, Eve

Current studies of star and galaxy formation have concluded that energetic feedback from young stars and supernovae (SNe) is crucial, both for controlling observed interstellar medium (ISM) properties and star formation rates in the Milky Way and other galaxies, and for driving galactic winds that govern the baryon abundance in dark matter halos. However, in many numerical studies of the ISM, energy inputs have not been implemented self-consistently with the evolving rate of gravitational collapse to make stars, or have considered only isolated star-forming clouds without a realistic galactic environment (including sheared rotation and externally-originating SNe), or have not directly incorporated radiation, magnetic, and chemical effects that are important or even dominant. In models of galaxy formation and evolution in the cosmic context, galactic winds are indispensable but highly uncertain as the physics of superbubble evolution and radiation-gas interactions cannot be resolved. Our central objectives are (1) to address the above limitations of current models, developing self-consistent simulations of the multiphase ISM in disk galaxies that resolve both star formation and stellar feedback, covering the range of scales needed to connect star cluster formation to galactic superwind ejection, and the range of environments from dwarfs to ULIRGs; and (2) to analyze the detailed properties of the gas, magnetic field, radiation field, and star formation/SNe in our simulations, including dependencies on local galactic disk environment, and to connect intrinsic properties with observable diagnostics. The proposed project will employ the Athena code for numerical magneto-hydrodynamic (MHD) and radiation-hydrodynamic (RHD) simulations, using comprehensive physics modules that have been developed, tested, and demonstrated in sample simulations. We will consider local ``shearing box'' disk models with gas surface density Sigma = 2 - 10,000 Msun/pc^2, and a range of stellar

Active Galactic Nuclei

NASA Astrophysics Data System (ADS)

Blandford, R. D.; Netzer, H.; Woltjer, L.; Courvoisier, T. J.-L.; Mayor, M.

Starting with this volume, the Lecture Notes of the renowned Advanced Courses of the Swiss Society for Astrophysics and Astronomy will be published annually. In each course, three extensive lectures given by leading experts in their respective fields cover different and essential aspects of the subject. The 20th course, held at Les Diablerets in April 1990, dealt with current research on active galactic nuclei; it represents the most up-to-date views on the subject, presented with particular regard for clarity. The previous courses considered a wide variety of subjects, beginning with "Theory of Stellar Athmospheres" in 1971 and ending with "The Milky Way as a Galaxy" in 1989. The Lecture Notes of these Saas-Fee Courses appeared as publications of the Geneva Observatory, from which they can still be ordered (chemin des Maillettes 51, CH-1290 Sauverny, Switzerland).

A Search for Extraterrestrial Intelligence (SETI) toward the Galactic Anticenter with the Murchison Widefield Array

NASA Astrophysics Data System (ADS)

Tingay, S. J.; Tremblay, C. D.; Croft, S.

2018-03-01

Following the results of the first systematic modern low-frequency search for extraterrestrial intelligence using the Murchison Widefield Array (MWA), which was directed toward a Galactic Center field, we report a second survey toward a Galactic Anticenter field. Using the MWA in the frequency range 99–122 MHz over a three-hour period, a 625 deg2 field centered on Orion KL (in the general direction of the Galactic Anticenter) was observed with a frequency resolution of 10 kHz. Within this field, 22 exoplanets are known. At the positions of these exoplanets, we searched for narrowband signals consistent with radio transmissions from intelligent civilizations. No such signals were found with a 5σ detection threshold. Our sample is significantly different to the 45 exoplanets previously studied with the MWA toward the Galactic Center, since the Galactic Center sample is dominated by exoplanets detected using microlensing, and hence at much larger distances than the exoplanets toward the Anticenter, found via radial velocity and transit detection methods. Our average effective sensitivity to extraterrestrial transmitter power is therefore much improved for the Anticenter sample. Added to this, our data processing techniques have improved, reducing our observational errors, leading to our best detection limit being reduced by approximately a factor of four compared to our previously published results.

Gamma-ray burst constraints on the galactic frequency of extrasolar Oort Clouds

NASA Technical Reports Server (NTRS)

Shull, J. Michael; Stern, S. Alan

1995-01-01

With the strong Compton Gamma-Ray Observatory/Burst and Transient Source Experiment (CGRO/BATSE) evidence that most gamma-ray bursts do not come from galactic neutron stars, models involving the accretion of a comet onto a neutron star (NS) no longer appear to be strong contenders for explaining the majority of bursts. If this is the case, then it is worth asking whether the lack of an observed galactic gamma-ray burst population provides a useful constraint on the number of comets and comet clouds in the galaxy. Owing to the previously unrecognized structural weakness of cometary nuclei, we find the capture cross sections for comet-NS events to be much higher than previously published estimates, with tidal breakup at distances R(sub b) approx. equals 4 x 10(exp 10) cm from the NS. As a result, impacts of comets onto field NSs penetrating the Oort Clouds of other stars are found to dominate all other galactic NS-comet capture rates by a factor of 100. This in turn predicts that if comet clouds are common, there should be a significant population of repeater sources with (1) a galactic distribution, (2) space-correlated repetition, and (3) a wide range of peak luminosities and luminosity time histories. If all main sequence stars have Oort Clouds like our own, we predict approximately 4000 such repeater sources in the Milky Way at any time, each repeating on time scales of months to years. Based on estimates of the sensitivity of the CGRO/BATSE instrument and assuming isotropic gamma-ray beaming from such events, we estimate that a population of approximately 20-200 of these galactic NS-Oort Cloud gamma-ray repeater sources should be detectable by CGRO. In addition, if giant planet formation is common in the galaxy, we estimate that the accretion of isolated comets injected to the interstellar medium by giant planet formation should produce an additional source of galactic, nonrepeating, events. Comparing these estimates to the 3-4 soft gamma-ray repeater sources

Uncovering the hidden iceberg structure of the Galactic halo

NASA Astrophysics Data System (ADS)

Moss, Vanessa A.; Di Teodoro, Enrico M.; McClure-Griffiths, Naomi M.; Lockman, Felix; Pisano, D. J.; Price, Daniel; Rees, Glen

2018-01-01

How the Milky Way gets its gas and keeps its measured star formation rate going are both long-standing mysteries in Galactic studies, with important implications for galaxy evolution across the Universe. I will present our recent discovery of two populations of neutral hydrogen (HI) in the halo of the Milky Way: 1) a narrow line-width dense population typical of the majority of bright high velocity cloud (HVC) components, and 2) a fainter, broad line-width diffuse population that aligns well with the population found in very sensitive pointings such as in Lockman et al. (2002). From our existing data, we concluded that the diffuse population likely outweighs the dense HI by a factor of 3. This discovery of diffuse HI, which appears to be prevalent throughout the halo, takes us closer to solving the Galactic mystery of accretion and reveals a gaseous neutral halo hidden from the view of most large-scale surveys. We are currently carrying out deep Parkes observations to investigate these results further, in order to truly uncover the nature of the diffuse HI and determine whether our 3:1 ratio (based on the limited existing data) is consistent with what is seen when Parkes and the 140 ft Green Bank telescope are employed at comparable sensitivity. With these data, through a combination of both known and new sightline measurements, we aim to reveal the structure of the Galactic halo in more detail than ever before.

Interstellar Matters: Neutral Hydrogen and the Galactic Magnetic Field

NASA Astrophysics Data System (ADS)

Verschuur, Gerrit; Schmelz, Joan T.; Asgari-Targhi asgari-Targhi, M.

2018-01-01

The physics of the interstellar medium was revolutionized by the observations of the Galactic Arecibo L-Band Feed Array (GALFA) HI survey done at the Arecibo Observatory. The high-resolution, high-sensitivity, high-dynamic- range images show complex, tangled, extended filaments, and reveal that the fabric of the neutral interstellar medium is deeply tied to the structure of the ambient magnetic field. This discovery prompts an obvious question – how exactly is the interstellar {\\it neutral} hydrogen being affected by the galactic magnetic field? We look into this question by examining a set of GALFA-HI data in great detail. We have chosen a long, straight filament in the southern galactic sky. This structure is both close by and isolated in velocity space. Gaussian analysis of profiles both along and across the filament reveal internal structure – braided strands that can be traced through the simplest part, but become tangled in more complex segments. These braids do not resemble in any way the old spherical HI clouds and rudimentary pressure balance models that were used to explain the pre-GALFA- HI interstellar medium. It is clear that these structures are created, constrained, and dominated by magnetic fields. Like many subfields of astronomy before it, e.g., physics of the solar coronal, extragalactic radio jets, and pulsar environment, scientists are confronted with observations that simply cannot be explained by simple hydrodynamics and are forced to consider magneto-hydrodynamics.

Photometry and brightening of Galactic transient ASASSN-18fv

NASA Astrophysics Data System (ADS)

Brown, M. J. I.; Upjohn, J.; Rol, E.; Obradovic, A.; Galloway, D. K.; Ackley, K.; Davies, J.; Lane, C.; Olofsson, S.; Reader, N.

2018-03-01

We report follow-up B and V photometry of Galactic transient ASASSN-18fv (Stanek et al. ATEL #11454). The photometry was taken with the 14-inch telescope at Hutton-Westfold Observatory, located at Monash University's Clayton campus.

STELLAR ARCHAEOLOGY IN THE GALACTIC HALO WITH THE ULTRA-FAINT DWARFS. VI. URSA MAJOR II