WorldWideScience

Sample records for variable stars vii

  1. Variable Stars in Local Group Galaxies. III. And VII, NGC 147, and NGC 185: Insight into the Building Blocks of the M31 Halo

    Science.gov (United States)

    Monelli, M.; Fiorentino, G.; Bernard, E. J.; Martínez-Vázquez, C. E.; Bono, G.; Gallart, C.; Dall’Ora, M.; Stetson, P. B.

    2017-06-01

    We present the discovery of 1568 RR Lyrae stars in three of the most luminous M31 satellites: And VII (573), NGC 147 (177), and NGC 185 (818). We use their properties to study the formation history of Local Group spiral haloes, and in particular, to infer about the nature of their possible building blocks by comparison with available data for RR Lyrae stars in the halo and in a sample of satellites of M31 and the Milky Way. We find that the brightest satellites and the halos of both galaxies host a number of High Amplitude Short Period (HASP) RR Lyrae variable stars, which are missing in the faintest satellites. HASP variable stars have been shown by Fiorentino et al. to be tracers of a population of stars as metal-rich as [Fe/H] ≃ ‑1.5 and older than ≃ 10 {Gyr}. This suggests that the metal-rich M31 and MW halo component, which manifests through the HASP phenomenon, comes from massive dwarf galaxy building blocks, as the low-mass dwarfs did not chemically enrich fast enough to produce them. All detected variable stars are new discoveries; in particular, this work presents the first detections of RR Lyrae stars in And VII. Moreover, a number of candidate Anomalous Cepheids, and binary and long-period variable stars have been detected. We provide pulsation properties (period, amplitude, mean magnitude), light curves, and time series photometry for all of the variable stars in the three galaxies. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with programs #10430 and #11724.

  2. Jonckheere Double Star Photometry - Part VII: Aquarius

    Science.gov (United States)

    Knapp, Wilfried R. A.

    2017-10-01

    If any double star discoverer is in urgent need of photometry then it is Jonckheere. There are over 3000 Jonckheere objects listed in the WDS catalog and a good part of them with magnitudes obviously far too bright. This report covers the Jonckheere objects in the constellation Aquarius. One image per object was taken with V-filter to allow for visual magnitude measurement by differential pho-tometry. All objects were additionally checked for common proper motion by comparing 2MASS to GAIA DR1 positions and a rather surprisingly large part of the objects qualify indeed as potential CPM pairs. For a few objects also WDS position errors were found.

  3. Historical Variable Star Catalogs

    OpenAIRE

    Pagnotta, Ashley; Graur, Or; Murray, Zachary; Kruk, Julia; Christie-Dervaux, Lucien; Chen, Dong Yi

    2015-01-01

    Slides from my talk during one of the Historical Astronomy Division sessions at AAS 225 in Seattle, WA (January 2015). A brief history of the variable star catalogs Henrietta Swan Leavitt and Cecilia Payne-Gaposchkin assembled at Harvard, and the update to them that some of our students at AMNH have done.(Figshare only previews the first few slides. Download the PDF to see all of them!)

  4. THE SUN AS A VARIABLE STAR III.

    Science.gov (United States)

    observations has taught us more about the variations of solar type stars than about the sun itself. The observations of 15 stars of spectral types F and...stars 40 Leo, beta CVn and eta Boo this deviation is less than 0.004 mag. No evidence of variability in the stars which are similar to the sun has been...detected during this program. If we assume the sun acts in similar fashion to each of these stars, its variability over a fifteen-year period probably

  5. Variable Star Search Using ROTSE3 Data

    Science.gov (United States)

    Ferrante, Farley; Kehoe, Robert

    2012-10-01

    I present results of a variable star search using data from the Robotic Optical Transient Search Experiment 3 (ROTSE3) telescopes. Variable stars fluctuate in magnitude as seen from Earth due either to changes in the star's luminosity or to changes in the amount of the star's light that reaches Earth. My research is focused on analysis of the time variation of optical light output as recorded in ROTSE 3 images. Specifically, I am attempting to identify short-period variable candidates such as delta Scuti stars, eclipsing binary stars, and contact binary stars. Amplitude variations for these classes of variables are on the order of one magnitude with periods on the order of two to five hours. The ROTSE3 telescope sensitivity holds the promise of significantly extending our reach to dimmer objects than previous searches and I will report on the confirmed discovery of a previously unidentified contact binary star in the constellation Sagittarius. This contact binary is now listed in the International Variable Star Index (VSX) maintained by the American Association of Variable Star Observers (AAVSO).

  6. Variable Stars in the Lepine List of Nearby Stars

    Science.gov (United States)

    Blake, Melvin; McNutt, J.

    2006-12-01

    An analysis of Lepine’s list (2005, AJ 130, 1680) of newly identified nearby stars was conducted at the Pisgah Astronomical Research Institute in Rosman, NC in hopes of supporting future searches for potential hosts for nearby, extraterrestrial planets. The celestial coordinates were extracted from Lepine’s list and cross-referenced with the Northern Sky Variability Survey to determine which stars among them were variable. The stars deemed variable were then cross referenced with the ROSAT all sky survey to determine if any were X-ray sources. It was determined that roughly half of the list of newly discovered nearby stars coincided to within 3arcseconds of a NSVS variable. The search done with the ROSAT all sky survey is, at this point, being verified. Future work will include statistical studies of the sample and follow-up observations of candidate variable stars. We would like to acknowledge support for this work for one of us (McNutt) through 2006 PARSEC Internship Program, and was supported by NASA Award NNG05GQ66, the North Carolina Space Grant, and the Glaxo-Wellcome Endowment at UNCA.

  7. A new pulsating variable star in Lynx

    Science.gov (United States)

    Fiacconi, Davide; Tinelli, Luciano

    2012-02-01

    We report the discovery of a new variable star in the Lynx constellation. The star is catalogued as GSC 03409-00999 (07 33 08.6, +48 03 53.5). From analysis of the light curve we are induced to think the star may be a RRab Lyrae-type variable. We calculated the epoch HJD0 = 2455644.363 +/- 0.007 and the period P = 0.61971 +/- 0.00003 d, during which the star changes its brightness from a minimum magnitude m_min = 13.65 +/- 0.01 to a maximum one m_max = 13.11 +/- 0.01. The light curve shows the asymmetry 0.248 +/- 0.001, with a rise time tau_ RT = 0.1539 +/- 0.0007 d.

  8. Machine learning techniques to select variable stars

    Science.gov (United States)

    García-Varela, Alejandro; Pérez, Muriel; Sabogal, Beatriz; Quiroz, Adolfo

    2017-09-01

    In order to perform a supervised classification of variable stars, we propose and evaluate a set of six features extracted from the magnitude density of the light curves. They are used to train automatic classification systems using state-of-the-art classifiers implemented in the R statistical computing environment. We find that random forests is the most successful method to select variables.

  9. Observing variable stars. A guide for beginners

    Science.gov (United States)

    Levy, David H.

    David Levy's entertaining, well-researched book is aimed at the amateur enthusiast who likes to learn enjoyably. Beginning with advice on binoculars and telescopes, and how to observe the night sky effectively, the author goes on to describe thoroughly the field of variable star observation, a field in which amateurs have made important contributions. He shows how to interpret variations in light output in terms of the life of a star, from birth through to sometimes violent death. All of the major variable stars are described and classified, as well as other variable objects such as active galaxies, asteroids, comets and the sun. The book also contains a guide to the seasonal night sky. Throughout, practical observations serve to complement the text, producing an exciting, very readable introduction to this fascinating subject.

  10. Forecasting neutron star temperatures: predictability and variability.

    Science.gov (United States)

    Page, Dany; Reddy, Sanjay

    2013-12-13

    It is now possible to model thermal relaxation of neutron stars after bouts of accretion during which the star is heated out of equilibrium by nuclear reactions in its crust. Major uncertainties in these models can be encapsulated in modest variations of a handful of control parameters that change the fiducial crustal thermal conductivity, specific heat, and heating rates. Observations of thermal relaxation constrain these parameters and allow us to predict longer term variability in terms of the neutron star core temperature. We demonstrate this explicitly by modeling ongoing thermal relaxation in the neutron star XTE J1701-462. Its future cooling, over the next 5 to 30 years, is strongly constrained and depends mostly on its core temperature, uncertainties in crust physics having essentially been pinned down by fitting to the first three years of observations.

  11. Machine learning techniques to select variable stars

    Directory of Open Access Journals (Sweden)

    García-Varela Alejandro

    2017-01-01

    Full Text Available In order to perform a supervised classification of variable stars, we propose and evaluate a set of six features extracted from the magnitude density of the light curves. They are used to train automatic classification systems using state-of-the-art classifiers implemented in the R statistical computing environment. We find that random forests is the most successful method to select variables.

  12. The variable stars of NGC 1866

    Science.gov (United States)

    Welch, Douglas L.; Cote, Patrick; Fischer, Philippe; Mateo, Mario; Madore, Barry F.

    1991-01-01

    A search has been conducted for new variables in the LMC cluster NGC 1866 using new multiepoch CCD photometry. Eight previously unknown Cepheid variables, most near the cluster core, are found. Of the new variables reported by Storm et al. (188), only six of 10 appear to be Cepheids and one of these is not a member. Periods and mean magnitudes and colors for sufficiently uncrowded variables are reported, as is one red giant variable of long period and one Cepheid which is a single-lined spectroscopic binary with a velocity semiamplitude greater than or equal to 10.5 km/s. The variation of light-curve amplitude with position in the instability strip is reported along with an apparently nonvariable star, which is a radial velocity member, in the strip. A true distance modulus of 18.57 + or - 0.01 mag is obtained for the cluster.

  13. Outbursts and Disk Variability in Be Stars

    Science.gov (United States)

    Labadie-Bartz, Jonathan; Chojnowski, S. Drew; Whelan, David G.; Pepper, Joshua; McSwain, M. Virginia; Borges Fernandes, Marcelo; Wisniewski, John P.; Stringfellow, Guy S.; Carciofi, Alex C.; Siverd, Robert J.; Glazier, Amy L.; Anderson, Sophie G.; Caravello, Anthoni J.; Stassun, Keivan G.; Lund, Michael B.; Stevens, Daniel J.; Rodriguez, Joseph E.; James, David J.; Kuhn, Rudolf B.

    2018-02-01

    In order to study the growth and evolution of circumstellar disks around classical Be stars, we analyze optical time-series photometry from the KELT survey with simultaneous infrared and visible spectroscopy from the Apache Point Observatory Galactic Evolution Experiment survey and Be Star Spectra database for a sample of 160 Galactic classical Be stars. The systems studied here show variability including transitions from a diskless to a disk-possessing state (and vice versa), and persistent disks that vary in strength, being replenished at either regularly or irregularly occurring intervals. We detect disk-building events (outbursts) in the light curves of 28% of our sample. Outbursts are more commonly observed in early- (57%), compared to mid- (27%) and late-type (8%) systems. A given system may show anywhere between 0 and 40 individual outbursts in its light curve, with amplitudes ranging up to ∼0.5 mag and event durations between ∼2 and 1000 days. We study how both the photometry and spectroscopy change together during active episodes of disk growth or dissipation, revealing details about the evolution of the circumstellar environment. We demonstrate that photometric activity is linked to changes in the inner disk, and show that, at least in some cases, the disk growth process is asymmetrical. Observational evidence of Be star disks both growing and clearing from the inside out is presented. The duration of disk buildup and dissipation phases are measured for 70 outbursts, and we find that the average outburst takes about twice as long to dissipate as it does to build up in optical photometry. Our analysis hints that dissipation of the inner disk occurs relatively slowly for late-type Be stars.

  14. ROAD (Remote Observatory Atacama Desert): Intensive Observations of Variable Stars

    Science.gov (United States)

    Hambsch, F.-J.

    2012-10-01

    The author discusses his new remote observatory under pristine skies and the intensive observations of variable stars he is accomplishing. The stars under investigation are mainly cataclysmic variables, observed in response to AAVSO, CBA, and VSNET alerts; other types, such as RR Lyrae stars, were also observed. Examples are presented of dense observations of different cataclysmic variables as well as an RR Lyrae star. Featured is the first bright outburst of SV Ari (Nova Ari 1905) since its discovery, as well as the first outburst of UGWZ candidate BW Scl. Results for VW Hyi, another cataclysmic variable, will also be shown. Furthermore, an intensively observed RR Lyrae star will be highlighted.

  15. Félix de Roy: a life of variable stars

    Science.gov (United States)

    Shears, J.

    2011-08-01

    Félix de Roy (1883-1942), an internationally recognised amateur astronomer, made significant contributions to variable star research. As an active observer, he made some 91,000 visual estimates of a number of different variable stars. A Belgian national, he took refuge in England during World War I. While there, de Roy became well enough known to serve later as Director of the BAA Variable Star Section for seventeen years. Through this office, and his connections with other organisations around the world, he encouraged others to pursue the observation of variable stars. Not merely content to accumulate observational data, de Roy also analysed the data and published numerous papers.

  16. Felix de Roy: a life of variable stars

    CERN Document Server

    Shears, Jeremy

    2010-01-01

    Felix de Roy (1883-1942), an internationality recognised amateur astronomer, made significant contributions to variable star research. As an active observer, he made some 91,000 visual estimates of a number of different variable stars. A Belgian national, he took refuge in England during World War 1. While there, de Roy became well enough known to later serve as Director of the BAA Variable Star Section for seventeen years. Through this office, and his connections with other organisations around the world, he encouraged others to pursue the observation of variable stars. Not merely content to accumulate observational data, de Roy also analysed the data and published numerous papers.

  17. Variable stars with the Kepler space telescope

    OpenAIRE

    Molnár, László; Szabó, Róbert; Plachy, Emese

    2016-01-01

    The Kepler space telescope has revolutionised our knowledge about exoplanets and stars and is continuing to do so in the K2 mission. The exquisite photometric precision, together with the long, uninterrupted observations opened up a new way to investigate the structure and evolution of stars. Asteroseismology, the study of stellar oscillations, allowed us to investigate solar-like stars and to peer into the insides of red giants and massive stars. But many discoveries have been made about cla...

  18. The Pan-Pacific Planet Search. VII. The Most Eccentric Planet Orbiting a Giant Star

    Science.gov (United States)

    Wittenmyer, Robert A.; Jones, M. I.; Horner, Jonathan; Kane, Stephen R.; Marshall, J. P.; Mustill, A. J.; Jenkins, J. S.; Pena Rojas, P. A.; Zhao, Jinglin; Villaver, Eva; Butler, R. P.; Clark, Jake

    2017-12-01

    Radial velocity observations from three instruments reveal the presence of a 4 M Jup planet candidate orbiting the K giant HD 76920. HD 76920b has an orbital eccentricity of 0.856 ± 0.009, making it the most eccentric planet known to orbit an evolved star. There is no indication that HD 76920 has an unseen binary companion, suggesting a scattering event rather than Kozai oscillations as a probable culprit for the observed eccentricity. The candidate planet currently approaches to about four stellar radii from its host star, and is predicted to be engulfed on a ∼100 Myr timescale due to the combined effects of stellar evolution and tidal interactions.

  19. Time Resolved Spectroscopy of Cepheid Variable Stars

    Science.gov (United States)

    Hartman, Katherine; Beaton, Rachael L.; SDSS-IV APOGEE-2 Team

    2018-01-01

    Galactic Cepheid variable stars have been used for over a century as standard candles and as the first rung of the cosmic distance ladder, integral to the calculation of the Hubble constant. However, it is challenging to observe Cepheids within the Milky Way Galaxy because of extinction, and there are still uncertainties in the Cepheid period-luminosity relation (or Leavitt Law) that affect these important distance calculations. The Apache Point Observatory Galactic Evolution Experiment (APOGEE) survey has provided spectra for a large sample of Galactic Cepheids, but the standard chemical abundance pipeline (ASPCAP) processing is not well-suited to pulsational variables, preventing us from using them to study metallicity effect in the Leavitt Law with standard processing. Using a standalone version of the ASPCAP pipeline, we present an analysis of individual visit spectra from a test sample of nine APOGEE Cepheids, and we compare its output to the stars’ literature abundance values. Based on the results of this comparison, we will be able to improve the standard analysis and process the entirety of APOGEE’s Cepheid catalogue to improve its abundance measurements. The resulting abundance data will allow us to constrain the effect of metallicity on the Leavitt Law and thus allow for more accurate Cepheid distance measurements for the determination of the Hubble constant.

  20. Variable Star Discovery with Ultra-Low Cost Equipment

    Science.gov (United States)

    Paust, Nathaniel; Wilson, Danielle

    2016-06-01

    We present preliminary results of a variable star search using commercial DSLR equipment. The camera in use images the sky at DEC=+44 every ten minutes, day and night. A wide variety of open-source tools, from photo editors to specialty programs like the astrometry.net suite, are used to process the images and identify variable stars.

  1. Meta-classification for Variable Stars

    Science.gov (United States)

    Pichara, Karim; Protopapas, Pavlos; León, Daniel

    2016-03-01

    The need for the development of automatic tools to explore astronomical databases has been recognized since the inception of CCDs and modern computers. Astronomers already have developed solutions to tackle several science problems, such as automatic classification of stellar objects, outlier detection, and globular clusters identification, among others. New scientific problems emerge, and it is critical to be able to reuse the models learned before, without rebuilding everything from the beginning when the sciencientific problem changes. In this paper, we propose a new meta-model that automatically integrates existing classification models of variable stars. The proposed meta-model incorporates existing models that are trained in a different context, answering different questions and using different representations of data. A conventional mixture of expert algorithms in machine learning literature cannot be used since each expert (model) uses different inputs. We also consider the computational complexity of the model by using the most expensive models only when it is necessary. We test our model with EROS-2 and MACHO data sets, and we show that we solve most of the classification challenges only by training a meta-model to learn how to integrate the previous experts.

  2. Pulsating variable stars and large spectroscopic surveys

    Science.gov (United States)

    De Cat, Peter

    2017-09-01

    In the past decade, the research of pulsating variable stars has taken a giant leap forward thanks to the photometric measurements provided by space missions like Most, CoRoT, Kepler/K2, and Brite. These missions have provided quasi uninterrupted photometric time-series with an ultra-high quality and a total length that is not achievable from Earth. However, many of the success stories could not have been told without ground-based spectroscopic follow-up observations. Indeed, spectroscopy has some important assets as it can provide (more) accurate information about stellar parameters (like the effective temperature, surface gravity, metallicity, and abundances that are mandatory parameters for an in-depth asteroseismic study), the radial velocity (that is important for the detection of binaries and for the confirmation of cluster membership, if applicable), and the projected rotational velocity (that allows the study of the effects of rotation on pulsations). Fortunately, several large spectroscopic surveys are (becoming) available that can be used for these purposes. For some of these surveys, sub-projects have been initiated with the specific goal to complement space-based photometry. In this review, several spectroscopic surveys are introduced and compared with each other. We show that a large amount of spectroscopic data is (becoming) available for a large variety of objects.

  3. Little Bear's pulsating stars: Variable star census of UMi dSph Galaxy

    Science.gov (United States)

    Kinemuchi, K.; Jeffery, E.; Kuehn, C.; Grabowski, K.; Nemec, J.

    2017-09-01

    Recent observations and a photometric search for variable stars in the Ursa Minor dwarf spheroidal galaxy (UMi dSph) are presented. Our observations were taken at Apache Point Observatory in 2014 and 2016 using the 0.5m ARCSAT telescope and the West Mountain Observatory (WMO) 0.9m telescope of Brigham Young University in 2016. Previously known RR Lyrae stars in our field of view of the UMi dSph are identified, and we also catalog new variable star candidates. Tentative classifications are given for some of the new variable stars. We have conducted period searches with the data collected with the WMO telescope. Our ultimate goal is to create an updated catalog of variable stars in the UMi dSph and to compare the RR Lyrae stellar characteristics to other RR Lyrae stars found in the Local Group dSph galaxies.

  4. Little Bear’s pulsating stars: Variable star census of UMi dSph Galaxy

    Directory of Open Access Journals (Sweden)

    Kinemuchi K.

    2017-01-01

    Full Text Available Recent observations and a photometric search for variable stars in the Ursa Minor dwarf spheroidal galaxy (UMi dSph are presented. Our observations were taken at Apache Point Observatory in 2014 and 2016 using the 0.5m ARCSAT telescope and the West Mountain Observatory (WMO 0.9m telescope of Brigham Young University in 2016. Previously known RR Lyrae stars in our field of view of the UMi dSph are identified, and we also catalog new variable star candidates. Tentative classifications are given for some of the new variable stars. We have conducted period searches with the data collected with the WMO telescope. Our ultimate goal is to create an updated catalog of variable stars in the UMi dSph and to compare the RR Lyrae stellar characteristics to other RR Lyrae stars found in the Local Group dSph galaxies.

  5. The Beginning of Variable star astronomy in Hungary

    Science.gov (United States)

    Zsoldos, Endre

    Variable star astronomy began in Hungary as elsewhere: new objects have been recognized in the sky. Comets appeared in 16th - 17th century chronicles. The first mention of the new star of 1572 seems to be the "Prognosticon" of Wilhelm Misocacus, printed in 1578. New stars were discussed in the 17th century by Jesuits as well as Protestants. The work of Jacob Schnitzler is especially interesting from this point. The Cartesians dealt with new stars with less enthusiasm, they hardly mentioned them. The beginning of the 19th century saw the development of science in Hungarian, variable stars, however, were left out. The birth of variable star astronomy might be linked to the Ógyalla Observatory, originally a private observatory of Miklós Konkoly Thege. The 1885 supernova in the Andromeda Nebula were observed there, as well as the spectra of a few interesting variable stars. Theoretical astrophysics also has its beginnings in Ógyalla through the work of Radó Kövesligethy. Professional variable star astronomy started here in the early 20th century through the work of Antal Tass

  6. Classification of variable stars in the WFCAM Transit Survey

    Directory of Open Access Journals (Sweden)

    Moya Andrés

    2013-04-01

    Full Text Available The WFCAM Transit Survey is a photometric survey in the near-infrared and aims at finding Earth-like planets transiting M-dwarf stars. As a by-product of the survey, a variety of variable stars has been detected. We report the discovery and classification of 192 periodic variable stars in the WFCAM Transit Survey. 185 of those objects are previously unknown variable sources. The derived parameters of their light curves will be helpful for the creation of a robust sample of light curves (and their parameters thereof of classified variable stars in the near-infrared for the automatic classification of light curves of stellar objects in the J-band.

  7. Discovering new variable stars at Key Stage 3

    Science.gov (United States)

    Chubb, Katy; Hood, Rosie; Wilson, Thomas; Holdship, Jonathan; Hutton, Sarah

    2017-05-01

    Details of the London pilot of the ‘Discovery Project’ are presented, where university-based astronomers were given the chance to pass on some real and applied knowledge of astronomy to a group of selected secondary school pupils. It was aimed at students in Key Stage 3 of their education, allowing them to be involved in real astronomical research at an early stage of their education, the chance to become the official discoverer of a new variable star, and to be listed in the International Variable Star Index database (The International Variable Star Index, Version 1.1, American Association of Variable Star Observers (AAVSO), 2016, http://aavso.org/vsx), all while learning and practising research-level skills. Future plans are discussed.

  8. The Bateson Legacy: Variable Stars Research at the Auckland Observatory

    Science.gov (United States)

    Christie, Grant

    2005-03-01

    Frank Bateson's advice to the Auckland Astronomical Society's members looking for projects for their new Auckland Observatory has stood the test of time. Decades later the observation of variable stars is still the mainstay of Auckland's research programmes.

  9. The Bateson legacy: variable star research at the Auckland Observatory

    Science.gov (United States)

    Christie, Grant

    2005-03-01

    Frank Bateson's advice to the Auckland Astronomical Society's members looking for projects for their new Auckland Observatory has stood the test of time. Decades later the observation of variable stars is still the mainstay of Auckland's research programmes.

  10. Variable Star Catalogs: Their Past, Present and Future

    Science.gov (United States)

    Samus, N. N.; Kazarovets, E. V.; Kireeva, N. N.; Pastukhova, E. N.; Durlevich, O. V.

    2010-02-01

    After the second World War, the International Astronomical Union made astronomers of the Soviet Union responsible for variable-star catalogues. This work has been continued ever since the first edition of the General Catalogue of Variable Stars compiled by the team headed by P. P. Parenago and B. V. Kukarkin and published in 1948. Currently, the catalogue work is a joint project of the Institute of Astronomy (Russian Academy of Sciences) and Sternberg Astronomical Institute (Moscow University). This paper is a brief review of recent trends in the field of variable-star catalogues. We discuss problems as well as new prospects related to modern large-scale automatic photometric sky surveys, and outline the state of discussions on the future of the variable-star catalogues in the profile commissions of the IAU.

  11. Orbital periods of cataclysmic variables identified by the SDSS. VII. Four new eclipsing systems

    Science.gov (United States)

    Southworth, J.; Copperwheat, C. M.; Gänsicke, B. T.; Pyrzas, S.

    2010-02-01

    We present photometry of nine cataclysmic variable stars identified by the Sloan Digital Sky Survey, aimed at measuring the orbital periods of these systems. Four of these objects show deep eclipses, from which we measure their orbital periods. The light curves of three of the eclipsing systems are also analysed using the lcurve code, and their mass ratios and orbital inclinations determined. SDSS J075059.97+141150.1 has an orbital period of 134.1564 ± 0.0008 min, making it a useful object with which to investigate the evolutionary processes of cataclysmic variables. SDSS J092444.48+080150.9 has a period of 131.2432 ± 0.0014 min and is probably magnetic. The white dwarf ingress and egress phases are very deep and short, and there is no clear evidence that this object has an accretion disc. SDSS J115207.00+404947.8 and SDSS J152419.33+220920.1 are nearly identical twins, with periods of 97.5 ± 0.4 and 93.6 ± 0.5 min and mass ratios of 0.14 ± 0.03 and 0.17 ± 0.03, respectively. Their eclipses have well-defined white dwarf and bright spot ingress and egress features, making them excellent candidates for detailed study. All four of the orbital periods presented here are shorter than the 2-3 h period gap observed in the known population of cataclysmic variables. The reduced observational data presented in this work are available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/510/A100 and at http://www.astro.keele.ac.uk/ jkt/.

  12. Variable Stars in the Globular Cluster M 80

    Science.gov (United States)

    Kopacki, G.

    2013-03-01

    We present results of a search for variable stars in the globular cluster M 80. Application of the image subtraction method to the ground-based times-series of CCD frames resulted in finding nine new RR Lyr stars, six of the RRc and three of the RRab type, and four SX Phe variables. Revised mean period of RRab stars, ab=0.68 d, and relative percentage of RRc stars, Nc/(Nab+Nc)=53%, strongly confirm that M 80 belongs to the Oosterhoff II group of globular clusters. The mean V magnitude of the horizontal branch of M 80 based on the ten RR Lyr stars has been estimated to be VHB=RR=16.14±0.03 mag. In two pulsating stars, one of the RR Lyr type and the other of the SX Phe type, oscillations with two close frequencies were detected, indicating excitation of nonradial modes in these stars. Moreover, we discovered two W UMa or ellipsoidal systems, two periodic stars of unknown type, one of which is probably a field star, and detected light variations in three red giants of the cluster.

  13. Variable stars in Leo A : RR Lyrae stars, short-period cepheids, and implications for stellar content

    NARCIS (Netherlands)

    Dolphin, AE; Saha, A; Claver, J; Skillman, ED; Cole, AA; Gallagher, JS; Tolstoy, E; Dohm-Palmer, RC; Mateo, M

    We present the results of a search for short-period variable stars in Leo A. We have found 92 candidate variables, including eight candidate RR Lyrae stars. From the RR Lyrae stars, we measure a distance modulus of (m - M)(0) = 24.51 +/- 0.12, or 0.80 +/- 0.04 Mpc. This discovery of RR Lyrae stars

  14. A Modern Update and Usage of Historical Variable Star Catalogs

    Science.gov (United States)

    Pagnotta, Ashley; Graur, Or; Murray, Zachary; Kruk, Julia; Christie-Dervaux, Lucien; Chen, Dong Yi

    2015-01-01

    One of the earliest modern variable star catalogs was constructed by Henrietta Swan Leavitt during her tenure at the Harvard College Observatory (HCO) in the early 1900s. Originally published in 1908, Leavitt's catalog listed 1777 variables in the Magellanic Clouds (MCs). The construction and analysis of this catalog allowed her to subsequently discover the Cepheid period-luminosity relationship, now known as the Leavitt Law. The MC variable star catalogs were updated and expanded by Cecilia Payne-Gaposchkin in 1966 and 1971. Although newer studies of the MC variables have been performed since then, the new information has not always been correlated with the old due to a lack of modern descriptors of the stars listed in the Harvard MC catalogs. We will discuss the history of MC variable star catalogs, especially those compiled using the HCO plates, as well as our modernized version of the Leavitt and Payne-Gaposchkin catalogs. Our modern catalog can be used in conjunction with the archival plates (primarily via the Digital Access to a Sky Century @ Harvard scanning project) to study the secular behavior of the MC variable stars over the past century.

  15. Caroline Furness and the Evolution of Visual Variable Star Observing

    Science.gov (United States)

    Larsen, Kristine

    2017-01-01

    An Introduction to the Study of Variable Stars by Dr. Caroline Ellen Furness (1869-1936), Director of the Vassar College Observatory, was published in October 2015. Issued in honor of the fiftieth anniversary of the founding of Vassar College, the work was meant to fill a void in the literature, namely as both an introduction to the topic of variable stars as well as a manual explaining how they should be observed and the resulting data analyzed. It was judged to be one of the hundred best books written by an American woman in the last hundred years at the 1933 World’s Fair in Chicago. The book covers the relevant history of and background on types of variable stars, star charts, catalogs, and the magnitude scale, then describes observing techniques, including visual, photographic, and photoelectric photometry. The work finishes with a discussion of light curves and patterns of variability, with a special emphasis on eclipsing binaries and long period variables. Furness’s work is therefore a valuable snapshot of the state of astronomical knowledge, technology, and observing techniques from a century ago. Furness’s book and its reception in the scientific community are analyzed, and parallels with (and departures from) the current advice given by the AAVSO to beginning variable star observers today are highlighted.

  16. The variability of magnetic activity in solar-type stars

    Science.gov (United States)

    Fabbian, D.; Simoniello, R.; Collet, R.; Criscuoli, S.; Korhonen, H.; Krivova, N. A.; Oláh, K.; Jouve, L.; Solanki, S. K.; Alvarado-Gómez, J. D.; Booth, R.; García, R. A.; Lehtinen, J.; See, V.

    2017-09-01

    This article reviews the current knowledge and status of investigations on the variable magnetic activity of cool stars. We discuss the Sun in the context of solar-type stars, highlighting peculiarities and common features in terms of its magnetic activity and variability over different time scales. We examine how both theory and observations are providing new clues about the main physical processes that generate magnetic fields in the interior of cool stars, as well as about those that lead to evolving stellar surface magnetism and varying chromospheric and coronal phenomena. We then proceed to discuss the relations between stellar age, rotation, and activity throughout the evolution of cool stars. Finally, we touch upon the importance of understanding stellar magnetism also in view of its effect on planetary environments.

  17. Synergies between exoplanet surveys and variable star research

    Directory of Open Access Journals (Sweden)

    Kovacs Geza

    2017-01-01

    Full Text Available With the discovery of the first transiting extrasolar planetary system back in 1999, a great number of projects started to hunt for other similar systems. Because the incidence rate of such systems was unknown and the length of the shallow transit events is only a few percent of the orbital period, the goal was to monitor continuously as many stars as possible for at least a period of a few months. Small aperture, large field of view automated telescope systems have been installed with a parallel development of new data reduction and analysis methods, leading to better than 1% per data point precision for thousands of stars. With the successful launch of the photometric satellites CoRoT and Kepler, the precision increased further by one-two orders of magnitude. Millions of stars have been analyzed and searched for transits. In the history of variable star astronomy this is the biggest undertaking so far, resulting in photometric time series inventories immensely valuable for the whole field. In this review we briefly discuss the methods of data analysis that were inspired by the main science driver of these surveys and highlight some of the most interesting variable star results that impact the field of variable star astronomy.

  18. Synergies between exoplanet surveys and variable star research

    Science.gov (United States)

    Kovacs, Geza

    2017-09-01

    With the discovery of the first transiting extrasolar planetary system back in 1999, a great number of projects started to hunt for other similar systems. Because the incidence rate of such systems was unknown and the length of the shallow transit events is only a few percent of the orbital period, the goal was to monitor continuously as many stars as possible for at least a period of a few months. Small aperture, large field of view automated telescope systems have been installed with a parallel development of new data reduction and analysis methods, leading to better than 1% per data point precision for thousands of stars. With the successful launch of the photometric satellites CoRoT and Kepler, the precision increased further by one-two orders of magnitude. Millions of stars have been analyzed and searched for transits. In the history of variable star astronomy this is the biggest undertaking so far, resulting in photometric time series inventories immensely valuable for the whole field. In this review we briefly discuss the methods of data analysis that were inspired by the main science driver of these surveys and highlight some of the most interesting variable star results that impact the field of variable star astronomy.

  19. Near-IR Spectral Variability of Be Stars

    Science.gov (United States)

    Cole, Austin; Eisner, J. A.; Rudolph, A. L.

    2013-01-01

    Be class stars exhibit variability across the electromagnetic spectrum, including in both the visible and infrared regions. While variability in the optical range has been explored previously, spectroscopic variability in the near-IR has not been investigated as thoroughly. This study is focused on tracking the spectral variability of K Dra, one of the Be stars for which we collected data. We observed our sample using the FSPEC instrument on the 90-inch Bok telescope at Kitt Peak. The data were collected during four five-night runs, two in 2010 separated by one month and two in 2011 also separated by one month. A reduction pipeline written in Interactive Data Language (IDL) was used to produce emission spectra of the star from these data. Here we present spectra from these epochs that show emission from the Brackett Gamma hydrogen transition. We use changes in these features to constrain variability in the Hydrogen gas comprising the disk of this star as a function of time.

  20. Automatic Survey-invariant Classification of Variable Stars

    Science.gov (United States)

    Benavente, Patricio; Protopapas, Pavlos; Pichara, Karim

    2017-08-01

    Machine learning techniques have been successfully used to classify variable stars on widely studied astronomical surveys. These data sets have been available to astronomers long enough, thus allowing them to perform deep analysis over several variable sources and generating useful catalogs with identified variable stars. The products of these studies are labeled data that enable supervised learning models to be trained successfully. However, when these models are blindly applied to data from new sky surveys, their performance drops significantly. Furthermore, unlabeled data become available at a much higher rate than their labeled counterpart, since labeling is a manual and time-consuming effort. Domain adaptation techniques aim to learn from a domain where labeled data are available, the source domain, and through some adaptation perform well on a different domain, the target domain. We propose a full probabilistic model that represents the joint distribution of features from two surveys, as well as a probabilistic transformation of the features from one survey to the other. This allows us to transfer labeled data to a study where they are not available and to effectively run a variable star classification model in a new survey. Our model represents the features of each domain as a Gaussian mixture and models the transformation as a translation, rotation, and scaling of each separate component. We perform tests using three different variability catalogs, EROS, MACHO, and HiTS, presenting differences among them, such as the number of observations per star, cadence, observational time, and optical bands observed, among others.

  1. Interactive online archive for short-period variable stars

    Science.gov (United States)

    Joner, Michael D.; Hintz, Eric G.

    1998-07-01

    We report initial results from a project to design an interactive on-line data archive for short-period variable stars. Our goal is to provide an easily accessible set of web pages for use by a researcher at the telescope. The first step is to provide the researcher with convenient access to data archives for a variety of short-period variable stars. In addition to the basic data archive, there is a page for each star that contains positional information, the most recent epoch and period data, basic physical parameters, and a set of helpful journal references. We also include a page for each of the program variables with a finder chart and a selection of comparison stars for use in differential photometry. Additionally, one entry point in the system is a phase calculator that will sort through the data and return a list of stars that are observable from various user input locations during a variety of time periods. The current system has a partial data set in place for over one hundred short-period variable stars. We intend to continue to expand this set to include a large number of complete data files. We are also considering a similar archive of galaxy images for comparison use in student conducted supernova searches. We find this system improves the scientific return form our two small telescopes at the West Mountain Observatory. We believe this model can also be employed to optimize data management and scientific return for a wide variety of projects from the new generation of large ground-based telescopes.

  2. The Chemical Compositions of RR Lyrae Type C Variable Stars

    Science.gov (United States)

    Govea, Jose; Gomez, Thomas; Preston, George W.; Sneden, Christopher

    2014-02-01

    We present a detailed chemical abundance study of eight RR Lyrae variable stars of subclass c (RRc). The target RRc stars chosen for study exhibit "Blazhko-effect" period and amplitude modulations to their pulsational cycles. Data for this study were gathered with the echelle spectrograph of the 100 inch du Pont telescope at Las Campanas Observatory. Spectra were obtained throughout each star's pulsation cycle. Atmospheric parameters—effective temperature, surface gravity, microturbulent velocity, and metallicity—were derived at multiple phase points. We found metallicities and element abundance ratios to be constant within observational uncertainties over the pulsational cycles of all stars. Moreover, the α-element and Fe-group abundance ratios with respect to iron are consistent with other horizontal-branch members (RRab, blue and red non-variables). Finally, we have used the [Fe/H] values of these eight RRc stars to anchor the metallicity estimates of a large-sample RRc snapshot spectroscopic study being conducted with the same telescope and instrument combination employed here.

  3. Software Development for Asteroid and Variable Star Research

    Science.gov (United States)

    Sweckard, Teaghen; Clason, Timothy; Kenney, Jessica; Wuerker, Wolfgang; Palser, Sage; Giles, Tucker; Linder, Tyler; Sanchez, Richard

    2018-01-01

    The process of collecting and analyzing light curves from variable stars and asteroids is almost identical. In 2016 a collaboration was created to develop a simple fundamental way to study both asteroids and variable stars using methods that would allow the process to be repeated by middle school and high school students.Using robotic telescopes at Cerro Tololo (Chile), Yerkes Observatory (US), and Stone Edge Observatory (US) data were collected on RV Del and three asteroids. It was discovered that the only available software program which could be easily installed on lab computers was MPO Canopus. However, after six months it was determined that MPO Canopus was not an acceptable option because of the steep learning curve, lack of documentation and technical support.Therefore, the project decided that the best option was to design our own python based software. Using python and python libraries we developed code that can be used for photometry and can be easily changed to the user's needs. We accomplished this by meeting with our mentor astronomer, Tyler Linder, and in the beginning wrote two different programs, one for asteroids and one for variable stars. In the end, though, we chose to combine codes so that the program would be capable of performing photometry for both moving and static objects.The software performs differential photometry by comparing the magnitude of known reference stars to the object being studied. For asteroids, the image timestamps are used to obtain ephemeris of the asteroid from JPL Horizons automatically.

  4. An Undergraduate Research Experience on Studying Variable Stars

    Science.gov (United States)

    Amaral, A.; Percy, J. R.

    2016-06-01

    We describe and evaluate a summer undergraduate research project and experience by one of us (AA), under the supervision of the other (JP). The aim of the project was to sample current approaches to analyzing variable star data, and topics related to the study of Mira variable stars and their astrophysical importance. This project was done through the Summer Undergraduate Research Program (SURP) in astronomy at the University of Toronto. SURP allowed undergraduate students to explore and learn about many topics within astronomy and astrophysics, from instrumentation to cosmology. SURP introduced students to key skills which are essential for students hoping to pursue graduate studies in any scientific field. Variable stars proved to be an excellent topic for a research project. For beginners to independent research, it introduces key concepts in research such as critical thinking and problem solving, while illuminating previously learned topics in stellar physics. The focus of this summer project was to compare observations with structural and evolutionary models, including modelling the random walk behavior exhibited in the (O-C) diagrams of most Mira stars. We found that the random walk could be modelled by using random fluctuations of the period. This explanation agreed well with observations.

  5. The variable stars of the young LMC cluster NGC 2164

    Science.gov (United States)

    Welch, Douglas L.; Mateo, Mario; Olszewski, Edward W.; Fischer, Philippe; Takamiya, Marianne

    1993-01-01

    The present search of the LMC cluster NGC 2164 for variable stars has uncovered one new member classical Cepheid variable with 3.772-day period; attention is also given to photometry for a previously unknown field overtone Cepheid variable with 3.4626-day period, and the 10.6878-day period HV 12078, which may be a member of the young NGC 2156 cluster. The clear separation of fundamental and overtone pulsators in the period-luminosity-color relation of known LMC cluster Cepheids establishes that the NGC 2164 member is a true overtone.

  6. Luminous blue variables and the fates of very massive stars.

    Science.gov (United States)

    Smith, Nathan

    2017-10-28

    Luminous blue variables (LBVs) had long been considered massive stars in transition to the Wolf-Rayet (WR) phase, so their identification as progenitors of some peculiar supernovae (SNe) was surprising. More recently, environment statistics of LBVs show that most of them cannot be in transition to the WR phase after all, because LBVs are more isolated than allowed in this scenario. Additionally, the high-mass H shells around luminous SNe IIn require that some very massive stars above 40  M ⊙ die without shedding their H envelopes, and the precursor outbursts are a challenge for understanding the final burning sequences leading to core collapse. Recent evidence suggests a clear continuum in pre-SN mass loss from super-luminous SNe IIn, to regular SNe IIn, to SNe II-L and II-P, whereas most stripped-envelope SNe seem to arise from a separate channel of lower-mass binary stars rather than massive WR stars.This article is part of the themed issue 'Bridging the gap: from massive stars to supernovae'. © 2017 The Author(s).

  7. Evolution of compact stars and dark dynamical variables

    Energy Technology Data Exchange (ETDEWEB)

    Bhatti, M.Z.; Yousaf, Z. [University of the Punjab, Department of Mathematics, Lahore (Pakistan); Ilyas, M. [University of the Punjab, Centre for High Energy Physics, Lahore (Pakistan)

    2017-10-15

    This work aims to explore the dark dynamical effects of the f(R, T) modified gravity theory on the dynamics of a compact celestial star. We have taken the interior geometry of a spherical star which is filled with an imperfect fluid distribution. The modified field equations are explored by taking a particular form of the f(R, T) model, i.e. f(R, T) = f{sub 1}(R) + f{sub 2}(R)f{sub 3}(T). These equations are utilized to formulate the well-known structure scalars under the dark dynamical effects of this higher-order gravity theory. Also, with the help of these scalar variables, the evolution equations for expansion and shear are formulated. The whole analysis is made under the condition of a constant R and T. We found a crucial significance of dark source terms and dynamical variables on the evolution and density inhomogeneity of compact objects. (orig.)

  8. Pulsating variable stars in the MACHO bulge database: the semiregular variables

    Energy Technology Data Exchange (ETDEWEB)

    Minniti, D.; Alcock, C.; Allsman, R.A. [and others

    1997-11-01

    We review the pulsating stars contained in the top 24 fields of the MACHO bulge database, with special emphasis on the red semireg-ular stars. Based on period, amplitude and color cuts, we have selected a sample of 2000 semireguku variables with 15 < P < 100 days. Their period-luminosity relation is studied, as well ss their spatial distribution. We find that they follow the bar, unlike the RR Lyrae in these fields.

  9. Kepler Full-Frame Image Variable Star Catalog

    Science.gov (United States)

    Kinemuchi, Karen; Still, M.; Fanelli, M.; Kepler Science Team

    2011-01-01

    Kepler, NASA's discovery mission to find Earth-sized planets within the habitable zone of nearby stars, provides an unique and powerful resource to perform serendipitous time-domain astrophysics. There are 107 sources brighter than the 21st magnitude Kepler confusion limit within the Kepler field. Thirty minute cadence relative photometry is good to 2% accuracy at 19th magnitude. However, telemetry bandwidth limits the data collection to only 170,000 targets per quarter, of which 96% are reserved for the primary, brighter than 16th magnitude, red-dominated exoplanet program. Through Guest Observer and open consortium avenues, the onus is upon the astrophysics community to choose their 4% share of the targets carefully so that serendipitous science opportunities with Kepler are optimized. One method for identifying potential targets of high astrophysical interest is to locate the variable objects in the Kepler field using the publicly available, 30-min exposure, Full-Frame Images (FFIs). These images are stored and transmitted by the spacecraft at one-month intervals, principally for engineering purposes. Here we describe a pilot study using eight FFIs obtained in rapid sequence over 1.5 days during the spacecraft commissioning phase. We present a catalog and light curves of variable objects mined from these "Golden" FFIs. Many of these objects will be eclipsing binaries, pulsators, eruptive stars, and other exotic variable stars exhibiting large brightness changes. This variable star catalog will provide an excellent stepping stone for Kepler astrophysics projects through the Kepler Asteroseismic Science Consortium (KASC), the Guest Observer Program, or Guest Observer Director's Discretionary Time. Kepler was selected as the 10th mission of the Discovery Program. Funding for this mission is provided by NASA, Science Mission Directorate.

  10. THE CARINA PROJECT. VI. THE HELIUM-BURNING VARIABLE STARS

    Energy Technology Data Exchange (ETDEWEB)

    Coppola, G.; Marconi, M.; Ripepi, V.; Dall' Ora, M.; Musella, I. [INAF-Osservatorio Astronomico di Capodimonte, Via Moiariello 16, I-80131 Napoli (Italy); Stetson, P. B. [Dominion Astrophysical Observatory, NRC-Herzberg, 5071 West Saanich Road, Victoria, BC V9E 2E7 (Canada); Bono, G.; Buonanno, R. [Dipartimento di Fisica-Universita di Roma Tor Vergata, Via della Ricerca Scientifica 1, I-00133 Roma (Italy); Fabrizio, M. [INAF-Osservatorio Astronomico di Collurania, via M. Maggini, I-64100 Teramo (Italy); Ferraro, I.; Iannicola, G.; Pulone, L. [INAF-Osservatorio Astronomico di Roma, Via Frascati 33, I-00040 Monte Porzio Catone (Italy); Fiorentino, G. [INAF-Osservatorio Astronomico di Bologna, via Ranzani 1, I-40127 Bologna (Italy); Monelli, M. [Instituto de Astrofisica de Canarias, Calle Via Lactea s/n, E-38205 La Laguna, Tenerife (Spain); Nonino, M. [INAF-Osservatorio Astronomico di Trieste, via G. B. Tiepolo 11, I-40131 Trieste (Italy); Thevenin, F. [Universite de Nice-Sophia Antipolis, Lab. Lagrange, UMR 7293, Observatoire de la Cote dAzur, BP 4229, F-06304 Nice (France); Walker, A. R., E-mail: coppola@na.astro.it [Cerro Tololo Inter-American Observatory, National Optical Astronomy Observatory, Casilla 603, La Serena (Chile)

    2013-09-20

    We present new optical (BVI) time-series data for the evolved variable stars in the Carina dwarf spheroidal galaxy. The quality of the data and the observing strategy allowed us to identify 14 new variable stars. Eight out of the 14 are RR Lyrae (RRL) stars, 4 are Anomalous Cepheids (ACs), and 2 are geometrical variables. Comparison of the period distribution for the entire sample of RRLs with similar distributions in nearby dwarf spheroidal galaxies and in the Large Magellanic Cloud indicates that the old stellar populations in these systems share similar properties. This finding is also supported by the RRL distribution in the Bailey diagram. On the other hand, the period distribution and the Bailey diagram of ACs display significant differences among the above stellar systems. This evidence suggests that the properties of intermediate-age stellar populations might be affected both by environmental effects and structural parameters. We use the BV Period-Wesenheit (PW) relation of RRLs together with evolutionary prescriptions and find a true distance modulus of 20.09 {+-} 0.07 (intrinsic) {+-} 0.1 (statistical) mag that agrees quite well with similar estimates available in the literature. We identified four peculiar variables. Taking into account their position in the Bailey diagram and in the BV PW relation, two of them (V14 and V149) appear to be candidate ACs, while two (V158 and V182) might be peculiar RRLs. In particular, the variable V158 has a period and a V-band amplitude very similar to the low-mass RRL-RRLR-02792-recently identified by Pietrzynski et al. in the Galactic bulge.

  11. Rapid variability of OB-stars: nature and diagnostic value.

    Science.gov (United States)

    Baade, D.

    In the past decade, rapid photospheric variability has been recognized as the non-standard property that perhaps is the most common one among early-type stars. These proceedings offer an unusually complete overview of the existing observations. They are equally complete in their reflectance of the presently considered models. Because the simple definition 'on a rotational time scale' of the qualifier 'rapid' used in the title is very adequate for many stars, modulation is a strong contender also as a general model. The model that can be made to formally reproduce the widest range of observations is nonradial pulsation which, therefore, has earned itself the somewhat ambiguous reputation as a model for everything. An attraction of this model is that it would give the possibility to infer also structural and evolutionary quantities. It was the second purpose of the workshop to offer at least a glimpse of this potential.

  12. Development of a Mailing List on Variable Stars, VSNET

    Science.gov (United States)

    Nogami, D.; Kato, T.; Baba, H.; Kunjaya, C.

    Various usages of the Internet have been developed and made remarkable progress these years, which is now dramatically changing the style of astronomical study. Among those, the maing list is thought to be most useful to study of unpredictable objects for the characteristics, especially rapidness and equality. We started a mailing list (VSNET) on variable stars, mainly on cataclysmic variables and supernovae, in 1994 July for mutual exchange of information and ideas between astronomers including professionals and amateurs. Up to now, the various articles have been distributed, for example, calls for follow up observations of transient objects discovered in the UV or X-ray region, calls for ground-based observations simultaneous with ones by the space telescopes, discoveries of supernovae, alert notices of outbursts in long dormant dwarf novae (EG Cnc, AL Com, UZ Boo, HT Cas, etc), and so on. You can get long-term light curves of variable stars drawn using VSNET data on the VSNET web pages http://www.kusastro.kyoto-u.ac.jp/vsnet/. The archives of VSNET mails are available via VSNET web pages and anonymous ftp ftp://ftp.kusastro.kyoto-u.ac.jp/pub/vsnet/Mail/. If you have any questions and suggestions on VSNET, please feel free to contact us (vsnet-adm@kusastro.kyoto-u.ac.jp).

  13. Automatic Detection and Classification of Variability for the RAO Variable Star Search

    Science.gov (United States)

    Williams, Michael D.; Milone, E. F.

    2006-06-01

    The RAO Variable Star Search (RAOVS) can sample on the order of 30000 stars in a single field. With so many light curves it is important to have an automated process for detecting variability and classifying the detections. To detect periodic variations we use an epoch shifting technique, based on an analysis of variance technique, ANOVA, described by S. R. Davis. This technique allows us to increase the signal to noise for periodic signals and requires no assumption about the shape of the intrinsic light curve. As well as automatically detecting variables we have also developed an automatic classification system. This work has been supported in part by Canadian NSERC grants to E. F. Milone.

  14. VizieR Online Data Catalog: AAVSO International Variable Star Index VSX (Watson+, 2006-2014)

    Science.gov (United States)

    Watson, C.; Henden, A. A.; Price, A.

    2017-11-01

    This file contains Galactic stars known or suspected to be variable. It lists all stars that have an entry in the AAVSO International Variable Star Index (VSX; http://www.aavso.org/vsx). The database consisted initially of the General Catalogue of Variable Stars (GCVS) and the New Catalogue of Suspected Variables (NSV) and was then supplemented with a large number of variable star catalogues, as well as individual variable star discoveries or variables found in the literature. Effort has also been invested to update the entries with the latest information regarding position, type and period and to remove duplicates. The VSX database is being continually updated and maintained. For historical reasons some objects outside of the Galaxy have been included. (3 data files).

  15. Uncertain Classification of Variable Stars: Handling Observational GAPS and Noise

    Science.gov (United States)

    Castro, Nicolás; Protopapas, Pavlos; Pichara, Karim

    2018-01-01

    Automatic classification methods applied to sky surveys have revolutionized the astronomical target selection process. Most surveys generate a vast amount of time series, or “lightcurves,” that represent the brightness variability of stellar objects in time. Unfortunately, lightcurves’ observations take several years to be completed, producing truncated time series that generally remain without the application of automatic classifiers until they are finished. This happens because state-of-the-art methods rely on a variety of statistical descriptors or features that present an increasing degree of dispersion when the number of observations decreases, which reduces their precision. In this paper, we propose a novel method that increases the performance of automatic classifiers of variable stars by incorporating the deviations that scarcity of observations produces. Our method uses Gaussian process regression to form a probabilistic model of each lightcurve’s observations. Then, based on this model, bootstrapped samples of the time series features are generated. Finally, a bagging approach is used to improve the overall performance of the classification. We perform tests on the MAssive Compact Halo Object (MACHO) and Optical Gravitational Lensing Experiment (OGLE) catalogs, results show that our method effectively classifies some variability classes using a small fraction of the original observations. For example, we found that RR Lyrae stars can be classified with ~80% accuracy just by observing the first 5% of the whole lightcurves’ observations in the MACHO and OGLE catalogs. We believe these results prove that, when studying lightcurves, it is important to consider the features’ error and how the measurement process impacts it.

  16. Understanding Space Weather: The Sun as a Variable Star

    Science.gov (United States)

    Strong, Keith; Saba, Julia; Kucera, Therese

    2012-01-01

    The Sun is a complex system of systems and until recently, less than half of its surface was observable at any given time and then only from afar. New observational techniques and modeling capabilities are giving us a fresh perspective of the solar interior and how our Sun works as a variable star. This revolution in solar observations and modeling provides us with the exciting prospect of being able to use a vastly increased stream of solar data taken simultaneously from several different vantage points to produce more reliable and prompt space weather forecasts. Solar variations that cause identifiable space weather effects do not happen only on solar-cycle timescales from decades to centuries; there are also many shorter-term events that have their own unique space weather effects and a different set of challenges to understand and predict, such as flares, coronal mass ejections, and solar wind variations.

  17. Variable Star Signature Classification using Slotted Symbolic Markov Modeling

    Science.gov (United States)

    Johnston, K. B.; Peter, A. M.

    2017-01-01

    With the advent of digital astronomy, new benefits and new challenges have been presented to the modern day astronomer. No longer can the astronomer rely on manual processing, instead the profession as a whole has begun to adopt more advanced computational means. This paper focuses on the construction and application of a novel time-domain signature extraction methodology and the development of a supporting supervised pattern classification algorithm for the identification of variable stars. A methodology for the reduction of stellar variable observations (time-domain data) into a novel feature space representation is introduced. The methodology presented will be referred to as Slotted Symbolic Markov Modeling (SSMM) and has a number of advantages which will be demonstrated to be beneficial; specifically to the supervised classification of stellar variables. It will be shown that the methodology outperformed a baseline standard methodology on a standardized set of stellar light curve data. The performance on a set of data derived from the LINEAR dataset will also be shown.

  18. Magnetic field measurements and wind-line variability of OB-type stars

    NARCIS (Netherlands)

    Schnerr, R.S.; Henrichs, H.F.; Neiner, C.; Verdugo, E.; de Jong, J.; Geers, V.C.; Wiersema, K.; van Dalen, B.; Tijani, A.; Plaggenborg, B.; Rygl, K.L.J.

    2008-01-01

    Context. The first magnetic fields in O- and B-type stars that do not belong to the Bp-star class, have been discovered. The cyclic UV wind-line variability, which has been observed in a significant fraction of early-type stars, is likely to be related to such magnetic fields. Aims. We attempt to

  19. Utilizing the AAVSO's Variable Star Index (VSX) in Undergraduate Research Projects (Poster abstract)

    Science.gov (United States)

    Larsen, K.

    2016-12-01

    (Abstract only) Among the many important services that the American Association of Variable Star Observers (AAVSO) provides to the astronomical community is the Variable Star Index (VSX; https://www.aavso.org/vsx/). This online catalog of variable stars is the repository of data on over 334,000 variable stars, including information on spectral type, range of magnitude, period, and type of variable, among other properties. A number of these stars were identified as being variable through automated telescope surveys, such as ASAS (All Sky Automated Survey). The computer code of this survey classified newly discovered variables as best it could, but a significant number of false classifications have been noted. The reclassification of ASAS variables in the VSX data, as well as a closer look at variables identified as miscellaneous type in VSX, are two of many projects that can be undertaken by interested undergraduates. In doing so, students learn about the physical properties of various types of variable stars as well as statistical analysis and computer software, especially the vstar variable star data visualization and analysis tool that is available to the astronomical community free of charge on the AAVSO website (https://www.aavso.org/vstar-overview). Three such projects are described in this presentation, to identify BY Draconis variables misidentified as Cepheids or "miscellaneous", and SRD semiregular variables and ELL (rotating ellipsoidal) variables misidentified as "miscellaneous", in ASAS data and VSX.

  20. Magnetic fields and wind variability in massive stars

    NARCIS (Netherlands)

    Schnerr, R.S.; Henrichs, H.F.; Hamann, W.-R.; Feldmeier, A.; Oskinova, L.

    2008-01-01

    This paper describes the thesis work of Schnerr (2007) entitled "Magnetic fields and mass loss in massive stars", which aimed at a better understanding of the impact of magnetic fields on the winds of massive stars.

  1. On the Variability of Blue Straggler Stars in the Globular Cluster M53

    Directory of Open Access Journals (Sweden)

    Soo-Chang Rey

    1998-06-01

    Full Text Available We present the results of a search for photometric variable blue straggler stars (BSSs in the globular cluster M53. Six of the 151 probable BSSs are identified as variable candidates based on the robust variable star detection technique of Welch & Stetson (1993. Most variable BSS candidates appear to occupy the instability strip in the color-magnitude diagram, and they appear to have visual light amplitudes of 0.2 mag - 0.3 mag. Further observations are required, however, to resolve the nature of variability between pulsating stars and eclipsing binaries for these variable BSS candidates.

  2. CLUSTERING-BASED FEATURE LEARNING ON VARIABLE STARS

    Energy Technology Data Exchange (ETDEWEB)

    Mackenzie, Cristóbal; Pichara, Karim [Computer Science Department, Pontificia Universidad Católica de Chile, Santiago (Chile); Protopapas, Pavlos [Institute for Applied Computational Science, Harvard University, Cambridge, MA (United States)

    2016-04-01

    The success of automatic classification of variable stars depends strongly on the lightcurve representation. Usually, lightcurves are represented as a vector of many descriptors designed by astronomers called features. These descriptors are expensive in terms of computing, require substantial research effort to develop, and do not guarantee a good classification. Today, lightcurve representation is not entirely automatic; algorithms must be designed and manually tuned up for every survey. The amounts of data that will be generated in the future mean astronomers must develop scalable and automated analysis pipelines. In this work we present a feature learning algorithm designed for variable objects. Our method works by extracting a large number of lightcurve subsequences from a given set, which are then clustered to find common local patterns in the time series. Representatives of these common patterns are then used to transform lightcurves of a labeled set into a new representation that can be used to train a classifier. The proposed algorithm learns the features from both labeled and unlabeled lightcurves, overcoming the bias using only labeled data. We test our method on data sets from the Massive Compact Halo Object survey and the Optical Gravitational Lensing Experiment; the results show that our classification performance is as good as and in some cases better than the performance achieved using traditional statistical features, while the computational cost is significantly lower. With these promising results, we believe that our method constitutes a significant step toward the automation of the lightcurve classification pipeline.

  3. The TAOS Project Stellar Variability II. Detection of 15 Variable Stars

    Energy Technology Data Exchange (ETDEWEB)

    Mondal, S; Lin, C C; Zhang, Z W; Alcock, C; Axelrod, T; Bianco, F B; Byun, Y I; Coehlo, N K; Cook, K H; Dave, R; Kim, D W; King, S K; Lee, T; Lehner, M J; Lin, H C; Marshall, S L; Protopapas, P; Rice, J A; Schwamb, M E; Wang, J H; Wang, S Y; Wen, C Y

    2010-01-28

    The Taiwanese-American Occultation Survey (TAOS) project has collected more than a billion photometric measurements since 2005 January. These sky survey data - covering timescales from a fraction of a second to a few hundred days - are a useful source to study stellar variability. A total of 167 star fields, mostly along the ecliptic plane, have been selected for photometric monitoring with the TAOS telescopes. This paper presents our initial analysis of a search for periodic variable stars from the time-series TAOS data on one particular TAOS field, No. 151 (RA = 17{sup h} 30{sup m} 6.67{sup s}, Dec = 27 degrees, 17 minutes, 30 seconds, J2000), which had been observed over 47 epochs in 2005. A total of 81 candidate variables are identified in the 3 square degree field, with magnitudes in the range 8 < R < 16. On the basis of the periodicity and shape of the lightcurves, 32 variables, 18 of which were previously unknown, are classified as RR Lyrae, Cepheid, {delta} Scuti, SX Phonencis, semi-regular and eclipsing binaries.

  4. Finding the most variable stars in the Orion Belt with the All Sky Automated Survey

    OpenAIRE

    Caballero, Jose A.; Cornide, M.; de Castro, E.

    2010-01-01

    We look for high-amplitude variable young stars in the open clusters and associations of the Orion Belt. We use public data from the ASAS-3 Photometric V-band Catalogue of the All Sky Automated Survey, infrared photometry from the 2MASS and IRAS catalogues, proper motions, and the Aladin sky atlas to obtain a list of the most variable stars in a survey area of side 5 deg centred on the bright star Alnilam (eps Ori) in the centre of the Orion Belt. We identify 32 highly-variable stars, of whic...

  5. The Nainital–Cape Survey: A Search for Variability in Ap and Am Stars

    Indian Academy of Sciences (India)

    The ``Nainital–Cape Survey” program for searching photometric variability in chemically peculiar (CP) stars was initiated in 1997 at ARIES, Nainital. We present here the results obtained to date. The Am stars HD 98851, HD 102480, HD 13079 and HD 113878 were discovered to exhibit Scuti type variability. Photometric ...

  6. Search for Variable Stars in Six Southern Globular Clusters

    Science.gov (United States)

    Lee, Dong-Joo; Lee, Chung-Uk; Kim, Dong-Jin; Hong, Kyeongsoo; Koo, Jae-Rim; Lee, Jae Woo; Ryu, Yoon-Hyun; Kim, Seung-Lee; Cha, Sang-Mok; Lee, Yongseok; Lim, Beomdu; Park, Byeong-Gon; Jeon, Young-Beom

    2015-08-01

    Korea Astronomy and Space Science Institute (KASI) has installed wide-field photometric survey systems called Korea Microlensing Telescope Network (KMTNet) at three Southern observatories of CTIO in Chile, SAAO in South Africa, and SSO in Australia. Each system consists of a wide-field optical telescope with 1.6m diameter and a mosaic CCD camera with 18k by 18k pixels, having a 2.0 by 2.0 square degree field of view. Its primary scientific goal is to search for extrasolar planets, especially Earth-mass planets in the habitable zone, by using the gravitational microlensing method. We have performed the pre-science run of these three telescopes, with attaching a 4k CCD camera for a few months at each site before installing the 18k mosaic CCD camera. Considering the rather small field of view of the 4k CCD camera, we chose six globular clusters NGC 288, NGC 1851, NGC 3201, NGC 4372, NGC 6752, and NGC 6809 to monitor photometrically. Difference Image Analysis (DIA) technique was applied to the time-series CCD images in order to minimize the blending effect in the crowded field of globular clusters. We will present the preliminary results to search for variable stars in the clusters.

  7. Finding the most variable stars in the Orion Belt with the All Sky Automated Survey

    Science.gov (United States)

    Caballero, J. A.; Cornide, M.; de Castro, E.

    2010-03-01

    We look for high-amplitude variable young stars in the open clusters and associations of the Orion Belt. We use public data from the ASAS-3 Photometric V-band Catalogue of the All Sky Automated Survey, infrared photometry from the 2MASS and IRAS catalogues, proper motions, and the Aladin sky atlas to obtain a list of the most variable stars in a survey area of side 5° centred on the bright star Alnilam (ɛ Ori) in the centre of the Orion Belt. We identify 32 highly variable stars, of which 16 had not been reported to vary before. They are mostly variable young stars and candidates (16) and background giants (8), but there are also field cataclysmic variables, contact binaries, and eclipsing binary candidates. Of the young stars, which typically are active Herbig Ae/Be and T Tauri stars with Hα emission and infrared flux excess, we discover four new variables and confirm the variability status of another two. Some of them belong to the well known σ Orionis cluster. Besides, six of the eight giants are new variables, and three are new periodic variables.

  8. On The Detection Of Periodic Variable Stars In The Explore II Database

    Science.gov (United States)

    Clement, Christine M.; Nguyen, D. C.; Rucinski, S. M.; Yee, H. K.; Mallen-Ornelas, G.; Gladders, M. D.; Seager, S.

    2006-06-01

    The EXPLORE (Extrasolar Planet Occulation Research) series of transit surveys uses 4m class telescopes to look for planetary transits in the Galactic plane (Mallen-Ornelas et al. 2003, ApJ, 582, 1123). The EXPLORE II search was carried out at the CFHT on 16 consecutive nights in December 2001-January 2002. Approximately 80,000 stars were identified in a field centered on the Galactic plane at l=203 degrees and b=0.85 degrees. Our investigation is based on an analysis of the observations of approximately 5500 of these stars on a total of 1950 frames.We used two period search methods (Fourier transform analysis and phase dispersion minimization) to identify periodic variable stars and derive their periods. As a result, 23 new variable stars have been discovered. This includes three binaries, three delta Scuti stars, one pulsating B star and sixteen variables of uncertain classification. Some of the unclassified variables are probably rotating stars that exhibit photometric variability because they have asymmetrically distributed starspots.To check on the success of our period searches, we inspected the individual light curve data for the 5500 stars and found that both methods were effective. In the future, we will apply these period search techniques to the remaining stars in the EXPLORE II database.Support from Science and Engineering research Canada (NSERC) and from a Clay Fellowship is gratefully acknowledged.

  9. Search for variable stars in the young open cluster Stock 18

    Science.gov (United States)

    Sinha, Tirthendu; Sharma, Saurabh; Pandey, Rakesh; Pandey, A. K.

    2017-09-01

    We have carried out multi-epoch deep I band photometry of the open cluster Stock 18 to search for variable stars in star forming regions. In the present study, we report identification of 28 periodic and 165 non-periodic variables stars. The periods of most of the periodic variables are in between 2 to 20 hours and their magnitude varies between 0.05 to 0.6 mag. We have derived spectral energy distributions for 48 probable pre-main sequence variables and the average age and mass is found to be 2.7 ± 0.3 Myrs and 2.7 ± 0.2 M⊙, respectively.

  10. Variable stars in the Cetus dwarf spheroidal galaxy: population gradients and connections with the star formation history

    Science.gov (United States)

    Monelli, M.; Bernard, E. J.; Gallart, C.; Fiorentino, G.; Drozdovsky, I.; Aparicio, A.; Bono, G.; Cassisi, S.; Skillman, E. D.; Stetson, P. B.

    2012-05-01

    We investigate the variable star content of the isolated, Local Group, dwarf spheroidal (dSph) galaxy Cetus. Multi-epoch, wide-field images collected with the Very Large Telescope/Visible Multiobject Spectrograph camera allowed us to detect 638 variable stars (630 RR Lyrae stars and eight anomalous Cepheids), 475 of which are new detections. We present a full catalogue of periods, amplitudes and mean magnitudes. Motivated by the recent discovery that the pulsational properties of the RR Lyrae stars in the Tucana dSph revealed the presence of a metallicity gradient within the oldest (>rsim10 Gyr old) stellar populations, we investigated the possibility of an analogous effect in Cetus. We found that, despite the obvious radial gradient in the horizontal branch and red giant branch morphologies, both becoming bluer on average for increasing distance from the centre of Cetus, the properties of the RR Lyrae stars are homogeneous within the investigated area (out to r˜ 15 arcmin), with no significant evidence of a radial gradient. We discuss this in connection with the star formation history previously derived for the two galaxies. The observed differences between these two systems show that even systems this small show a variety of early evolutionary histories. These differences could be due to different merger or accretion histories.

  11. Massive star evolution: Luminous Blue Variables as unexpected Supernova progenitors

    OpenAIRE

    Groh, Jose H.; Meynet, Georges; Ekström, Sylvia

    2013-01-01

    Stars more massive than about 8 Msun end their lives as a Supernova (SN), an event of fundamental importance Universe-wide. Theoretically, these stars have been expected to be either at the red supergiant, blue supergiant, or Wolf-Rayet stage before the explosion. We performed coupled stellar evolution and atmospheric modeling of stars with initial masses between 20 Msun and 120 Msun. We found that the 20 Msun and 25 Msun rotating models, before exploding as SN, have spectra that do not resem...

  12. Modernizing the Harvard Observatory Catalog of Variable Stars in the Magellanic Clouds

    Science.gov (United States)

    Murray, Zachary; Kruk, Julia; Christie-Dervaux, Lucien; Chen, Dong Yi; Graur, Or; Pagnotta, Ashley

    2015-01-01

    We have modernized the Harvard College Observatory's catalog of variable stars in the Magellanic Clouds, compiled by Henrietta Swan Leavitt in 1908 and expanded by Cecilia Payne-Gaposchkin in 1966 and 1971. This catalog was originally used by Leavitt in 1912 to formulate the period-luminosity relation for Cepheid variable stars, one of the most important rungs on the extragalactic distance ladder. Many of the stars were identified in current catalogs by only their Harvard Variable number, without coordinates or magnitudes. We have digitized the variable-star catalog and converted the coordinates of the 2,184 variable stars from the Harvard College Observatory's now-defunct planar-grid system to the spherical Equatorial coordinate system. Our modernized version of the catalog will allow for more efficient use of the Harvard archival plates currently being scanned by the Digital Access to a Sky Century @ Harvard (DASCH) project. The combination of DASCH and our catalog allows users to readily access more than a century's worth of data on the variable stars in the Magellanic Clouds, leading to such projects as studying the long-term evolution of variable stars.

  13. The VESPA Survey: 100 New Variable Stars Discovered in Two Years

    Science.gov (United States)

    Quadri, U.; Strabla, L.; Girelli, R.

    2017-06-01

    We describe the VESPA project made at IAU station 565, Astronomical Observatory in Bassano Bresciano (BS), Italy. It is one photometric survey of the northern hemisphere which has the aim of discovering and investigating new variable stars. In the first two years of activity we have discovered 100 new variable stars in the course of observations carried out from August 2014 to September 2016. The newly discovered stars comprise 80 eclipsing binary stars (66 of them classified as W Ursae Majoris, 11 as beta Lyrae, and 3 beta Persei), one rotating (ROT), one ellipsoidal variable (ELL), and 18 pulsating variables (5 of them classified as RRAB, 7 RRC, 3 HADS, 2 delta Scuti and one Cepheid). Variability classification is based on the properties of the optical light curves that we obtained using our 255 mm F/4.7 Newton robotic telescope.

  14. About the new B- and A-type periodic variable stars

    Science.gov (United States)

    Mowlavi, Nami; Saesen, Sophie; Barblan, Fabio; Semaan, Thierry; Eyer, Laurent

    2015-08-01

    New periodic variable stars of type B and A were discovered in 2013 in the open cluster NGC 3766 (Mowlavi et al. 2013), in a region of the Hertzsprung-Rusell diagram on the main sequence, between delta-Scuti and Slowly Pulsating B stars, where no periodic star was expected to be found. The observational properties of the potentially new class of variability challenged model predictions of pulsating stars that were available at the time of their discovery, and triggered new theoretical developments in the field.Meanwhile, we obtained additional observational elements that shed new light on these new periodic variable stars. First, we analyzed photometric data of three other young clusters with ages between about 15 to about 70 million years, for which we had up to seven years of observations. The analysis reveals the presence of the new periodic B- and A-type stars in those clusters as well, with properties similar to those found in NGC 3766, but with also new features. Second, we took spectra of all new periodic variables found in NGC 3766, using Giraffe multi-fiber spectrometer mounted on the VLT. Those data enable a better characterization of the nature of those stars.We present in this contribution the results of those two new studies, and their impacts on our understanding of the new periodic stars.

  15. The ancient stellar population of M 32 : RR Lyrae variable stars confirmed

    NARCIS (Netherlands)

    Fiorentino, G.; Ramos, R. Contreras; Tolstoy, E.; Clementini, G.; Saha, A.

    Using archival multi-epoch ACS/WFC images in the F606W and F814W filters of a resolved stellar field in Local Group dwarf elliptical galaxy M 32 we have made an accurate colour-magnitude diagram and a careful search for RR Lyr variable stars. We identified 416 bona fide RR Lyr stars over our field

  16. Angular Size Measurements of 18 Mira Variable Stars at 2.2 microns

    Science.gov (United States)

    van Belle, G. T.; Dyck, H. M.; Benson, J. A.; Lacasse, M. G.

    1996-11-01

    We present angular size measurements of 18 oxygen-rich Mira variable stars. These data are part of a long term observational program using the Infrared Optical Telescope Array (IOTA) to characterize the observable behavior of these stars. Complementing the infrared angular size measurements, values for variable star phase, spectral type, bolometric flux, and distance were established for stars in the sample; flux and distance led to values for effective temperature (TEFF), and linear radius, respectively. We are able to define an effective temperature versus spectral type scale for Mira variables that we compare to the temperature scales for K and M giants and supergiants. TEFF'S and linear radii for these stars are shown to lie between approximately 2100 and 3200 K, and 200 and 600 Rsun, respectively. Relationships among the Mira variable parameters are explored for significant trends. Notably, the phase dependence of TEFF is shown to follow simple expectations, and examination of the radius-T relationship yields a plausible description of the V and K band light curves of these stars. A simple examination of the oscillation mode of the stars in the sample does not strongly suggest either fundamental or first-overtone oscillation as the primary mode of oscillation. This conclusion differs from that recently presented by Haniff et al. (1995), who argue that Mira variables are all first-overtone pulsators. We discuss some possible reasons for the different conclusions between the two studies.

  17. General Catalogue of Variable Stars: Current Status and New Name-Lists

    Science.gov (United States)

    Samus, N. N.; Kazarovets, E. V.; Kireeva, N. N.; Pastukhova, E. N.; Durlevich, O. V.

    2010-12-01

    A short history of variable-star catalogs is presented. After the second World War, the International Astronomical Union asked astronomers of the Soviet Union to become responsible for variable-star catalogs. Currently, the catalog is kept electronically and is a joint project of the Institute of Astronomy (Russian Academy of Sciences) and Sternberg Astronomical Institute (Moscow University). We review recent trends in the field of variable-star catalogs, discuss problems and new prospects related to modern large-scale automatic photometric sky surveys, outline the subject of discussions on the future of the variable-star catalogs in the profile commissions of the IAU, and call for suggestions from the astronomical community.

  18. HST Snapshot Study of Variable Stars in Globular Clusters: Inner Region of NGC 6441

    Science.gov (United States)

    Pritzl, Barton J.; Smith, Horace A.; Stetson, Peter B.; Catelan, Marcio; Sweigart, Allen V.; Layden, Andrew C.; Rich, R. Michael

    2003-01-01

    We present the results of a Hubble Space Telescope snapshot program to survey the inner region of the metal-rich globular cluster NGC 6441 for its variable stars. A total of 57 variable stars was found including 38 RR Lyrae stars, 6 Population II Cepheids, and 12 long period variables. Twenty-four of the RR Lyrae stars and all of the Population II Cepheids were previously undiscovered in ground-based surveys. Of the RR Lyrae stars observed in h s survey, 26 are pulsating in the fundamental mode with a mean period of 0.753 d and 12 are first-overtone mode pulsators with a mean period of 0.365 d. These values match up very well with those found in ground-based surveys. Combining all the available data for NGC 6441, we find mean periods of 0.759 d and 0.375 d for the RRab and RRc stars, respectively. We also find that the RR Lyrae in this survey are located in the same regions of a period-amplitude diagram as those found in ground-based surveys. The overall ratio of RRc to total RR Lyrae is 0.33. Although NGC 6441 is a metal-rich globular cluster and would, on that ground, be expected either to have few RR Lyrae stars, or to be an Oosterhoff type I system, its RR Lyrae more closely resemble those in Oosterhoff type II globular clusters. However, even compared to typical Oosterhoff type II systems, the mean period of its RRab stars is unusually long. We also derived I-band period-luminosity relations for the RR Lyrae stars. Of the six Population II Cepheids, five are of W Virginis type and one is a BL Herculis variable star. This makes NGC 6441, along with NGC 6388, the most metal-rich globular cluster known to contain these types of variable stars. Another variable, V118, may also be a Population II Cepheid given its long period and its separation in magnitude from the RR Lyrae stars. We examine the period-luminosity relation for these Population II Cepheids and compare it to those in other globular clusters and in the Large Magellanic Cloud. We argue that there does

  19. The Kepler characterization of the variability among A- and F-type stars. I. General overview

    DEFF Research Database (Denmark)

    Uytterhoeven, K.; Moya, A.; Grigahcène, A.

    2011-01-01

    candidate A-F type stars, and observationally investigate the relation between γ Doradus (γ Dor), δ Scuti (δ Sct), and hybrid stars. Methods: We compile a database of physical parameters for the sample stars from the literature and new ground-based observations. We analyse the Kepler light curve of each...... star and extract the pulsational frequencies using different frequency analysis methods. We construct two new observables, "energy" and "efficiency", related to the driving energy of the pulsation mode and the convective efficiency of the outer convective zone, respectively. Results: We propose three...... constructed variables, "efficiency" and "energy", as a means to explore the relation between γ Dor and δ Sct stars. Conclusions: Our results suggest a revision of the current observational instability strips of δ Sct and γ Dor stars and imply an investigation of pulsation mechanisms to supplement the κ...

  20. Photometric Variability of Four Coronally Active Stars J. C. Pandey ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    S. A. Drake. 4. 1State Observatory, Naini Tal 263 129, India. 2Tata Institute of Fundamental Research, Mumbai, India. 3Indian Institute of Astrophysics, Bangalore, India. 4Code 668, LHEA, NASA/Goddard Space Flight Center, Greenbelt, MD 20771, USA. Abstract. We present photometric observations of four stars that are.

  1. Spectroscopic Variability of Supergiant Star HD14134, B3Ia

    Indian Academy of Sciences (India)

    Y. M. Maharramov

    2017-06-19

    Jun 19, 2017 ... Abstract. Profile variations in the Hα and Hβ lines in the spectra of the star HD14134 are investigated using observations carried out in 2013–2014 and 2016 with the 2-m telescope at the Shamakhy Astrophysical Obser- vatory. The absorption and emission components of the Hα line are found to disappear ...

  2. The motion of a star with variable mass inside a layered inhomogeneous elliptical galaxy

    Science.gov (United States)

    Gasanov, S. A.

    2009-08-01

    We consider the motion of a variable-mass star inside a layered, inhomogeneous, rotating elliptical variable-mass galaxy. Under certain conditions, the differential equations of motion of a star inside the galaxy admit autonomization. The autonomized differential equations in this problem are similar to those for the motion of a constant-mass star. We have found analogs for the Jacobi integral and the Eddington-Jeans law for the variation of the density of the galaxy in its center and layers.

  3. Variable Stars in Leo A: RR Lyrae Stars, Short-Period Cepheids, and Implications for Stellar Content

    Science.gov (United States)

    Dolphin, Andrew E.; Saha, A.; Claver, Jennifer; Skillman, Evan D.; Cole, A. A.; Gallagher, J. S.; Tolstoy, Eline; Dohm-Palmer, R. C.; Mateo, Mario

    2002-06-01

    We present the results of a search for short-period variable stars in Leo A. We have found 92 candidate variables, including eight candidate RR Lyrae stars. From the RR Lyrae stars, we measure a distance modulus of (m-M)0=24.51+/-0.12, or 0.80+/-0.04 Mpc. This discovery of RR Lyrae stars confirms for the first time the presence of an ancient (older than ~11 Gyr) population in Leo A, accounting for at least 0.1% of the galaxy's V luminosity. We have also discovered a halo of old (more than ~2 Gyr) stars surrounding Leo A, with a scale length roughly 50% larger than that of the dominant young population. We also report the discovery of a large population of Cepheids in Leo A. The median absolute magnitude of our Cepheid sample is MV=-1.1, fainter than 96% of SMC and 99% of LMC Cepheids. Their periods are also unusual, with three Cepheids that are deduced to be pulsating in the fundamental mode having periods of under 1 day. Upon examination, these characteristics of the Leo A Cepheid population appear to be a natural extension of the classical Cepheid period-luminosity relations to low metallicity, rather than being indicative of a large population of ``anomalous'' Cepheids. We demonstrate that the periods and luminosities are consistent with the expected values of low-metallicity blue helium-burning stars (BHeB's), which populate the instability strip at lower luminosities than do higher metallicity BHeB's.

  4. Optical and Infrared Variability of UX Ori-Type Stars

    Science.gov (United States)

    Rostopchina-Shakhovskaya, A.; Grinin, V.; Shenavrin, V.; Shakhovskoy, D.; Demidova, T.; Belan, S.

    2017-06-01

    Analyzing data of the long-term simultaneous NIR and optical photometry of five UX Ori type stars we estimate intrinsic NIR luminosity of their circumstellar disks in I, J, H bands. The H to J flux ratio for WW Vul, CQ Tau, RR Tau, UX Ori is consistent with 1500 K blackbody radiation, a typical temperature of dust sublimation. For the same stars except RR Tau, J to I flux ratio suggests much hotter source with T>2000 K, probably the inner dust-free disk. In case of RR Tau this value is close to 1500 K, implying sublimating dust as a main contributor in all three bands. The SED for BF Ori differs from the rest of objects, with flux density peaking in J band, probably due to an unresolved cool companion.

  5. Blue large-amplitude pulsators as a new class of variable stars

    Science.gov (United States)

    Pietrukowicz, Paweł; Dziembowski, Wojciech A.; Latour, Marilyn; Angeloni, Rodolfo; Poleski, Radosław; di Mille, Francesco; Soszyński, Igor; Udalski, Andrzej; Szymański, Michał K.; Wyrzykowski, Łukasz; Kozłowski, Szymon; Skowron, Jan; Skowron, Dorota; Mróz, Przemek; Pawlak, Michał; Ulaczyk, Krzysztof

    2017-08-01

    Regular intrinsic brightness variations observed in many stars are caused by pulsations. These pulsations provide information on the global and structural parameters of the star. The pulsation periods range from seconds to years, depending on the compactness of the star and properties of the matter that forms its outer layers. Here, we report the discovery of more than a dozen previously unknown short-period variable stars: blue large-amplitude pulsators. These objects show very regular brightness variations with periods in the range of 20-40 min and amplitudes of 0.2-0.4 mag in the optical passbands. The phased light curves have a characteristic sawtooth shape, similar to the shape of classical Cepheids and RR Lyrae-type stars pulsating in the fundamental mode. The objects are significantly bluer than main-sequence stars observed in the same fields, which indicates that all of them are hot stars. Follow-up spectroscopy confirms a high surface temperature of about 30,000 K. Temperature and colour changes over the cycle prove the pulsational nature of the variables. However, large-amplitude pulsations at such short periods are not observed in any known type of stars, including hot objects. Long-term photometric observations show that the variable stars are very stable over time. Derived rates of period change are of the order of 10-7 per year and, in most cases, they are positive. According to pulsation theory, such large-amplitude oscillations may occur in evolved low-mass stars that have inflated helium-enriched envelopes. The evolutionary path that could lead to such stellar configurations remains unknown.

  6. Amplitude Variability in gamma Dor and delta Sct Stars Observed by Kepler

    Energy Technology Data Exchange (ETDEWEB)

    Guzik, Joyce Ann [Los Alamos National Laboratory; Kosak, Mary Katherine [Los Alamos National Laboratory; Bradley, Paul Andrew [Los Alamos National Laboratory; Jackiewicz, Jason [New Mexico State University, Las Cruces, NM

    2015-08-17

    The NASA Kepler spacecraft data revealed a large number of new multimode nonradially pulsating gamma Dor and delta Sct variable stars. The Kepler high-precision long time-series photometry makes it possible to study amplitude variations of the frequencies, and recent literature on amplitude and frequency variations in nonradially pulsating variables is summarized. Several methods are applied to study amplitude variability in about a dozen gamma Doradus or delta Scuti candidate variable stars observed for several quarters as part of the Kepler Guest Observer program. The magnitude and timescale of the amplitude variations are discussed, along with the presence or absence of correlations between amplitude variations for different frequencies of a given star. Proposed causes of amplitude spectrum variability that will require further investigation are also discussed.

  7. Stellar Variability of the Exoplanet Hosting Star HD 63454

    OpenAIRE

    {Kane} S.~R.; {Dragomir} D.; {Ciardi} D.~R.; {Lee} J.-W.; {Lo Curto} G.; {Lovis} C.; {Naef} D.; {Mahadevan} S.; {Pilyavsky} G.; {Udry} S.; {Wang} X.; {Wright} J.

    2011-01-01

    Of the hundreds of exoplanets discovered using the radial velocity technique, many are orbiting close to their host stars with periods less than 10 days. One of these, HD 63454, is a young active K dwarf which hosts a Jovian planet in a 2.82 day period orbit. The planet has a 14% transit probability and a predicted transit depth of 1.2%. Here we provide a re-analysis of the radial velocity data to produce an accurate transit ephemeris. We further analyse 8 nights of time series data to search...

  8. Variable stars around selected open clusters in the VVV area: Young Stellar Objects

    Science.gov (United States)

    Medina, Nicolas; Borissova, Jura; Bayo, Amelia; Kurtev, Radostin; Lucas, Philip

    2017-09-01

    Time-varying phenomena are one of the most substantial sources of astrophysical information, and led to many fundamental discoveries in modern astronomy. We have developed an automated tool to search and analyze variable sources in the near infrared Ks band, using the data from the Vista Variables in the Vía Láctea (VVV) ESO Public Survey ([5, 8]). One of our main goals is to investigate the Young Stellar Objects (YSOs) in the Galactic star forming regions, looking for: •Variability. •New pre-main sequence star clusters. Here we present the newly discovered YSOs within some selected stellar clusters in our Galaxy.

  9. All-Sky Census of Variable Stars from the ATLAS Survey

    Science.gov (United States)

    Heinze, Aren Nathaniel; Tonry, John; Denneau, Larry; Stalder, Brian

    2018-01-01

    The Asteroid Terrestrial-Impact Last Alert Survey uses two custom-built 0.5 meter telescopes to scan the whole accessible sky down to magnitude 19.5 every two nights, with a cadence optimized to detect small asteroids on their 'final plunge' toward impact with Earth. This cadence is also well suited to the detection of variable stars with a huge range of periods and properties, while ATLAS' use of two filters provides additional scientific depth. From the first two years of ATLAS data we have constructed a catalog of several hundred thousand variable objects with periods from one hour to hundreds of days. These include RR Lyrae stars, Cepheids, eclipsing binaries, spotted stars, ellipsoidal variables, Miras; and other objects both regular and irregular. We describe the construction of this catalog, including our multi-step confirmation process for genuine variables; some big-picture scientific conclusions; and prospects for more detailed results.

  10. Search for variable stars in the young open cluster Stock 18

    Directory of Open Access Journals (Sweden)

    Sinha Tirthendu

    2017-01-01

    Full Text Available We have carried out multi-epoch deep I band photometry of the open cluster Stock 18 to search for variable stars in star forming regions. In the present study, we report identification of 28 periodic and 165 non-periodic variables stars. The periods of most of the periodic variables are in between 2 to 20 hours and their magnitude varies between 0.05 to 0.6 mag. We have derived spectral energy distributions for 48 probable pre-main sequence variables and the average age and mass is found to be 2.7 ± 0.3 Myrs and 2.7 ± 0.2 M⊙, respectively.

  11. Faint (and bright variable stars in the satellites of the Milky Way

    Directory of Open Access Journals (Sweden)

    Vivas A. Katherina

    2017-01-01

    Full Text Available I describe two ongoing projects related with variable stars in the satellites of the MilkyWay. In the first project, we are searching for dwarf Cepheid stars (a.k.a δ Scuti and/or SX Phe in some of the classical dwarf spheroidal galaxies. Our goal is to characterize the population of these variable stars under different environments (age, metallicity in order to study their use as standard candles in systems for which the metallicity is not necessarily known. In the second project we search for RR Lyrae stars in the new ultra-faint satellite galaxies that have been discovered around the Milky Way in recent years.

  12. Photometric variability of 14 PMS stars in the NGC 7000/IC 5070 complex

    OpenAIRE

    Ibryamov, Sunay I.; Semkov, Evgeni H.

    2015-01-01

    New photometric data from CCD multicolour BVRI observations of 14 pre-main sequence stars during the period from 2013 April to 2015 September are presented. The studied objects are located in the field of 'Gulf of Mexico' in the NGC 7000/IC 5070 star-forming complex. The stars from our study exhibit different types of photometric variability in all optical passbands. Using our long-term observations and data published by other authors, we tried to define the reasons for the observed brightnes...

  13. On the Central Helium-burning Variable Stars of the LeoI Dwarf Spheroidal Galaxy

    Science.gov (United States)

    Fiorentino, G.; Stetson, P. B.; Monelli, M.; Bono, G.; Bernard, E. J.; Pietrinferni, A.

    2012-11-01

    We present a study of short-period, central helium-burning variable stars in the Local Group dwarf spheroidal galaxy LeoI, including 106 RR Lyrae stars and 51 Cepheids. So far, this is the largest sample of Cepheids and the largest Cepheids to RR Lyrae ratio found in such a kind of galaxy. Comparison with other Local Group dwarf spheroidals, Carina and Fornax, shows that the period distribution of RR Lyrae stars is quite similar, suggesting similar properties of the parent populations, whereas the Cepheid period distribution in LeoI peaks at longer periods (P ~ 1.26 days instead of ~0.5 days) and spans over a broader range, from 0.5 to 1.78 days. Evolutionary and pulsation predictions indicate, assuming a mean metallicity peaked within -1.5 <~ [Fe/H] <~ -1.3, that the current sample of LeoI Cepheids traces a unique mix of anomalous Cepheids (blue extent of the red-clump, partially electron-degenerate central helium-burning stars) and short-period classical Cepheids (blue-loop, quiescent central helium-burning stars). Current evolutionary prescriptions also indicate that the transition mass between the two different groups of stars is M HeF ~ 2.1 M ⊙, and it is constant for stars metal-poorer than [Fe/H] ~ -0.7. Finally, we briefly outline the different implications of the current findings on the star formation history of LeoI.

  14. Analysis of the variability in the sdB star KIC 10670103: DFA approach

    Science.gov (United States)

    Zebende, Gilney F.; Fernandez, Basilio F.; Pereira, Marildo G.

    2017-01-01

    The brightness variation of the stars is an object of study in astronomy and astrophysics for representing the rich inherent source of physical information. Launched in 2009, the Kepler spacecraft with the primary mission of identifying equivalent to the Earth by the Sun transits also gave birth to thousands of light curves of targets of scientific interest. KIC 10670103, the richest pulsating sub-dwarf B (sdB) star, is one of the many stars identified by the mission. With 3.72 yr of Kepler spacecraft observations, we analysed in this paper the light curve of this sdB star, by the detrended fluctuation analysis (DFA) method. The behaviour of this pulsating star reveals self-affinity at specific time-scales, with changes in DFA exponent, αDFA. This fact suggests some light variability in KIC 10670103, as for example, from a non-periodic to a periodic case, among others. Therefore, we propose to connect the pulsation pattern of the KIC 10670103 star, which presents trends and non-stationarity, with the αDFA exponent. In this sense, we obtain five values of αDFA related to the light variability properties of KIC 10670103. A pictorial figure will describe the relationship between these variables.

  15. Disk Variability and Pulsation in the Be Star π Aquarii

    Science.gov (United States)

    Peters, Geraldine J.; Gies, Douglas R.; Wang, Luqian

    2015-01-01

    π Aqr is a bright Be star that lost its circumstellar disk in the late-1990s after showing strong disk emission lines for about five decades. We have analyzed spectra in the Hα/He I 6678 region that were obtained during the hiatus in its mass loss and the epoch of early disk buildup afterwards to investigate the star's pulsation and its possible connection with mass loss activity. The spectra were obtained with the Coudé Feed Telescope at KPNO during three observing runs on 1999 November 20-29, 2000 October 29 - November 3, and 2001 January 4-8. A total of 55 images with a S/N~350 and spectral resolution of 0.103 Å/pixel were obtained. The time resolution was 15 m and the observation sets spanned 1.5-3.0 hr. Rapid nonradial pulsations (NRP) with l=|m| =5 were observed with a period of 1.88 ± 0.02 hours. The motion was prograde for a rotation period of 1.8 days. Pulsation amplitudes were largest during the middle observing run. The power in the high frequency signal declined in the final run accompanied by an increase in the low frequency power (as in HD 49330, Huat et al. 2009) suggesting that p waves may have been replaced with g waves. The photospheric lines are broader during a mass loss episode (increased Hα emission). The NRP variations in Hα during 2000 Nov. 1 suggest a formation in a low pressure gas perhaps at the equator. The NRP bumps are slightly broader in Hα than in He I and C II, which implies a photospheric origin. Since the structure is quite visible in Hα, the apparent NRP is probably occurring in the upper atmosphere, as Stark line broadening would render the features more diffuse if they prevailed at deep layers. Narrow stationary violet and red-shifted features that varied in strength on the time scale of the pulsations were observed in Hα, and suggest that disk changes may be driven by pulsation. Additional spectra from KPNO and the BeSS archive reveal that Hα disk emission peaked in 2011 July (comparable to that observed in 1993

  16. Mythological Evidence for Ancient Observations of Variable Stars

    Science.gov (United States)

    Wilk, Stephen R.

    I suggest that the variability of Algol was known in pre-classical Greece, and that knowledge of its period is reflected in the myth of Perseus. Moreover, knowledge of the variability of Algol, Mira, delta Cephei, and gamma Cassiopeiae accounts for all their parent constellations being associated in the same myth as antagonists of Perseus. Finally, I propose alternative interpretations of the same constellations which show their influence upon classical myth.

  17. H-alpha/H-beta Light Curves for Pulsating Variable Stars

    Science.gov (United States)

    Hintz, Eric G.; Joner, Michael D.; Barnes, Jonathan

    2017-06-01

    In Joner & Hintz (2015) they discuss the development of a new calibrated H-alpha index similar in nature to the traditional H-beta index. It is demonstrated that the new H-alpha index tracks very well with the equivalent width of the line and the surface temperature. Therefore, we selected a sample of pulsating variable stars to test the possible use of the new index to track temperature changes in those stars over a pulsation cycle. We will present data on a sample of Cepheid, RR Lyrae, and delta Scuti variables. We will also examine changes in the H-alpha index potentially related to period changes in these objects.

  18. Variable Stars and Stellar Populations in Andromeda XXVII. IV. An Off-centered, Disrupted Galaxy

    Science.gov (United States)

    Cusano, Felice; Garofalo, Alessia; Clementini, Gisella; Cignoni, Michele; Muraveva, Tatiana; Tessicini, Gianni; Testa, Vincenzo; Paris, Diego; Federici, Luciana; Marconi, Marcella; Ripepi, Vincenzo; Musella, Ilaria

    2017-12-01

    We present B and V time-series photometry of the M31 satellite galaxy Andromeda XXVII (And XXVII) that we observed with the Large Binocular Cameras of the Large Binocular Telescope. In the field of And XXVII we have discovered a total of 90 variables: 89 RR Lyrae stars and 1 Anomalous Cepheid. The average period of the fundamental mode RR Lyrae stars (RRab) =0.59 {days} (σ = 0.05 day) and the period-amplitude diagram place And XXVII in the class of Oosterhoff I/Intermediate objects. Combining information from the color-magnitude diagram (CMD) and the variable stars, we find evidence for a single old and metal-poor stellar population with [Fe/H] ˜ -1.8 dex and t ˜ 13 Gyr in And XXVII. The spatial distributions of RR Lyrae and red giant branch (RGB) stars give clear indication that And XXVII is a completely disrupted system. This is also supported by the spread observed along the line of sight in the distance to the RR Lyrae stars. The highest concentration of RGB and RR Lyrae stars is found in a circular area of 4 arcmin in radius, centered about 0.°2 in the southeast direction from Richardson et al.’s center coordinates of And XXVII. The CMD of this region is well-defined, with a prominent RGB and 15 RR Lyrae stars (out of the 18 found in the region) tracing a very tight horizontal branch at =25.24 {mag} σ = 0.06 mag (average over 15 stars). We show that And XXVII is a strong candidate building block of the M31 halo. Based on data collected with the Large Binocular Cameras at the Large Binocular Telescope, PI: G. Clementini.

  19. VizieR Online Data Catalog: RR Lyr variable stars in M32 (Fiorentino+, 2012)

    Science.gov (United States)

    Fiorentino, G.; Contreras Ramos, R.; Tolstoy, E.; Clementini, G.; Saha, A.

    2012-01-01

    Using archival multi-epoch ACS/WFC images in the F606W and F814W filters of a resolved stellar field in Local Group dwarf elliptical galaxy M 32 we have made an accurate Colour-Magnitude Diagram and a careful search for RR Lyr variable stars. We identified 416 bona fide RR Lyr stars over our field of view, and their spatial distribution shows a rising number density towards the centre of M 32. These new observations clearly confirm the tentative result of Fiorentino et al. (2010ApJ...708..817F), on a much smaller field of view, associating an ancient population of RR Lyr variables to M 32. We associate at least 83 RR Lyr stars in our field to M 32. (1 data file).

  20. Photometric variability of the Be star population with the KELT survey

    Science.gov (United States)

    Labadie-Bartz, Jonathan; Pepper, Joshua; Chojnowski, S. Drew; McSwain, M. Virginia

    2017-11-01

    We are using light curves from the KELT exoplanet transit survey (Pepper et al. 2007) to study the variability of hundreds of Be stars. Combining these light curves with simultaneous time-series spectra from the APOGEE survey (Majewski et al. 2015) provides a glimpse into how changes in the circumstellar environment are correlated to brightness variations.

  1. The OGLE Collection of Variable Stars. Classical, Type II, and Anomalous Cepheids toward the Galactic Center

    Science.gov (United States)

    Soszyński, I.; Udalski, A.; Szymański, M. K.; Wyrzykowski, Ł.; Ulaczyk, K.; Poleski, R.; Pietrukowicz, P.; Kozłowski, S.; Skowron, D. M.; Skowron, J.; Mróz, P.; Pawlak, M.; Rybicki, K.; Jacyszyn-Dobrzeniecka, A.

    2017-12-01

    We present a collection of classical, typeII, and anomalous Cepheids detected in the OGLE fields toward the Galactic center. The sample contains 87 classical Cepheids pulsating in one, two or three radial modes, 924 type II Cepheids divided into BL Her, W Vir, peculiar W Vir, and RV Tau stars, and 20 anomalous Cepheids - first such objects found in the Galactic bulge. Additionally, we upgrade the OGLE Collection of RR Lyr stars in the Galactic bulge by adding 828 newly identified variables. For all Cepheids and RRLyr stars, we publish time-series VI photometry obtained during the OGLE-IV project, from 2010 through 2017. We discuss basic properties of our classical pulsators: their spatial distribution, light curve morphology, period-luminosity relations, and position in the Petersen diagram. We present the most interesting individual objects in our collection: a typeII Cepheid with additional eclipsing modulation, WVir stars with the period doubling effect and the RVb phenomenon, a mode-switching RR Lyr star, and a triple-mode anomalous RRd star.

  2. Luminous and Variable Stars in M31 and M33. V. The Upper HR Diagram

    Energy Technology Data Exchange (ETDEWEB)

    Humphreys, Roberta M.; Davidson, Kris; Hahn, David [Minnesota Institute for Astrophysics, 116 Church St SE, University of Minnesota, Minneapolis, MN 55455 (United States); Martin, John C. [Barber Observatory, University of Illinois, Springfield, IL 62703 (United States); Weis, Kerstin, E-mail: roberta@umn.edu [Astronomical Institute, Ruhr-Universitaet Bochum (Germany)

    2017-07-20

    We present HR diagrams for the massive star populations in M31 and M33, including several different types of emission-line stars: the confirmed luminous blue variables (LBVs), candidate LBVs, B[e] supergiants, and the warm hypergiants. We estimate their apparent temperatures and luminosities for comparison with their respective massive star populations and evaluate the possible relationships of these different classes of evolved, massive stars, and their evolutionary state. Several of the LBV candidates lie near the LBV/S Dor instability strip that supports their classification. Most of the B[e] supergiants, however, are less luminous than the LBVs. Many are very dusty with the infrared flux contributing one-third or more to their total flux. They are also relatively isolated from other luminous OB stars. Overall, their spatial distribution suggests a more evolved state. Some may be post-RSGs (red supergiants) like the warm hypergiants, and there may be more than one path to becoming a B[e] star. There are sufficient differences in the spectra, luminosities, spatial distribution, and the presence or lack of dust between the LBVs and B[e] supergiants to conclude that one group does not evolve into the other.

  3. White Dwarfs in Cataclysmic Variable Stars: Surface Temperatures and Evolution

    Directory of Open Access Journals (Sweden)

    Edward M. Sion

    2012-06-01

    Full Text Available A summary is presented of what is currently known about the surface temperatures of accreting white dwarfs (WDs detected in non-magnetic and magnetic cataclysmic variables (CVs based upon synthetic spectral analyses of far ultraviolet data. A special focus is placed on WD temperatures above and below the CV period gap as a function of the orbital period, Porb. The principal uncertainty of the temperatures for the CV WDs in the Teff - Porb distribution, besides the distance to the CV, is the mass of the WD. Only in eclipsing CV systems, an area of eclipsing binary studies, which was so central to Robert H. Koch’s career, is it possible to know CV WD masses with high precision.

  4. Variable stars in the VVV globular clusters. I. 2MASS-GC 02 and Terzan 10

    Energy Technology Data Exchange (ETDEWEB)

    Alonso-García, Javier; Dékány, István; Catelan, Márcio; Ramos, Rodrigo Contreras; Gran, Felipe; Leyton, Paul; Minniti, Dante [Instituto de Astrofísica, Facultad de Física, Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna 4860, 782-0436 Macul, Santiago (Chile); Amigo, Pía, E-mail: jalonso@astro.puc.cl, E-mail: idekany@astro.puc.cl, E-mail: mcatelan@astro.puc.cl, E-mail: rcontrer@astro.puc.cl, E-mail: fgran@astro.puc.cl, E-mail: pia.amigo@uv.cl, E-mail: pleyton@astro.puc.cl, E-mail: dante@astrofisica.cl [Millennium Institute of Astrophysics, Av. Vicuña Mackenna 4860, 782-0436 Macul, Santiago (Chile)

    2015-03-01

    The VISTA Variables in the Vía Láctea (VVV) ESO Public Survey is opening a new window to study inner Galactic globular clusters (GCs) using their variable stars. These GCs have been neglected in the past due to the difficulties caused by the presence of elevated extinction and high field stellar densities in their lines of sight. However, the discovery and study of any present variables in these clusters, especially RR Lyrae stars, can help to greatly improve the accuracy of their physical parameters. It can also help to shed some light on the questions raised by the intriguing Oosterhoff dichotomy in the Galactic GC system. In a series of papers we plan to explore variable stars in the GCs falling inside the field of the VVV survey. In this first paper, we search for and study the variables present in two highly reddened, moderately metal-poor, faint, inner Galactic GCs: 2MASS-GC 02 and Terzan 10. We report the discovery of sizable populations of RR Lyrae stars in both GCs. We use near-infrared period–luminosity relations to determine the color excess of each RR Lyrae star, from which we obtain both accurate distances to the GCs and the ratios of the selective-to-total extinction in their directions. We find the extinction toward both clusters to be elevated, non-standard, and highly differential. We also find both clusters to be closer to the Galactic center than previously thought, with Terzan 10 being on the far side of the Galactic bulge. Finally, we discuss their Oosterhoff properties, and conclude that both clusters stand out from the dichotomy followed by most Galactic GCs.

  5. SpecDB: The AAVSO’s Public Repository for Spectra of Variable Stars

    Science.gov (United States)

    Kafka, Stella; Weaver, John; Silvis, George; Beck, Sara

    2018-01-01

    SpecDB is the American Association of Variable Star Observers (AAVSO) spectral database. Accessible to any astronomer with the capability to perform spectroscopy, SpecDB provides an unprecedented scientific opportunity for amateur and professional astronomers around the globe. Backed by the Variable Star Index, one of the most utilized variable star catalogs, SpecDB is expected to become one of the world leading databases of its kind. Once verified by a team of expert spectroscopists, an observer can upload spectra of variable stars target easily and efficiently. Uploaded spectra can then be searched for, previewed, and downloaded for inclusion in publications. Close community development and involvement will ensure a user-friendly and versatile database, compatible with the needs of 21st century astrophysics. Observations of 1D spectra are submitted as FITS files. All spectra are required to be preprocessed for wavelength calibration and dark subtraction; Bias and flat are strongly recommended. First time observers are required to submit a spectrum of a standard (non-variable) star to be checked for errors in technique or equipment. Regardless of user validation, FITS headers must include several value cards detailing the observation, as well as information regarding the observer, equipment, and observing site in accordance with existing AAVSO records. This enforces consistency and provides necessary details for follow up analysis. Requirements are provided to users in a comprehensive guidebook and accompanying technical manual. Upon submission, FITS headers are automatically checked for errors and any anomalies are immediately fed back to the user. Successful candidates can then submit at will, including multiple simultaneous submissions. All published observations can be searched and interactively previewed. Community involvement will be enhanced by an associated forum where users can discuss observation techniques and suggest improvements to the database.

  6. Field #3 of the Palomar-Groningen Survey; 1, Variable stars at the edge of the Sagittarius dwarf galaxy

    NARCIS (Netherlands)

    Schultheis, M.

    1996-01-01

    Submitted to: Astron. Astrophys. Abstract: A catalogue is presented with variable (RR Lyrae, semiregular and Mira) stars located inside field #3 of the Palomar-Groningen Survey, at the outer edge of the Sagittarius dwarf galaxy. One of the semiregular variables is a carbon star, comparable with

  7. Multi-Epoch Hubble Space Telescope Observations of IZw18 : Characterization of Variable Stars at Ultra-Low Metallicities

    NARCIS (Netherlands)

    Fiorentino, G.; Ramos, R. Contreras; Clementini, G.; Marconi, M.; Musella, I.; Aloisi, A.; Annibali, F.; Saha, A.; Tosi, M.; van der Marel, R. P.

    2010-01-01

    Variable stars have been identified for the first time in the very metal-poor blue compact dwarf galaxy IZw18, using deep multi-band (F606W, F814W) time-series photometry obtained with the Advanced Camera for Surveys on board the Hubble Space Telescope. We detected 34 candidate variable stars in the

  8. Mira Variable Stars from LAMOST DR4 Data: Emission Features, Temperature Types, and Candidate Selection

    Science.gov (United States)

    Yao, Yuhan; Liu, Chao; Deng, Licai; de Grijs, Richard; Matsunaga, Noriyuki

    2017-09-01

    Based on an extensive spectral study of a photometrically confirmed sample of Mira variables, we find a relationship between the relative Balmer emission-line strengths and spectral temperatures of O-rich Mira stars. The {F}{{H}δ }/{F}{{H}γ } flux ratio increases from less than unity to five as stars cool down from M0 to M10, which is likely driven by increasing TiO absorption above the deepest shock-emitting regions. We also discuss the relationship between the equivalent widths of the Balmer emission lines and the photometric luminosity phase of our Mira sample stars. Using our 291 Mira spectra as templates for reference, 191 Mira candidates are newly identified from the LAMOST DR4 catalog. We summarize the criteria adopted to select Mira candidates based on emission-line indices and molecular absorption bands. This enlarged spectral sample of Mira variables has the potential to contribute significantly to our knowledge of the optical properties of Mira stars and will facilitate further studies of these late-type, long-period variables.

  9. The Carina project. VII. Toward the breaking of the age-metallicity degeneracy of red giant branch stars using the C {sub U,} {sub B,} {sub I} index

    Energy Technology Data Exchange (ETDEWEB)

    Monelli, M.; Milone, A. P.; Gallart, C.; Aparicio, A. [Instituto de Astrofísica de Canarias, Calle Via Lactea s/n, E-38205 La Laguna, Tenerife (Spain); Fabrizio, M.; Cassisi, S.; Buonanno, R. [Istituto Nazionale di Astrofisica-Osservatorio Astronomico Collurania, Via M. Maggini, I-64100 Teramo (Italy); Bono, G. [Dipartimento di Fisica, Universitá di Roma Tor Vergata, Via della Ricerca Scientifica 1, I-00133 Rome (Italy); Stetson, P. B. [Dominion Astrophysical Observatory, NRC-Herzberg, 5071 West Saanich Road, Victoria, BC, V9E 2E7 (Canada); Walker, A. R. [Cerro Tololo Inter-American Observatory, National Optical Astronomy Observatory, Casilla 603, La Serena (Chile); Nonino, M. [Istituto Nazionale di Astrofisica-Osservatorio Astronomico di Trieste, Via G. B. Tiepolo 11, I-40131 Trieste (Italy); Dall' Ora, M. [INAF—Osservatorio Astronomico di Capodimonte, Salita Moiariello 16, I-80131 Napoli (Italy); Ferraro, I.; Iannicola, G.; Pulone, L. [Istituto Nazionale di Astrofisica-Osservatorio Astronomico di Roma, Via Frascati 33, Monte Porzio Catone, I-00044 Rome (Italy); Thévenin, F., E-mail: monelli@iac.es [Université de Nice Sophia-antipolis, CNRS, Observatoire de la Côte d' Azur, Laboratoire Lagrange, BP 4229, F-06304 Nice (France)

    2014-12-01

    We present an analysis of photometric and spectroscopic data of the Carina dSph galaxy, testing a new approach similar to that used to disentangle multiple populations in Galactic globular clusters (GCs). We show that a proper color combination is able to separate a significant fraction of the red giant branch (RGB) of the two main Carina populations (the old one, ∼12 Gyr, and the intermediate-age one, 4-8 Gyr). In particular, the c {sub U,} {sub B,} {sub I} = (U – B) – (B – I) pseudo-color allows us to follow the RGB of both populations along a relevant portion of the RGB. We find that the oldest stars have a more negative c {sub U,} {sub B,} {sub I} pseudo-color than intermediate-age ones. We correlate the pseudo-color of RGB stars with their chemical properties, finding a significant trend between the iron content and the c {sub U,} {sub B,} {sub I}. Stars belonging to the old population are systematically more metal-poor ([Fe/H] =–2.32 ± 0.08 dex) than the intermediate-age ones ([Fe/H] =–1.82 ± 0.03 dex). This gives solid evidence of the chemical evolution history of this galaxy, and we have a new diagnostic that can allow us to break the age-metallicity degeneracy of H-burning advanced evolutionary phases. We compared the distribution of stars in the c {sub U,} {sub B,} {sub I} plane with theoretical isochrones, finding that no satisfactory agreement can be reached with models developed in a theoretical framework based on standard heavy element distributions. Finally, we discuss possible systematic differences when compared with multiple populations in GCs.

  10. The POINT-AGAPE Survey I: The Variable Stars in M31

    CERN Document Server

    An Jun Hong; Hewett, P C; Baillon, Paul; Calchi-Novati, S; Carr, B J; Creze, M; Giraud-Héraud, Yannick; Gould, A; Jetzer, P; Kaplan, J; Kerins, E; Paulin-Henriksson, S; Smartt, S J; Stalin, C S; Tsapras, Y; An, Jin H.; Jetzer, Ph.

    2004-01-01

    The POINT-AGAPE collaboration has been monitoring M31 for three seasons with the Wide Field Camera on the Isaac Newton Telescope. In each season, data are taken for one hour per night for roughly sixty nights during the six months that M31 is visible. The two fields of view straddle the central bulge, northwards and southwards. We have calculated the locations, periods and amplitudes of 35414 variable stars in M31 as a by-product of our microlensing search. The variables are classified according to their period and amplitude of variation. They are classified into population I and II Cepheids, Miras and semi-regular long-period variables. The population I Cepheids are associated with the spiral arms, while the central concentration of the Miras and long-period variables varies noticeably, the stars with brighter (and shorter) variations being much more centrally concentrated. A crucial role in the microlensing experiment is played by the asymmetry signal. It was initially assumed that the variable stars would ...

  11. Active Learning to Overcome Sample Selection Bias: Application to Photometric Variable Star Classification

    Science.gov (United States)

    Richards, Joseph W.; Starr, Dan L.; Brink, Henrik; Miller, Adam A.; Bloom, Joshua S.; Butler, Nathaniel R.; James, J. Berian; Long, James P.; Rice, John

    2012-01-01

    Despite the great promise of machine-learning algorithms to classify and predict astrophysical parameters for the vast numbers of astrophysical sources and transients observed in large-scale surveys, the peculiarities of the training data often manifest as strongly biased predictions on the data of interest. Typically, training sets are derived from historical surveys of brighter, more nearby objects than those from more extensive, deeper surveys (testing data). This sample selection bias can cause catastrophic errors in predictions on the testing data because (1) standard assumptions for machine-learned model selection procedures break down and (2) dense regions of testing space might be completely devoid of training data. We explore possible remedies to sample selection bias, including importance weighting, co-training, and active learning (AL). We argue that AL—where the data whose inclusion in the training set would most improve predictions on the testing set are queried for manual follow-up—is an effective approach and is appropriate for many astronomical applications. For a variable star classification problem on a well-studied set of stars from Hipparcos and Optical Gravitational Lensing Experiment, AL is the optimal method in terms of error rate on the testing data, beating the off-the-shelf classifier by 3.4% and the other proposed methods by at least 3.0%. To aid with manual labeling of variable stars, we developed a Web interface which allows for easy light curve visualization and querying of external databases. Finally, we apply AL to classify variable stars in the All Sky Automated Survey, finding dramatic improvement in our agreement with the ASAS Catalog of Variable Stars, from 65.5% to 79.5%, and a significant increase in the classifier's average confidence for the testing set, from 14.6% to 42.9%, after a few AL iterations.

  12. The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/Virgo GW170817. VII. Properties of the Host Galaxy and Constraints on the Merger Timescale

    Energy Technology Data Exchange (ETDEWEB)

    Blanchard, P. K.; Berger, E.; Fong, W.; Nicholl, M.; Leja, J.; Conroy, C.; Alexander, K. D.; Margutti, R.; Williams, P. K. G.; Doctor, Z.; Chornock, R.; Villar, V. A.; Cowperthwaite, P. S.; Annis, J.; Brout, D.; Brown, D. A.; Chen, H. -Y.; Eftekhari, T.; Frieman, J. A.; Holz, D. E.; Metzger, B. D.; Rest, A.; Sako, M.; Soares-Santos, M.

    2017-10-16

    We present the properties of NGC 4993, the host galaxy of GW170817, the first gravitational wave (GW) event from the merger of a binary neutron star (BNS) system and the first with an electromagnetic (EM) counterpart. We use both archival photometry and new optical/near-IR imaging and spectroscopy, together with stellar population synthesis models to infer the global properties of the host galaxy. We infer a star formation history peaked at $\\gtrsim 10$ Gyr ago, with subsequent exponential decline leading to a low current star formation rate of 0.01 M$_{\\odot}$ yr$^{-1}$, which we convert into a binary merger timescale probability distribution. We find a median merger timescale of $11.2^{+0.7}_{-1.4}$ Gyr, with a 90% confidence range of $6.8-13.6$ Gyr. This in turn indicates an initial binary separation of $\\approx 4.5$ R$_{\\odot}$, comparable to the inferred values for Galactic BNS systems. We also use new and archival $Hubble$ $Space$ $Telescope$ images to measure a projected offset of the optical counterpart of $2.1$ kpc (0.64$r_{e}$) from the center of NGC 4993 and to place a limit of $M_{r} \\gtrsim -7.2$ mag on any pre-existing emission, which rules out the brighter half of the globular cluster luminosity function. Finally, the age and offset of the system indicates it experienced a modest natal kick with an upper limit of $\\sim 200$ km s$^{-1}$. Future GW$-$EM observations of BNS mergers will enable measurement of their population delay time distribution, which will directly inform their viability as the dominant source of $r$-process enrichment in the Universe.

  13. The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/Virgo GW170817. VII. Properties of the Host Galaxy and Constraints on the Merger Timescale

    Science.gov (United States)

    Blanchard, P. K.; Berger, E.; Fong, W.; Nicholl, M.; Leja, J.; Conroy, C.; Alexander, K. D.; Margutti, R.; Williams, P. K. G.; Doctor, Z.; Chornock, R.; Villar, V. A.; Cowperthwaite, P. S.; Annis, J.; Brout, D.; Brown, D. A.; Chen, H.-Y.; Eftekhari, T.; Frieman, J. A.; Holz, D. E.; Metzger, B. D.; Rest, A.; Sako, M.; Soares-Santos, M.

    2017-10-01

    We present the properties of NGC 4993, the host galaxy of GW170817, the first gravitational-wave (GW) event from the merger of a binary neutron star (BNS) system and the first with an electromagnetic (EM) counterpart. We use both archival photometry and new optical/near-IR imaging and spectroscopy, together with stellar population synthesis models to infer the global properties of the host galaxy. We infer a star formation history peaked at ≳ 10 {Gyr} ago, with subsequent exponential decline leading to a low current star formation rate of 0.01 {M}⊙ yr-1, which we convert into a binary merger timescale probability distribution. We find a median merger timescale of {11.2}-1.4+0.7 Gyr, with a 90% confidence range of 6.8{--}13.6 {Gyr}. This in turn indicates an initial binary separation of ≈ 4.5 {R}⊙ , comparable to the inferred values for Galactic BNS systems. We also use new and archival Hubble Space Telescope images to measure a projected offset of the optical counterpart of 2.1 kpc (0.64r e ) from the center of NGC 4993 and to place a limit of {M}r≳ -7.2 mag on any pre-existing emission, which rules out the brighter half of the globular cluster luminosity function. Finally, the age and offset of the system indicates it experienced a modest natal kick with an upper limit of ˜200 km s-1. Future GW-EM observations of BNS mergers will enable measurement of their population delay time distribution, which will directly inform their viability as the dominant source of r-process enrichment in the universe.

  14. HAZMAT. II. Ultraviolet Variability of Low-mass Stars in the GALEX Archive

    Science.gov (United States)

    Miles, Brittany E.; Shkolnik, Evgenya L.

    2017-08-01

    The ultraviolet (UV) light from a host star influences a planet’s atmospheric photochemistry and will affect interpretations of exoplanetary spectra from future missions like the James Webb Space Telescope. These effects will be particularly critical in the study of planetary atmospheres around M dwarfs, including Earth-sized planets in the habitable zone. Given the higher activity levels of M dwarfs compared to Sun-like stars, time-resolved UV data are needed for more accurate input conditions for exoplanet atmospheric modeling. The Galaxy Evolution Explorer (GALEX) provides multi-epoch photometric observations in two UV bands: near-ultraviolet (NUV; 1771-2831 Å) and far-ultraviolet (FUV; 1344-1786 Å). Within 30 pc of Earth, there are 357 and 303 M dwarfs in the NUV and FUV bands, respectively, with multiple GALEX observations. Simultaneous NUV and FUV detections exist for 145 stars in both GALEX bands. Our analyses of these data show that low-mass stars are typically more variable in the FUV than the NUV. Median variability increases with later spectral types in the NUV with no clear trend in the FUV. We find evidence that flares increase the FUV flux density far more than the NUV flux density, leading to variable FUV to NUV flux density ratios in the GALEX bandpasses.The ratio of FUV to NUV flux is important for interpreting the presence of atmospheric molecules in planetary atmospheres such as oxygen and methane as a high FUV to NUV ratio may cause false-positive biosignature detections. This ratio of flux density in the GALEX bands spans three orders of magnitude in our sample, from 0.008 to 4.6, and is 1 to 2 orders of magnitude higher than for G dwarfs like the Sun. These results characterize the UV behavior for the largest set of low-mass stars to date.

  15. HAZMAT. II. Ultraviolet Variability of Low-mass Stars in the GALEX Archive

    Energy Technology Data Exchange (ETDEWEB)

    Miles, Brittany E. [Department of Astronomy and Astrophysics, University of California, 1156 High Street, Santa Cruz, CA 95064 (United States); Shkolnik, Evgenya L., E-mail: bmiles@ucsc.edu [School of Earth and Space Exploration, Arizona State University, 781 S Terrace Road, Tempe, AZ 85281 (United States)

    2017-08-01

    The ultraviolet (UV) light from a host star influences a planet’s atmospheric photochemistry and will affect interpretations of exoplanetary spectra from future missions like the James Webb Space Telescope . These effects will be particularly critical in the study of planetary atmospheres around M dwarfs, including Earth-sized planets in the habitable zone. Given the higher activity levels of M dwarfs compared to Sun-like stars, time-resolved UV data are needed for more accurate input conditions for exoplanet atmospheric modeling. The Galaxy Evolution Explorer ( GALEX ) provides multi-epoch photometric observations in two UV bands: near-ultraviolet (NUV; 1771–2831 Å) and far-ultraviolet (FUV; 1344–1786 Å). Within 30 pc of Earth, there are 357 and 303 M dwarfs in the NUV and FUV bands, respectively, with multiple GALEX observations. Simultaneous NUV and FUV detections exist for 145 stars in both GALEX bands. Our analyses of these data show that low-mass stars are typically more variable in the FUV than the NUV. Median variability increases with later spectral types in the NUV with no clear trend in the FUV. We find evidence that flares increase the FUV flux density far more than the NUV flux density, leading to variable FUV to NUV flux density ratios in the GALEX bandpasses.The ratio of FUV to NUV flux is important for interpreting the presence of atmospheric molecules in planetary atmospheres such as oxygen and methane as a high FUV to NUV ratio may cause false-positive biosignature detections. This ratio of flux density in the GALEX bands spans three orders of magnitude in our sample, from 0.008 to 4.6, and is 1 to 2 orders of magnitude higher than for G dwarfs like the Sun. These results characterize the UV behavior for the largest set of low-mass stars to date.

  16. Low-amplitude Variables: Distinguishing RR Lyrae Stars from Eclipsing Binaries

    Science.gov (United States)

    Kinman, T. D.; Brown, Warren R.

    2010-05-01

    It is not easy to identify and classify low-amplitude variables, but it is important that the classification is done correctly. We use photometry and spectroscopy to classify low-amplitude variables in a 246 deg2 part of the Akerlof et al. field. Akerlof and Collaborators found that 38% of the RR Lyrae stars in their 2000 deg2 test field were RR1 (type c). This suggests that these RR Lyrae stars belong to an Oosterhoff Type II population, while their period distribution is primarily Oosterhoff Type I. Our observations support their RR0 (type ab) classifications; however, six of the seven stars that they classified as RR1 (type c) are eclipsing binaries. Our classifications are supported by spectroscopic metallicities, line-broadening, and Galactic rotation measurements. Our 246 deg2 field contains 16 RR Lyrae stars that are brighter than mR = 14.5; only four of these are RR1 (type c). This corresponds to an Oosterhoff Type I population in agreement with the period distribution.

  17. New variable stars discovered in the fields of three Galactic open clusters using the VVV survey

    Science.gov (United States)

    Palma, T.; Minniti, D.; Dékány, I.; Clariá, J. J.; Alonso-García, J.; Gramajo, L. V.; Ramírez Alegría, S.; Bonatto, C.

    2016-11-01

    This project is a massive near-infrared (NIR) search for variable stars in highly reddened and obscured open cluster (OC) fields projected on regions of the Galactic bulge and disk. The search is performed using photometric NIR data in the J-, H- and Ks- bands obtained from the Vista Variables in the Vía Láctea (VVV) Survey. We performed in each cluster field a variability search using Stetson's variability statistics to select the variable candidates. Later, those candidates were subjected to a frequency analysis using the Generalized Lomb-Scargle and the Phase Dispersion Minimization algorithms. The number of independent observations range between 63 and 73. The newly discovered variables in this study, 157 in total in three different known OCs, are classified based on their light curve shapes, periods, amplitudes and their location in the corresponding color-magnitude (J -Ks ,Ks) and color-color (H -Ks , J - H) diagrams. We found 5 possible Cepheid stars which, based on the period-luminosity relation, are very likely type II Cepheids located behind the bulge. Among the newly discovered variables, there are eclipsing binaries, δ Scuti, as well as background RR Lyrae stars. Using the new version of the Wilson & Devinney code as well as the "Physics Of Eclipsing Binaries" (PHOEBE) code, we analyzed some of the best eclipsing binaries we discovered. Our results show that these studied systems turn out to be ranging from detached to double-contact binaries, with low eccentricities and high inclinations of approximately 80°. Their surface temperatures range between 3500 K and 8000 K.

  18. Early-20th-century visual observations of M13 variable stars

    Science.gov (United States)

    Osborn, W.; Barnard, E. E.

    2016-08-01

    In 1900 E. E. Barnard published 37 visual observations of Variable 2 (V2) in the globular clustter M13 made in 1899 and 1900. A review of Barnard's notebooks revealed he made many additional brightness estimates up to 1911, and he had also recorded the variations of V1 starting in 1904. These data provide the earliest-epoch light curves for these stars and thus are useful for studying their period changes. This paper presents Barnard's observations of the M13 variables along with their derived heliocentric Julian Dates and approximate V magnitudes. These include 231 unpublished observations of V2 and 94 of V1. How these data will be of value for determing period changes by these stars is described.

  19. The ancient stellar population of M 32: RR Lyrae variable stars confirmed

    Science.gov (United States)

    Fiorentino, G.; Contreras Ramos, R.; Tolstoy, E.; Clementini, G.; Saha, A.

    2012-03-01

    Using archival multi-epoch ACS/WFC images in the F606W and F814W filters of a resolved stellar field in Local Group dwarf elliptical galaxy M 32 we have made an accurate colour-magnitude diagram and a careful search for RR Lyr variable stars. We identified 416 bona fide RR Lyr stars over our field of view, and their spatial distribution shows a rising number density towards the centre of M 32. These new observations clearly confirm the tentative result of Fiorentino et al. (2010b, ApJ, 708, 817), on a much smaller field of view, associating an ancient population of RR Lyr variables to M 32. We associate at least 83 RR Lyr stars in our field to M 32. In addition the detection of 4 anomalous Cepheids with masses in the range 1.2-1.9 M⊙ indicates the presence of relatively young, 1-4 Gyr old, stars in this field. They are most likely associated to the presence of the blue plume in the colour-magnitude diagram. However these young stars are unlikely to be associated with M 32 because the radial distribution of the blue plume does not follow the M 32 density profile, and thus they are more likely to belong to the underlying M 31 stellar population. Finally the detection of 3 Population II Cepheids in this field gives an independent measurement of the distance modulus in good agreement with that obtained from the RR Lyr, μ0 = 24.33 ± 0.21 mag. Full Table 2 is available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/539/A138

  20. Automated Classification of Variable Stars in the Asteroseismology Program of the Kepler Space Mission

    DEFF Research Database (Denmark)

    Blomme, J.; Debosscher, J.; De Ridder, J.

    2010-01-01

    We present the first results of the application of supervised classification methods to the Kepler Q1 long-cadence light curves of a subsample of 2288 stars measured in the asteroseismology program of the mission. The methods, originally developed in the framework of the CoRoT and Gaia space...... missions, are capable of identifying the most common types of stellar variability in a reliable way. Many new variables have been discovered, among which a large fraction are eclipsing/ellipsoidal binaries unknown prior to launch. A comparison is made between our classification from the Kepler data...

  1. Examining the infrared variable star population discovered in the Small Magellanic Cloud using the SAGE-SMC survey

    Energy Technology Data Exchange (ETDEWEB)

    Polsdofer, Elizabeth; Marengo, M. [Iowa State University, Department of Physics and Astronomy, 12 Physics Hall, Ames, Iowa 50011 (United States); Seale, J.; Sewiło, M. [The Johns Hopkins University, Department of Physics and Astronomy, 366 Bloomberg Center, 3400 N. Charles Street, Baltimore, MD 21218 (United States); Vijh, U. P.; Terrazas, M. [Ritter Astrophysical Research Center, University of Toledo, Toledo, OH 43606 (United States); Meixner, M., E-mail: empolsdofer@gmail.com [Space Telescope Science Institute, 3700 San Martin Dr., Baltimore, MD 21218 (United States)

    2015-02-01

    We present our study on the infrared variability of point sources in the Small Magellanic Cloud (SMC). We use the data from the Spitzer Space Telescope Legacy Program “Surveying the Agents of Galaxy Evolution in the Tidally Stripped, Low Metallicity Small Magellanic Cloud” (SAGE-SMC) and the “Spitzer Survey of the Small Magellanic Cloud” (S{sup 3}MC) survey, over three different epochs, separated by several months to 3 years. Variability in the thermal infrared is identified using a combination of Spitzer’s InfraRed Array Camera 3.6, 4.5, 5.8, and 8.0 μm bands, and the Multiband Imaging Photometer for Spitzer 24 μm band. An error-weighted flux difference between each pair of three epochs (“variability index”) is used to assess the variability of each source. A visual source inspection is used to validate the photometry and image quality. Out of ∼2 million sources in the SAGE-SMC catalog, 814 meet our variability criteria. We matched the list of variable star candidates to the catalogs of SMC sources classified with other methods, available in the literature. Carbon-rich Asymptotic Giant Branch (AGB) stars make up the majority (61%) of our variable sources, with about a third of all of our sources being classified as extreme AGB stars. We find a small, but significant population of oxygen-rich (O-rich) AGB (8.6%), Red Supergiant (2.8%), and Red Giant Branch (<1%) stars. Other matches to the literature include Cepheid variable stars (8.6%), early type stars (2.8%), Young-stellar objects (5.8%), and background galaxies (1.2%). We found a candidate OH maser star, SSTISAGE1C J005212.88-730852.8, which is a variable O-rich AGB star, and would be the first OH/IR star in the SMC, if confirmed. We measured the infrared variability of a rare RV Tau variable (a post-AGB star) that has recently left the AGB phase. 59 variable stars from our list remain unclassified.

  2. Orbital variations and outbursts of the unusual variable star V1129 Centauri

    Science.gov (United States)

    Bruch, Albert

    2017-11-01

    The variable star V1129 Cen is classified in the GCVS as being of β Lyr type. Unusual for such stars, it exhibits outbursts roughly once a year, lasting for ∼ 40 days. For this reason, a relationship to the dwarf novae has been suspected. Here, for the first time a detailed analysis of the light curve of the system is presented. Based on observations with high time resolution obtained at the Observatório do Pico dos Dias and on the long term ASAS light curve the orbital variations of the system are studied. They are dominated by ellipsoidal variations and partial eclipses of a probably slightly evolved F2 star in a binary with an orbital period of 21h 26m. Comparison with the characteristics of dwarf novae show that the observational properties of V1129 Cen can be explained if it is just another dwarf novae, albeit with an unusually bright and early type mass donor which outshines the accretion disk and the mass gainer to a degree that many normal photometric and spectroscopic hallmarks of cataclysmic variables remain undetected.

  3. Variable Stars in (Not Only) Dwarf Galaxies: Key Tools to Constrain Distances and Stellar Content

    Science.gov (United States)

    Fiorentino, G.

    2011-07-01

    The important role of Cepheid and RR Lyrae variable stars and what they teach us about dwarf galaxies is discussed. Despite ever improving star formation histories of Local Group dwarf galaxies uncertainties remain, in particular in the identification and characterisation of the oldest stellar populations. The old stellar populations sometimes can be hard to interpret, or even to detect, due to their inherent faintness and scarcity, and often a strong overlying young population makes the crowding due to much brighter stars difficult to overcome. Recent and some preliminary results for RR Lyrae searches (in M 32 and Leo A) carried out with HST and Gemini-North/GMOS are presented. In these cases variables represent the only way to constrain the nature and, sometimes, the presence of a stellar population ≥10 Gyrs old. The recent discovery of Cepheids in I Zw 18 with HST is discussed. This allowed the first accurate distance determination, enabling a more secure detection of the Tip of the Red Giant Branch, and confirmed the existence of a population ≥2 Gyrs old.

  4. Homogeneous Photometry VI: Variable Stars in the Leo I Dwarf Spheroidal Galaxy

    Science.gov (United States)

    Stetson, Peter B.; Fiorentino, Giuliana; Bono, Giuseppe; Bernard, Edouard J.; Monelli, Matteo; Iannicola, Giacinto; Gallart, Carme; Ferraro, Ivan

    2014-07-01

    We have characterized the pulsation properties of 164 candidate RR Lyrae variables (RRLs) and 55 candidate Anomalous and/or short-period Cepheids in Leo I dwarf spheroidal galaxy. On the basis of its RRLs Leo I is confirmed to be an Oosterhoff-intermediate type galaxy, like several other dwarfs. We show that in their pulsation properties, the RRLs representing the oldest stellar population in the galaxy are not significantly different from those of five other nearby, isolated dwarf spheroidal galaxies. A similar result is obtained when comparing them to RR Lyrae stars in recently discovered ultra-faint dwarf galaxies. We are able to compare the period distributions and period-amplitude relations for a statistically significant sample of ab type RR Lyrae stars in dwarf galaxies (~1300stars) with those in the Galactic halo field (~14,000stars) and globular clusters (~1000stars). Field RRLs show a significant change in their period distribution when moving from the inner (dG14kpc) halo regions. This suggests that the halo formed from (at least) two dissimilar progenitors or types of progenitor. Considered together, the RRLs in classical dwarf spheroidal and ultra-faint dwarf galaxies-as observed today-do not appear to follow the well defined pulsation properties shown by those in either the inner or the outer Galactic halo, nor do they have the same properties as RRLs in globular clusters. In particular, the samples of fundamental-mode RRLs in dwarfs seem to lack High Amplitudes and Short Periods ("HASP":AV>1.0mag and P <0.48d) when compared with those observed in the Galactic halo field and globular clusters. The observed properties of RRLs do not support the idea that currently existing classical dwarf spheroidal and ultra-faint dwarf galaxies are surviving representative examples of the original building blocks of the Galactic halo.

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

    Science.gov (United States)

    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.

  6. First-Ever Census of Variable Mira-Type Stars in Galaxy Outside the Local Group

    Science.gov (United States)

    2003-05-01

    First-Ever Census of Variable Mira-Type Stars in Galaxy Outsidethe Local Group Summary An international team led by ESO astronomer Marina Rejkuba [1] has discovered more than 1000 luminous red variable stars in the nearby elliptical galaxy Centaurus A (NGC 5128) . Brightness changes and periods of these stars were measured accurately and reveal that they are mostly cool long-period variable stars of the so-called "Mira-type" . The observed variability is caused by stellar pulsation. This is the first time a detailed census of variable stars has been accomplished for a galaxy outside the Local Group of Galaxies (of which the Milky Way galaxy in which we live is a member). It also opens an entirely new window towards the detailed study of stellar content and evolution of giant elliptical galaxies . These massive objects are presumed to play a major role in the gravitational assembly of galaxy clusters in the Universe (especially during the early phases). This unprecedented research project is based on near-infrared observations obtained over more than three years with the ISAAC multi-mode instrument at the 8.2-m VLT ANTU telescope at the ESO Paranal Observatory . PR Photo 14a/03 : Colour image of the peculiar galaxy Centaurus A . PR Photo 14b/03 : Location of the fields in Centaurus A, now studied. PR Photo 14c/03 : "Field 1" in Centaurus A (visual light; FORS1). PR Photo 14d/03 : "Field 2" in Centaurus A (visual light; FORS1). PR Photo 14e/03 : "Field 1" in Centaurus A (near-infrared; ISAAC). PR Photo 14f/03 : "Field 2" in Centaurus A (near-infrared; ISAAC). PR Photo 14g/03 : Light variation of six variable stars in Centaurus A PR Photo 14h/03 : Light variation of stars in Centaurus A (Animated GIF) PR Photo 14i/03 : Light curves of four variable stars in Centaurus A. Mira-type variable stars Among the stars that are visible in the sky to the unaided eye, roughly one out of three hundred (0.3%) displays brightness variations and is referred to by astronomers as a

  7. The ISLAnds Project. III. Variable Stars in Six Andromeda Dwarf Spheroidal Galaxies

    Science.gov (United States)

    Martínez-Vázquez, Clara E.; Monelli, Matteo; Bernard, Edouard J.; Gallart, Carme; Stetson, Peter B.; Skillman, Evan D.; Bono, Giuseppe; Cassisi, Santi; Fiorentino, Giuliana; McQuinn, Kristen B. W.; Cole, Andrew A.; McConnachie, Alan W.; Martin, Nicolas F.; Dolphin, Andrew E.; Boylan-Kolchin, Michael; Aparicio, Antonio; Hidalgo, Sebastian L.; Weisz, Daniel R.

    2017-12-01

    We present a census of variable stars in six M31 dwarf spheroidal satellites observed with the Hubble Space Telescope. We detect 870 RR Lyrae (RRL) stars in the fields of And I (296), II (251), III (111), XV (117), XVI (8), and XXVIII (87). We also detect a total of 15 Anomalous Cepheids, three eclipsing binaries, and seven field RRL stars compatible with being members of the M31 halo or the Giant Stellar Stream. We derive robust and homogeneous distances to the six galaxies using different methods based on the properties of the RRL stars. Working with the up-to-date set of Period-Wesenheit (I, B-I) relations published by Marconi et al., we obtain distance moduli of μ 0 = [24.49, 24.16, 24.36, 24.42, 23.70, 24.43] mag (respectively), with systematic uncertainties of 0.08 mag and statistical uncertainties <0.11 mag. We have considered an enlarged sample of 16 M31 satellites with published variability studies, and compared their pulsational observables (e.g., periods and amplitudes) with those of 15 Milky Way satellites for which similar data are available. The properties of the (strictly old) RRL in both satellite systems do not show any significant difference. In particular, we found a strikingly similar correlation between the mean period distribution of the fundamental RRL pulsators (RRab) and the mean metallicities of the galaxies. This indicates that the old RRL progenitors were similar at the early stage in the two environments, suggesting very similar characteristics for the earliest stages of evolution of both satellite systems. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with programs 13028 and 13739.

  8. A Comprehensive GALEX Catalog of UV Variable Hot Stars with Broad Science Applications

    Science.gov (United States)

    Bianchi, Luciana

    The Galaxy Evolution Explorer (GALEX) has performed sky surveys in the Ultraviolet (UV) with different depth and coverage. Its database of about 300 million photometric source measurements in far-UV and near-UV offers unique sensitivity for identifying and studying classes of astrophysical objects such as hot stars, star-forming galaxies, and zMCP detectors. Until now, only integrated images and photometry from each observation were available in the public archive. Now it is possible to search through the photon list, and extract photometry with chosen time integrations for a given source. Such facility opens up unprecedented opportunities for investigations of short-term UV variability, serendipitous and unbiased, over samples orders-of-magnitude larger than any dedicated variability search could afford, and the only one in the UV. We will search for variability on all time scales afforded by the database (from seconds to the >9 years of GALEX operations), but especially on the fast cadences, for all hot stellar sources in the GALEX database. Most of these are very hot white dwarfs (WD), elusive at all wavelengths except the UV owing to their small radii and hot temperatures. We have identified about half a million hot WD candidates in the GALEX database, with corollary data at longer wavelengths. The GALEX-selected hot-WD samples are orders of magnitude larger than previous catalogs, and unbiased thanks to the UV selection (e.g., Bianchi et al. 2011a). Of particular interest are the hot WDs in binaries with a cooler (less evolved) star, uniquely identified and characterized from matched UV-À

  9. VizieR Online Data Catalog: Updated catalog of variable stars in globular clusters (Clement+ 2017)

    Science.gov (United States)

    Clement, C. M.

    2017-02-01

    This Catalogue is an update to Helen Sawyer Hogg's Third Catalogue on Variable Stars in Globular Clusters (1973, David Dunlap Observatory Publications, Volume 3, Number 6: 1973PDDO....3....6S; see Cat V/97; see also Clement+, 2001AJ....122.2587C). This catalogue is based on the individual cluster files downloaded on http://www.astro.utoronto.ca/~cclement/cat/listngc.html on the 01-Feb-2017. Later updates are indicated in clusters.dat; column "Update". (7 data files).

  10. Effect of process variables on the osmotic dehydration of star-fruit slices

    Directory of Open Access Journals (Sweden)

    Camila Dalben Madeira Campos

    2012-06-01

    Full Text Available The objective of this work was to study the effect of blanching and the influence of temperature, solution concentration, and the initial fruit:solution ratio on the osmotic dehydration of star-fruit slices. For blanching, different concentrations of citric and ascorbic acids were studied. The samples immersed in 0.75% citric acid presented little variation in color in relation to the fresh star-fruit. Osmotic dehydration was carried out in an incubator with orbital shaking, controlled temperature, and constant shaking at 120 rpm. The influence of process variables was studied in trials defined by a complete 23 central composite design. In general, water loss and solids gain were positively influenced by temperature and by solution concentration. Nevertheless, lower temperatures reduced water loss throughout the osmotic dehydration process. An increase in the amount of dehydrating solution (initial fruit:solution ratio slightly influenced the evaluated responses. The process carried out at 50 ºC with a solution concentration of 50% resulted in a product with lower solids gain and greater water loss. Under these conditions, blanching minimized the effect of the osmotic treatment on star-fruit browning, and therefore the blanched fruits showed little variation in color in relation to the fresh fruit.

  11. RR Lyrae variable stars in M31-M33 super-halo

    Science.gov (United States)

    Tanakul, Nahathai; Sarajedini, Ata

    2017-01-01

    RR Lyrae variable stars can serve as powerful probes of their host stellar populations. Information such as distance, metallicity, reddening, and age can be gleaned from their pulsation properties. Therefore, studying them in the nearest spiral galaxies M31 and M33 will yield important information about the early history of these galaxies. The main goals of this study are: 1) To investigate the Oosterhoff type of RR Lyrae stars in M31 and M33 and compare them with the Milky Way to better understand the formation of these galaxies. 2) To investigate the early formation history of these two galaxies through knowledge of their RR Lyrae stars. In order to achieve these goals, we have analyzed 10 fields in M31 and M33 (6 fields in M31 and 4 fields in M33) 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. The results are then compared with those in the Milky Way galaxy.

  12. The optical gravitational lensing experiment. Variable stars in globular clusters. I. Fields 5139A-C in ω Centauri.

    Science.gov (United States)

    Kaluzny, J.; Kubiak, M.; Szymanski, M.; Udalski, A.; Krzeminski, W.; Mateo, M.

    1996-11-01

    Three fields covering the central part of the globular cluster ω Cen were surveyed in a search for variable stars. We present V-band light curves for 39 periodic variables: 24 SX Phe stars, 7 contact binaries, 5 detached or semi-detached binaries, and 3 likely spotted variables (FK Com or RS CVn type stars). Only 2 of these variables were previously known. All SX Phe stars and all contact binaries from our sample belong to blue stragglers. Observed properties of these stars are consistent with their cluster membership. Of particular interest is detection of two well detached binaries with periods P=1.50day and P=2.47day. Further study of these two binaries can provide direct information about properties of turnoff stars in ω Cen. An incomplete light curve of a Mira variable known as V2 was obtained. We present V vs. V-I color-magnitude diagrams for the monitored part of the cluster.

  13. Application of multivariate analysis methods to search for variable stars in the Pi of the Sky experiment

    Science.gov (United States)

    Obara, Lukasz

    2017-08-01

    The purpose of this article is to present novel algorithm for searching variable stars in the Pi of the Sky data, based on Multivariate Analysis (MVA). Pi of the Sky is a system of wide field-of-view robotic telescopes, which search for short timescale astrophysical phenomena, especially for prompt optical emission from GRB. The system was designed for autonomous operation, monitoring a large fraction of the sky with 12m -13m range and time resolution of the order of 1 - 100 seconds. Dedicated photometric algorithm was implemented in the LUIZA framework and optimized on a sample of test sky images. It was then used on a "training" image sample, which was obtained by modifying the test sample of images, using different patterns of variability to selected constant stars. Different statistical estimators were considered to find the most efficient algorithm, based on MVA method, for variable star identification. Analysis of the test results indicated that most efficient candidate star selection can be based on the so called Boosted Decision Tree (BDT) approach. The algorithm is then used to search for variable star candidates in the actual data. New results of the analysis and three candidate stars found are presented.

  14. The Gaia spectrophotometric standard stars survey - III. Short-term variability monitoring

    Science.gov (United States)

    Marinoni, S.; Pancino, E.; Altavilla, G.; Bellazzini, M.; Galleti, S.; Tessicini, G.; Valentini, G.; Cocozza, G.; Ragaini, S.; Braga, V.; Bragaglia, A.; Federici, L.; Schuster, W. J.; Carrasco, J. M.; Castro, A.; Figueras, F.; Jordi, C.

    2016-11-01

    We present the results of the short-term constancy monitoring of candidate Gaia Spectrophotometric Standard Stars (SPSS). We obtained time series of typically 1.24 h - with sampling periods from 1-3 min to a few hours, depending on the case - to monitor the constancy of our candidate SPSS down to 10 mmag, as required for the calibration of Gaia photometric data. We monitored 162 out of a total of 212 SPSS candidates. The observing campaign started in 2006 and finished in 2015, using 143 observing nights on nine different instruments covering both hemispheres. Using differential photometry techniques, we built light curves with a typical precision of 4 mmag, depending on the data quality. As a result of our constancy assessment, 150 SPSS candidates were validated against short-term variability, and only 12 were rejected because of variability including some widely used flux standards such as BD+174708, SA 105-448, 1740346, and HD 37725.

  15. A recurrent neural network for classification of unevenly sampled variable stars

    Science.gov (United States)

    Naul, Brett; Bloom, Joshua S.; Pérez, Fernando; van der Walt, Stéfan

    2018-02-01

    Astronomical surveys of celestial sources produce streams of noisy time series measuring flux versus time (`light curves'). Unlike in many other physical domains, however, large (and source-specific) temporal gaps in data arise naturally due to intranight cadence choices as well as diurnal and seasonal constraints1-5. With nightly observations of millions of variable stars and transients from upcoming surveys4,6, efficient and accurate discovery and classification techniques on noisy, irregularly sampled data must be employed with minimal human-in-the-loop involvement. Machine learning for inference tasks on such data traditionally requires the laborious hand-coding of domain-specific numerical summaries of raw data (`features')7. Here, we present a novel unsupervised autoencoding recurrent neural network8 that makes explicit use of sampling times and known heteroskedastic noise properties. When trained on optical variable star catalogues, this network produces supervised classification models that rival other best-in-class approaches. We find that autoencoded features learned in one time-domain survey perform nearly as well when applied to another survey. These networks can continue to learn from new unlabelled observations and may be used in other unsupervised tasks, such as forecasting and anomaly detection.

  16. NuSTAR and XMM-Newton observations of NGC 1365: Extreme absorption variability and a constant inner accretion disk

    DEFF Research Database (Denmark)

    Walton, D. J.; Risaliti, G.; Harrison, F. A.

    2014-01-01

    We present a spectral analysis of four coordinated NuSTAR+XMM-Newton observations of the Seyfert galaxy NGC 1365. These exhibit an extreme level of spectral variability, which is primarily due to variable line-of-sight absorption, revealing relatively unobscured states in this source for the first...

  17. Haemophilus influenzae biotype VII.

    OpenAIRE

    Gratten, M

    1983-01-01

    A hitherto unreported biotype of Haemophilus influenzae is described. The isolate is noncapsulate and fails to decarboxylate ornithine or hydrolyze urea but is a strong indole producer. Its frequency is low. It is suggested that this newly recognized biotype of H. influenzae be designated biotype VII.

  18. The nova-like variable KQ Mon and the nature of the UX Ursa Majoris stars

    Science.gov (United States)

    Sion, E. M.; Guinan, E. F.

    1982-01-01

    The KQ Mon is a UX UMa type nova-like variable discovered by Howard Bond. Optical spectra taken by Bond in 1978 reveal very shallow Balmer absorption lines and He I absorption. Bond also did UBV and high speed photometry in 1978 and early 1981. There has been no evidence of orbital variations but the appearance of the optical spectrum and the presence of low amplitude flickering suggested a strong similarity to CD-42-14462 (=V3885 Sgr) and other members of the UX UMa class. Low dispersion observations of KQ Mon were made with the International Ultraviolet Explorer satellite. Six spectra taken with the shot wavelength prime camera are dominated by strong broad absorption lines due to N V, O I, Si III, Si IV, C IV, He II, N IV, and Al III. There is little evidence of orbital phase modulation over the time baseline of the observations. Unlike UV observations of other UX UMa type objects, KQ Mon exhibits no emission lines or P Cygni type profiles and the velocity displacements appear to be smaller, suggesting the absence of a hot, high velocity wind characterizing other UX UMa stars. The relationship of KQ Mon to other UX UMa disk stars is discussed and a model is suggested to explain their observed properties and the lack of major outbursts.

  19. Radial-Velocity Variability of the Sun as a Star with HAPRS And HAPRS-N

    Science.gov (United States)

    Haywood, Raphaëlle D.; Collier Cameron, Andrew; Dumusque, Xavier; Glenday, Alex; Latham, David W.; Lovis, Christophe; Maldonado, Jesus; Micela, Giusi; Molinari, Emiliano; Mortier, Annelies; Pepe, Francesco; Phillips, David F.; Udry, Stephane

    2016-06-01

    Since we can resolve the surface of the Sun directly, we can explore the origin of radial-velocity variations induced by individual solar surface features such as faculae/plage, sunspots and granulation.I will present my recent investigation of the radial-velocity variations of the Sun as a star, based on high-resolution HARPS spectra of reflected sunlight and simultaneous images from the Solar Dynamics Observatory. We found that faculae are the dominant source of activity-induced radial-velocity variations, via suppression of convective blueshift. We investigated possible proxies for activity-induced radial-velocity variations and found that optical lightcurves can only provide a partial representation of these signals; the full-disc magnetic flux, however, is an excellent tracer. In addition to this dataset, the HARPS-N spectrograph has been operating with a new solar telescope feed since 2015 July. I will present results from the first year observations, which show radial-velocity variations of up to 7-8 m/s.Identifying proxies for solar radial-velocity variations is key to understanding the radial-velocity variability of other Sun-like stars, and is also essential for other investigations such as exoplanet detection surveys.

  20. Periodic Variability of Low-mass Stars in Sloan Digital Sky Survey Stripe 82

    Science.gov (United States)

    Becker, A. C.; Bochanski, J. J.; Hawley, S. L.; Ivezić, Ž.; Kowalski, A. F.; Sesar, B.; West, A. A.

    2011-04-01

    We present a catalog of periodic stellar variability in the "Stripe 82" region of the Sloan Digital Sky Survey. After aggregating and re-calibrating catalog-level data from the survey, we ran a period-finding algorithm (Supersmoother) on all point-source light curves. We used color selection to identify systems that are likely to contain low-mass stars, in particular M dwarfs and white dwarfs. In total, we found 207 candidates, the vast majority of which appear to be in eclipsing binary systems. The catalog described in this paper includes 42 candidate M dwarf/white dwarf pairs, four white dwarf pairs, 59 systems whose colors indicate they are composed of two M dwarfs and whose light-curve shapes suggest they are in detached eclipsing binaries, and 28 M dwarf systems whose light-curve shapes suggest they are in contact binaries. We find no detached systems with periods longer than 3 days, thus the majority of our sources are likely to have experienced orbital spin-up and enhanced magnetic activity. Indeed, 26 of 27 M dwarf systems that we have spectra for show signs of chromospheric magnetic activity, far higher than the 24% seen in field stars of the same spectral type. We also find binaries composed of stars that bracket the expected boundary between partially and fully convective interiors, which will allow the measurement of the stellar mass-radius relationship across this transition. The majority of our contact systems have short orbital periods, with small variance (0.02 days) in the sample near the observed cutoff of 0.22 days. The accumulation of these stars at short orbital period suggests that the process of angular momentum loss, leading to period evolution, becomes less efficient at short periods. These short-period systems are in a novel regime for studying the effects of orbital spin-up and enhanced magnetic activity, which are thought to be the source of discrepancies between mass-radius predictions and measurements of these properties in eclipsing

  1. Investigating the potential magnetic origin of wind variability in OB stars

    Science.gov (United States)

    David-Uraz, Alexandre

    2016-05-01

    In this thesis, the origin of large-scale structures in hot star winds, believed to be responsible for the presence of discrete absorption components (DACs) in the absorption troughs of ultraviolet resonance lines, is constrained using both observations and numerical simulations. These structures are understood as arising from bright regions on the stellar surface, although their physical cause remains unknown. First, we use high quality circular spectropolarimetric observations of 13 well-studied OB stars to evaluate the potential role of dipolar magnetic fields in producing DACs. We perform longitudinal field measurements and place limits on the field strength using Bayesian inference, assuming that it is dipolar. No magnetic field was detected within this sample. The derived constraints statistically refute any significant dynamical influence from a magnetic dipole on the wind for all of these stars, ruling out such fields as a cause for DACs. Second, we perform numerical simulations using bright spots constrained by broadband optical photometric observations. We calculate hydrodynamical wind models using three sets of spot sizes and strengths. Co-rotating interaction regions are yielded in each model, and radiative transfer shows that the properties of the variations in the UV resonance lines synthesized from these models are consistent with those found in observed UV spectra, establishing the first consistent link between UV spectroscopic line profile variability and photometric variations and thus supporting the bright spot paradigm (BSP). Finally, we develop and apply a phenomenological model to quantify the measurable effects co-rotating bright spots would have on broadband optical photometry and on the profiles of photospheric lines in optical spectra. This model can be used to evaluate the existence of these spots, and, in the event of their detection, characterize them. Furthermore, a tentative spot evolution model is presented. A preliminary analysis of

  2. Variable stars in the field of the open cluster NGC 6939

    Science.gov (United States)

    Maciejewski, G.; Georgiev, Ts.; Niedzielski, A.

    2008-05-01

    The results of CCD photometric survey performed with the 90/180 cm Schmidt-Cassegrain Telescope of the Nicolaus Copernicus University Astronomical Observatory in Piwnice (Poland) and the 70/172 cm Schmidt Telescope of the National Astronomical Observatory (NAO) at Rozhen (Bulgaria) of the field of the 1 Gyr old open cluster NGC 6939 are presented. Twenty two variable stars were detected, four of them previously known. Four eclipsing systems (3 detached and 1 contact binary) were found to be members of the cluster. Analysis of the brightness of the contact binary V20 strongly supports the distance to the cluster of 1.74 ± 0.20 kpc. The small population of contact binaries in NGC 6939 confirms also the relatively young age of the cluster.

  3. Results from the Rothney Astrophysical Observatory Variable Star Search Program: Background, Procedure, and Results from RAO Field 1

    Science.gov (United States)

    Williams, Michael D.; Milone, E. F.

    2013-12-01

    We describe a variable star search program and present the fully reduced results of a search in a 19 square degree (4.4 × 4.4) field centered on J2000 RA = 22:03:24, DEC= +18:54:32. The search was carried out with the Baker-Nunn Patrol Camera located at the Rothney Astrophysical Observatory in the foothills of the Canadian Rockies. A total of 26,271 stars were detected in the field, over a range of about 11-15 (instrumental) magnitudes. Our image processing made use of the IRAF version of the DAOPHOT aperture photometry routine and we used the ANOVA method to search for periodic variations in the light curves. We formally detected periodic variability in 35 stars, that we tentatively classify according to light curve characteristics: 6 EA (Algol), 5 EB (?? Lyrae), 19 EW (W UMa), and 5 RR (RR Lyrae) stars. Eleven of the detected variable stars have been reported previously in the literature. The eclipsing binary light curves have been analyzed with a package of light curve modeling programs and 25 have yielded converged solutions. Ten of these are of systems that are detached, 3 semi-detached, 10 overcontact, and 2 are of systems that appear to be in marginal contact. We discuss these results as well as the advantages and disadvantages of the instrument and of the program.

  4. Searching for variable stars in the cores of five metal-rich globular clusters using EMCCD observations

    DEFF Research Database (Denmark)

    Skottfelt, Jesper; Bramich, D. M.; Jaimes, R. Figuera

    2015-01-01

    In this paper, we present the analysis of time-series observations from 2013 and 2014 of five metal rich ([Fe/H] $>$ -1) globular clusters: NGC~6388, NGC~6441, NGC~6528, NGC~6638, and NGC~6652. The data have been used to perform a census of the variable stars in the central parts of these cluster...... Virginis stars, and the rest are long period semi-regular/irregular variables on the red giant branch. We have also detected the first double mode RR Lyrae in the cluster.......In this paper, we present the analysis of time-series observations from 2013 and 2014 of five metal rich ([Fe/H] $>$ -1) globular clusters: NGC~6388, NGC~6441, NGC~6528, NGC~6638, and NGC~6652. The data have been used to perform a census of the variable stars in the central parts of these clusters...... known or suspected variable stars in the central regions of the five clusters. Furthermore, we were able to identify, and in most cases classify 48, 49, 7, 8, and 2 previously unknown variables in NGC~6388, NGC~6441, NGC~6528, NGC~6638, and NGC~6652, respectively. Especially interesting is the case...

  5. Variability of Disk Emission in Pre-Main Sequence and Related Stars. II. Variability in the Gas and Dust Emission of the Herbig Fe Star SAO 206462

    Science.gov (United States)

    Sitko, Michael L.; Day, Amanda N.; Kimes, Robin L.; Beerman, Lori C.; Martus, Cameron; Lynch, David K.; Russell, Ray W.; Grady, Carol A.; Schneider, Glenn; Lisse, Carey M.; hide

    2011-01-01

    We present thirteen epochs of near-infrared (0.8-5 microns) spectroscopic observations of the pre-transitional, "gapped" disk system in SAO 206462 (=HD 135344B). In all, six gas emission lines (Br(alpha) , Br(gamma), Pa(beta), Pa(delta), Pa(epsilon), and the 0.8446 microns line of O I) along with continuum measurements made near the standard J, H, K, and L photometric bands were measured. A mass accretion rate of approximately 2 x 10(exp 8)Solar Mass/yr was derived from the Br(gamma) and Pa(beta) lines. However, the fluxes of these lines varied by a factor of over two during the course of a few months. The continuum also varied, but by only approx.30%, and even decreased at a time when the gas emission was increasing. The H I line at 1.083 microns was also found to vary in a manner inconsistent with that of either the hydrogen lines or the dust. Both the gas and dust variabilities indicate significant changes in the region of the inner gas and the inner dust belt that may be common to many young disk systems. If planets are responsible for defining the inner edge of the gap, they could interact with the material on time scales commensurate with what is observed for the variations in the dust, while other disk instabilities (thermal, magneto-rotational) would operate there on longer time scales than we observe for the inner dust belt. For SAO 206462, the orbital period would likely be 1-3 years. If the changes are being induced in the disk material closer to the star than the gap, a variety of mechanisms (disk instabilities, interactions via planets) might be responsible for the changes seen. The He I feature is most likely due to a wind whose orientation changes with respect to the observer on time scales of a day or less. To further constrain the origin of the gas and dust emission will require multiple spectroscopic and interferometric observations on both shorter and longer time scales that have been sampled so far.

  6. Globular cluster photometry with the Hubble Space Telescope. 3: Blue stragglers and variable stars in the core of M3

    Science.gov (United States)

    Guhathakurta, Puragra; Yanny, Brian; Bahcall, John N.; Schneider, Donald P.

    1994-01-01

    This paper describes Hubble Space Telescope (HST)/Planetary Camera-I images of the core of the dense globular cluster M3 (NGC 5272). Stellar photometry in the F555W (V) and F785LP (I) bands, with a 1-sigma photometric accuracy of about 0.1 mag, has been used to construct color-magnitude diagrams of about 4700 stars above the main-sequence turnoff within r less than or approximately equal to 1 min of the cluster center. We have also analyzed archival HST F336W (U) images of M3 obtained by the Wide Field/Planetary Camera-I Instrument Definition Team. The UVI data are used to identify 28 blue straggler (BS) stars within the central 0.29 sq. arcmin. The specific frequency of BSs in this region of M3, N(sub BS)/N(sub V less than (V(HB)+2)) = 0.094 +/- 0.019, is about a factor of 2 - 3 higher than that found by Bolte et al. in a recent ground-based study of the same region, but comparable to that seen in the sparse outer parts of the same cluster and in HST observations of the core of the higher density cluster 47 Tuc. The BSs in M3 are slightly more centrally concentrated than red giant branch stars while horizontal branch stars are somewhat less concentrated red giants. The radial distribution of V-selected subgiant and turnoff stars is well fit by a King model with a core radius r(sub core) = 28 arcmin +/- 2 arcmin (90% confidence limits), which corresponds to 1.4 pc. Red giant and horizontal branch stars selected in the ultraviolet data (U less than 18) have a somewhat more compact distribution (r(sub core) = 22.5 arcmin). The HST U data consist of 17 exposures acquired over a span of three days. We have used these data to isolate 40 variable stars for which relative astrometry, brightnesses, colors, and light curves are presented. A Kolmogorov-Smirnov test indicates that, typically, the variability for each star is significant at the 95% level. We identify two variable BS candidates (probably of the SX Phe type), out of a sample of approximately 25 BSs in which

  7. Long-term Variability of H2CO Masers in Star-forming Regions

    Science.gov (United States)

    Andreev, N.; Araya, E. D.; Hoffman, I. M.; Hofner, P.; Kurtz, S.; Linz, H.; Olmi, L.; Lorran-Costa, I.

    2017-10-01

    We present results of a multi-epoch monitoring program on variability of 6 cm formaldehyde (H2CO) masers in the massive star-forming region NGC 7538 IRS 1 from 2008 to 2015, conducted with the Green Bank Telescope, the Westerbork Radio Telescope , and the Very Large Array. We found that the similar variability behaviors of the two formaldehyde maser velocity components in NGC 7538 IRS 1 (which was pointed out by Araya and collaborators in 2007) have continued. The possibility that the variability is caused by changes in the maser amplification path in regions with similar morphology and kinematics is discussed. We also observed 12.2 GHz methanol and 22.2 GHz water masers toward NGC 7538 IRS 1. The brightest maser components of CH3OH and H2O species show a decrease in flux density as a function of time. The brightest H2CO maser component also shows a decrease in flux density and has a similar LSR velocity to the brightest H2O and 12.2 GHz CH3OH masers. The line parameters of radio recombination lines and the 20.17 and 20.97 GHz CH3OH transitions in NGC 7538 IRS 1 are also reported. In addition, we observed five other 6 cm formaldehyde maser regions. We found no evidence of significant variability of the 6 cm masers in these regions with respect to previous observations, the only possible exception being the maser in G29.96-0.02. All six sources were also observed in the {{{H}}}213{CO} isotopologue transition of the 6 cm H2CO line; {{{H}}}213{CO} absorption was detected in five of the sources. Estimated column density ratios [{{{H}}}212{CO}]/[{{{H}}}213{CO}] are reported.

  8. The spectral variability and magnetic field characteristics of the Of?p star HD 148937

    Science.gov (United States)

    Wade, G. A.; Grunhut, J.; Gräfener, G.; Howarth, I. D.; Martins, F.; Petit, V.; Vink, J. S.; Bagnulo, S.; Folsom, C. P.; Nazé, Y.; Walborn, N. R.; Townsend, R. H. D.; Evans, C. J.

    2012-01-01

    We report magnetic and spectroscopic observations and modelling of the Of?p star HD 148937 within the context of the Magnetism in Massive Stars (MiMeS) Large Program at the Canada-France-Hawaii Telescope. 32 high signal-to-noise ratio circularly polarized (Stokes V) spectra and 13 unpolarized (Stokes I) spectra of HD 148937 were acquired in 2009 and 2010. A definite detection of a Stokes V Zeeman signature is obtained in the grand mean of all observations [in both least-squares deconvolved (LSD) mean profiles and individual spectral lines]. The longitudinal magnetic field inferred from the Stokes V LSD profiles is consistently negative, in contrast to the essentially zero field strength measured from the diagnostic null profiles. A period search of new and archival equivalent width measurements confirms the previously reported 7.03 d variability period. The variation of equivalent widths is not strictly periodic: we present evidence for evolution of the amount or distribution of circumstellar plasma. Interpreting the 7.03 d period as the stellar rotational period within the context of the oblique rotator paradigm, we have phased the equivalent widths and longitudinal field measurements. The longitudinal field measurements show a weak sinusoidal variation of constant sign, with extrema out of phase with the Hα variation by about 0.25 cycles. From our constraint on v sin i≤ 45 km s-1, we infer that the rotational axis inclination i≤ 30°. Modelling the longitudinal field phase variation directly, we obtain the magnetic obliquity β= 38+17-28° and dipole polar intensity Bd= 1020-380+310 G. Simple modelling of the Hα equivalent width variation supports the derived geometry. The inferred magnetic configuration confirms the suggestion of Nazé et al., who proposed that the weaker variability of HD 148937 as compared to other members of this class is a consequence of the stellar geometry. Based on the derived magnetic properties and published wind characteristics

  9. Active optics: variable curvature mirrors for ELT laser guide star refocusing systems

    Science.gov (United States)

    Challita, Zalpha; Hugot, Emmanuel; Madec, Fabrice; Ferrari, Marc; Le Mignant, David; Vivès, Sébastien; Cuby, Jean-Gabriel

    2011-10-01

    The future generation of Extremely Large Telescopes will require a complex combination of technologies for adaptive optics (AO) systems assisted by laser guide stars (LGS). In this context, the distance from the LGS spot to the telescope pupil ranges from about 80 to 200 km, depending on the Sodium layer altitude and the elevation of the telescope. This variation leads to a defocusing effect on the LGS wave-front sensor which needs to be compensated. We propose an active mirror able to compensate for this variation, based on an original optical design including this active optics component. This LGS Variable Curvature Mirror (LGS-VCM) is a 120 mm spherical active mirror able to achieve 820 μm deflection sag with an optical quality better than 150 nm RMS, allowing the radius of curvature variation from F/12 to F/2. Based on elasticity theory, the deformation of the metallic mirror is provided by an air pressure applied on a thin meniscus with a variable thickness distribution. In this article, we detail the analytical development leading to the specific geometry of the active component, the results of finite element analysis and the expected performances in terms of surface error versus the range of refocalisation. Three prototypes have been manufactured to compare the real behavior of the mirror and the simulations data. Results obtained on the prototypes are detailed, showing that the deformation of the VCM is very close to the simulation, and leads to a realistic active concept.

  10. The multi-layer variable absorbers in NGC 1365 revealed by XMM-Newton and NuSTAR

    DEFF Research Database (Denmark)

    Rivers, E.; Risaliti, G.; Walton, D. J.

    2015-01-01

    Between 2012 July and 2013 February, NuSTAR and XMM-Newton performed four long-look joint observations of the type 1.8 Seyfert, NGC 1365. We have analyzed the variable absorption seen in these observations in order to characterize the geometry of the absorbing material. Two of the observations...

  11. The mass-metallicity relations for gas and stars in star-forming galaxies: strong outflow versus variable IMF

    Science.gov (United States)

    Lian, Jianhui; Thomas, Daniel; Maraston, Claudia; Goddard, Daniel; Comparat, Johan; Gonzalez-Perez, Violeta; Ventura, Paolo

    2018-02-01

    We investigate the mass-metallicity relations for the gaseous (MZRgas) and stellar components (MZRstar) of local star-forming galaxies based on a representative sample from Sloan Digital Sky Survey Data Release 12. The mass-weighted average stellar metallicities are systematically lower than the gas metallicities. This difference in metallicity increases towards galaxies with lower masses and reaches 0.4-0.8 dex at 109 M⊙ (depending on the gas metallicity calibration). As a result, the MZRstar is much steeper than the MZRgas. The much lower metallicities in stars compared to the gas in low-mass galaxies imply dramatic metallicity evolution with suppressed metal enrichment at early times. The aim of this paper is to explain the observed large difference in gas and stellar metallicity and to infer the origin of the mass-metallicity relations. To this end we develop a galactic chemical evolution model accounting for star formation, gas inflow and outflow. By combining the observed mass-metallicity relation for both gas and stellar components to constrain the models, we find that only two scenarios are able to reproduce the observations. Either strong metal outflow or a steep initial mass function (IMF) slope at early epochs of galaxy evolution is needed. Based on these two scenarios, for the first time we successfully reproduce the observed MZRgas and MZRstar simultaneously, together with other independent observational constraints in the local Universe. Our model also naturally reproduces the flattening of the MZRgas at the high-mass end leaving the MZRstar intact, as seen in observational data.

  12. The optical gravitational lensing experiment. Variable stars in globular clusters. IV. Fields 104A-E in 47 Tucanae

    Science.gov (United States)

    Kaluzny, J.; Kubiak, M.; Szymanski, M.; Udalski, A.; Krzeminski, W.; Mateo, M.; Stanek, K. Z.

    1998-02-01

    Five fields located close to the center of the globular cluster NGC 104=47 Tuc were surveyed in a search for variable stars. We present V-band light curves for 42 variables. This sample includes 13 RR Lyr stars - 12 of them belong to the Small Magellanic Cloud (SMC) and 1 is a background object from the galactic halo. Twelve eclipsing binaries were identified - 9 contact systems and 3 detached/semi-detached systems. Seven eclipsing binaries are located in the blue straggler region on the cluster color-magnitude diagram (CMD) and four binaries can be considered main-sequence systems. One binary is probably a member of the SMC. Eight contact binaries are likely members of the cluster and one is most probably a foreground star. We show that for the surveyed region of 47 Tuc, the relative frequency of contact binaries is very low as compared with other recently surveyed globular clusters. The sample of identified variables also includes 15 red variables with periods ranging from about 2 days to several weeks. A large fraction of these 15 variables probably belong to the SMC but a few stars are likely to be red giants in 47 Tuc. VI photometry for about 50 000 stars from the cluster fields was obtained as a by product of our survey The photometric data presented in this paper are available in electronic form at the CDS, via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/Abstract.html}. Based on observations collected at the Las Campanas Observatory of the Carnegie Institution of Washington.

  13. CSI 2264: Simultaneous optical and X-ray variability in pre-main sequence stars. I. Time resolved X-ray spectral analysis during optical dips and accretion bursts in stars with disks

    Science.gov (United States)

    Guarcello, M. G.; Flaccomio, E.; Micela, G.; Argiroffi, C.; Sciortino, S.; Venuti, L.; Stauffer, J.; Rebull, L.; Cody, A. M.

    2017-06-01

    Context. Pre-main sequence stars are variable sources. The main mechanisms responsible for their variability are variable extinction, unsteady accretion, and rotational modulation of both hot and dark photospheric spots and X-ray-active regions. In stars with disks, this variability is related to the morphology of the inner circumstellar region (≤0.1 AU) and that of the photosphere and corona, all impossible to be spatially resolved with present-day techniques. This has been the main motivation for the Coordinated Synoptic Investigation of NGC 2264, a set of simultaneous observations of NGC 2264 with 15 different telescopes. Aims: In this paper, we focus on the stars with disks. We analyze the X-ray spectral properties extracted during optical bursts and dips in order to unveil the nature of these phenomena. Stars without disks are studied in a companion paper. Methods: We analyze simultaneous CoRoT and Chandra/ACIS-I observations to search for coherent optical and X-ray flux variability in stars with disks. Then, stars are analyzed in two different samples. In stars with variable extinction, we look for a simultaneous increase of optical extinction and X-ray absorption during the optical dips; in stars with accretion bursts, we search for soft X-ray emission and increasing X-ray absorption during the bursts. Results: We find evidence for coherent optical and X-ray flux variability among the stars with variable extinction. In 9 of the 24 stars with optical dips, we observe a simultaneous increase of X-ray absorption and optical extinction. In seven dips, it is possible to calculate the NH/AV ratio in order to infer the composition of the obscuring material. In 5 of the 20 stars with optical accretion bursts, we observe increasing soft X-ray emission during the bursts that we associate to the emission of accreting gas. It is not surprising that these properties are not observed in all the stars with dips and bursts, since favorable geometric configurations are

  14. 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

    Science.gov (United States)

    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 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.

  15. Stellar parameters and H α line profile variability of Be stars in the BeSOS survey

    Science.gov (United States)

    Arcos, C.; Kanaan, S.; Chávez, J.; Vanzi, L.; Araya, I.; Curé, M.

    2018-03-01

    The Be phenomenon is present in about 20 per cent of B-type stars. Be stars show variability on a broad range of time-scales, which in most cases is related to the presence of a circumstellar disc of variable size and structure. For this reason, a time-resolved survey is highly desirable in order to understand the mechanisms of disc formation, which are still poorly understood. In addition, a complete observational sample would improve the statistical significance of the study of stellar and disc parameters. The `Be Stars Observation Survey' (BeSOS) is a survey containing reduced spectra obtained using the Pontifica Universidad Católica High Echelle Resolution Optical Spectrograph (PUCHEROS) with a spectral resolution of 17 000 in the range 4260-7300 Å. BeSOS's main objective is to offer consistent spectroscopic and time-resolved data obtained with one instrument. The user can download or plot the data and obtain stellar parameters directly from the website. We also provide a star-by-star analysis based on photometric, spectroscopic and interferometric data, as well as general information about the whole BeSOS sample. Recently, BeSOS led to the discovery of a new Be star HD 42167 and facilitated study of the V/R variation of HD 35165 and HD 120324, the steady disc of HD 110335 and the Be shell status of HD 127972. Optical spectra used in this work, as well as the stellar parameters derived, are available online at http://besos.ifa.uv.cl.

  16. The Kepler characterization of the variability among A- and F-type stars. - I: General overview

    NARCIS (Netherlands)

    Uytterhoeven, K.; Moya, A.; Grigahcène, A.; Guzik, J.A.; Gutiérrez-Soto, J.; Smalley, B.; Handler, G.; Balona, L.A.; Niemczura, E.; Fox Machado, L.; Benatti, S.; Chapellier, E.; Tkachenko, A.; Szabó, R.; Suárez, J.C.; Ripepi, V.; Pascual, J.; Mathias, P.; Martín-Ruíz, S.; Lehmann, H.; Jackiewicz, J.; Hekker, S.; Gruberbauer, M.; García, R.A.; Dumusque, X.; Díaz-Fraile, D.; Bradley, P.; Antoci, V.; Roth, M.; Leroy, B.; Murphy, S.J.; De Cat, P.; Cuypers, J.; Kjeldsen, H.; Christensen-Dalsgaard, J.; Breger, M.; Pigulski, A.; Kiss, L.L.; Still, M.; Thompson, S.E.; Van Cleve, J.

    2011-01-01

    Context. The Kepler spacecraft is providing time series of photometric data with micromagnitude precision for hundreds of A-F type stars. Aims. We present a first general characterization of the pulsational behaviour of A-F type stars as observed in the Kepler light curves of a sample of 750

  17. NuSTAR Detection of High-Energy X-Ray Emission and Rapid Variability from Sagittarius A(star) Flares

    Science.gov (United States)

    Barriere, Nicolas M.; Tomsick, John A.; Baganoff, Frederick K.; Boggs, Steven E.; Christensen, Finn E.; Craig, William W.; Dexter, Jason; Grefenstette, Brian; Hailey, Charles J.; Zhang, William W.

    2014-01-01

    Sagittarius A(star) harbors the supermassive black hole that lies at the dynamical center of our Galaxy. Sagittarius A(star) spends most of its time in a low luminosity emission state but flares frequently in the infrared and X-ray, increasing up to a few hundred fold in brightness for up to a few hours at a time. The physical processes giving rise to the X-ray flares are uncertain. Here we report the detection with the NuSTAR observatory in Summer and Fall 2012 of four low to medium amplitude X-ray flares to energies up to 79 keV. For the first time, we clearly see that the power-law spectrum of Sagittarius A(star) X-ray flares extends to high energy, with no evidence for a cut off. Although the photon index of the absorbed power-law fits are in agreement with past observations, we find a difference between the photon index of two of the flares (significant at the 95% confidence level). The spectra of the two brightest flares (approx. 55 times quiescence in the 2- 10 keV band) are compared to simple physical models in an attempt to identify the main X-ray emission mechanism, but the data do not allow us to significantly discriminate between them. However, we confirm the previous finding that the parameters obtained with synchrotron models are, for the X-ray emission, physically more reasonable than those obtained with inverse-Compton models. One flare exhibits large and rapid (less than 100 s) variability, which, considering the total energy radiated, constrains the location of the flaring region to be within approx. 10 Schwarzschild radii of the black hole.

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

    Science.gov (United States)

    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.

  19. The Soft State of Cygnus X-1 Observed with NuSTAR: A Variable Corona and a Stable Inner Disk

    Science.gov (United States)

    Walton, D. J.; Tomsick, J. A.; Madsen, K. K.; Grinberg, V.; Barret, D.; Boggs, S. E.; Christensen, F. E.; Clavel, M.; Craig, W. W.; Fabian, A. C.; hide

    2016-01-01

    We present a multi-epoch hard X-ray analysis of Cygnus X-1 in its soft state based on four observations with the Nuclear Spectroscopic Telescope Array (NuSTAR). Despite the basic similarity of the observed spectra, there is clear spectral variability between epochs. To investigate this variability, we construct a model incorporating both the standard disk-corona continuum and relativistic reflection from the accretion disk, based on prior work on Cygnus X-1, and apply this model to each epoch independently. We find excellent consistency for the black hole spin and the iron abundance of the accretion disk, which are expected to remain constant on observational timescales. In particular, we confirm that Cygnus X-1 hosts a rapidly rotating black hole, 0.93 < approx. a* < approx. 0.96, in broad agreement with the majority of prior studies of the relativistic disk reflection and constraints on the spin obtained through studies of the thermal accretion disk continuum. Our work also confirms the apparent misalignment between the inner disk and the orbital plane of the binary system reported previously, finding the magnitude of this warp to be approx.10deg-15deg. This level of misalignment does not significantly change (and may even improve) the agreement between our reflection results and the thermal continuum results regarding the black hole spin. The spectral variability observed by NuSTAR is dominated by the primary continuum, implying variability in the temperature of the scattering electron plasma. Finally, we consistently observe absorption from ionized iron at approx. 6.7 keV, which varies in strength as a function of orbital phase in a manner consistent with the absorbing material being an ionized phase of the focused stellar wind from the supergiant companion star.

  20. Multi-Epoch Hubble Space Telescope Observations of IZw18: Characterization of Variable Stars at Ultra-Low Metallicities

    Science.gov (United States)

    Fiorentino, G.; Contreras Ramos, R.; Clementini, G.; Marconi, M.; Musella, I.; Aloisi, A.; Annibali, F.; Saha, A.; Tosi, M.; van der Marel, R. P.

    2010-03-01

    Variable stars have been identified for the first time in the very metal-poor blue compact dwarf galaxy IZw18, using deep multi-band (F606W, F814W) time-series photometry obtained with the Advanced Camera for Surveys on board the Hubble Space Telescope. We detected 34 candidate variable stars in the galaxy. We classify three of them as Classical Cepheids, with periods of 8.71, 125.0, and 130.3 days, respectively, and other two as long period variables with periodicities longer than 100 days. These are the lowest metallicity Classical Cepheids known so far, thus providing the opportunity to explore and fit models of stellar pulsation for Classical Cepheids at previously inaccessible metallicities. The period distribution of the confirmed Cepheids is markedly different from what is seen in other nearby galaxies, which is likely related to the star bursting nature of IZw18. The long period Cepheids we have detected in IZw18 seem to indicate that massive stars at the metallicity of IZw18 (Z = 0.0004) may cross the instability strip long enough to be observed. By applying to the 8.71 days Cepheid theoretical Wesenheit (V, I) relations based on new pulsation models of Classical Cepheids specifically computed for the extremely low metallicity of this galaxy (Z = 0.0004, Y = 0.24), we estimate the distance modulus of IZw18 to be μ0 = 31.4 ± 0.3 (D = 19.0+2.8 -2.5 Mpc) for canonical models of Classical Cepheids, and of 31.2 ± 0.3 mag (D = 17.4+2.6 -2.2 Mpc) using over luminous models. The theoretical modeling of the star's light curves provides μ0 = 31.4± 0.2 mag, D = 19.0+1.8 -1.7 Mpc, in good agreement with the results from the theoretical Wesenheit relations. These pulsation distances bracket the distance of 18.2 ±1.5 Mpc inferred by Aloisi et al. using the galaxy's red giant branch tip. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA Inc., under NASA contract NAS 5-26555.

  1. Astronomical Observatory at Kolonicke Sedlo and its Results in Variable Stars Observing

    Science.gov (United States)

    Kudzej, I.; Karetnikov, V. G.; Dubovsky, P. A.; Paulin, L. S.; Fashchevskyi, N. N.; Ryabov, A. V.; Dorokhova, T. N.; Dorokhov, N. I.; Koshkin, N. I.; Vadila, M.; Parimucha, S.

    There is presented a brief report of the actual equipments in the Astronomical Observa tory at the Kolonicke Sedlo. Description of Vihorlat National Telescope of 1 meter diameter equipped with the two-star high-speed photoelectric photometer and autoguiding system as well as various small telescopes capabilities are included. The results of CCD and PMT observations are presented. The future observational programs are presented as well.

  2. ASTRONOMICAL OBSERVATORY AT KOLONICKE SEDLO AND ITS RESULTS IN VARIABLE STARS OBSERVING

    OpenAIRE

    Kudzej, I.; Karetnikov, V. G.; Dubovsky, P. A.; Paulin, L. S.; Fashchevskyi, N. N.; Ryabov, A. V.; Dorokhova, T. N.; Dorokhov, N.I.; Koshkin, N. I.; Vadila, M.; Parimucha, S.

    2007-01-01

    There is presented a brief report of the actual equipments in the Astronomical Observa tory at the Kolonicke Sedlo. Description of Vihorlat National Telescope of 1 meter diameter equipped with the two-star high-speed photoelectric photometer and autoguiding system as well as various small telescopes capabilities are included. The results of CCD and PMT observations are presented. The future observational programs are presented as well.

  3. Self-assembly of star micelle into vesicle in solvents of variable quality: the star micelle retains its core-shell nanostructure in the vesicle.

    Science.gov (United States)

    Liu, Nijuan; He, Qun; Bu, Weifeng

    2015-03-03

    Intra- and intermolecular interactions of star polymers in dilute solutions are of fundamental importance for both theoretical interest and hierarchical self-assembly into functional nanostructures. Here, star micelles with a polystyrene corona and a small ionic core bearing platinum(II) complexes have been regarded as a model of star polymers to mimic their intra- and interstar interactions and self-assembled behaviors in solvents of weakening quality. In the chloroform/methanol mixture solvents, the star micelles can self-assemble to form vesicles, in which the star micelles shrink significantly and are homogeneously distributed on the vesicle surface. Unlike the morphological evolution of conventional amphiphiles from micellar to vesicular, during which the amphiphilic molecules are commonly reorganized, the star micelles still retain their core-shell nanostructures in the vesicles and the coronal chains of the star micelle between the ionic cores are fully interpenetrated.

  4. Rapid Spectral Variability of the Symbiotic Star CH Cyg During One Night

    Science.gov (United States)

    Mikayilov, Kh. M.; Rustamov, B. N.; Alakbarov, I. A.; Rustamova, A. B.

    2017-06-01

    During one night (15.07.2015), within 6 hours 14 echelle spectrograms of this star were obtained. It was revealed that the profile of Ha and Hβ lines have two-component emission structure with a central absorption, parameters which vary from spectrum to spectrum during the night. The intensity of blue emission component (V) have been changed strongly during the night: the value of ratio of intensities of violet and red components (V/R) of line Hα decreased from 0:93 to 0:49 in the beginning and then increased to a value of 0.97. The synchronous variations of values of V/R for the Hα and Hβ lines have been revealed. The parameters of blue emission components of Hα and of line Hel λ5876 Å are correlated. We propose that revealed by us the rapid spectral changes in the spectrum of the star CH Cyg could be connected with a flickering in the optical brightness of the star that is typical for the active phase of this system.

  5. Photometric and spectroscopic variability of the B5IIIe star HD 171219

    Science.gov (United States)

    Andrade, L.; Janot-Pacheco, E.; Emilio, M.; Frémat, Y.; Neiner, C.; Poretti, E.; Mathias, P.; Rainer, M.; Suárez, J. C.; Uytterhoeven, K.; Briquet, M.; Diago, P. D.; Fabregat, J.; Gutiérrez-Soto, J.

    2017-07-01

    We analyzed the star HD 171219, one of the relatively bright Be stars observed in the seismo field of the CoRoT satellite, in order to determine its physical and pulsation characteristics. Classical Be stars are main-sequence objects of mainly B-type, whose spectra show, or have shown at some epoch, Balmer lines in emission and an infrared excess. Both characteristics are attributed to an equatorially concentrated circumstellar disk fed by non-periodic mass-loss episodes (outbursts). Be stars often show nonradial pulsation gravity modes and, as more recently discovered, stochastically excited oscillations. Applying the CLEANEST algorithm to the high-cadence and highly photometrically precise measurements of the HD 171219 light curve led us to perform an unprecedented detailed analysis of its nonradial pulsations. Tens of frequencies have been detected in the object compatible with nonradial g-modes. Additional high-resolution ground-based spectroscopic observations were obtained at La Silla (HARPS) and Haute Provence (SOPHIE) observatories during the month preceding CoRoT observations. Additional information was obtained from low-resolution spectra from the BeSS database. From spectral line fitting we determined physical parameters of the star, which is seen equator-on (I = 90°). We also found in the ground data the same frequencies as in CoRoT data. Additionally, we analyzed the circumstellar activity through the traditional method of violet to red emission Hα line variation. A quintuplet was identified at approximately 1.113 c d-1 (12.88 μHz) with a separation of 0.017 c d-1 that can be attributed to a pulsation degree ℓ 2. The light curve shows six small- to medium-scale outbursts during the CoRoT observations. The intensity of the main frequencies varies after each outburst, suggesting a possible correlation between the nonradial pulsations regime and the feeding of the envelope. The CoRoT space mission was developed and operated by the French space agency

  6. Reducing the impact of insulin sensitivity variability on glycaemic outcomes using separate stochastic models within the STAR glycaemic protocol.

    Science.gov (United States)

    Thomas, Felicity; Pretty, Christopher G; Fisk, Liam; Shaw, Geoffrey M; Chase, J Geoffrey; Desaive, Thomas

    2014-04-16

    The metabolism of critically ill patients evolves dynamically over time. Post critical insult, levels of counter-regulatory hormones are significantly elevated, but decrease rapidly over the first 12-48 hours in the intensive care unit (ICU). These hormones have a direct physiological impact on insulin sensitivity (SI). Understanding the variability of SI is important for safely managing glycaemic levels and understanding the evolution of patient condition. The objective of this study is to assess the evolution of SI over the first two days of ICU stay, and using this data, propose a separate stochastic model to reduce the impact of SI variability during glycaemic control using the STAR glycaemic control protocol. The value of SI was identified hourly for each patient using a validated physiological model. Variability of SI was then calculated as the hour-to-hour percentage change in SI. SI was examined using 6 hour blocks of SI to display trends while mitigating the effects of noise. To reduce the impact of SI variability on achieving glycaemic control a new stochastic model for the most variable period, 0-18 hours, was generated. Virtual simulations were conducted using an existing glycaemic control protocol (STAR) to investigate the clinical impact of using this separate stochastic model during this period of increased metabolic variability. For the first 18 hours, over 80% of all SI values were less than 0.5 × 10(-3) L/mU x min, compared to 65% for >18 hours. Using the new stochastic model for the first 18 hours of ICU stay reduced the number of hypoglycaemic measurements during virtual trials. For time spent below 4.4, 4.0, and 3.0 mmol/L absolute reductions of 1.1%, 0.8% and 0.1% were achieved, respectively. No severe hypoglycaemic events (BG < 2.2 mmol/L) occurred for either case. SI levels increase significantly, while variability decreases during the first 18 hours of a patients stay in ICU. Virtual trials, using a separate stochastic model for this

  7. Photometric variability of the T Tauri star TW Hya on time-scales of hours to years

    Science.gov (United States)

    Rucinski, Slavek M.; Matthews, Jaymie M.; Kuschnig, Rainer; Pojmański, Grzegorz; Rowe, Jason; Guenther, David B.; Moffat, Anthony F. J.; Sasselov, Dimitar; Walker, Gordon A. H.; Weiss, Werner W.

    2008-12-01

    Microvariability & Oscillations of STars (MOST) and All Sky Automated Survey (ASAS) observations have been used to characterize photometric variability of TW Hya on time-scales from a fraction of a day to 7.5 weeks and from a few days to 8 yr, respectively. The two data sets have very different uncertainties and temporal coverage properties and cannot be directly combined, nevertheless, they suggest a global variability spectrum with `flicker-noise' properties, that is with amplitudes , over >4 decades in frequency, in the range f = 0.0003-10cd-1. A 3.7d period is clearly present in the continuous 11d, 0.07d time resolution, observations by MOST in 2007. Brightness extrema coincide with zero-velocity crossings in periodic (3.56d) radial-velocity variability detected in contemporaneous spectroscopic observations of Setiawan et al. and interpreted as caused by a planet. The 3.56/3.7d periodicity was entirely absent in the second, 4 times longer MOST run in 2008, casting doubt on the planetary explanation. Instead, a spectrum of unstable single periods within the range of 2-9d was observed; the tendency of the periods to progressively shorten was well traced using the wavelet analysis. The evolving periodicities and the overall flicker-noise characteristics of the TW Hya variability suggest a combination of several mechanisms, with the dominant ones probably related to the accretion processes from the disc around the star. Based on data from the MOST satellite, a Canadian Space Agency mission jointly operated by Dynacon Inc., the University of Toronto Institute for Aerospace Studies and the University of British Columbia, with the assistance of the University of Vienna, and on data from the All Sky Automated Survey (ASAS) conducted by the Warsaw University Observatory, Warsaw, Poland at the Las Campanas Observatory, Chile. E-mail: rucinski@astro.utoronto.ca

  8. Southern RS CVn systems - Candidate list. [spectral catalog of variable binary stars

    Science.gov (United States)

    Weiler, E. J.; Stencel, R. E.

    1979-01-01

    A list of 43 candidate RS CVn binary systems in the far southern hemisphere of the sky (south of -40 deg declination) is presented. The candidate systems were selected from the first two volumes of the Michigan Spectral Catalog (1975, 1978), which provides MK classifications for southern HD stars and identifies any unusual characteristics noted for individual stellar spectra. The selection criteria used were: (1) the occurrence of Ca II H and K emission; (2) known or suspected binary nature; (3) regular light variations of zero to one magnitude; and (4) spectral type between F0 and K2 and luminosity less than bright giant (II).

  9. Oscillation Mode Variability in Evolved Compact Pulsators from Kepler Photometry. I. The Hot B Subdwarf Star KIC 3527751

    Science.gov (United States)

    Zong, Weikai; Charpinet, Stéphane; Fu, Jian-Ning; Vauclair, Gérard; Niu, Jia-Shu; Su, Jie

    2018-02-01

    We present the first results of an ensemble and systematic survey of oscillation mode variability in pulsating hot B subdwarf (sdB) and white dwarf stars observed with the original Kepler mission. The satellite provides uninterrupted high-quality photometric data with a time baseline that can reach up to 4 yr collected on pulsating stars. This is a unique opportunity to characterize long-term behaviors of oscillation modes. A mode modulation in amplitude and frequency can be independently inferred by its fine structure in the Fourier spectrum, from the sLSP, or with prewhitening methods applied to various parts of the light curve. We apply all these techniques to the sdB star KIC 3527751, a long-period-dominated hybrid pulsator. We find that all the detected modes with sufficiently large amplitudes to be thoroughly studied show amplitude and/or frequency variations. Components of three identified quintuplets around 92, 114, and 253 μHz show signatures that can be linked to nonlinear interactions according to the resonant mode coupling theory. This interpretation is further supported by the fact that many oscillation modes are found to have amplitudes and frequencies showing correlated or anticorrelated variations, a behavior that can be linked to the amplitude equation formalism, where nonlinear frequency corrections are determined by their amplitude variations. Our results suggest that oscillation modes varying with diverse patterns are a very common phenomenon in pulsating sdB stars. Close structures around main frequencies therefore need to be carefully interpreted in light of this finding to secure a robust identification of real eigenfrequencies, which is crucial for seismic modeling. The various modulation patterns uncovered should encourage further developments in the field of nonlinear stellar oscillation theory. It also raises a warning to any long-term project aiming at measuring the rate of period change of pulsations caused by stellar evolution, or at

  10. Mira and SR type variable stars from the ROTSE-IIID archive

    Science.gov (United States)

    Gucsav, B.; Yesilyaprak, C.

    2016-12-01

    Applications of machine-learned algorithms in the field of variable classification have been popular as they are simple to implement and performing as well. A few years back, a small MPI application developed as the core of a variable detection pipeline for the ROTSE-IIID robotic telescope archive. Now it has been extended to involve the parallel approach for machine learned classification specifically for the long-term variables like Mira and Semi-regular variables. This presentation mainly covers the efforts to put the methodology in reality.

  11. Large-scale Periodic Variability of the Wind of the Wolf-Rayet Star WR 1 (HD 4004)

    Science.gov (United States)

    Chené, A.-N.; St-Louis, N.

    2010-06-01

    We present the results of an intensive photometric and spectroscopic monitoring campaign of the WN4 Wolf-Rayet (WR) star WR 1 = HD 4004. Our broadband V photometry covering a timespan of 91 days shows variability with a period of P = 16.9+0.6 -0.3 days. The same period is also found in our spectral data. The light curve is non-sinusoidal with hints of a gradual change in its shape as a function of time. The photometric variations nevertheless remain coherent over several cycles and we estimate that the coherence timescale of the light curve is of the order of 60 days. The spectroscopy shows large-scale line-profile variability which can be interpreted as excess emission peaks moving from one side of the profile to the other on a timescale of several days. Although we cannot unequivocally exclude the unlikely possibility that WR 1 is a binary, we propose that the nature of the variability we have found strongly suggests that it is due to the presence in the wind of the WR star of large-scale structures, most likely corotating interaction regions (CIRs), which are predicted to arise in inherently unstable radiatively driven winds when they are perturbed at their base. We also suggest that variability observed in WR 6, WR 134, and WR 137 is of the same nature. Finally, assuming that the period of CIRs is related to the rotational period, we estimate the rotation rate of the four stars for which sufficient monitoring has been carried out, i.e., v rot = 6.5, 40, 70, and 275 km s-1 for WR 1, WR 6, WR 134, and WR 137, respectively. Based on observations obtained at the Canada-France-Hawaii Telescope (CFHT) which is operated by the National Research Council of Canada, the Institut National des Sciences de l'Univers of the Centre National de Recherche Scientifique of France, and the University of Hawaii. Also based on observations obtained at the Observatoire du Mont Mégantic with is operated by the Centre de Recherche en Astrophysique du Québec and the Observatoire de

  12. A Suzaku, NuSTAR, and XMM-Newton view on variable absorption and relativistic reflection in NGC 4151

    Science.gov (United States)

    Beuchert, T.; Markowitz, A. G.; Dauser, T.; García, J. A.; Keck, M. L.; Wilms, J.; Kadler, M.; Brenneman, L. W.; Zdziarski, A. A.

    2017-07-01

    We disentangle X-ray disk reflection from complex line-of-sight absorption in the nearby Seyfert NGC 4151, using a suite of Suzaku, NuSTAR, and XMM-Newton observations. Extending upon earlier published work, we pursue a physically motivated model using the latest angle-resolved version of the lamp-post geometry reflection model relxillCp_lp together with a Comptonization continuum. We use the long-look simultaneous Suzaku/NuSTAR observation to develop a baseline model wherein we model reflected emission as a combination of lamp-post components at the heights of 1.2 and 15.0 gravitational radii. We argue for a vertically extended corona as opposed to two compact and distinct primary sources. We find two neutral absorbers (one full-covering and one partial-covering), an ionized absorber (log ξ = 2.8), and a highly-ionized ultra-fast outflow, which have all been reported previously. All analyzed spectra are well described by this baseline model. The bulk of the spectral variability between 1 keV and 6 keV can be accounted for by changes in the column density of both neutral absorbers, which appear to be degenerate and inversely correlated with the variable hard continuum component flux. We track variability in absorption on both short (2 d) and long ( 1 yr) timescales; the observed evolution is either consistent with changes in the absorber structure (clumpy absorber at distances ranging from the broad line region to the inner torus or a dusty radiatively driven wind) or a geometrically stable neutral absorber that becomes increasingly ionized at a rising flux level. The soft X-rays below 1 keV are dominated by photoionized emission from extended gas that may act as a warm mirror for the nuclear radiation.

  13. Factor VII-activating protease

    DEFF Research Database (Denmark)

    Ramanathan, Ramshanker; Gram, Jørgen B; Sand, Niels Peter R

    2017-01-01

    : Factor VII-activating protease (FSAP) may regulate development of cardiovascular disease (CVD). We evaluated sex differences in FSAP measures and examined the association between FSAP and coronary artery calcification (CAC) in a middle-aged population. Participants were randomly selected citizens...

  14. SHORT- AND LONG-TERM RADIO VARIABILITY OF YOUNG STARS IN THE ORION NEBULA CLUSTER AND MOLECULAR CLOUD

    Energy Technology Data Exchange (ETDEWEB)

    Rivilla, V. M.; Martín-Pintado, J. [Osservatorio Astrofisico di Arcetri, Largo Enrico Fermi 5, I-50125, Firenze (Italy); Chandler, C. J. [National Radio Astronomy Observatory, P.O. Box O, Socorro, NM 87801 (United States); Sanz-Forcada, J. [Centro de Astrobiología (CSIC/INTA), ESAC Campus, P.O. Box 78, E-28691 Villanueva de la Cañada, Madrid (Spain); Jiménez-Serra, I. [European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748, Garching (Germany); Forbrich, J., E-mail: rivilla@arcetri.astro.it [Department of Astrophysics, University of Vienna, Türkenschanzstr. 17, 1180 Vienna (Austria)

    2015-08-01

    We have used the Karl G. Jansky Very Large Array (VLA) to carry out multi-epoch radio continuum monitoring of the Orion Nebula Cluster (ONC) and the background Orion Molecular Cloud (OMC; 3 epochs at Q band and 11 epochs at Ka band). Our new observations reveal the presence of 19 radio sources, mainly concentrated in the Trapezium Cluster and the Orion Hot Core (OHC) regions. With the exception of the Becklin–Neugebauer object and source C (which we identify here as dust emission associated with a proplyd) the sources all show radio variability between the different epochs. We have found tentative evidence of variability in the emission from the massive object related to source I. Our observations also confirm radio flux density variations of a factor >2 on timescales of hours to days in five sources. One of these flaring sources, OHC-E, has been detected for the first time. We conclude that the radio emission can be attributed to two different components: (i) highly variable (flaring) non-thermal radio gyrosynchrotron emission produced by electrons accelerated in the magnetospheres of pre-main-sequence low-mass stars and (ii) thermal emission due to free–free radiation from ionized gas and/or heated dust around embedded massive objects and proplyds. Combining our sample with other radio monitoring at 8.3 GHz and the X-ray catalog provided by Chandra, we have studied the properties of the entire sample of radio/X-ray stars in the ONC/OMC region (51 sources). We have found several hints of a relation between the X-ray activity and the mechanisms responsible for (at least some fraction of) the radio emission. We have estimated a radio flaring rate of ∼0.14 flares day{sup −1} in the dense stellar cluster embedded in the OHC region. This suggests that radio flares are more common events during the first stages of stellar evolution than previously thought. The advent of improved sensitivity with the new VLA and ALMA will dramatically increase the number of stars

  15. Carbon Stars

    Indian Academy of Sciences (India)

    Abstract. In this paper, the present state of knowledge of the carbon stars is discussed. Particular attention is given to issues of classification, evolution, variability, populations in our own and other galaxies, and circumstellar material.

  16. A Suzaku, NuSTAR and XMMNewton} view on variable absorption and relativistic reflection in NGC 4151

    Science.gov (United States)

    Beuchert, T.; Markowitz, A.; Dauser, T.; Garcia, J.; Keck, M.; Wilms, J.; Kadler, M.; Brenneman, L.; Zdziarski, A.

    2017-10-01

    We disentangle X-ray disk reflection from complex line-of-sight absorption in NGC 4151 using Suzaku, NuSTAR, and XMMNewton}. Extending upon Keck et al. (2015), we develop a physically-motivated baseline model using the latest lamp-post reflection code relxillCp_lp, which includes a Comptonization continuum. We identify two components at heights of 1.2 and 15.0 gravitational radii using a long-look simultaneous Suzaku/NuSTAR observation but argue for a vertically extended corona as opposed to distinct primary sources. We also find two neutral absorbers (one full-covering and one partial-covering), an ionized absorber (log ξ=2.8), and a highly-ionized ultra-fast outflow, all reported previously. All analyzed spectra are well described by this baseline model. The bulk of the spectral variability on time-scales from days to years can be attributed to changes of both neutral absorbers, which are inversely correlated with the hard X-ray continuum flux. The observed evolution is either consistent with changes in the absorber structure (clumpy absorber in the outer BLR or a dusty radiatively driven wind) or a geometrically stable neutral absorber that becomes increasingly ionized at a rising flux level. The soft X-rays below 1 keV are dominated by photoionized emission from extended gas, which may act as a warm mirror for the nuclear radiation.

  17. THE RHYTHM OF FAIRALL 9. I. OBSERVING THE SPECTRAL VARIABILITY WITH XMM-NEWTON AND NuSTAR

    Energy Technology Data Exchange (ETDEWEB)

    Lohfink, A. M.; Pinto, C.; Alston, W.; Fabian, A. C.; Kara, E.; Parker, M. L. [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); Reynolds, C. S. [Department of Astronomy, University of Maryland College Park, College Park, Maryland 20742 (United States); Boggs, S. E.; Craig, W. W. [Space Sciences Laboratory, University of California, Berkeley, 7 Gauss Way, Berkeley, CA 94720-7450 (United States); Christensen, F. E.; Hailey, C. J. [Danish Technical University, DK-2800 Lyngby (Denmark); Harrison, F. A. [Cahill Center for Astronomy and Astrophysics, Caltech, Pasadena, CA 91125 (United States); Matt, G. [Dipartimento di Matematica e Fisica, Università degli Studi Roma Tre, via della Vasca Navale 84, I-00146 Roma (Italy); Stern, D.; Walton, D. [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Zhang, W. W., E-mail: alohfink@ast.cam.ac.uk [X-ray Astrophysics Laboratory, NASA/Goddard Space Flight Center, Greenbelt, MD, 20771 (United States)

    2016-04-10

    We present a multi-epoch X-ray spectral analysis of the Seyfert 1 galaxy Fairall 9. Our analysis shows that Fairall 9 displays unique spectral variability in that its ratio residuals to a simple absorbed power law in the 0.5–10 keV band remain constant with time in spite of large variations in flux. This behavior implies an unchanging source geometry and the same emission processes continuously at work at the timescale probed. With the constraints from NuSTAR on the broad-band spectral shape, it is clear that the soft excess in this source is a superposition of two different processes, one being blurred ionized reflection in the innermost parts of the accretion disk, and the other a continuum component such as a spatially distinct Comptonizing region. Alternatively, a more complex primary Comptonization component together with blurred ionized reflection could be responsible.

  18. The Rhythm of Fairall 9. I. Observing the Spectral Variability with XMM-Newton and NuSTAR

    DEFF Research Database (Denmark)

    Lohfink, A. M.; Reynolds, C. S.; Pinto, C.

    2016-01-01

    We present a multi-epoch X-ray spectral analysis of the Seyfert 1 galaxy Fairall 9. Our analysis shows that Fairall 9 displays unique spectral variability in that its ratio residuals to a simple absorbed power law in the 0.5–10 keV band remain constant with time in spite of large variations in flux....... This behavior implies an unchanging source geometry and the same emission processes continuously at work at the timescale probed. With the constraints from NuSTAR on the broad-band spectral shape, it is clear that the soft excess in this source is a superposition of two different processes, one being blurred...

  19. The Rhythm of Fairall 9. I. Observing the Spectral Variability With XMM-Newton and NuSTAR

    Science.gov (United States)

    Lohfink, A. M.; Reynolds, S. C.; Pinto, C.; Alston, W.; Boggs, S. E.; Christensen, F. E.; Craig, W. W.; Fabian, A.C; Hailey, C. J.; Harrison, F. A.; hide

    2016-01-01

    We present a multi-epoch X-ray spectral analysis of the Seyfert 1 galaxy Fairall 9. Our analysis shows that Fairall 9 displays unique spectral variability in that its ratio residuals to a simple absorbed power law in the 0.510 keV band remain constant with time in spite of large variations in flux. This behavior implies an unchanging source geometry and the same emission processes continuously at work at the timescale probed. With the constraints from NuSTAR on the broad-band spectral shape, it is clear that the soft excess in this source is a superposition of two different processes, one being blurred ionized reflection in the innermost parts of the accretion disk, and the other a continuum component such as a spatially distinct Comptonizing region. Alternatively, a more complex primary Comptonization component together with blurred ionized reflection could be responsible.

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

    Science.gov (United States)

    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

  1. A 10-h period revealed in optical spectra of the highly variable WN8 Wolf-Rayet star WR 123

    Science.gov (United States)

    Chené, A.-N.; Foellmi, C.; Marchenko, S. V.; St-Louis, N.; Moffat, A. F. J.; Ballereau, D.; Chauville, J.; Zorec, J.; Poteet, C. A.

    2011-06-01

    Aims: What is the origin of the large-amplitude variability in Wolf-Rayet WN8 stars in general and WR123 in particular? A dedicated spectroscopic campaign targets the ten-hour period previously found in the high-precision photometric data obtained by the MOST satellite. Methods: In June-August 2003 we obtained a series of high signal-to-noise, mid-resolution spectra from several sites in the λλ 4000-6940 Å domain. We also followed the star with occasional broadband (Johnson V) photometry. The acquired spectroscopy allowed a detailed study of spectral variability on timescales from ~5 min to months. Results: We find that all observed spectral lines of a given chemical element tend to show similar variations and that there is a good correlation between the lines of different elements, without any significant time delays, save the strong absorption components of the Hei lines, which tend to vary differently from the emission parts. We find a single sustained periodicity, P ~ 9.8 h, which is likely related to the relatively stable pulsations found in MOST photometry obtained one year later. In addition, seemingly stochastic, large-amplitude variations are also seen in all spectral lines on timescales of several hours to several days. Based on observations obtained at the Canada-France-Hawaii Telescope (CFHT) which is operated by the National Research Concil of Canada, the Institut National des Sciences de l'Univers of the Centre National de Recherche Scientifique of France, and the University of Hawaii. Based also on observations made with ESO Telescopes at the La Silla Observatory, under programme ID 271.D-5025.Photometric data presented in Fig. 1 are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/530/A151

  2. Studies of early-type variable stars. XIV. Spectroscopic orbit and absolute parameters of HU Tauri.

    Science.gov (United States)

    Maxted, P. F. L.; Hill, G.; Hilditch, R. W.

    1995-09-01

    We present a new spectroscopic orbit for the Algol-type eclipsing binary system HU Tau (HD 29365, P=2.0563 days α(2000.0) = 04 38 15.80, δ= +20 41 05.3, V=5.87-6.8, B8V + G2). We find : m_1_ sin^3^i=4.17+/-0.09Msun_, m_2_ sin^3^i=1.07+/-0.025Msun_, (a_p_+a_s_)sin i=11.8 +/-0.1Rsun_, m_1_/m_2_=3.90+/-0.07. The spectroscopic orbit includes corrections for non-Keplerian effects derived from the solutions of the BV light curves of Ito (1988). We have been able to derive much improved absolute parameters for this system as follows: M_1_=4.43+/-0.09Msun_, M_2_=1.14+/-0.03Msun_, R _1_=2.57+/-0.03Rsun_, R _2_=4.21+/-0.03Rsun_, log(L_1_/Lsun_)= 2.09+/-0.15, log(L_2_/Lsun_)= 0.92+/-0.05. Comparison of HU Tau with non-conservative case B evolution models of De Greve (1993) suggests that the system evolved from an initial mass ratio <~0.5. However, the orbital period of HU Tau is more than 3 days shorter than any of the model systems, and the observed secondary luminosity of order 10 times less than a model star of the same mass during the slow mass transfer phase.

  3. Positivity VII (Zaanen Centennial Conference)

    CERN Document Server

    Pagter, Ben; Gaans, Onno; Veraar, Mark

    2016-01-01

    This book presents the proceedings of Positivity VII, held from 22-26 July 2013, in Leiden, the Netherlands. Positivity is the mathematical field concerned with ordered structures and their applications in the broadest sense of the word. A biyearly series of conferences is devoted to presenting the latest developments in this lively and growing discipline. The lectures at the conference covered a broad spectrum of topics, ranging from order-theoretic approaches to stochastic processes, positive solutions of evolution equations and positive operators on vector lattices, to order structures in the context of algebras of operators on Hilbert spaces. The contributions in the book reflect this variety and appeal to university researchers in functional analysis, operator theory, measure and integration theory and operator algebras. Positivity VII was also the Zaanen Centennial Conference to mark the 100th birth year of Adriaan Cornelis Zaanen, who held the chair of Analysis in Leiden for more than 25 years and was ...

  4. Highlights of Spanish Astrophysics VII

    Science.gov (United States)

    Guirado, J. C.; Lara, L. M.; Quilis, V.; Gorgas, J.

    2013-05-01

    "Highlights of Astronomy and Astrophysics VII" contains the Proceedings of the biannual meeting of the Spanish Astronomical Society held in Valencia from July 9 to 13, 2012. Over 300 astronomer, both national and international researchers, attended to the conference covering a wide variety of astrophysical topics: Galaxies and Cosmology, The Milky Way and Its Components, Planetary Sciences, Solar Physics, Instrumentation and Computation, and Teaching and Outreach of Astronomy.

  5. Congenital deficiency of factor VII.

    Science.gov (United States)

    Sikka, M; Gomber, S; Madan, N; Rusia, U; Sharma, S

    1996-01-01

    A case of congenital factor VII deficiency in a five-year-old child is reported. The patient, born of a non-consanguineous marriage, presented with repeated bouts of epistaxis since childhood. The prothrombin time (PT) was markedly prolonged with a normal bleeding time (BT), partial thromboplastin time with Kaolin (PTTK) and platelet count. The patient has been on follow up for the last four years and is doing apparently well.

  6. The Multi-Layer Variable Absorbers in NGC 1365 Revealed by XMM-Newton and NuSTAR

    Science.gov (United States)

    Rivers, E.; Risaliti, G.; Walton, D. J.; Harrison, F.; Arevalo, P.; Baur, F. E.; Boggs, S. E.; Brenneman, L. W.; Brightman, M.; Zhang, W. W.

    2015-01-01

    Between 2012 July and 2013 February, NuSTAR and XMM-Newton performed four long-look joint observations of the type 1.8 Seyfert, NGC 1365. We have analyzed the variable absorption seen in these observations in order to characterize the geometry of the absorbing material. Two of the observations caught NGC 1365 in an unusually low absorption state, revealing complexity in the multi-layer absorber that had previously been hidden. We find the need for three distinct zones of neutral absorption in addition to the two zones of ionized absorption and the Compton-thick torus previously seen in this source. The most prominent absorber is likely associated with broad-line region clouds with column densities of around approximately 10 (sup 23) per square centimeter and a highly clumpy nature as evidenced by an occultation event in 2013 February. We also find evidence of a patchy absorber with a variable column around approximately 10 (sup 22) per square centimeter and a line-of-sight covering fraction of 0.3-0.9, which responds directly to the intrinsic source flux, possibly due to a wind geometry. A full-covering, constant absorber with a low column density of approximately 1 by 10 (sup 22) per square centimeter is also present, though the location of this low density haze is unknown.

  7. Binary Central Stars of Planetary Nebulae Discovered Through Photometric Variability. V. The Central Stars of HaTr 7 and ESO 330-9

    Science.gov (United States)

    Hillwig, Todd C.; Frew, David J.; Reindl, Nicole; Rotter, Hannah; Webb, Andrew; Margheim, Steve

    2017-01-01

    We find the central stars (CSs) of the planetary nebulae (PNe) HaTr 7 and ESO 330-9 to be close-binary systems. Both have orbital periods of less than half a day and contain an irradiated cool companion to the hot CS. We provide light curves, spectra, radial velocity curves, orbital periods, and binary modeling results for both systems. The binary modeling leads to system parameters, or ranges of allowed parameters for each system. We find that for the CS of HaTr 7 we need to use limb-darkening values for the cool companion that are different than the expected values for an isolated star. We also fit the CS spectrum to determine {log}g and temperature values independent of the binary modeling. For ESO 330-9 we find that based on our binary modeling, the hot CS is most likely a post-red giant branch (RGB) star with a mass of around 0.4 {M}⊙ . We discuss our derived stellar and nebular parameters in the broader context of close-binary CSs and their surrounding planetary nebulae (PNe). We also discuss the present status of known or suspected post-RGB stars in PNe.

  8. Concluding Henrietta Leavitt's Work on Classical Cepheids in the Magellanic System and Other Updates of the OGLE Collection of Variable Stars

    Science.gov (United States)

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

    2017-06-01

    More than a century ago, Henrietta Leavitt discovered the first Cepheids in the Magellanic Clouds together with the famous period-luminosity relationship revealed by these stars, which soon after revolutionized our view of the Universe. Over the years, the number of known Cepheids in these galaxies has steadily increased with the breakthrough in the last two decades thanks to the new generation of large-scale long-term sky variability surveys. Here we present the final upgrade of the OGLE Collection of Cepheids in the Magellanic System which already contained the vast majority of known Cepheids. The updated collection now comprises 9649 classical and 262 anomalous Cepheids. Type-II Cepheids will be updated shortly. Thanks to high completeness of the OGLE survey the sample of classical Cepheids includes virtually all stars of this type in the Magellanic Clouds. Thus, the OGLE survey concludes the work started by Henrietta Leavitt. Additionally, the OGLE sample of RR Lyr stars in the Magellanic System has been updated. It now counts 46 443 variables. A collection of seven anomalous Cepheids in the halo of our Galaxy detected in front of the Magellanic Clouds is also presented. OGLE photometric data are available to the astronomical community from the OGLE Internet Archive. The time-series photometry of all pulsating stars in the OGLE Collection has been supplemented with new observations.

  9. Kepler sheds new and unprecedented light on the variability of a blue supergiant: Gravity waves in the O9.5Iab star HD 188209

    Science.gov (United States)

    Aerts, C.; Símon-Díaz, S.; Bloemen, S.; Debosscher, J.; Pápics, P. I.; Bryson, S.; Still, M.; Moravveji, E.; Williamson, M. H.; Grundahl, F.; Fredslund Andersen, M.; Antoci, V.; Pallé, P. L.; Christensen-Dalsgaard, J.; Rogers, T. M.

    2017-06-01

    Stellar evolution models are most uncertain for evolved massive stars. Asteroseismology based on high-precision uninterrupted space photometry has become a new way to test the outcome of stellar evolution theory and was recently applied to a multitude of stars, but not yet to massive evolved supergiants.Our aim is to detect, analyse and interpret the photospheric and wind variability of the O9.5 Iab star HD 188209 from Kepler space photometry and long-term high-resolution spectroscopy. We used Kepler scattered-light photometry obtained by the nominal mission during 1460 d to deduce the photometric variability of this O-type supergiant. In addition, we assembled and analysed high-resolution high signal-to-noise spectroscopy taken with four spectrographs during some 1800 d to interpret the temporal spectroscopic variability of the star. The variability of this blue supergiant derived from the scattered-light space photometry is in full in agreement with the one found in the ground-based spectroscopy. We find significant low-frequency variability that is consistently detected in all spectral lines of HD 188209. The photospheric variability propagates into the wind, where it has similar frequencies but slightly higher amplitudes. The morphology of the frequency spectra derived from the long-term photometry and spectroscopy points towards a spectrum of travelling waves with frequency values in the range expected for an evolved O-type star. Convectively-driven internal gravity waves excited in the stellar interior offer the most plausible explanation of the detected variability. Based on photometric observations made with the NASA Kepler satellite and on spectroscopic observations made with four telescopes: the Nordic Optical Telescope operated by NOTSA and the Mercator Telescope operated by the Flemish Community, both at the Observatorio del Roque de los Muchachos (La Palma, Spain) of the Instituto de Astrofísica de Canarias, the T13 2.0 m Automatic Spectroscopic

  10. Variability in stellar granulation and convective blueshift with spectral type and magnetic activity . II. From young to old main-sequence K-G-F stars

    Science.gov (United States)

    Meunier, N.; Mignon, L.; Lagrange, A.-M.

    2017-11-01

    Context. The inhibition of small-scale convection in the Sun dominates the long-term radial velocity (RV) variability: it therefore has a critical effect on light exoplanet detectability using RV techniques. Aims: We here extend our previous analysis of stellar convective blueshift and its dependence on magnetic activity to a larger sample of stars in order to extend the Teff range, to study the impact of other stellar properties, and finally to improve the comparison between observed RV jitter and expected RV variations. Methods: We estimate a differential velocity shift for Fe and Ti lines of different depths and derive an absolute convective blueshift using the Sun as a reference for a sample of 360 F7-K4 stars with different properties (age, Teff, metallicity). Results: We confirm the strong variation in convective blueshift with Teff and its dependence on (as shown in the line list in Paper I) activity level. Although we do not observe a significant effect of age or cyclic activity, stars with a higher metallicity tend to have a lower convective blueshift, with a larger effect than expected from numerical simulations. Finally, we estimate that for 71% of the stars in our sample the RV and Log R' _HK variations are compatible with the effect of activity on convection, as observed in the solar case, while for the other stars, other sources (such as binarity or companions) must be invoked to explain the large RV variations. We also confirm a relationship between Log R' _HK and metallicity, which may affect discussions of the possible relationship between metallicity and exoplanets, as RV surveys are biased toward low Log R' _HK and possibly toward high-metallicity stars. Conclusions: We conclude that activity and metallicity strongly affect the small-scale convection levels in stars in the F7-K4 range, with a lower amplitude for the lower mass stars and a larger amplitude for low-metallicity stars. Full Table A.1 is only available at the CDS via anonymous ftp to

  11. Penalaran Proporsional Siswa Kelas VII

    Directory of Open Access Journals (Sweden)

    Yandika Nugraha

    2016-10-01

    Full Text Available [Bahasa]: Penelitian ini merupakan penelitian kualitatif deskriptif yang bertujuan untuk mendeskripsikan karakteristik penalaran proporsional siswa. Subjek penelitian adalah siswa kelas VII SMP Negeri 1 Tasikmadu Kabupaten Karanganyar. Prosedur pemilihan subjek dengan cara purposive sampling. Pengumpulan data dilakukan dengan cara think aloud method. Validitas data menggunakan triangulasi waktu. Teknik analisis data dilakukan dengan cara: (1 mengelompokkan data dalam 2 kategori, kemudian mereduksi data yang tidak termasuk dalam 2 kategori tersebut, (2 menyajikan data dalam teks naratif, dan (3 menyimpulkan karakteristik penalaran proporsional siswa kemudian membandingkan subjek yang berada pada level yang sama. Berdasarkan penelitian yang dilakukan pada enam subjek siswa kelas VII SMP Negeri Tasikmadu, terdapat empat siswa yang sudah bisa bernalar kuantitatif yaitu mampu memanipulasi situasi perbandingan dengan menggunakan suatu bilangan dan dua siswa menggunakan perkalian silang tetapi tidak sepenuhnya memahami hubungan invarian dan kovarian. [English]: This descriptive qualitative research is aimed at describing the characteristics of students proportional reasoning. The subjects are the seventh grade students at SMP Negeri 1 Tasikmadu Karanganyar. The subjects are selected through purposive sampling methods. Data collection applies think aloud method. Time triangulation is used for data validation. Data is analyzed by: (1 classifying data in two categories then reducing them which do not belong to both categories, (2 presenting the data in narrative text, and (3 summarizing the characteristics of students proportional reasoning then comparing the subjects based on same level. The research shows that 4 of 6 students are able to reason quantitatively which mean that they can manipulate the proportional situation using number and the remaining students use cross product but they did not fully understand about the relation of invariant and

  12. Variable stars in Local Group Galaxies - I. Tracing the early chemical enrichment and radial gradients in the Sculptor dSph with RR Lyrae stars

    Science.gov (United States)

    Martínez-Vázquez, C. E.; Monelli, M.; Bono, G.; Stetson, P. B.; Ferraro, I.; Bernard, E. J.; Gallart, C.; Fiorentino, G.; Iannicola, G.; Udalski, A.

    2015-12-01

    We identified and characterized the largest (536) RR Lyrae (RRL) sample in a Milky Way dSph satellite (Sculptor) based on optical photometry data collected over ˜24 years. The RRLs display a spread in V-magnitude (˜0.35 mag) which appears larger than photometric errors and the horizontal branch (HB) luminosity evolution of a mono-metallic population. Using several calibrations of two different reddening free and metal independent period-Wesenheit relations we provide a new distance estimate μ = 19.62 mag (σμ = 0.04 mag) that agrees well with literature estimates. We constrained the metallicity distribution of the old population, using the MI period-luminosity relation, and we found that it ranges from -2.3 to -1.5 dex. The current estimate is narrower than suggested by low and intermediate spectroscopy of RGBs (Δ [Fe/H]≤ 1.5). We also investigated the HB morphology as a function of the galactocentric distance. The HB in the innermost regions is dominated by red HB stars and by RRLs, consistent with a more metal-rich population, while in the outermost regions it is dominated by blue HB stars and RRLs typical of a metal-poor population. Our results suggest that fast chemical evolution occurred in Sculptor, and that the radial gradients were in place at an early epoch.

  13. New Variable Stars Discovered by Data Mining Images Taken during Recent Asteroid Photometric Observations. II. Results from July 2015 through December 2016

    Science.gov (United States)

    Papini, R.; Marchini, A.; Salvaggio, F.; Agnetti, D.; Bacci, P.; Banfi, M.; Bianciardi, G.; Collina, M.; Franco, L.; Galli, G.; Milani, M. G. A.; Lopresti, C.; Marino, G.; Rizzuti, L.; Ruocco, N.; Quadri, U.

    2017-12-01

    This paper follows the previous publication of new variables discovered at Astronomical Observatory, DSFTA, University of Siena, while observing asteroids in order to determine their rotational periods. Usually, this task requires time series images acquisition on a single field for as long as possible on a few nights not necessarily consecutive. Checking continually this "goldmine" allowed us to discover 57 variable stars not yet listed in catalogues or databases. While most of the new variables are eclipsing binaries, a few belong to the RR Lyrae or delta Scuti class. Since asteroid work is definitely a time-consuming activity, coordinated campaigns of follow-up with other observatories have been fundamental in order to determine the elements of the ephemeris and sometimes the right subclass of variability. Further observations of these new variables are therefore strongly encouraged in order to better characterize these stars, especially pulsating ones whose data combined with those taken during professional surveys seem to suggest the presence of light curve amplitude and period variations.

  14. Tidal effects in pulsating stars. III. l=1p/sub 5/-modes in the ellipsoidal variable 14 Aurigae A

    Energy Technology Data Exchange (ETDEWEB)

    Fitch, W.S.; Wisniewski, W.Z.

    1979-08-01

    The noneclipsing single-lined spectroscopic binary 14 Aur A has a circular orbit of period 3.78858 days, and the A9 IV primary is a delta Scuti variable. Analysis of our 158 hours of blue light photometry obtained on 40 nights in 1972--1975 and of others' radial velocity measures provides an identification of three standing wave (in the rotating frame) pulsation modes as the tidal m=0, +- 1 substates belonging to an l=1 surface harmonic, with periods, P/sub 1,+1/=0./sup d/088088, P/sub 1,0/=0./sup d/096533, and P/sub 1,-1/=0./sup d/088243. These l=1 surface harmonics are probably p/sub 5/ global modes. The observed amplitudes A/sub l/m of these periods P/sub l/m, when combined with approximate theoretical visibility functions for the integrated flux variations (for l< or approx. =2, vertical-barmvertical-bar< or approx. =l) and with the assumption of energy equipartition among the observed substates, lead to an orbital inclination i=21./sup 0/2 ( +- 1./sup 0/4). The photometrically defined ellipticity of figure of the primary, the orbital velocity variation, published uvby..beta.. photometry and calibrations, pulsation theory, double-star theory, and stellar evolution theory all combine to yield these system characteristics: T/sub e,1/=7900 +- 110 K; M/sub 1//Msun=2.6 +- 0.7; /Rsun=5.2 +- 0.7; /Lsun=96 +- 26; Q/sub 1/=0./sup d/0124 +- 0./sup d/0011; M/sub 2//Msun=1.1 +- 0.3. The relative differences in the principal semiaxes are (b/sub 1/--b/sub 2/)/ =0.022 +- 0.004 and (b/sub 2/--b/sub 3/)/=0.025 +- 0.004 if rotation is synchronous with orbital motion. Both components of the binary are well detached from their respective Roche lobes. The relative amplitudes and phase of the pulsations in light and velocity agree satisfactorily with both theory and other observations.

  15. Rotationally modulated variability and pulsations of the He-rich star CPD -62°2124 with an extraordinarily strong magnetic field

    Science.gov (United States)

    Hubrig, S.; Mikulášek, Z.; Kholtygin, A. F.; Ilyin, I.; Schöller, M.; Järvinen, S. P.; Scholz, R.-D.; Zejda, M.

    2017-11-01

    A longitudinal magnetic field with a strength of 5.2 kG was recently detected in CPD -62°2124, which has a fractional main-sequence lifetime of about 60 per cent. Strongly magnetic early-B type chemically peculiar stars in an advanced evolutionary state are of special interest to understand the evolution of the angular momentum and spin-down time-scales in the presence of a global magnetic field. We made use of 17 FORS 2 low-resolution spectropolarimetric observations and 844 ASAS3 photometric measurements for the determination of the rotation period, pulsationsand the magnetic field geometry of the star. We calculated periodograms and applied phenomenological models of photometric, spectral and spectropolarimetric variability. We found that all quantities studied, specifically equivalent widths, the mean longitudinal magnetic field 〈Bz〉 and the flux in the V filter, vary with the same period P = 2.628 d, which was identified as the rotation period. The observed variations can be fully explained by a rigidly rotating main-sequence star with an uneven distribution of chemical elements, photometric spots and a stable, nearly dipolar magnetic field with a polar field strength of about 21 kG, frozen into the body of the star. The magnetic field of CPD -62°2124 is tilted to the rotation axis by β = 28° ± 7°, while the inclination of the rotation axis towards the line of sight is only I = 20° ± 5°. In the acquired FORS 2 spectra, we detect short-term line profile variations indicating the presence of β Cephei type pulsations. As of today, no other pulsating star of this type is known to possess such a strong magnetic field.

  16. The Seyfert 2 galaxy NGC 2110: hard X-ray emission observed by NuSTAR and variability of the iron Kα line

    DEFF Research Database (Denmark)

    Marinucci, A.; Matt, G.; Bianchi, S.

    2015-01-01

    We present NuSTAR observations of the bright Seyfert 2 galaxy NGC 2110 obtained in 2012, when the source was at the highest flux level ever observed, and in 2013, when the source was at a more typical flux level. We include archival observations from other X-ray satellites, namely XMM-Newton, Suz......We present NuSTAR observations of the bright Seyfert 2 galaxy NGC 2110 obtained in 2012, when the source was at the highest flux level ever observed, and in 2013, when the source was at a more typical flux level. We include archival observations from other X-ray satellites, namely XMM...... is found and, by using temporal information collected over more than a decade, we investigate variations of the iron Kα line on time-scales of years. The Fe K alpha line is likely the sum of two components: one constant (originating from distant Compton-thick material) and the other one variable...

  17. An extremely luminous and variable ultraluminous x-ray source in the outskirts of circinus observed with NuSTAR

    DEFF Research Database (Denmark)

    Walton, D. J.; Fuerst, F.; Harrison, F.

    2013-01-01

    Following a serendipitous detection with the Nuclear Spectroscopic Telescope Array (NuSTAR), we present a multi-epoch spectral and temporal analysis of an extreme ultraluminous X-ray source (ULX) located in the outskirts of the Circinus galaxy, hereafter Circinus ULX5, including coordinated XMM-N...

  18. The Variable Quiescent X-Ray Emission of the Neutron Star Transient XTE J1701-462

    NARCIS (Netherlands)

    Fridriksson, Joel K.; Homan, J.; Wijnands, R.; Cackett, E. M.; Degenaar, N.; Mendez, M.; Altamirano, D.; Brown, E. F.; Belloni, T. M.; Lewin, W. H. G.

    We have monitored the cooling of the neutron star in the transient low-mass X-ray binary XTE J1701-462 with Chandra and XMM-Newton since the source entered quiescence in 2007 after an exceptionally luminous 19-month outburst. A recent Chandra observation made almost 1200 days into quiescence

  19. Mid-Infrared Interferometric Monitoring of Evolved Stars: The Dust Shell Around the Mira Variable RR Aquilae at 13 Epochs

    Science.gov (United States)

    2011-01-01

    Prescribed by ANSI Std Z39-18 A&A 532, A134 (2011) the planetary nebula phase, leaving the core as a white dwarf . Generally many aspects of the...mass loss is important, as AGB stars play a cru- cial role in the chemical enrichment and evolution of galaxies by returning gas and dust to the ISM

  20. Dance of the double stars

    Energy Technology Data Exchange (ETDEWEB)

    Theokas, A.

    1985-09-19

    The paper concerns pairs of stars orbiting one another. The evolutionary path model for close binary stars, involving a mass transfer of gases between the stars, is described. The life history of a single star; cataclysmic variables; the algol paradox, matter and lagranges' point; x-ray binaries and bursters; and pulsars; are all briefly discussed.

  1. Investigating the origin of cyclical wind variability in hot massive stars - II. Hydrodynamical simulations of corotating interaction regions using realistic spot parameters for the O giant ξ Persei

    Science.gov (United States)

    David-Uraz, A.; Owocki, S. P.; Wade, G. A.; Sundqvist, J. O.; Kee, N. D.

    2017-09-01

    OB stars exhibit various types of spectral variability historically associated with wind structures, including the apparently ubiquitous discrete absorption components (DACs). These features have been proposed to be caused either by magnetic fields or non-radial pulsations. In this second paper of this series, we revisit the canonical phenomenological hydrodynamical modelling used to explain the formation of DACs by taking into account modern observations and more realistic theoretical predictions. Using constraints on putative bright spots located on the surface of the O giant ξ Persei derived from high precision space-based broad-band optical photometry obtained with the Microvariability and Oscillations of Stars (MOST) space telescope, we generate 2D hydrodynamical simulations of corotating interaction regions in its wind. We then compute synthetic ultraviolet (UV) resonance line profiles using Sobolev Exact Integration and compare them with historical timeseries obtained by the International Ultraviolet Explorer (IUE) to evaluate if the observed behaviour of ξ Persei's DACs is reproduced. Testing three different models of spot size and strength, we find that the classical pattern of variability can be successfully reproduced for two of them: the model with the smallest spots yields absorption features that are incompatible with observations. Furthermore, we test the effect of the radial dependence of ionization levels on line driving, but cannot conclusively assess the importance of this factor. In conclusion, this study self-consistently links optical photometry and UV spectroscopy, paving the way to a better understanding of cyclical wind variability in massive stars in the context of the bright spot paradigm.

  2. Luminous and Variable Stars in M31 and M33. IV. Luminous Blue Variables, Candidate LBVs, B[e] Supergiants, and the Warm Hypergiants: How to Tell Them Apart

    Science.gov (United States)

    Humphreys, Roberta M.; Gordon, Michael S.; Martin, John C.; Weis, Kerstin; Hahn, David

    2017-02-01

    In this series of papers we have presented the results of a spectroscopic survey of luminous stars in the nearby spirals M31 and M33. Here, we present spectroscopy of 132 additional stars. Most have emission-line spectra, including luminous blue variables (LBVs) and candidate LBVs, Fe II emission line stars, the B[e] supergiants, and the warm hypergiants. Many of these objects are spectroscopically similar and are often confused with each other. We examine their similarities and differences and propose the following guidelines that can be used to help distinguish these stars in future work. (1) The B[e] supergiants have emission lines of [O I] and [Fe II] in their spectra. Most of the spectroscopically confirmed sgB[e] stars also have warm circumstellar dust in their spectral energy distributions (SEDs). (2) Confirmed LBVs do not have the [O I] emission lines in their spectra. Some LBVs have [Fe II] emission lines, but not all. Their SEDs show free-free emission in the near-infrared but no evidence for warm dust. Their most important and defining characteristic is the S Dor-type variability. (3) The warm hypergiants spectroscopically resemble the LBVs in their dense wind state and the B[e] supergiants. However, they are very dusty. Some have [Fe II] and [O I] emission in their spectra like the sgB[e] stars, but are distinguished by their A- and F-type absorption-line spectra. In contrast, the B[e] supergiant spectra have strong continua and few if any apparent absorption lines. Candidate LBVs should share the spectral characteristics of the confirmed LBVs with low outflow velocities and the lack of warm circumstellar dust. Based on observations with the Multiple Mirror Telescope, a joint facility of the Smithsonian Institution and the University of Arizona and on observations obtained with the Large Binocular Telescope (LBT), an international collaboration among institutions in the United States, Italy, and Germany. LBT Corporation partners are The University of

  3. Extraction of Tc(VII) and Re(VII) on TRU resin

    Energy Technology Data Exchange (ETDEWEB)

    Guerin, Nicolas; Riopel, Remi; Kramer-Tremblay, Sheila [Canadian Nuclear Laboratories (CNL), Chalk River, ON (Canada). Radiobiology and Health Branch; De Silva, Nimal; Cornett, Jack [Ottawa Univ., ON (Canada). Dept. of Earth and Environmental Sciences; Dai, Xiongxin [China Institute for Radiation Protection, Beijing (China)

    2017-06-01

    TRU resin can be used to rapidly and selectively extract Tc(VII) and Re(VII). The retention capacity curves of Tc(VII) and Re(VII) for HNO{sub 3}, HCl, H{sub 2}SO{sub 4} and H{sub 3}PO{sub 4} solutions were studied and prepared. Tc(VII) and Re(VII) were simultaneously extracted in 2 M H{sub 2}SO{sub 4} and 1.5 M H{sub 3}PO{sub 4} and were effectively separated from Mo(VI) and Ru(III). Tc(VII) and Re(VII) remained strongly bonded to the resin even after washing using a large volume of 2 M H{sub 2}SO{sub 4} at a relatively high flow rate. Also, they were both completely eluted from the resin using 15 mL of near boiling water, an eluent directly compatible for ICP-MS instrument measurements.

  4. SN2015bh: NGC2770's 4th supernova or a luminous blue variable on its way to a Wolf-Rayet star?

    DEFF Research Database (Denmark)

    Thone, C. C.; de Ugarte Postigo, A.; Leloudas, G.

    2017-01-01

    shell plunging into a dense CSM. The emission lines show a single narrow P Cygni profile during the LBV phase and a double P Cygni profile post maximum suggesting an association of the second component with the possible SN. Since 1994 the star has been redder than an LBV in an S-Dor-like outburst. SN......Very massive stars in the final phases of their lives often show unpredictable outbursts that can mimic supernovae, so-called, "SN impostors", but the distinction is not always straightforward. Here we present observations of a luminous blue variable (LBV) in NGC2770 in outburst over more than 20...... 2015bh lies within a spiral arm of NGC2770 next to several small star-forming regions with a metallicity of similar to 0.5 solar and a stellar population age of 7-10 Myr. SN 2015bh shares many similarities with SN 2009ip and may form a new class of objects that exhibit outbursts a few decades prior...

  5. Rapid X-ray variability properties during the unusual very hard state in neutron-star low-mass X-ray binaries

    Science.gov (United States)

    Wijnands, R.; Parikh, A. S.; Altamirano, D.; Homan, J.; Degenaar, N.

    2017-11-01

    Here, we study the rapid X-ray variability (using XMM-Newton observations) of three neutron-star low-mass X-ray binaries (1RXS J180408.9-342058, EXO 1745-248 and IGR J18245-2452) during their recently proposed very hard spectral state. All our systems exhibit a strong to very strong noise component in their power density spectra (rms amplitudes ranging from 34 per cent to 102 per cent) with very low characteristic frequencies (as low as 0.01 Hz). These properties are more extreme than what is commonly observed in the canonical hard state of neutron-star low-mass X-ray binaries observed at X-ray luminosities similar to those we observe from our sources. This suggests that indeed the very hard state is a spectral-timing state distinct from the hard state, although we argue that the variability behaviour of IGR J18245-2452 is very extreme and possibly this source was in a very unusual state. We also compare our results with the rapid X-ray variability of the accreting millisecond X-ray pulsars IGR J00291+5934 and Swift J0911.9-6452 (also using XMM-Newton data) for which previously similar variability phenomena were observed. Although their energy spectra (as observed using the Swift X-ray telescope) were not necessarily as hard (i.e. for Swift J0911.9-6452) as for our other three sources, we conclude that likely both sources were also in very similar state during their XMM-Newton observations. This suggests that different sources that are found in this new state might exhibit different spectral hardness and one has to study both the spectral and the rapid variability to identify this unusual state.

  6. High-resolution TNG spectra of T Tauri stars. Near-IR GIANO observations of the young variables XZ Tauri and DR Tauri

    Science.gov (United States)

    Antoniucci, S.; Nisini, B.; Biazzo, K.; Giannini, T.; Lorenzetti, D.; Sanna, N.; Harutyunyan, A.; Origlia, L.; Oliva, E.

    2017-10-01

    Aims: We aim to characterise the star-disk interaction region in T Tauri stars that show photometric and spectroscopic variability. Methods: We used the GIANO instrument at the Telescopio Nazionale Galileo to obtain near-infrared high-resolution spectra (R 50 000) of XZ Tau and DR Tau, which are two actively accreting T Tauri stars classified as EXors. Equivalent widths and profiles of the observed features are used to derive information on the properties of the inner disk, the accretion columns, and the winds. Results: Both sources display composite H I line profiles, where contributions from both accreting gas and high-velocity winds can be recognised. These lines are progressively more symmetric and narrower with increasing upper energy which may be interpreted in terms of two components with different decrements or imputed to self-absorption effects. XZ Tau is observed in a relatively high state of activity with respect to literature observations. The variation of the He I 1.08 μm line blue-shifted absorption, in particular, suggests that the inner wind has undergone a dramatic change in its velocity structure, connected with a recent accretion event. DR Tau has a more stable wind as its He I 1.08 μm absorption does not show variations with time in spite of strong variability of the emission component. The IR veiling in the two sources can be interpreted as due to blackbody emission at temperatures of 1600 K and 2300 K for XZ Tau and DR Tau, respectively, with emitting areas 30 times larger than the central star. While for XZ Tau these conditions are consistent with emission from the inner rim of the dusty disk, the fairly high temperature inferred for DR Tau might suggest that its veiling originates from a thick gaseous disk located within the dust sublimation radius. Strong and broad metallic lines, mainly from C I and Fe I, are detected in XZ Tau, similar to those observed in other EXor sources during burst phases. At variance, DR Tau shows weaker and

  7. Multi-technique investigation of the binary fraction of A-F type candidate hybrid variable stars discovered by Kepler

    Science.gov (United States)

    Lampens, P.; Frémat, Y.; Vermeylen, L.; Sódor, Á.; Skarka, M.; De Cat, P.; Bognár, Zs.; De Nutte, R.; Dumortier, L.; Escorza, A.; Oomen, G. M.; Van de Steene, G.; Kamath, D.; Laverick, M.; Samadi, A.; Triana, S.; Lehmann, H.

    2018-02-01

    Context. Hundreds of candidate hybrid pulsators of intermediate type A-F were revealed by recent space missions. Hybrid pulsators allow us to study the full stellar interiors, where both low-order p- and high-order g-modes are simultaneously excited. The true hybrid stars must be identified since other processes, related to stellar multiplicity or rotation, might explain the presence of (some) low frequencies observed in their periodograms. Aims: We measured the radial velocities of 50 candidate δ Scuti -γ Doradus hybrid stars from the Kepler mission with the Hermes and ACE spectrographs over a time span of months to years. We aim to derive the fraction of binary and multiple systems and to provide an independent and homogeneous determination of the atmospheric properties and v sin i for all targets. The long(er)-term objective is to identify the (probable) physical cause of the low frequencies. Methods: We computed one-dimensional cross-correlation functions (CCFs) in order to find the best set of parameters in terms of the number of components, spectral type(s), and v sin i for each target. Radial velocities were measured using spectrum synthesis and a two-dimensional cross-correlation technique in the case of double- and triple-lined systems. Fundamental parameters were determined by fitting (composite) synthetic spectra to the normalised median spectra corrected for the appropriate Doppler shifts. Results: We report on the analysis of 478 high-resolution Hermes and 41 ACE spectra of A/F-type candidate hybrid pulsators from the Kepler field. We determined their radial velocities, projected rotational velocities, and atmospheric properties and classified our targets based on the shape of the CCFs and the temporal behaviour of the radial velocities. We derived orbital solutions for seven new systems. Three preliminary long-period orbital solutions are confirmed by a photometric time-delay analysis. Finally, we determined a global multiplicity fraction of 27% in

  8. Non-contrast-enhanced 4D MR angiography with STAR spin labeling and variable flip angle sampling: a feasibility study for the assessment of Dural Arteriovenous Fistula

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Jinhee; Kim, Bom-yi; Choi, Hyun Seok; Jung, So-Lyung; Ahn, Kook-Jin; Kim, Bum-soo [The Catholic University of Korea, Department of Radiology, Seoul St. Mary' s Hospital, College of Medicine, Seoul (Korea, Republic of); Schmitt, Peter [Siemens AG, Healthcare Sector, Erlangen (Germany); Kim, Inseong; Paek, Munyoung [Siemens AG, Healthcare, Seoul (Korea, Republic of)

    2014-04-15

    This study aimed to evaluate the feasibility of non-contrast-enhanced 4D magnetic resonance angiography (NCE 4D MRA) with signal targeting with alternative radiofrequency (STAR) spin labeling and variable flip angle (VFA) sampling in the assessment of dural arteriovenous fistula (DAVF) in the transverse sinus. Nine patients underwent NCE 4D MRA for the evaluation of DAVF in the transverse sinus at 3 T. One patient was examined twice, once before and once after the interventional treatment. All patients also underwent digital subtraction angiography (DSA) and/or contrast-enhanced magnetic resonance angiography (CEMRA). For the acquisition of NCE 4D MRA, a STAR spin tagging method was used, and a VFA sampling was applied in the data readout module instead of a constant flip angle. Two readers evaluated the NCE 4D MRA data for the diagnosis of DAVF and its type with consensus. The results were compared with those from DSA and/or CEMRA. All patients underwent NCE 4D MRA without any difficulty. Among seven patients with patent DAVFs, all cases showed an early visualization of the transverse sinus on NCE 4D MRA. Except for one case, the type of DAVF of NCE 4D MRA was agreed with that of reference standard study. Cortical venous reflux (CVR) was demonstrated in two cases out of three patients with CVR. NCE 4D MRA with STAR tagging and VFA sampling is technically and clinically feasible and represents a promising technique for assessment of DAVF in the transverse sinus. Further technical developments should aim at improvements of spatial and temporal coverage. (orig.)

  9. A new method for studying the thermospheric density variability derived from CHAMP/STAR accelerometer data for magnetically active conditions

    Directory of Open Access Journals (Sweden)

    M. Menvielle

    2007-10-01

    Full Text Available Thermospheric densities deduced from STAR accelerometer measurements onboard the CHAMP satellite are used to characterize the thermosphere and its response to space weather events. The STAR thermospheric density estimates are analysed using a Singular Value Decomposition (SVD approach allowing one to decouple large scale spatial and temporal variations from fast and local transients. Because SVD achieves such decomposition by using the reproducibility of orbital variations, it provides more meaningful results than any method based upon data smoothing or filtering.

    SVD analysis enables us to propose a new thermosphere proxy, based on the projection coefficient of the CHAMP densities on the first singular vector. The large scale spatial variations in the density, mostly related to altitude/latitude variations are captured by the first singular vector; time variations are captured by the associated projection coefficient.

    The study presented here is focused on time dependent global scale variations in the thermospheric density between 50 N and 50 S geographic latitudes. We show that the time variations in the projection coefficient do in fact represent those in the global density that are associated with magnetic activity as well as with solar EUV radiations. We also show that the NRLMSISE-00 empirical model better accounts for the density forcing by Solar radiations when tuned using Mg II indices. Using the so modified model with an additional geomagnetic parameterization corresponding to quiet geomagnetic situation enables one to define time reference values which are then used to evaluate the impact of geomagnetic activity. The ratio of CHAMP density projection coefficient to the quiet model projection coefficient is a global quantity, independent of altitude and latitude, which quantifies the thermospheric density response to auroral energy deposition. It will serve as a proxy of the response of thermospheric density to

  10. A new method for studying the thermospheric density variability derived from CHAMP/STAR accelerometer data for magnetically active conditions

    Directory of Open Access Journals (Sweden)

    M. Menvielle

    2007-10-01

    Full Text Available Thermospheric densities deduced from STAR accelerometer measurements onboard the CHAMP satellite are used to characterize the thermosphere and its response to space weather events. The STAR thermospheric density estimates are analysed using a Singular Value Decomposition (SVD approach allowing one to decouple large scale spatial and temporal variations from fast and local transients. Because SVD achieves such decomposition by using the reproducibility of orbital variations, it provides more meaningful results than any method based upon data smoothing or filtering. SVD analysis enables us to propose a new thermosphere proxy, based on the projection coefficient of the CHAMP densities on the first singular vector. The large scale spatial variations in the density, mostly related to altitude/latitude variations are captured by the first singular vector; time variations are captured by the associated projection coefficient. The study presented here is focused on time dependent global scale variations in the thermospheric density between 50 N and 50 S geographic latitudes. We show that the time variations in the projection coefficient do in fact represent those in the global density that are associated with magnetic activity as well as with solar EUV radiations. We also show that the NRLMSISE-00 empirical model better accounts for the density forcing by Solar radiations when tuned using Mg II indices. Using the so modified model with an additional geomagnetic parameterization corresponding to quiet geomagnetic situation enables one to define time reference values which are then used to evaluate the impact of geomagnetic activity. The ratio of CHAMP density projection coefficient to the quiet model projection coefficient is a global quantity, independent of altitude and latitude, which quantifies the thermospheric density response to auroral energy deposition. It will serve as a proxy of the response of thermospheric density to geomagnetic activity

  11. Cleveland Bilingual Education Program: Title VII ESEA.

    Science.gov (United States)

    Halasa, Ofelia

    This 1974-75 evaluation report of the Title VII Cleveland Bilingual Education Program discusses the degree to which process objectives were implemented and product objectives attained, and the impressions of project and school staff and parents. The goals of the bilingual program were to develop the ability to communicate and function in Spanish…

  12. Canine specific ELISA for coagulation factor VII

    DEFF Research Database (Denmark)

    Knudsen, Tom; Kjelgaard-Hansen, Mads; Tranholm, Mikael

    2011-01-01

    Canine coagulation factor VII (FVII) deficiency can be hereditary or acquired and may cause life threatening bleeding episodes if untreated. FVII procoagulant activity can be measured by FVII activity (FVII:C), but assays for measurement of canine specific FVII antigen (FVII:Ag) have not been...

  13. 29 CFR 1601.93 - Opinions-title VII.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 4 2010-07-01 2010-07-01 false Opinions-title VII. 1601.93 Section 1601.93 Labor Regulations Relating to Labor (Continued) EQUAL EMPLOYMENT OPPORTUNITY COMMISSION PROCEDURAL REGULATIONS Title VII Interpretations and Opinions by the Commission § 1601.93 Opinions—title VII. Only the following...

  14. Constraints on Variability of Brightness and Surface Magnetism on Time Scales of Decades to Centuries in the Sun and Sun-Like Stars: A Source of Potential Terrestrial Climate Variability

    Science.gov (United States)

    Baliunas, Sallie L.; Sharber, James (Technical Monitor)

    2001-01-01

    These four points summarize our work to date. (1) Conciliation of solar and stellar photometric variability. Previous research by us and colleagues suggested that the Sun might at present be showing unusually low photometric variability compared to other sun-like stars. Those early results would question the suitability of the technique of using sun-like stars as proxies for solar irradiance change on time scales of decades to centuries. However, our results indicate the contrary: the Sun's observed short-term (seasonal) and longterm (year-to-year) brightness variations closely agree with observed brightness variations in stars of similar mass and age. (2) We have demonstrated an inverse correlation between the global temperature of the terrestrial lower troposphere, inferred from the NASA Microwave Sounding Unit (MSU) radiometers, and the total area of the Sun covered by coronal holes from January 1979 to present (up to May 2000). Variable fluxes of either solar charged particles or cosmic rays, or both, may influence the terrestrial tropospheric temperature. The geographical pattern of the correlation is consistent with our interpretation of an extra-terrestrial charged particle forcing. (3) Possible climate mechanism amplifying the impact of solar ultraviolet irradiance variations. The key points of our proposed climate hypersensitivity mechanism are: (a) The Sun is more variable in the UV (ultraviolet) than in the visible. However, the increased UV irradiance is mainly absorbed in the lower stratosphere/upper troposphere rather than at the surface. (b) Absorption in the stratosphere raises the temperature moderately around the vicinity of the tropopause, and tends to stabilize the atmosphere against vertical convective/diffusive transport, thus decreasing the flux of heat and moisture carried upward from surface. (c) The decrease in the upward convection of heat and moisture tends to raise the surface temperature because a drier upper atmosphere becomes less

  15. VLT/X-shooter observations of the low-metallicity blue compact dwarf galaxy PHL 293B including a luminous blue variable star

    Science.gov (United States)

    Izotov, Y. I.; Guseva, N. G.; Fricke, K. J.; Henkel, C.

    2011-09-01

    Context. We present VLT/X-shooter spectroscopic observations in the wavelength range λλ3000-23 000 Å of the extremely metal-deficient blue compact dwarf (BCD) galaxy PHL 293B containing a luminous blue variable (LBV) star and compare them with previous data. Aims: This BCD is one of the two lowest-metallicity galaxies where LBV stars were detected, allowing us to study the LBV phenomenon in the extremely low metallicity regime. Methods: We determine abundances of nitrogen, oxygen, neon, sulfur, argon, and iron by analyzing the fluxes of narrow components of the emission lines using empirical methods and study the properties of the LBV from the fluxes and widths of broad emission lines. Results: We derive an interstellar oxygen abundance of 12+log O/H = 7.71 ± 0.02, which is in agreement with previous determinations. The observed fluxes of narrow Balmer, Paschen and Brackett hydrogen lines correspond to the theoretical recombination values after correction for extinction with a single value C(Hβ) = 0.225. This implies that the star-forming region observed in the optical range is the only source of ionisation and there is no additional source of ionisation that is seen in the NIR range but is hidden in the optical range. We detect three v = 1-0 vibrational lines of molecular hydrogen. Their flux ratios and non-detection of v = 2-1 and 3-1 emission lines suggest that collisional excitation is the main source producing H2 lines. For the LBV star in PHL 293B we find broad emission with P Cygni profiles in several Balmer hydrogen emission lines and for the first time in several Paschen hydrogen lines and in several He i emission lines, implying temporal evolution of the LBV on a time scale of 8 years. The Hα luminosity of the LBV star is by one order of magnitude higher than the one obtained for the LBV star in NGC 2363 ≡ Mrk 71 which has a slightly higher metallicity 12+logO/H = 7.87. The terminal velocity of the stellar wind in the low-metallicity LBV of PHL293

  16. NuSTAR detection of high-energy X-ray emission and rapid variability from sagittarius A* flares

    DEFF Research Database (Denmark)

    Barrière, Nicolas M.; Tomsick, John A.; Baganoff, Frederick K.

    2014-01-01

    Sagittarius A* harbors the supermassive black hole that lies at the dynamical center of our Galaxy. Sagittarius A* spends most of its time in a low luminosity emission state but flares frequently in the infrared and X-ray, increasing up to a few hundred fold in brightness for up to a few hours...... at a time. The physical processes giving rise to the X-ray flares are uncertain. Here we report the detection with the NuSTAR observatory in Summer and Fall 2012 of four low to medium amplitude X-ray flares to energies up to 79 keV. For the first time, we clearly see that the power-law spectrum...... of Sagittarius A* X-ray flares extends to high energy, with no evidence for a cutoff. Although the photon index of the absorbed power-law fits are in agreement with past observations, we find a difference between the photon index of two of the flares (significant at the 95% confidence level). The spectra...

  17. The Astrophysics of Emission-Line Stars

    CERN Document Server

    Kogure, Tomokazu

    2007-01-01

    Many types of stars show conspicuous emission lines in their optical spectra. These stars are broadly referred to as emission line stars. Emission line stars are attractive to many people because of their spectacular phenomena and their variability. The Astrophysics of Emission Line Stars offers general information on emission line stars, starting from a brief introduction to stellar astrophysics, and then moving toward a broad overview of emission line stars including early and late type stars as well as pre-main sequence stars. Detailed references have been prepared along with an index for further reading.

  18. Additional photoelectric observations and analysis of the variability of the beta Cephei stars 12 and 16 Lacertae

    Science.gov (United States)

    Jarzebowski, T.; Jerzykiewicz, M.; Rios Herrera, M.; Rios Berumen, M.

    1980-04-01

    We present photoelectric observations of two Cephei variables - 12 and 16 Lacertae- made in 1977 in the Observatory of Zacatecas. The results of a frequency analysis made with these data and with the data obtained in the same year at the San Pedro Martir, Chiran and Bialkow Observatories are also given.

  19. Study of a Variable Star Discovered with the 0.5-M F/1 Baker-nunn Patrol Camera of the RAO

    Science.gov (United States)

    Lenhardt, Tyler; Williams, M.; Milone, E.; Langill, P.

    2006-06-01

    At the Rothney Astrophysical Observatory (RAO) of the University of Calgary, the Baker-Nunn Patrol Camera (BNPC) has discovered dozens of variable stars. Follow-up observations on RAOVS001-000107, a close binary system, were carried out using the 0.4-m telescope at the RAO. Whereas the BNPC is limited to a single passband ( RJ) the 0.4-m telescope provides observations in UBVRI passbands, fills in gaps in the BNPC light curve, and provides higher-resolution images. The measured light curve will be analyzed with a version of the Wilson-Devinney program (WD2006) developed by J. Kallrath and EM to attempt to determine as many of this stellar systems' fundamental properties. RAOVS001-000107 was discovered by MW, who developed the pipeline process to carry out image processing, identify variables, and produce preliminary light curves. The field of the camera is 19 square degrees.The BNPC was developed under a provincial research infrastructure improvement grant from the Alberta Science Research Authority to EM and A. Hildebrand, with major contributions from several partners and other agencies. The FLI CCD has been available by special arrangement with Peter Brown, UWO. This work has been funded in part with Canadian NSERC grants to EM and a federal SCPP grant, for which TL is appreciative.

  20. Stars and Star Myths.

    Science.gov (United States)

    Eason, Oliver

    Myths and tales from around the world about constellations and facts about stars in the constellations are presented. Most of the stories are from Greek and Roman mythology; however, a few Chinese, Japanese, Polynesian, Arabian, Jewish, and American Indian tales are also included. Following an introduction, myths are presented for the following 32…

  1. 2FGL J0846.0+2820: A New Neutron Star Binary with a Giant Secondary and Variable γ-Ray Emission

    Science.gov (United States)

    Swihart, Samuel J.; Strader, Jay; Johnson, Tyrel J.; Cheung, C. C.; Sand, David; Chomiuk, Laura; Wasserman, Asher; Larsen, Søren; Brodie, Jean P.; Simonian, Gregory V.; Tremou, Evangelia; Shishkovsky, Laura; Reichart, Daniel E.; Haislip, Joshua

    2017-12-01

    We present optical photometric and spectroscopic observations of the likely stellar counterpart to the unassociated Fermi Large Area Telescope (LAT) γ-ray source 2FGL J0846.0+2820, selected for study based on positional coincidences of optical variables with unassociated LAT sources. Using optical spectroscopy from the SOAR telescope, we have identified a late-G giant in an eccentric (e = 0.06) 8.133-day orbit with an invisible primary. Modeling the spectroscopy and photometry together led us to infer a heavy neutron star primary of ˜ 2 {M}⊙ and a partially stripped giant secondary of ˜ 0.8 {M}⊙ . Hα emission is observed in some of the spectra, perhaps consistent with the presence of a faint accretion disk. We find that the γ-ray flux of 2FGL J0846.0+2820 dropped substantially in mid-2009, accompanied by an increased variation in the optical brightness, and since then, it has not been detected by Fermi. The long period and giant secondary are reminiscent of the γ-ray bright binary 1FGL J1417.7-4407, which hosts a millisecond pulsar (MSP) apparently in the final stages of the pulsar recycling process. The discovery of 2FGL J0846.0+2820 suggests the identification of a new subclass of MSP binaries that are the likely progenitors of typical field MSPs.

  2. Analisis Pelaksanaan Program Kemitraan Bumn terhadap Kesejahteraan UMKM: Pendekatan Corporate Responsibility (CSR). (Studi Kasus PTPN VII)

    OpenAIRE

    Mukhan, Unang; Pratama, Maulana Agung

    2012-01-01

    Partnership and Environment Development Program is the implementation of Corporate Social Responsibility (CSR) in State Owned Enterprises (SOEs). Policy Partnership program is very interesting in terms of implementation that much getting about whether the purpose of the provision of an effective CSR program and on target. Descriptive and explanatory research was conducted in partner SMEs assisted PTPN VII. The independent variable used is CSR goal (X1), CSR issue (X2) and...

  3. A Stellar Population Gradient in VII ZW 403: Implications for the Formation of Blue Compact Dwarf Galaxies

    Science.gov (United States)

    Schulte-Ladbeck, Regina E.; Hopp, Ulrich; Crone, Mary M.; Greggio, Laura

    1999-11-01

    We present evidence for the existence of an old stellar halo in the blue compact dwarf galaxy VII Zw 403. VII Zw 403 is the first blue compact dwarf galaxy for which a clear spatial segregation of the resolved stellar content into a core-halo structure is detected. Multicolor Hubble Space Telescope WFPC2 (HST/WFPC2) observations indicate that active star formation occurs in the central region, but is strikingly absent at large radii. Instead, a globular-cluster-like red giant branch suggests the presence of an old (>10 Gyr) and metal-poor (=-1.92) stellar population in the halo. While the vast majority of blue compact dwarf galaxies have been recognized to possess halos of red color in ground-based surface photometry, our observations of VII Zw 403 establish for the first time a direct correspondence between a red halo color and the presence of old, red giant stars. If the halos of blue compact dwarf galaxies are all home to such ancient stellar populations, then the fossil record conflicts with delayed-formation scenarios for dwarfs. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained and supported in part through grant AR-06404.01-95A from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555.

  4. Frederik VII og folkets kærlighed

    DEFF Research Database (Denmark)

    Perlt, Michael; Vinding, Niels Valdemar

    2013-01-01

    I den turbulente tid mellem de to slesvigske krige drog kong Frederik VII under en rejse til Jylland i 1857 i procession op på højene i Jelling for at modtage folkets hyldest. På det historiske sted lod Frederik VII sig fejre som danskernes konge under en stor folkefest med bønder og deres familier...

  5. In silico dissection of Type VII Secretion System components across ...

    Indian Academy of Sciences (India)

    2016-02-12

    Feb 12, 2016 ... [Das C, Ghosh TS and Mande SS 2016 In silico dissection of Type VII Secretion System components across bacteria: New directions towards functional characterization. J. Biosci. 41 133–143] DOI 10.1007/s12038-016-9599-8. 1. Introduction. Type VII Secretion System (T7SS) was first identified in.

  6. Variability of Disk Emission in Pre-main Sequence and Related Stars. IV. Occultation Events from the Innermost Disk Region of the Herbig AE Star HD 163296 = MWC 275

    Science.gov (United States)

    Pikhartova, Monika; Long, Zachary; Fernandes, Rachel; Sitko, Michael; Grady, Carol; Rich, Evan; Wisniewski, John

    2018-01-01

    We studied the structure and the dynamics of the innermost region of the circumstellar disk around the star HD 163296, MWC 275. We extracted the emission line strengths of Pa beta and Br gamma and calculated the line fluxes, from which we then computed the mass accretion rates onto the star. We investigated the brightness drop at visible wavelengths in 2001 using the Monte Carlo Radiative Transfer Code, hochunk3d. Since the star has bipolar outflows, we looked at whether changes in the outflow, with dust entrained with the gas, could produce such a drop in brightness. We fitted data from 2001 and 2005 onto SED and temperaturedensity models of the disk and generated JHK disk images, then noted the changes in image brightness and in SED plots. Our models succesfully produce the drop in brightness.

  7. Wave Star

    DEFF Research Database (Denmark)

    Kramer, Morten; Brorsen, Michael; Frigaard, Peter

    Denne rapport beskriver numeriske beregninger af forskellige flydergeometrier for bølgeenergianlæget Wave Star.......Denne rapport beskriver numeriske beregninger af forskellige flydergeometrier for bølgeenergianlæget Wave Star....

  8. NuSTAR detection of high-energy X-ray emission and rapid variability from Sagittarius A{sup *} flares

    Energy Technology Data Exchange (ETDEWEB)

    Barrière, Nicolas M.; Tomsick, John A.; Boggs, Steven E.; Craig, William W.; Zoglauer, Andreas [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Baganoff, Frederick K. [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139-4307 (United States); Christensen, Finn E. [DTU Space, National Space Institute, Technical University of Denmark, Elektrovej 327, DK-2800 Kgs. Lyngby (Denmark); Dexter, Jason [Departments of Physics and Astronomy, University of California, Berkeley, CA 94720 (United States); Grefenstette, Brian; Harrison, Fiona A.; Madsen, Kristin K. [Cahill Center for Astronomy and Astrophysics, Caltech, Pasadena, CA 91125 (United States); Hailey, Charles J.; Mori, Kaya; Zhang, Shuo [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Stern, Daniel [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Zhang, William W. [X-ray Astrophysics Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2014-05-01

    Sagittarius A{sup *} harbors the supermassive black hole that lies at the dynamical center of our Galaxy. Sagittarius A{sup *} spends most of its time in a low luminosity emission state but flares frequently in the infrared and X-ray, increasing up to a few hundred fold in brightness for up to a few hours at a time. The physical processes giving rise to the X-ray flares are uncertain. Here we report the detection with the NuSTAR observatory in Summer and Fall 2012 of four low to medium amplitude X-ray flares to energies up to 79 keV. For the first time, we clearly see that the power-law spectrum of Sagittarius A{sup *} X-ray flares extends to high energy, with no evidence for a cutoff. Although the photon index of the absorbed power-law fits are in agreement with past observations, we find a difference between the photon index of two of the flares (significant at the 95% confidence level). The spectra of the two brightest flares (∼55 times quiescence in the 2-10 keV band) are compared to simple physical models in an attempt to identify the main X-ray emission mechanism, but the data do not allow us to significantly discriminate between them. However, we confirm the previous finding that the parameters obtained with synchrotron models are, for the X-ray emission, physically more reasonable than those obtained with inverse Compton models. One flare exhibits large and rapid (<100 s) variability, which, considering the total energy radiated, constrains the location of the flaring region to be within ∼10 Schwarzschild radii of the black hole.

  9. Star clusters

    NARCIS (Netherlands)

    Gieles, M.

    2006-01-01

    Star clusters are observed in almost every galaxy. In this thesis we address several fundamental problems concerning the formation, evolution and disruption of star clusters. From observations of (young) star clusters in the interacting galaxy M51, we found that clusters are formed in complexes of

  10. Hybrid stars

    Indian Academy of Sciences (India)

    from two classes of EOS's and discuss their implications. Keywords. Neutron stars; phase transition. It is generally believed that the evolutionary journey of a star after it has exhausted all its fuel culminates into the formation of a compact object in the form of a white dwarf, a neutron star or a black hole depending on its mass.

  11. Massive Stars

    Science.gov (United States)

    Livio, Mario; Villaver, Eva

    2009-11-01

    Participants; Preface Mario Livio and Eva Villaver; 1. High-mass star formation by gravitational collapse of massive cores M. R. Krumholz; 2. Observations of massive star formation N. A. Patel; 3. Massive star formation in the Galactic center D. F. Figer; 4. An X-ray tour of massive star-forming regions with Chandra L. K. Townsley; 5. Massive stars: feedback effects in the local universe M. S. Oey and C. J. Clarke; 6. The initial mass function in clusters B. G. Elmegreen; 7. Massive stars and star clusters in the Antennae galaxies B. C. Whitmore; 8. On the binarity of Eta Carinae T. R. Gull; 9. Parameters and winds of hot massive stars R. P. Kudritzki and M. A. Urbaneja; 10. Unraveling the Galaxy to find the first stars J. Tumlinson; 11. Optically observable zero-age main-sequence O stars N. R. Walborn; 12. Metallicity-dependent Wolf-Raynet winds P. A. Crowther; 13. Eruptive mass loss in very massive stars and Population III stars N. Smith; 14. From progenitor to afterlife R. A. Chevalier; 15. Pair-production supernovae: theory and observation E. Scannapieco; 16. Cosmic infrared background and Population III: an overview A. Kashlinsky.

  12. The VLTI/MIDI view on the inner mass loss of evolved stars from the Herschel MESS sample

    Science.gov (United States)

    Paladini, C.; Klotz, D.; Sacuto, S.; Lagadec, E.; Wittkowski, M.; Richichi, A.; Hron, J.; Jorissen, A.; Groenewegen, M. A. T.; Kerschbaum, F.; Verhoelst, T.; Rau, G.; Olofsson, H.; Zhao-Geisler, R.; Matter, A.

    2017-04-01

    Context. The mass-loss process from evolved stars is a key ingredient for our understanding of many fields of astrophysics, including stellar evolution and the chemical enrichment of the interstellar medium (ISM) via stellar yields. Nevertheless, many questions are still unsolved, one of which is the geometry of the mass-loss process. Aims: Taking advantage of the results from the Herschel Mass loss of Evolved StarS (MESS) programme, we initiated a coordinated effort to characterise the geometry of mass loss from evolved red giants at various spatial scales. Methods: For this purpose we used the MID-infrared interferometric Instrument (MIDI) to resolve the inner envelope of 14 asymptotic giant branch stars (AGBs) in the MESS sample. In this contribution we present an overview of the interferometric data collected within the frame of our Large Programme, and we also add archive data for completeness. We studied the geometry of the inner atmosphere by comparing the observations with predictions from different geometric models. Results: Asymmetries are detected for the following five stars: R Leo, RT Vir, π1Gruis, omi Ori, and R Crt. All the objects are O-rich or S-type, suggesting that asymmetries in the N band are more common among stars with such chemistry. We speculate that this fact is related to the characteristics of the dust grains. Except for one star, no interferometric variability is detected, i.e. the changes in size of the shells of non-mira stars correspond to changes of the visibility of less than 10%. The observed spectral variability confirms previous findings from the literature. The detection of dust in our sample follows the location of the AGBs in the IRAS colour-colour diagram: more dust is detected around oxygen-rich stars in region II and in the carbon stars in region VII. The SiC dust feature does not appear in the visibility spectrum of the U Ant and S Sct, which are two carbon stars with detached shells. This finding has implications for

  13. "Viies aastaaeg" kui voolav ruum / Veronika Valk

    Index Scriptorium Estoniae

    Valk, Veronika, 1976-

    2015-01-01

    Arhitektuurivõistluse eesmärk oli leida Suure-Jaani tervisekeskusele sobivaim lahendus. 2015. aasta sügisel toimunud võistlusele laekus 12 tööd, millest hankija esitatud tingimusele vastas 11. Võitjaks osutus Arhitekt Musta ja Novarci ühistööna valminud kavand "Viies aastaaeg" (autorid: Ott Alver, Alvin Järving, Mari Rass, Gert Guriev, Liina Liis Pihu, Märten Peterson ja Reino Rass). Teise koha sai töö "Polüfoonia" (autorid: Urmo Mets, Kaur Talpsep, Kristiina Aasvee ja Lauri Eltermaa Kauss Arhitektuurist). Kolmanda koha sai töö "Akord" (autorid: Joel Kopli, Koit Ojaliiv ja Rene Sauemägi Amhold/Kuust)

  14. The hot γ Doradus and Maia stars

    Science.gov (United States)

    Balona, L. A.; Engelbrecht, C. A.; Joshi, Y. C.; Joshi, S.; Sharma, K.; Semenko, E.; Pandey, G.; Chakradhari, N. K.; Mkrtichian, David; Hema, B. P.; Nemec, J. M.

    2016-08-01

    The hot γ Doradus stars have multiple low frequencies characteristic of γ Dor or SPB variables, but are located between the red edge of the SPB and the blue edge of the γ Dor instability strips where all low-frequency modes are stable in current models of these stars. Though δ Sct stars also have low frequencies, there is no sign of high frequencies in hot γ Dor stars. We obtained spectra to refine the locations of some of these stars in the H-R diagram and conclude that these are, indeed, anomalous pulsating stars. The Maia variables have multiple high frequencies characteristic of β Cep and δ Sct stars, but lie between the red edge of the β Cep and the blue edge of the δ Sct instability strips. We compile a list of all Maia candidates and obtain spectra of two of these stars. Again, it seems likely that these are anomalous pulsating stars which are currently not understood.

  15. Stars and Flowers, Flowers and Stars

    Science.gov (United States)

    Minti, Hari

    2012-12-01

    The author, a graduated from the Bucharest University (1964), actually living and working in Israel, concerns his book to variable stars and flowers, two domains of his interest. The analogies includes double stars, eclipsing double stars, eclipses, Big Bang. The book contains 34 chapters, each of which concerns various relations between astronomy and other sciences and pseudosciences such as Psychology, Religion, Geology, Computers and Astrology (to which the author is not an adherent). A special part of the book is dedicated to archeoastronomy and ethnoastronomy, as well as to history of astronomy. Between the main points of interest of these parts: ancient sanctuaries in Sarmizegetusa (Dacia), Stone Henge(UK) and other. The last chapter of the book is dedicated to flowers. The book is richly illustrated. It is designed for a wide circle of readers.

  16. The Grism Lens-Amplified Survey from Space (GLASS). VII. The Diversity of the Distribution of Star Formation in Cluster and Field Galaxies at 0.3 less than or equal to z less than or equal to 0.7

    Science.gov (United States)

    Vulcani, Benedetta; Treu, Tommaso; Schmidt, Kasper B.; Morishita, Takahiro; Dressler, Alan; Poggianti, Bianca M.; Abramson, Louis; Bradač, Marusa; Brammer, Gabriel B.; Hoag, Austin; Malkan, Matthew; Pentericci, Laura; Trenti, Michele

    2016-12-01

    Exploiting the slitless spectroscopy taken as part of the Grism Lens-Amplified Survey from Space (GLASS), we present an extended analysis of the spatial distribution of star formation in 76 galaxies in 10 clusters at 0.3\\lt z\\lt 0.7. We use 85 foreground and background galaxies in the same redshift range as a field sample. The samples are well matched in stellar mass (108-1011 {M}⊙ ) and star formation rate (0.5-50 {M}⊙ {{yr}}-1). We visually classify galaxies in terms of broad band morphology, Hα morphology, and likely physical process acting on the galaxy. Most Hα emitters have a spiral morphology (41% ± 8% in clusters, 51% ± 8% in the field), followed by mergers/interactions (28% ± 8%, 31% ± 7%, respectively) and early-type galaxies (remarkably as high as 29% ± 8% in clusters and 15% ± 6% in the field). A diversity of Hα morphologies is detected, suggesting a diversity of physical processes. In clusters, 30% ± 8% of the galaxies present a regular morphology, mostly consistent with star formation diffused uniformly across the stellar population (mostly in the disk component, when present). The second most common morphology (28% ± 8%) is asymmetric/jellyfish, consistent with ram-pressure stripping or other non-gravitational processes in 18% ± 8% of the cases. Ram-pressure stripping appears significantly less prominent in the field (2% ± 2%), where the most common morphology/mechanism appears to be consistent with minor gas-rich mergers or clump accretion. This work demonstrates that while environment-specific mechanisms affect galaxy evolution at this redshift, they are diverse and their effects are subtle. A full understanding of this complexity requires larger samples and detailed and spatially resolved physical models.

  17. The nebular variables

    CERN Document Server

    Glasby, John S

    1974-01-01

    The Nebular Variables focuses on the nebular variables and their characteristics. Discussions are organized by type of nebular variable, namely, RW Aurigae stars, T Orionis stars, T Tauri stars, and peculiar nebular objects. Topics range from light variations of the stars to their spectroscopic and physical characteristics, spatial distribution, interaction with nebulosity, and evolutionary features. This volume is divided into four sections and consists of 25 chapters, the first of which provides general information on nebular variables, including their stellar associations and their classifi

  18. 29 CFR 1601.91 - Request for title VII interpretation or opinion.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 4 2010-07-01 2010-07-01 false Request for title VII interpretation or opinion. 1601.91... PROCEDURAL REGULATIONS Title VII Interpretations and Opinions by the Commission § 1601.91 Request for title VII interpretation or opinion. Any interested person desiring a written title VII interpretation or...

  19. Stark broadening parameter tables for F VI and Cl VII

    Directory of Open Access Journals (Sweden)

    Dimitrijević M.S.

    1998-01-01

    Full Text Available Using a semiclassical approach, we have calculated electron−, proton−, and He III−impact line widths and shifts for 2 F VI and 10 Cl VII multiplets as a function of temperature and perturber density.

  20. Star Wreck

    CERN Document Server

    Kusenko, A; Tinyakov, Peter G; Tkachev, Igor I; Kusenko, Alexander; Shaposhnikov, Mikhail; Tkachev, Igor I.

    1998-01-01

    Electroweak models with low-energy supersymmetry breaking predict the existence of stable non-topological solitons, Q-balls, that can be produced in the early universe. The relic Q-balls can accumulate inside a neutron star and gradually absorb the baryons into the scalar condensate. This causes a slow reduction in the mass of the star. When the mass reaches a critical value, the neutron star becomes unstable and explodes. The cataclysmic destruction of the distant neutron stars may be the origin of the gamma-ray bursts.

  1. Neutron Stars

    Science.gov (United States)

    Cottam, J.

    2007-01-01

    Neutron stars were discovered almost 40 years ago, and yet many of their most fundamental properties remain mysteries. There have been many attempts to measure the mass and radius of a neutron star and thereby constrain the equation of state of the dense nuclear matter at their cores. These have been complicated by unknown parameters such as the source distance and burning fractions. A clean, straightforward way to access the neutron star parameters is with high-resolution spectroscopy. I will present the results of searches for gravitationally red-shifted absorption lines from the neutron star atmosphere using XMM-Newton and Chandra.

  2. Compression Freezing Kinetics of Water to Ice VII

    Science.gov (United States)

    Gleason, A. E.; Bolme, C. A.; Galtier, E.; Lee, H. J.; Granados, E.; Dolan, D. H.; Seagle, C. T.; Ao, T.; Ali, S.; Lazicki, A.; Swift, D.; Celliers, P.; Mao, W. L.

    2017-07-01

    Time-resolved x-ray diffraction (XRD) of compressed liquid water shows transformation to ice VII in 6 nsec, revealing crystallization rather than amorphous solidification during compression freezing. Application of classical nucleation theory indicates heterogeneous nucleation and one-dimensional (e.g., needlelike) growth. These first XRD data demonstrate rapid growth kinetics of ice VII with implications for fundamental physics of diffusion-mediated crystallization and thermodynamic modeling of collision or impact events on ice-rich planetary bodies.

  3. VII Congrés Internacional de Conflictologia i Pau

    OpenAIRE

    Planell Estany, Josep A.

    2014-01-01

    Discurso del rector de la Universitat Oberta de Catalunya, Josep A. Planell, en el VII Congreso Internacional de Conflictología y Paz. Speech by the president of the Universitat Oberta de Catalunya, Josep A. Planell, at the 7th International Congress on Conflictology and Peace. Discurs del rector de la Universitat Oberta de Catalunya, Josep A. Planell, en el VII Congrés Internacional de Conflictologia i Pau.

  4. Periodic Variations in DQ Herculis Stars

    Science.gov (United States)

    Bless, Robert

    1991-07-01

    The DQ Herculis Stars are cataclysmic variables showing rapid, strictly periodic luminosity variations at either optical or X-ray wavelengths, and usually both. The periods range from 33 sec in AE AQR through 71 sec in DQ Her to 18690 sec in TV Col. The cataclysmic variables are all close binary stars consisting of a late-type star transferring mass to its companion white dwarf star. The white dwarf in the DQ Her stars is magnetized. The periodicities of the DQ Her stars are caused by rotation of the magnetized, acreting white dwarf. We propose to observe the DQ Her stars at ultraviolet wavelengths using the high speed photometer on the space telescope. The purpose of the observations is to investigate the physics of accretion onto compact stars. Revision History: Prepared for future cycles submission--BJW 4/22/92; Cycle 3 to cycle 2, PRISM to SINGLE--BJW 8/27/92;

  5. Star Imager

    DEFF Research Database (Denmark)

    Madsen, Peter Buch; Jørgensen, John Leif; Thuesen, Gøsta

    1997-01-01

    The version of the star imager developed for Astrid II is described. All functions and features are described as well as the operations and the software protocol.......The version of the star imager developed for Astrid II is described. All functions and features are described as well as the operations and the software protocol....

  6. Star Polymers.

    Science.gov (United States)

    Ren, Jing M; McKenzie, Thomas G; Fu, Qiang; Wong, Edgar H H; Xu, Jiangtao; An, Zesheng; Shanmugam, Sivaprakash; Davis, Thomas P; Boyer, Cyrille; Qiao, Greg G

    2016-06-22

    Recent advances in controlled/living polymerization techniques and highly efficient coupling chemistries have enabled the facile synthesis of complex polymer architectures with controlled dimensions and functionality. As an example, star polymers consist of many linear polymers fused at a central point with a large number of chain end functionalities. Owing to this exclusive structure, star polymers exhibit some remarkable characteristics and properties unattainable by simple linear polymers. Hence, they constitute a unique class of technologically important nanomaterials that have been utilized or are currently under audition for many applications in life sciences and nanotechnologies. This article first provides a comprehensive summary of synthetic strategies towards star polymers, then reviews the latest developments in the synthesis and characterization methods of star macromolecules, and lastly outlines emerging applications and current commercial use of star-shaped polymers. The aim of this work is to promote star polymer research, generate new avenues of scientific investigation, and provide contemporary perspectives on chemical innovation that may expedite the commercialization of new star nanomaterials. We envision in the not-too-distant future star polymers will play an increasingly important role in materials science and nanotechnology in both academic and industrial settings.

  7. Wave Star

    DEFF Research Database (Denmark)

    Kramer, Morten; Brorsen, Michael; Frigaard, Peter

    Nærværende rapport beskriver numeriske beregninger af den hydrodynamiske interaktion mellem 5 flydere i bølgeenergianlægget Wave Star.......Nærværende rapport beskriver numeriske beregninger af den hydrodynamiske interaktion mellem 5 flydere i bølgeenergianlægget Wave Star....

  8. The detection of variable radio emission from the fast rotating magnetic hot B-star HR\\xA07355 and evidence for its X-ray aurorae

    Science.gov (United States)

    Leto, P.; Trigilio, C.; Oskinova, L.; Ignace, R.; Buemi, C. S.; Umana, G.; Ingallinera, A.; Todt, H.; Leone, F.

    2017-05-01

    In this paper, we investigate the multiwavelength properties of the magnetic early B-type star HR 7355. We present its radio light curves at several frequencies, taken with the Jansky Very Large Array, and X-ray spectra, taken with the XMM-Newton X-ray telescope. Modelling of the radio light curves for the Stokes I and V provides a quantitative analysis of the HR 7355 magnetosphere. A comparison between HR 7355 and a similar analysis for the Ap star CU Vir allows us to study how the different physical parameters of the two stars affect the structure of the respective magnetospheres where the non-thermal electrons originate. Our model includes a cold thermal plasma component that accumulates at high magnetic latitudes that influences the radio regime, but does not give rise to X-ray emission. Instead, the thermal X-ray emission arises from shocks generated by wind stream collisions close to the magnetic equatorial plane. The analysis of the X-ray spectrum of HR 7355 also suggests the presence of a non-thermal radiation. Comparison between the spectral index of the power-law X-ray energy distribution with the non-thermal electron energy distribution indicates that the non-thermal X-ray component could be the auroral signature of the non-thermal electrons that impact the stellar surface, the same non-thermal electrons that are responsible for the observed radio emission. On the basis of our analysis, we suggest a novel model that simultaneously explains the X-ray and the radio features of HR 7355 and is likely relevant for magnetospheres of other magnetic early-type stars.

  9. The Compton Hump and Variable Blue Wing in the Extreme Low-Flux NuSTAR Observations of 1H0707-495

    Science.gov (United States)

    Kara, E.; Fabian, A.C.; Lohfink, A. M.; Parker, M. L.; Walton, D. J.; Boggs, S. E.; Christensen, F. E.; Hailey, C. J.; Harrison, F. A.; Matt, G.; hide

    2015-01-01

    The narrow-line Seyfert I galaxy, 1H0707-495, has been well observed in the 0.3-10 kiloelectronvolt band, revealing a dramatic drop in flux in the iron K-alpha band, a strong soft excess, and short time-scale reverberation lags associated with these spectral features. In this paper, we present the first results of a deep 250-kilosecond NuSTAR (Nuclear Spectroscopic Telescope Array) observation of 1H0707-495, which includes the first sensitive observations above 10 kiloelectronvolts. Even though the NuSTAR observations caught the source in an extreme low-flux state, the Compton hump is still significantly detected. NuSTAR, with its high effective area above 7 kiloelectronvolts, clearly detects the drop in flux in the iron K-alpha band, and by comparing these observations with archival XMM-Newton observations, we find that the energy of this drop increases with increasing flux. We discuss possible explanations for this, the most likely of which is that the drop in flux is the blue wing of the relativistically broadened iron K-alpha emission line. When the flux is low, the coronal source height is low, thus enhancing the most gravitationally red-shifted emission.

  10. Pulsating star research and the Gaia revolution

    Directory of Open Access Journals (Sweden)

    Eyer Laurent

    2017-01-01

    Full Text Available In this article we present an overview of the ESA Gaia mission and of the unprecedented impact that Gaia will have on the field of variable star research. We summarise the contents and impact of the first Gaia data release on the description of variability phenomena, with particular emphasis on pulsating star research. The Tycho-Gaia astrometric solution, although limited to 2.1 million stars, has been used in many studies related to pulsating stars. Furthermore a set of 3,194 Cepheids and RR Lyrae stars with their times series have been released. Finally we present the plans for the ongoing study of variable phenomena with Gaia and highlight some of the possible impacts of the second data release on variable, and specifically, pulsating stars.

  11. VII International Congress of Engineering Physics

    Science.gov (United States)

    2015-01-01

    In the frame of the fortieth anniversary celebration of the Universidad Autónoma Metropolitana and the Physics Engineering career, the Division of Basic Science and Engineering and its Departments organized the "VII International Congress of Physics Engineering". The Congress was held from 24 to 28 November 2014 in Mexico City, Mexico. This congress is the first of its type in Latin America, and because of its international character, it gathers experts on physics engineering from Mexico and all over the globe. Since 1999, this event has shown research, articles, projects, technological developments and vanguard scientists. These activities aim to spread, promote, and share the knowledge of Physics Engineering. The topics of the Congress were: • Renewable energies engineering • Materials technology • Nanotechnology • Medical physics • Educational physics engineering • Nuclear engineering • High precision instrumentation • Atmospheric physics • Optical engineering • Physics history • Acoustics This event integrates lectures on top trending topics with pre-congress workshops, which are given by recognized scientists with an outstanding academic record. The lectures and workshops allow the exchange of experiences, and create and strengthen research networks. The Congress also encourages professional mobility among all universities and research centres from all countries. CIIF2014 Organizing and Editorial Committee Dr. Ernesto Rodrigo Vázquez Cerón Universidad Autónoma Metropolitana - Azcapotzalco ervc@correo.azc.uam.mx Dr. Luis Enrique Noreña Franco Universidad Autónoma Metropolitana - Azcapotzalco lnf@correo.azc.uam.mx Dr. Alberto Rubio Ponce Universidad Autónoma Metropolitana - Azcapotzalco arp@correo.azc.uam.mx Dr. Óscar Olvera Neria Universidad Autónoma Metropolitana - Azcapotzalco oon@correo.azc.uam.mx Professor Jaime Granados Samaniego Universidad Autónoma Metropolitana - Azcapotzalco jgs@correo.azc.uam.mx Dr. Roberto Tito Hern

  12. Wave Star

    DEFF Research Database (Denmark)

    Kramer, Morten; Andersen, Thomas Lykke

    Nærværende rapport beskriver modelforsøg udført på Aalborg Universitet, Institut for Vand, Jord og Miljøteknik med bølgeenergianlægget Wave Star.......Nærværende rapport beskriver modelforsøg udført på Aalborg Universitet, Institut for Vand, Jord og Miljøteknik med bølgeenergianlægget Wave Star....

  13. Wave Star

    DEFF Research Database (Denmark)

    Kramer, Morten; Frigaard, Peter

    Nærværende rapport beskriver modelforsøg udført på Aalborg Universitet, Institut for Byggeri og Anlæg med bølgeenergianlæget Wave Star.......Nærværende rapport beskriver modelforsøg udført på Aalborg Universitet, Institut for Byggeri og Anlæg med bølgeenergianlæget Wave Star....

  14. Newly diagnosed congenital factor VII deficiency and utilization of recombinant activated factor VII (NovoSeven®

    Directory of Open Access Journals (Sweden)

    Bartosh NS

    2013-03-01

    Full Text Available Nicole S Bartosh, Tara Tomlin, Christian Cable, Kathleen HalkaDepartment of Internal Medicine, Division of Medical Oncology, Scott and White Healthcare and Texas A and M Health Science Center College of Medicine, Temple, TX, USAAbstract: This case report presents a newly diagnosed congenital factor VII deficiency treated with recombinant activated factor VII (rFVIIa. Congenital factor VII deficiency is a rare autosomal-recessive bleeding disorder that occurs in fewer than 1/500,000 persons. Its presentation can vary from epistaxis to hemarthroses and severe central nervous system bleeding, and correlates poorly with factor VII levels. Our patient had not had a significant hemostatic challenge prior to his presentation and therefore never had any symptomatology suggestive of this disease. He was treated with rFVIIa, and was able to undergo repair of his fractures without bleeding.Case report: A 19-year-old African-American male presented to the emergency room after an altercation that resulted in significant trauma. He sustained bilateral mandibular angle fractures and orbital floor fractures, requiring urgent surgical correction. On initial evaluation, he was noted to have a prolonged prothrombin time of 40.1 seconds, with an International Normalized Ratio of 4.0, a normal activated partial thromboplastin time of 29.9 seconds, and a platelet count of 241. After receiving vitamin K and fresh frozen plasma, he was taken to the operating room for a temporary rigid maxillomandibular fixation. A 1:1 mixing study with normal plasma corrected the prothrombin time (decreasing from 40.7 to 14.7 seconds and a factor VII assay revealed 5% of the normal factor VII level. The patient was diagnosed with congenital factor VII deficiency. Due to his coagulopathy and the extensive surgical correction needed, rFVIIa was administered and surgery was accomplished without hemorrhagic sequelae.Conclusion: This case report and review describes a rare congenital

  15. Stark broadening parameter tables for O VII and Mg XI

    Directory of Open Access Journals (Sweden)

    Dimitrijević M.S.

    1998-01-01

    Full Text Available By using the semiclassical-perturbation formalism, we have calculated electron-, proton-, and He III-impact line widths and shifts for 14 O VII multiplets and 18 Mg XI multiplets, of importance for research, diagnostic and modeling of various astrophysical, laser produced, fusion and laboratory plasmas. For O VII calculations were performed for temperature range from 100,000 K to 2,000,000 K. and perturber densities (1017cm−3 - 1023cm−3. For Mg XI calculations were performed for temperature range from 500,000 K to 5,000,000 K. and perturber densities 1018cm−3 - 1024cm−3.

  16. The lupus band: do the autoantibodies target collagen VII?

    Science.gov (United States)

    Alahlafi, A M; Wordsworth, P; Wojnarowska, F

    2004-03-01

    Circulating autoantibodies directed against basement membrane zone (BMZ) components from patients with bullous pemphigoid and epidermolysis bullosa acquisita have been used to identify their target antigen in the skin and to confirm pathogenicity. Although the pattern of immunofluorescence in those diseases is similar to the lupus band, little is known about the origin and pathogenesis of the lupus band. Identifying the binding sites of the lupus band could provide a clue to the nature of the autoantigen that stimulates autoantibody formation in the skin of patients with systemic lupus erythematosus (SLE) and might provide valuable insight into the factors that influence the localization and pathogenicity of the lupus band. To investigate the relation between the lupus band and the main BMZ components and to identify the target epitopes of autoantibodies deposited in the skin of patients with SLE. Colocalization of the main components of the skin BMZ in nonlesional SLE skin with the lupus band was investigated using conventional immunofluorescence and confocal laser scanning microscopy. The effect of collagenase and pepsin on the expression of the lupus band was correlated with the differential sensitivity of these proteases on the collagenous and noncollagenous (NC) domains of collagen VII. Reactivity of sera from patients with SLE to a complete recombinant human NC1 domain of type VII collagen was then investigated by enzyme-linked immunosorbent assay (ELISA). Near complete colocalization of the lupus band with collagen VII was found in this study, and chemical degradation of the skin attenuated the expression of the lupus band. Collectively, the NC1 domain of collagen VII was suggested as the target antigen of the lupus band, but none of the sera from patients with SLE reacted with recombinant NC1 domain-coated ELISA plates. Alternative explanations for the results of the colocalization of the lupus band with collagen VII are discussed. The lupus band

  17. The OmegaWhite Survey for Short-period Variable Stars. V. Discovery of an Ultracompact Hot Subdwarf Binary with a Compact Companion in a 44-minute Orbit

    Science.gov (United States)

    Kupfer, T.; Ramsay, G.; van Roestel, J.; Brooks, J.; MacFarlane, S. A.; Toma, R.; Groot, P. J.; Woudt, P. A.; Bildsten, L.; Marsh, T. R.; Green, M. J.; Breedt, E.; Kilkenny, D.; Freudenthal, J.; Geier, S.; Heber, U.; Bagnulo, S.; Blagorodnova, N.; Buckley, D. A. H.; Dhillon, V. S.; Kulkarni, S. R.; Lunnan, R.; Prince, T. A.

    2017-12-01

    We report the discovery of the ultracompact hot subdwarf (sdOB) binary OW J074106.0-294811.0 with an orbital period of {P}{orb}=44.66279+/- 1.16× {10}-4 minutes, making it the most compact hot subdwarf binary known. Spectroscopic observations using the VLT, Gemini and Keck telescopes revealed a He-sdOB primary with an intermediate helium abundance, {T}{eff} = 39 400+/- 500 K and {log}g = 5.74 ± 0.09. High signal-to-noise ratio light curves show strong ellipsoidal modulation resulting in a derived sdOB mass {M}{sdOB}=0.23+/- 0.12 {M}⊙ with a WD companion ({M}{WD}=0.72+/- 0.17 {M}⊙ ). The mass ratio was found to be q={M}{sdOB}/{M}{WD}=0.32+/- 0.10. The derived mass for the He-sdOB is inconsistent with the canonical mass for hot subdwarfs of ≈ 0.47 {M}⊙ . To put constraints on the structure and evolutionary history of the sdOB star we compared the derived {T}{eff}, {log}g, and sdOB mass to evolutionary tracks of helium stars and helium white dwarfs calculated with Modules for Experiments in Stellar Astrophysics (MESA). We find that the best-fitting model is a helium white dwarf with a mass of 0.320 {M}⊙ , which left the common envelope ≈ 1.1 {Myr} ago, which is consistent with the observations. As a helium white dwarf with a massive white dwarf companion, the object will reach contact in 17.6 Myr at an orbital period of 5 minutes. Depending on the spin-orbit synchronization timescale the object will either merge to form an R CrB star or end up as a stably accreting AM CVn-type system with a helium white dwarf donor.

  18. Pulsating Star Mystery Solved

    Science.gov (United States)

    2010-11-01

    By discovering the first double star where a pulsating Cepheid variable and another star pass in front of one another, an international team of astronomers has solved a decades-old mystery. The rare alignment of the orbits of the two stars in the double star system has allowed a measurement of the Cepheid mass with unprecedented accuracy. Up to now astronomers had two incompatible theoretical predictions of Cepheid masses. The new result shows that the prediction from stellar pulsation theory is spot on, while the prediction from stellar evolution theory is at odds with the new observations. The new results, from a team led by Grzegorz Pietrzyński (Universidad de Concepción, Chile, Obserwatorium Astronomiczne Uniwersytetu Warszawskiego, Poland), appear in the 25 November 2010 edition of the journal Nature. Grzegorz Pietrzyński introduces this remarkable result: "By using the HARPS instrument on the 3.6-metre telescope at ESO's La Silla Observatory in Chile, along with other telescopes, we have measured the mass of a Cepheid with an accuracy far greater than any earlier estimates. This new result allows us to immediately see which of the two competing theories predicting the masses of Cepheids is correct." Classical Cepheid Variables, usually called just Cepheids, are unstable stars that are larger and much brighter than the Sun [1]. They expand and contract in a regular way, taking anything from a few days to months to complete the cycle. The time taken to brighten and grow fainter again is longer for stars that are more luminous and shorter for the dimmer ones. This remarkably precise relationship makes the study of Cepheids one of the most effective ways to measure the distances to nearby galaxies and from there to map out the scale of the whole Universe [2]. Unfortunately, despite their importance, Cepheids are not fully understood. Predictions of their masses derived from the theory of pulsating stars are 20-30% less than predictions from the theory of the

  19. Instabilities in Interacting Binary Stars

    Science.gov (United States)

    Andronov, I. L.; Andrych, K. D.; Antoniuk, K. A.; Baklanov, A. V.; Beringer, P.; Breus, V. V.; Burwitz, V.; Chinarova, L. L.; Chochol, D.; Cook, L. M.; Cook, M.; Dubovský, P.; Godlowski, W.; Hegedüs, T.; Hoňková, K.; Hric, L.; Jeon, Y.-B.; Juryšek, J.; Kim, C.-H.; Kim, Y.; Kim, Y.-H.; Kolesnikov, S. V.; Kudashkina, L. S.; Kusakin, A. V.; Marsakova, V. I.; Mason, P. A.; Mašek, M.; Mishevskiy, N.; Nelson, R. H.; Oksanen, A.; Parimucha, S.; Park, J.-W.; Petrík, K.; Quiñones, C.; Reinsch, K.; Robertson, J. W.; Sergey, I. M.; Szpanko, M.; Tkachenko, M. G.; Tkachuk, L. G.; Traulsen, I.; Tremko, J.; Tsehmeystrenko, V. S.; Yoon, J.-N.; Zola, S.; Shakhovskoy, N. M.

    2017-07-01

    The types of instability in the interacting binary stars are briefly reviewed. The project “Inter-Longitude Astronomy” is a series of smaller projects on concrete stars or groups of stars. It has no special funds, and is supported from resources and grants of participating organizations, when informal working groups are created. This “ILA” project is in some kind similar and complementary to other projects like WET, CBA, UkrVO, VSOLJ, BRNO, MEDUZA, AstroStatistics, where many of us collaborate. Totally we studied 1900+ variable stars of different types, including newly discovered variables. The characteristic timescale is from seconds to decades and (extrapolating) even more. The monitoring of the first star of our sample AM Her was initiated by Prof. V.P. Tsesevich (1907-1983). Since more than 358 ADS papers were published. In this short review, we present some highlights of our photometric and photo-polarimetric monitoring and mathematical modeling of interacting binary stars of different types: classical (AM Her, QQ Vul, V808 Aur = CSS 081231:071126+440405, FL Cet), asynchronous (BY Cam, V1432 Aql), intermediate (V405 Aql, BG CMi, MU Cam, V1343 Her, FO Aqr, AO Psc, RXJ 2123, 2133, 0636, 0704) polars and magnetic dwarf novae (DO Dra) with 25 timescales corresponding to different physical mechanisms and their combinations (part “Polar”); negative and positive superhumpers in nova-like (TT Ari, MV Lyr, V603 Aql, V795 Her) and many dwarf novae stars (“Superhumper”); eclipsing “non-magnetic” cataclysmic variables(BH Lyn, DW UMa, EM Cyg; PX And); symbiotic systems (“Symbiosis”); super-soft sources (SSS, QR And); spotted (and not spotted) eclipsing variables with (and without) evidence for a current mass transfer (“Eclipser”) with a special emphasis on systems with a direct impact of the stream into the gainer star's atmosphere, which we propose to call “Impactor” (short from “Extreme Direct Impactor”), or V361 Lyr-type stars. Other

  20. The Sun: Our Nearest Star

    Science.gov (United States)

    Adams, M. L.; Six, N. Frank (Technical Monitor)

    2002-01-01

    We have in our celestial backyard, a prime example of a variable star. The Sun, long thought to be "perfect" and unvarying, began to reveal its cycles in the early 1600s as Galileo Galilei and Christoph Scheiner used a telescope to study sunspots. For the past four hundred years, scientists have accumulated data, showing a magnetic cycle that repeats, on average, every eleven (or twenty-two) years. In addition, modern satellites have shown that the energy output at radio and x-ray wavelengths also varies with this cycle. This talk will showcase the Sun as a star and discuss how solar studies may be used to understand other stars.

  1. Kasuperest viidi viis last ja algatati kriminaalmenetlus piinamises / Rasmus Rekand

    Index Scriptorium Estoniae

    Rekand, Rasmus

    2011-01-01

    Lugu asenduskodu teenust pakkuvast perekonnast, kelle hoole all oli lisaks pere enda 3 lapsele 6 võõrast last ning kuidas lastega mittehakkama saamine viis olukorrani, kus lapsed viidi kasupere juurest ära ja lisaks algatati uurimine keelatud võtete kasutamise kohta kasvatamistegevuses

  2. Viis armastuslugu suurel ekraanil / Tristan Priimägi

    Index Scriptorium Estoniae

    Priimägi, Tristan, 1976-

    2008-01-01

    Viis näidet filmiajaloost, kus režissööri ja staari vahel on tunded : Roger Vadim ja Tema Naised, Werner Herzog ja Klaus Kinski, Federico Fellini ja Anita Ekberg, Quentin Tarantino ja Uma Thurman, Rainer Werner Fassbinder ja Mr/Mrs X

  3. Recombinant-activated factor VII in the paediatric cardiac surgery ...

    African Journals Online (AJOL)

    V Agarwal, KE Okonta, PS Lal. Abstract. Background: The control of excessive bleeding after paediatric cardiac surgery can be challenging. This may make the use of recombinant-activated factor VII (rFVIIa) in preventing this excessive bleeding, after adopted conventional methods have failed, desirable. Our aim is to ...

  4. In silico dissection of Type VII Secretion System components across ...

    Indian Academy of Sciences (India)

    Type VII Secretion System (T7SS) is one of the factors involved in virulence of Mycobacteriun tuberculosis H37Rv. Numerous research efforts have been made in the last decade towards characterizing the components of this secretion system. An extensive genome-wide analysis through compilation of isolated information ...

  5. Viis aastakümmet raamatukogunduse radadel / Anne Veinberg

    Index Scriptorium Estoniae

    Veinberg, Anne

    2008-01-01

    Arvustus: Kikas, Konrad. Verba volant, scripta manent : viis aastakümmet raamatukogunduse ja infoteaduse radadel = Verba volant, scripta manent : five decades on the field of librarianship and information science. - Tallinn : Tallinna Tehnikaülikooli Kirjastus, 2008. - 366 lk. : ill. portr. - (Tallinna Tehnikaülikooli Raamatukogu töid. A ; 5)

  6. Photosynthetic pigments of oceanic Chlorophyta belonging to prasinophytes clade VII.

    Science.gov (United States)

    Lopes Dos Santos, Adriana; Gourvil, Priscillia; Rodríguez, Francisco; Garrido, José Luis; Vaulot, Daniel

    2016-02-01

    The ecological importance and diversity of pico/nanoplanktonic algae remains poorly studied in marine waters, in part because many are tiny and without distinctive morphological features. Amongst green algae, Mamiellophyceae such as Micromonas or Bathycoccus are dominant in coastal waters while prasinophytes clade VII, yet not formerly described, appear to be major players in open oceanic waters. The pigment composition of 14 strains representative of different subclades of clade VII was analyzed using a method that improves the separation of loroxanthin and neoxanthin. All the prasinophytes clade VII analyzed here showed a pigment composition similar to that previously reported for RCC287 corresponding to pigment group prasino-2A. However, we detected in addition astaxanthin for which it is the first report in prasinophytes. Among the strains analyzed, the pigment signature is qualitatively similar within subclades A and B. By contrast, RCC3402 from subclade C (Picocystis) lacks loroxanthin, astaxanthin, and antheraxanthin but contains alloxanthin, diatoxanthin, and monadoxanthin that are usually found in diatoms or cryptophytes. For subclades A and B, loroxanthin was lowest at highest light irradiance suggesting a light-harvesting role of this pigment in clade VII as in Tetraselmis. © 2015 Phycological Society of America.

  7. Pulsating stars

    CERN Document Server

    Catelan, M?rcio

    2014-01-01

    The most recent and comprehensive book on pulsating stars which ties the observations to our present understanding of stellar pulsation and evolution theory.  Written by experienced researchers and authors in the field, this book includes the latest observational results and is valuable reading for astronomers, graduate students, nuclear physicists and high energy physicists.

  8. Stars Underground

    CERN Multimedia

    Jean Leyder

    1996-01-01

    An imaginary voyage in time where we were witness of the birth of the universe itself, the time of the Big-Bang 15 billion years ago. Particules from the very first moments of time : protons, neutrons and electrons, and also much more energetic one. These particules are preparing to interact collider and generating others which will be the birth to the stars ........

  9. Multiperiodicity, modulations and flip-flops in variable star light curves. II. Analysis of II Pegasus photometry during 1979-2010

    Science.gov (United States)

    Lindborg, M.; Mantere, M. J.; Olspert, N.; Pelt, J.; Hackman, T.; Henry, G. W.; Jetsu, L.; Strassmeier, K. G.

    2013-11-01

    Aims: According to previously published Doppler images of the magnetically active primary giant component of the RS CVn binary II Peg, the surface of the star was dominated by one single active longitude that was clearly drifting in the rotational frame of the binary system during 1994-2002; later imaging for 2004-2010, however, showed decreased and chaotic spot activity, with no signs of the drift pattern. Here we set out to investigate from a more extensive photometric dataset whether this drift is a persistent phenomenon, in which case it could be caused either by an azimuthal dynamo wave or be an indication that the binary system's orbital synchronization is still incomplete. On a differentially rotating stellar surface, spot structures preferentially on a certain latitude band could also cause such a drift, the disruption of which could arise from the change of the preferred spot latitude. Methods: We analyzed the datasets using the carrier fit (CF) method, which is especially suitable for analyzing time series in which a fast clocking frequency (such as the rotation of the star) is modulated with a slower process (such as the stellar activity cycle). Results: We combined all collected photometric data into one single data set and analyzed it with the CF method. We confirm the previously published results that the spot activity has been dominated by one primary spotted region almost through the entire data set and also confirm a persistent, nearly linear drift. Disruptions of the linear trend and complicated phase behavior are also seen, but the period analysis reveals a rather stable periodicity with Pspot = 6.71054d ± 0.00005d. After removing the linear trend from the data, we identified several abrupt phase jumps, three of which are analyzed in more detail with the CF method. These phase jumps closely resemble what is called a flip-flop event, but the new spot configurations do not persist for longer than a few months in most cases. Conclusions: There is

  10. The space distribution of AGB stars

    Science.gov (United States)

    Jura, M.

    1990-01-01

    The AGB stars can be classified into three main types on the basis of their atmospheric composition: carbon-rich, oxygen-rich, and S-type. The carbon-rich stars typically have 1.5-solar-mass main sequence stars as progenitors. There are about 40 of these stars per sq kpc projected onto the plane of the Milky Way galaxy in the neighborhood of the sun with an exponential scale height above the galactic disk of about 200 pc. Contrary to the general distribution of mass, there is no decrease with galactocentric radius of the surface density of these stars for at least 3 kpc beyond the solar circle. The S-type stars appear to have the same spatial distribution as the carbon stars; there are about 1/3 as many 'pure' S stars as there are luminous carbon stars. One major class of oxygen-rich AGB stars is the Mira variables. There are approximately between 1 and 2 times as many of these stars per sq kpc projected onto the galactic plane of the Milky Way as there are carbon stars.

  11. Plasma factor VII-activating protease is increased by oral contraceptives and induces factor VII activation in-vivo

    DEFF Research Database (Denmark)

    Sidelmann, Johannes J; Skouby, Sven O; Kluft, Cornelis

    2011-01-01

    Oral contraceptive (OC) use influences the hemostatic system significantly and is a risk factor for development of cardiovascular disease. Factor VII-activating protease (FSAP) has potential effects on hemostasis. The 1601GA genotype of the 1601G/A polymorphism in the FSAP gene expresses a FSAP...

  12. Star Products and Applications

    OpenAIRE

    Iida, Mari; Yoshioka, Akira

    2010-01-01

    Star products parametrized by complex matrices are defined. Especially commutative associative star products are treated, and star exponentials with respect to these star products are considered. Jacobi's theta functions are given as infinite sums of star exponentials. As application, several concrete identities are obtained by properties of the star exponentials.

  13. A SOFIA FORCAST Grism Study of the Mineralogy of Dust in the Winds of Proto-planetary Nebulae: RV Tauri Stars and SRd Variables

    Science.gov (United States)

    Arneson, R. A.; Gehrz, R. D.; Woodward, C. E.; Helton, L. A.; Shenoy, D.; Evans, A.; Keller, L. D.; Hinkle, K. H.; Jura, M.; Lebzelter, T.; Lisse, C. M.; Rushton, M. T.; Mizrachi, J.

    2017-07-01

    We present a SOFIA FORCAST grism spectroscopic survey to examine the mineralogy of the circumstellar dust in a sample of post-asymptotic giant branch (post-AGB) yellow supergiants that are believed to be the precursors of planetary nebulae. Our mineralogical model of each star indicates the presence of both carbon-rich and oxygen-rich dust species—contrary to simple dredge-up models—with a majority of the dust in the form of amorphous carbon and graphite. The oxygen-rich dust is primarily in the form of amorphous silicates. The spectra do not exhibit any prominent crystalline silicate emission features. For most of the systems, our analysis suggests that the grains are relatively large and have undergone significant processing, supporting the hypothesis that the dust is confined to a Keplerian disk and that we are viewing the heavily processed, central regions of the disk from a nearly face-on orientation. These results help to determine the physical properties of the post-AGB circumstellar environment and to constrain models of post-AGB mass loss and planetary nebula formation.

  14. Wave Star

    DEFF Research Database (Denmark)

    Kramer, Morten; Frigaard, Peter; Brorsen, Michael

    Nærværende rapport beskriver foreløbige hovedkonklusioner på modelforsøg udført på Aalborg Universitet, Institut for Vand, Jord og Miljøteknik med bølgeenergianlægget Wave Star i perioden 13/9 2004 til 12/11 2004.......Nærværende rapport beskriver foreløbige hovedkonklusioner på modelforsøg udført på Aalborg Universitet, Institut for Vand, Jord og Miljøteknik med bølgeenergianlægget Wave Star i perioden 13/9 2004 til 12/11 2004....

  15. Rainbow's Stars

    OpenAIRE

    Garattini, Remo; Mandanici, Gianluca

    2016-01-01

    In recent years, a growing interest in the equilibrium of compact astrophysical objects like white dwarf and neutron stars has been manifested. In particular, various modifications due to Planck-scale energy effects have been considered. In this paper we analyze the modification induced by gravity’s rainbow on the equilibrium configurations described by the Tolman–Oppenheimer–Volkoff (TOV) equation. Our purpose is to explore the possibility that the rainbow Planck-scale deformation of space-t...

  16. PENGARUH KEMANDIRIAN BELAJAR DAN PENGGUNAAN UANG SAKU TERHADAP PRESTASI BELAJAR KOMPETENSI DASAR EKONOMI KELAS VII DAN VIII

    Directory of Open Access Journals (Sweden)

    Apri Dwi Astuti

    2012-10-01

    kriteria ketuntasan minimum (KKM � � Learning Independency is crucial for students. Additionality, learning independence helps students to be responsible and grows the willing of learning. The management of the use of pocket money creates a feeling of responsibility, commitment and discipline. The finale of this research to know learning independence and the use of pocket money influence the learning achievement in Economics subject on VII and VIII of SMP Semesta Boarding School in the Academic year of 2011/2012. The populations of this research are all VII and VIII grade studentsof SMP Semesta Boarding School. Learning Independency and The use of Pocket Money act as free variable, while students�learning achievement acts asbound variable. The data was gathered from interview, questionnaire and teacher�s documentation. The analysis of the data applies double regression linear analysis.Based on the double linear analysis simultaneously, it is revealed that Learning Independency and The use of Pocket Money influene� the learning achievement in Economics subject on VII and VIII until up to 51,3%. Partially, thev ariable of Learning Independency influence the learning achievement in Economics is 66,2% and The use of Pocket Money influene� the learning achievement in Economics is 62,5%.According to the result of the research above, it can be concluded that learning independence and the use of Pocket Money influence the learning independence and the use of pocket money influence the learning achievement of Econimics subject for VII and VIII grade of SMP Semesta Boarding School Semarang in the academic year of 2011/2012 on simultan and partially . Based on this research, hopefullythe, 1 School give a little change to student when they go home. 2 Parents observe give of pocket money by the students activity in the dormitory.3 student hopefully to progress their learning independency actually to the learning achievement that still under minimum criteria (KKM.

  17. Mangostanaxanthone VII, a new cytotoxic xanthone from Garcinia mangostana.

    Science.gov (United States)

    Ibrahim, Sabrin R M; Mohamed, Gamal A; Elfaky, Mahmoud A; Zayed, Mohamed F; El-Kholy, Amal A; Abdelmageed, Osama H; Ross, Samir A

    2017-11-08

    Garcinia mangostana L. (the queen of fruits, mangosteen, family Guttiferae) is a wealthy source of xanthones. The CHCl3 soluble fraction of the air-dried pericarps of G. mangostana provided a new xanthone: mangostanaxanthone VII (5), along with four known xanthones: mangostanaxanthones I (1) and II (2), gartanin (3) and γ-mangostin (4). The structural verification of these metabolites was achieved by different spectral techniques, including UV, IR, 1D and 2D NMR and HRESIMS. The new metabolite was assessed for cytotoxic potential, using sulforhodamine B (SRB) assay towards the A549 and MCF-7 cancer cell lines. Moreover, its antimicrobial effects were evaluated against various bacterial and fungal strains, using agar disc diffusion assay. Mangostanaxanthone VII showed moderate cytotoxic activity against the A549 and MCF7 cell lines with IC50s 26.1 and 34.8 μM, respectively, compared with doxorubicin (0.74 and 0.41 μM, respectively).

  18. Association of factor VII protein concentration with lifestyle factors

    DEFF Research Database (Denmark)

    Bladbjerg, E-M; Møller, L; Jespersen, J

    1998-01-01

    Several studies have demonstrated that changes in fasting levels of factor VII coagulant activity (FVII:C), a thrombotic risk marker, are due to changes in FVII protein concentrations (FVII:Ag). Consequently, studies on FVII now often include measurements of FVII:Ag. The present cross-sectional s......Several studies have demonstrated that changes in fasting levels of factor VII coagulant activity (FVII:C), a thrombotic risk marker, are due to changes in FVII protein concentrations (FVII:Ag). Consequently, studies on FVII now often include measurements of FVII:Ag. The present cross....... These results suggest that blood lipids are major determinants of FVII:Ag, but that other lifestyle factors such as insulin, BMI and physical activity can also influence FVII:Ag. Furthermore, the association between FVII:Ag and bleeding time suggests an effect of FVII or the FVII pathway on primary haemostasis...

  19. Vena porta thrombosis in patient with inherited factor VII deficiency

    DEFF Research Database (Denmark)

    Klovaite, Jolanta; Friis-Hansen, Lennart Jan; Larsen, Fin S

    2010-01-01

    Most clotting factor VII (FVII)-deficient patients suffer from bleeding episodes and occasionally thromboembolic complications after surgical interventions or replacement therapy. However, thromboses without apparent triggering factors may occur as well. We report a case of a pregnant woman...... vein with well expressed portosystemic collaterals, heterozygosity for three common polymorphisms in FVII gene, associated with reduction in plasma FVII levels, and no other factors predisposing to thrombosis....

  20. The Chemical Compositions of the SRd Variable Stars. III. KK Aquilae, AG Aurigae, Z Aurigae, W Leo Minoris, and WW Tauri

    OpenAIRE

    Giridhar, S.; Lambert, D. L.; Gonzalez, G.

    2000-01-01

    Chemical compositions are derived from high-resolution spectra for five field SRd variables. These supergiants not previously analysed are shown to be metal-poor: KK Aql with [Fe/H] = -1.2, AG Aur with [Fe/H] = -1.8, Z Aur with [Fe/H] = -1.4, W LMi with [Fe/H] = -1.1, and WW Tau with [Fe/H] = -1.1. Their compositions are, except for two anomalies, identical to within the measurement errors with the compositions of subdwarfs, subgiants, and less evolved giants of the same [Fe/H]. One anomaly i...

  1. CROSS SECTION EVALUATIONS FOR ENDF/B-VII.

    Energy Technology Data Exchange (ETDEWEB)

    HERMAN, M.; ROCHMAN, D.; OBLOZINSKY, P.

    2006-06-05

    This is the final report of the work performed under the LANL contract on neutron cross section evaluations for ENDF/B-VII (April 2005-May 2006). The purpose of the contract was to ensure seamless integration of the LANL neutron cross section evaluations in the new ENDF/B-VII library. The following work was performed: (1) LANL evaluated data files submitted for inclusion in ENDF/B-VII were checked and, when necessary, formal formatting errors were corrected. As a consequence, ENDF checking codes, run on all LANL files, do not report any errors that would rise concern. (2) LANL dosimetry evaluations for {sup 191}Ir and {sup 193}Ir were completed to match ENDF requirements for the general purpose library suitable for transport calculations. A set of covariances for both isotopes is included in the ENDF files. (3) Library of fission products was assembled and successfully tested with ENDF checking codes, processed with NJOY-99.125 and simple MCNP calculations. (4) KALMAN code has been integrated with the EMPIRE system to allow estimation of covariances based on the combination of measurements and model calculations. Covariances were produced for 155,157-Gd and also for 6 remaining isotopes of Gd.

  2. Constraints on the Distance Moduli, Helium, and Metal Abundances, and Ages of Globular Clusters from Their RR Lyrae and Non-variable Horizontal Branch Stars. II. Multiple Stellar Populations in 47 Tuc, M3, and M13

    Science.gov (United States)

    Denissenkov, Pavel A.; VandenBerg, Don A.; Kopacki, Grzegorz; Ferguson, Jason W.

    2017-11-01

    We present a new set of horizontal branch (HB) models computed with the MESA stellar evolution code. The models adopt α-enhanced Asplund et al. metal mixtures and include the gravitational settling of He. They are used in our HB population synthesis tool to generate theoretical distributions of HB stars in order to describe the multiple stellar populations in the globular clusters 47 Tuc, M3, and M13. The observed HB in 47 Tuc is reproduced very well by our simulations for [{Fe}/{{H}}]=-0.70 and [α /{Fe}]=+0.4 if the initial helium mass fraction varies by {{Δ }}{Y}0˜ 0.03, and approximately 21%, 37%, and 42% of the stars have {Y}0=0.257, 0.270, and 0.287, respectively. These simulations yield {(m-M)}V=13.27, implying an age near 13.0 Gyr. In the case of M3 and M13, our synthetic HBs for [{Fe}/{{H}}]=-1.55 and [α /{Fe}]=0.4 match the observed ones quite well if M3 has {{Δ }}{Y}0˜ 0.01 and {(m-M)}V=15.02, resulting in an age of 12.6 Gyr, whereas M13 has {{Δ }}{Y}0˜ 0.08 and {(m-M)}V=14.42, implying an age of 12.9 Gyr. Mass loss during giant branch evolution and {{Δ }}{Y}0 appear to be the primary second parameters for M3 and M13. New observations for seven of the nine known RR Lyrae in M13 are also reported. Surprisingly, periods predicted for the c-type variables tend to be too high (by up to ˜0.1 days).

  3. When stars collide

    NARCIS (Netherlands)

    Glebbeek, E.; Pols, O.R.

    2007-01-01

    When two stars collide and merge they form a new star that can stand out against the background population in a star cluster as a blue straggler. In so called collision runaways many stars can merge and may form a very massive star that eventually forms an intermediate mass blackhole. We have

  4. Delta Scuti and related stars - Review

    Science.gov (United States)

    Breger, M.; Stockenhuber, H.

    Present knowledge on Delta Scuti stars, short-period pulsators of spectral types A and F situated on or above the main sequence, is reviewed. The topics discussed include: pulsation periods, pulsational mode-typing through line profiles, cluster stars, and SX Phe-type variables. The position of Delta Scuti stars in the H-R diagram is shown along with the observed period-luminosity-color relation for the stars. Correlations of average pulsation period and M(v) with cluster age are given, showing that the observed correlations can be explained by the PLC relation and main sequence evolution of the clusters.

  5. Separable metrics and radiating stars

    Indian Academy of Sciences (India)

    We study the junction condition relating the pressure to heat flux at the boundary of an accelerating and expanding spherically symmetric radiating star. We transform the junction condition to an ordinary differential equation by making a separability assumption on the metric functions in the space–time variables.

  6. Separable metrics and radiating stars

    Indian Academy of Sciences (India)

    2016-12-14

    Dec 14, 2016 ... and expanding spherically symmetric radiating star. We transform the junction condition to an ordinary differ- ential equation by making a separability assumption on the metric functions in the space–time variables. The condition of separability on the metric functions yields several new exact solutions.

  7. Stellar laboratories . VIII. New Zr iv-vii, Xe iv-v, and Xe vii oscillator strengths and the Al, Zr, and Xe abundances in the hot white dwarfs G191-B2B and RE 0503-289

    Science.gov (United States)

    Rauch, T.; Gamrath, S.; Quinet, P.; Löbling, L.; Hoyer, D.; Werner, K.; Kruk, J. W.; Demleitner, M.

    2017-03-01

    Context. For the spectral analysis of high-resolution and high-signal-to-noise spectra of hot stars, state-of-the-art non-local thermodynamic equilibrium (NLTE) model atmospheres are mandatory. These are strongly dependent on the reliability of the atomic data that is used for their calculation. Aims: To search for zirconium and xenon lines in the ultraviolet (UV) spectra of G191-B2B and RE 0503-289, new Zr iv-vii, Xe iv-v, and Xe vii oscillator strengths were calculated. This allows, for the first time, determination of the Zr abundance in white dwarf (WD) stars and improvement of the Xe abundance determinations. Methods: We calculated Zr iv-vii, Xe iv-v, and Xe vii oscillator strengths to consider radiative and collisional bound-bound transitions of Zr and Xe in our NLTE stellar-atmosphere models for the analysis of their lines exhibited in UV observations of the hot WDs G191-B2B and RE 0503-289. Results: We identified one new Zr iv, 14 new Zr v, and ten new Zr vi lines in the spectrum of RE 0503-289. Zr was detected for the first time in a WD. We measured a Zr abundance of -3.5 ± 0.2 (logarithmic mass fraction, approx. 11 500 times solar). We identified five new Xe vi lines and determined a Xe abundance of -3.9 ± 0.2 (approx. 7500 times solar). We determined a preliminary photospheric Al abundance of -4.3 ± 0.2 (solar) in RE 0503-289. In the spectra of G191-B2B, no Zr line was identified. The strongest Zr iv line (1598.948 Å) in our model gave an upper limit of -5.6 ± 0.3 (approx. 100 times solar). No Xe line was identified in the UV spectrum of G191-B2B and we confirmed the previously determined upper limit of -6.8 ± 0.3 (ten times solar). Conclusions: Precise measurements and calculations of atomic data are a prerequisite for advanced NLTE stellar-atmosphere modeling. Observed Zr iv-vi and Xe vi-vii line profiles in the UV spectrum of RE 0503-289 were simultaneously well reproduced with our newly calculated oscillator strengths. Based on observations

  8. NIR properties of Be stars in star clusters in the Magellanic Clouds

    Science.gov (United States)

    Paul, K. T.; Subramaniam, Annapurni; Mathew, Blesson; Shruthi, S. B.

    2017-10-01

    Magellanic Clouds are the nearby galaxies which are ideal to study the properties of metal poor stellar population. In this study, we explore the near-IR properties of optically identified classical Be stars in 19 star clusters in the Magellanic Clouds. From an optically identified sample of 835 Be stars we obtained the J, H, K magnitudes of 389 stars from the IRSF MCPS catalog. Among these, 247 stars (36.4%) are found in 9 clusters in the Large Magellanic Cloud and 142 stars (55.5%) in 10 clusters in the Small Magellanic Cloud. After correcting for reddening, we studied their NIR properties in the (H - K)0 vs (J - H)0 diagram. We identified 14 stars with abnormally large near IR excesses, which were removed from the analysis, there by restricting our study to 355 classical Be stars. We propose an extended area in the near-IR (H - K)0 vs (J - H)0 diagram as the diagnostic location of Classical Be stars in the Magellanic Clouds. We identified 14 stars to have near-IR excess, higher than those seen in classical Be stars. From the analysis based on spectral energy distribution and luminosity estimate, we found that 8 candidate Be stars may be Herbig Ae/Be stars. We identified a new sample of 6 sgB[e] stars, which when added to the sparse existing sample of 15 sgB[e] stars in the Magellanic Clouds can provide insight to understand the evolutionary link between sgB[e] stars and Luminous Blue variables.

  9. RR Lyrae Stars in M4

    Directory of Open Access Journals (Sweden)

    Kuehn Charles A

    2017-01-01

    Full Text Available 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.

  10. The role of Title VII funding in academic general pediatrics fellowships and leadership.

    Science.gov (United States)

    DeWitt, Thomas G; Cheng, Tina L

    2008-11-01

    Since 1979, the Health Resources and Services Administration, Bureau of Health Professionals Title VII, Section 747 (Title VII) programs have been critical to both fellowship and leadership training in academic general pediatrics. Title VII-funded faculty development programs and targeted contract funding have played an important role in training pediatric academic generalist faculty, supporting individual fellowship programs, defining the core elements of such programs, and expanding faculty development to include leadership training. As the major continuing source of external funding for these programs, Title VII has produced documented successful outcomes in all areas in terms of both numbers and accomplishments of trainees. Title VII-funded fellows, as well as the leaders trained, have formed and extended the field of general pediatrics, ultimately improving the health of children, especially in underserved and vulnerable populations.This article is part of a theme issue of Academic Medicine on the Title VII health professions training programs.

  11. Anticancer Activity of the Antimicrobial Peptide Scolopendrasin VII Derived from the Centipede, Scolopendra subspinipes mutilans.

    Science.gov (United States)

    Lee, Joon Ha; Kim, In-Woo; Kim, Sang-Hee; Kim, Mi-Ae; Yun, Eun-Young; Nam, Sung-Hee; Ahn, Mi-Young; Kang, Dongchul; Hwang, Jae Sam

    2015-08-01

    Previously, we performed de novo RNA sequencing of Scolopendra subspinipes mutilans using high-throughput sequencing technology and identified several antimicrobial peptide candidates. Among them, a cationic antimicrobial peptide, scolopendrasin VII, was selected based on its physicochemical properties, such as length, charge, and isoelectric point. Here, we assessed the anticancer activities of scolopendrasin VII against U937 and Jurkat leukemia cell lines. The results showed that scolopendrasin VII decreased the viability of the leukemia cells in MTS assays. Furthermore, flow cytometric analysis and acridine orange/ethidium bromide staining revealed that scolopendrasin VII induced necrosis in the leukemia cells. Scolopendrasin VII-induced necrosis was mediated by specific interaction with phosphatidylserine, which is enriched in the membrane of cancer cells. Taken together, these data indicated that scolopendrasin VII induced necrotic cell death in leukemia cells, probably through interaction with phosphatidylserine. The results provide a useful anticancer peptide candidate and an efficient strategy for new anticancer peptide development.

  12. Japanese collaborative study to assess inter-laboratory variation in factor VII activity assays.

    Science.gov (United States)

    Takamiya, O; Ishikawa, S; Ohnuma, O; Suehisa, H; Iijima, K; Kayamori, Y; Bando, S; Higashi, K

    2007-08-01

    The clinical phenotype manifest by patients with factor VII (FVII) deficiency correlates poorly with that predicted by laboratory tests. Despite its importance, there are no data on the variability of inter-laboratory determinations of low to very low plasma FVII activity (FVII:C). We distributed three FVII-deficient plasma samples, prepared by immunoaffinity chromatography, to 58 laboratories in Japan. All samples were assayed using standardized reference plasma as a calibrator. Recombinant thromboplastin was also supplied as a common reagent. In the case of sample A, which had a very low FVII:C, the use of standardized reference plasma and thromboplastin, lowered the variability of inter-laboratory measurements, when compared with the variability observed when samples were assayed using the respective laboratory's routine method. The data obtained indicated that results for samples with a very low FVII:C were greatly influenced by the number of plasma dilutions used in constructing a standard activity curve, and also by the type of calibrator and thromboplastin. Such variability was not seen for samples with moderate FVII:C. We conclude that it is necessary to develop a more sensitive and accurate FVII:C measurement system for the diagnosis and treatment of FVII deficiency.

  13. EFEKTIVITAS PENERAPAN METODE PEMBELAJARAN KOOPERATIF TIPE TGT (TEAM GAME TOURNAMENT UNTUK MENINGKATKAN HASIL BELAJAR KOMPETENSI DASAR KEGIATAN POKOK EKONOMI SISWA KELAS VII SMP N 1 JATI KUDUS

    Directory of Open Access Journals (Sweden)

    Dian Retno Astrini

    2014-02-01

    taking the entire population of a class VII student of SMP Negeri 1 Jati Kudus school year 2012/2013. The object of research consists of a class VII C as an experimental class VII and class D as the control class. The variables of this study consisted of learning outcomes ( Y and cooperative learning methods TGT ( X . The method of data collection is done by documentation, observation, and testing. Methods of data analysis is done by applying a normality test, homogeneity, and hypothesis testing. The results showed that an increase in learning outcomes between the two classes seen from pre-test to post-test. Based on the study gained an average pre test control class is 66.85 while the experimental class was 68.71. after learning the different methods of post test values ​​obtained control class is 79.02, while the experimental class was 86.61. Based on the research that has been done can be concluded that the results of social studies, students learn the basic competencies principal economic activities using cooperative learning methods TGT significantly better compared to using conventional learning methods.

  14. Uudised : Baltimaade suurim, XII "Jazzkaar". VII rahvusvaheline koorifestival. Leipzigis improviseeriti edukalt

    Index Scriptorium Estoniae

    2001-01-01

    23.-29. apr. toimuvast festivalist "Jazzkaar 2001". VII rahvusvahelisest koorifestivalist "Tallinn "2001". 6. ja 7. apr. Leipzigis toimunud V rahvusvahelisest improvisatsioonikonkursist, kus osalesid ka eesti interpreedid

  15. Immune reactivity to type VII collagen: implications for gene therapy of recessive dystrophic epidermolysis bullosa.

    Science.gov (United States)

    Pendaries, V; Gasc, G; Titeux, M; Leroux, C; Vitezica, Z G; Mejía, J E; Décha, A; Loiseau, P; Bodemer, C; Prost-Squarcioni, C; Hovnanian, A

    2010-07-01

    Recessive dystrophic epidermolysis bullosa (RDEB) is a severe genodermatosis caused by loss-of-function mutations in COL7A1 encoding type VII collagen, the component of anchoring fibrils. As exogenous type VII collagen may elicit a deleterious immune response in RDEB patients during upcoming clinical trials of gene therapies or protein replacement therapies, we developed enzyme-linked immunosorbent assay (ELISA) and enzyme-linked immunosorbent spot (ELISPOT) assays to analyze B- and T-cell responses, to the full-length type VII collagen. The ELISA was highly sensitive and specific when tested against sera from 41 patients with epidermolysis bullosa acquisita (EBA), and the IFN-gamma ELISPOT detected a cellular response that correlated with ongoing EBA manifestations. Both tests were next applied to assess the risk of an immune response to type VII collagen in seven RDEB patients with a range of type VII collagen expression profiles. Immune responses against type VII collagen were dependent on the expression of type VII collagen protein, and consequently on the nature and position of the respective COL7A1 mutations. These immunologic tests will be helpful for the selection of RDEB patients for future clinical trials aiming at restoring type VII collagen expression, and in monitoring their immune response to type VII collagen after treatment.

  16. Lithium preferentially inhibits adenylyl cyclase V and VII isoforms.

    Science.gov (United States)

    Mann, Liad; Heldman, Eliahu; Shaltiel, Galit; Belmaker, R H; Agam, Galila

    2008-06-01

    Lithium ions' inhibition of adenylyl cyclase (AC) has not been previously studied for the newly discovered AC isoforms. COS7 cells were transfected with each of the nine membrane-bound AC isoforms cDNAs with or without D1- or D2-dopamine receptor cDNA. AC activity was measured as [3H]cAMP accumulation in cells pre-incubated with [3H]adenine followed by incubation with phosphodiesterase inhibitors together with either the D1 agonist SKF-82958 alone, or forskolin, in the presence or absence of the D2 agonist quinpirole. At 1 mm or 2 mm lithium inhibited only AC-V activity when the enzyme was stimulated by forskolin, a direct activator of AC. Lithium inhibited AC-V (by 50%), AC-VII (by 40%) and AC-II (by 25%) when stimulated via the D1 receptors, but did not affect the Ca2+-activated isoforms when stimulated by the Ca2+ ionophore A23187. Quinpirole inhibits AC via the Gi protein. Lithium did not affect quinpirole-inhibited FSK-activated AC-V activity nor did it affect superactivated AC-V or AC-I following the removal of quinpirole. The data suggest interference of lithium with transduction pathways mediated via AC-V or AC-VII; only the active conformation of these AC isoforms is inhibited by lithium; the inhibitory effect of lithium is abolished when the enzyme is superactivated. The marked inhibition of AC-V and AC-VII by lithium suggests that these two isoforms may be involved in mediating the mood-stabilizing effect of lithium.

  17. Abnormal deposition of type VII collagen in Kindler syndrome.

    Science.gov (United States)

    Wiebe, C B; Larjava, H S

    1999-01-01

    Kindler syndrome is an extremely rare genetic disorder with features of epidermolysis bullosa and poikiloderma congenitale. Approximately 70 cases have been documented in the past 50 years, but only a few investigations of the basement membrane components have been done on these patients. The aim of this study was to examine the components of the basement membrane zone in search of the pathobiological defect(s) responsible for the clinical findings from a female 16-year-old patient diagnosed with Kindler syndrome. This patient also suffered from advanced early-onset periodontal disease. Biopsies were taken from inflamed gingiva and noninflamed oral mucosa as part of periodontal treatment. The basement membrane zone was examined using immunofluorescence microscopy to bullous pemphigoid antigens 1 and 2, collagen types IV and VII, laminins-1 and -5, and integrins alpha3beta1 and alpha6beta4. The biopsies studied revealed blistering with trauma above the level of lamina densa based on distribution of type IV collagen and laminin-1 at the blister floor. In the noninflamed mucosa, discontinuous areas of the basement membrane zone were found. Expression of the basement membrane zone components and the integrins studied appeared otherwise normal with the exception of type VII collagen which was found in abnormal locations deep in the connective tissue stroma. Our results suggest that Kindler syndrome is associated with abnormalities in the construction of the basement membrane, especially in the expression of type VII collagen. These alterations are likely to play a role as etiological factors leading to blister formation and early onset periodontal disease.

  18. Pengembangan Vaksin Inaktif Tetelo Genotipe VII Isolat Lokal pada Kondisi Laboratorium. (DEVELOPMENT OF TETELO INACTIVATED VACCINE GENOTYPE VII LOCAL ISOLATE IN LABORATORY CONDITION

    Directory of Open Access Journals (Sweden)

    Risa Indriani

    2016-11-01

    Full Text Available Tetelo/Newcastle disease (ND inactive vaccine of genotipe VII virus local isolate have been developedin laboratory condition and compared with commercial ND vaccine. A total of 200 commercial layer chickenat 4 weeks age were divided into four groups, that were (1 vaccinated with ND genotype VII Indonesia/GTT/11, (2 vaccinated with commercial ND vaccine genotype VII, (3 vaccinated with commercial genotypeVI and (4 unvaccinated as control group. After two weeks post vaccination, 10 chicken from each groupwere sellected randomly and challenged with 105 EID50 per 0,1 mL of ND virus genotype VII Indonesian/GTT/11 by intramuscular. Chicken were observed, and swab were collected from oropharyngeal and cloacaat 2, 5, 7, 12 and 14 days post challenge. The result of this study showed inactived vaccine genotype VIIIndonesia/GTT/11 can induced a good antibody titer response to vaccinated chicken with mean titer 7.30log2 and CI 6.3 to 7.8, while commercial ND vaccine genotipe VII was 5.30 log2 with CI 3.8-6.7, andcommercial genotype VI was 4.8 log2 with CI 4.1-5.4. The level of protection which determined by noclinical signs, mortality and viral shedding showed 100% protection in chicken vaccinated with Indonesia/GTT/11 and commercial genotype VII were 100%, compared with control chicken, and vaccined commercialND vaccine genotype VII, compared with control chicken. While in chicken vaccinated commercial NDvaccine genotype VI showed viral shedding on day two post challenge, but there were no clinical sign andmortality. Based on this results, Indonesia/GTT/11 genotype VII ND vaccine could be used as an alternativeND vaccine to protect chicken from infection of ND virus genotype VII in the field.

  19. Imagining Ferdinand VII, a Catholic and felon King

    OpenAIRE

    Gregorio Alonso

    2015-01-01

    The public image of King Ferdinand VII (1784-1833) was built through a process of exaltation and sacralization as a result of the Napoleonic invasion of the Iberian Peninsula that started in the fall of 1807. This article tackles the mechanisms put in place in order to achieve such a target. It also unravels the ways in which wide sectors of the Catholic clergy collaborated in the identification of the King’s image with that of the Spanish nation in danger. The text also sheds light on the Am...

  20. The H i Chronicles of LITTLE THINGS BCDs. III. Gas Clouds in and around Mrk 178, VII Zw 403, and NGC 3738

    Energy Technology Data Exchange (ETDEWEB)

    Ashley, Trisha; Simpson, Caroline E.; Pokhrel, Nau Raj [Department of Physics, Florida International University, 11200 SW 8th Street, CP 204, Miami, FL 33199 (United States); Elmegreen, Bruce G. [IBM T. J. Watson Research Center, 1101 Kitchawan Road, Yorktown Heights, NY 10598 (United States); Johnson, Megan, E-mail: trisha.l.ashley@nasa.gov, E-mail: simpsonc@fiu.edu, E-mail: npokh001@fiu.edu, E-mail: bge@us.ibm.com, E-mail: megan.johnson@csiro.au [CSIRO Astronomy and Space Science, P.O. Box 76, Epping, NSW 1710 Australia (Australia)

    2017-03-01

    In most blue compact dwarf (BCD) galaxies, it remains unclear what triggers their bursts of star formation. We study the H i of three relatively isolated BCDs, Mrk 178, VII Zw 403, and NGC 3738, in detail to look for signatures of star formation triggers, such as gas cloud consumption, dwarf–dwarf mergers, and interactions with companions. High angular and velocity resolution atomic hydrogen (H i) data from the Very Large Array (VLA) dwarf galaxy H i survey, Local Irregulars That Trace Luminosity Extremes, The H i Nearby Galaxy Survey (LITTLE THINGS), allow us to study the detailed kinematics and morphologies of the BCDs in H i. We also present high-sensitivity H i maps from the NRAO Green Bank Telescope (GBT) of each BCD to search their surrounding regions for extended tenuous emission or companions. The GBT data do not show any distinct galaxies obviously interacting with the BCDs. The VLA data indicate several possible star formation triggers in these BCDs. Mrk 178 likely has a gas cloud impacting the southeast end of its disk or it is experiencing ram pressure stripping. VII Zw 403 has a large gas cloud in its foreground or background that shows evidence of accreting onto the disk. NGC 3738 has several possible explanations for its stellar morphology and H i morphology and kinematics: an advanced merger, strong stellar feedback, or ram pressure stripping. Although apparently isolated, the H i data of all three BCDs indicate that they may be interacting with their environments, which could be triggering their bursts of star formation.

  1. The HI Chronicles of LITTLE THINGS BCDs. III. Gas Clouds in and around Mrk 178, VII Zw 403, and NGC 3738

    Science.gov (United States)

    Ashley, Trisha; Simpson, Caroline E.; Elmegreen, Bruce G.; Johnson, Megan; Pokhrel, Nau Raj

    2017-03-01

    In most blue compact dwarf (BCD) galaxies, it remains unclear what triggers their bursts of star formation. We study the H I of three relatively isolated BCDs, Mrk 178, VII Zw 403, and NGC 3738, in detail to look for signatures of star formation triggers, such as gas cloud consumption, dwarf-dwarf mergers, and interactions with companions. High angular and velocity resolution atomic hydrogen (H I) data from the Very Large Array (VLA) dwarf galaxy H I survey, Local Irregulars That Trace Luminosity Extremes, The H I Nearby Galaxy Survey (LITTLE THINGS), allow us to study the detailed kinematics and morphologies of the BCDs in H I. We also present high-sensitivity H I maps from the NRAO Green Bank Telescope (GBT) of each BCD to search their surrounding regions for extended tenuous emission or companions. The GBT data do not show any distinct galaxies obviously interacting with the BCDs. The VLA data indicate several possible star formation triggers in these BCDs. Mrk 178 likely has a gas cloud impacting the southeast end of its disk or it is experiencing ram pressure stripping. VII Zw 403 has a large gas cloud in its foreground or background that shows evidence of accreting onto the disk. NGC 3738 has several possible explanations for its stellar morphology and H I morphology and kinematics: an advanced merger, strong stellar feedback, or ram pressure stripping. Although apparently isolated, the H I data of all three BCDs indicate that they may be interacting with their environments, which could be triggering their bursts of star formation.

  2. Effect of process variables on the osmotic dehydration of star-fruit slices Efeito das variáveis de processo na desidratação osmótica de fatias de carambola

    Directory of Open Access Journals (Sweden)

    Camila Dalben Madeira Campos

    2012-06-01

    Full Text Available The objective of this work was to study the effect of blanching and the influence of temperature, solution concentration, and the initial fruit:solution ratio on the osmotic dehydration of star-fruit slices. For blanching, different concentrations of citric and ascorbic acids were studied. The samples immersed in 0.75% citric acid presented little variation in color in relation to the fresh star-fruit. Osmotic dehydration was carried out in an incubator with orbital shaking, controlled temperature, and constant shaking at 120 rpm. The influence of process variables was studied in trials defined by a complete 23 central composite design. In general, water loss and solids gain were positively influenced by temperature and by solution concentration. Nevertheless, lower temperatures reduced water loss throughout the osmotic dehydration process. An increase in the amount of dehydrating solution (initial fruit:solution ratio slightly influenced the evaluated responses. The process carried out at 50 ºC with a solution concentration of 50% resulted in a product with lower solids gain and greater water loss. Under these conditions, blanching minimized the effect of the osmotic treatment on star-fruit browning, and therefore the blanched fruits showed little variation in color in relation to the fresh fruit.O objetivo deste trabalho foi estudar o efeito do branqueamento e a influência da temperatura, concentração de sacarose e da relação fruta:solução inicial na desidratação osmótica de fatias de carambola. Para o branqueamento, diferentes concentrações de ácido cítrico e ascórbico foram estudadas. As amostras imersas em 0,75% de ácido cítrico apresentaram pouca variação de cor em relação à carambola fresca. A desidratação osmótica foi conduzida em uma incubadora com agitação orbital, com temperatura controlada e agitação constante de 120 rpm. A influência das variáveis de processo foi avaliada através de ensaios definidos

  3. Lifestyles of the Stars.

    Science.gov (United States)

    National Aeronautics and Space Administration, Cocoa Beach, FL. John F. Kennedy Space Center.

    Some general information on stars is provided in this National Aeronautics and Space Administration pamphlet. Topic areas briefly discussed are: (1) the birth of a star; (2) main sequence stars; (3) red giants; (4) white dwarfs; (5) neutron stars; (6) supernovae; (7) pulsars; and (8) black holes. (JN)

  4. Egyptian "Star Clocks"

    Science.gov (United States)

    Symons, Sarah

    Diagonal, transit, and Ramesside star clocks are tables of astronomical information occasionally found in ancient Egyptian temples, tombs, and papyri. The tables represent the motions of selected stars (decans and hour stars) throughout the Egyptian civil year. Analysis of star clocks leads to greater understanding of ancient Egyptian constellations, ritual astronomical activities, observational practices, and pharaonic chronology.

  5. Interleukin VII Receptor Gene Polymorphism in Multiple Sclerosis Patients

    Directory of Open Access Journals (Sweden)

    M Ahmadzadeh Raji

    2011-10-01

    Full Text Available Introduction: Multiple Sclerosis is a chronic disease of central nervous system. Disease is more common in young adults and females and causes neurologic symptoms and signs. Cytokine IL-7 is a 25– kDa glycoprotein that has an important role in Lymphopoiesis. Interleukin VII receptor gene has been identified to be associated with multiple sclerosis, so its assessment is important. Methods: We investigated 60 Iranian patients with clinically definite MS and 60 normal healthy controls with negative family history for MS. After blood sampling, DNA was extracted from the whole blood, then we used 2 sets of primers for promoter and exon 4 of IL-VII gene. These fragments were amplified by PCR technique and early screening was performed by SSCP technic in the presence of control samples. Then different patterns with control samples were sent for DNA sequencing. Results: We observed one SNP in promoter. Most of the alleles of the patients were homozygote. There were two 2 SNPs and two sequence variations in exon 4 as P.H165H and P.V138I, which has been submitted in European Bioinformatics Institute under the access number of FR863587. Conclusion: Further studies on control group will be required to reveal the effects of these SNPs on the ILVII-R α protein and they can probably be useed as a biomarker for early diagnosis of MS.

  6. Characterization of a Myosin VII MyTH/FERM domain

    Science.gov (United States)

    Moen, Rebecca J.; Johnsrud, Daniel O.; Thomas, David D.; Titus, Margaret A.

    2011-01-01

    A group of closely related myosins are characterized by the presence of at least one MyTH/FERM (myosin talin homology 4; band 4.1, ezrin, radixin, moesin) domain in their C-terminal tails. This domain interacts with a variety of binding partners, and mutations in either the MyTH4 or FERM domains of myosin VII and XV result in deafness, highlighting the functional importance of each domain. The N-terminal MyTH/FERM region of Dictyostelium myosin VII (M7) has been isolated as a first step toward gaining insight into the function of this domain and its interaction with binding partners. The M7 MyTH4/FERM domain (MF1) binds to both actin and microtubules in vitro, with dissociation constants of 13.7 and 1.7 μM, respectively. Gel filtration and UV spectroscopy reveal that MF1 exists as a monomer in solution and forms a well-folded, compact conformation with a high degree of secondary structure. These results indicate that MF1 forms an integrated structural domain that serves to couple actin filaments and microtubules in specific regions of the cytoskeleton. PMID:21875595

  7. Mucopolysaccharidosis type VII in a German Shepherd Dog.

    Science.gov (United States)

    Silverstein Dombrowski, Deborah C; Carmichael, K Paige; Wang, Ping; O'Malley, Thomas M; Haskins, Mark E; Giger, Urs

    2004-02-15

    A 12-week-old male German Shepherd Dog was evaluated because of a 3-week history of a progressive inability to ambulate. Clinical and laboratory findings included skeletal deformities, corneal cloudiness, cytoplasmic granules in the neutrophils and lymphocytes of blood and CSF and glycosaminoglycans in a urine sample (detected via a toluidine blue spot test). Enzyme activity and DNA analyses confirmed mucopolysaccharidosis type VII as a result of severe beta-glucuronidase deficiency; this condition had been identified in a mixed-breed dog (likely of German Shepherd Dog descent) that was reported 20 years earlier and caused by the same missense mutation. Because of the progressive nature of this disease, the puppy was euthanatized and all tissues examined contained evidence of lysosomal storage leading to marked cellular distention. Mucopolysaccharidosis type VII is only one of many hereditary lysosomal storage diseases identified in companion animals. It is important that clinicians recognize the typical signs of lysosomal storage diseases and are aware of the cytologic and urinary screening tests for mucopolysaccharidosis disorders. Furthermore, there are specific blood enzyme and DNA-based tests to distinguish the forms of mucopolysaccharidosis in affected and carrier animals.

  8. PENINGKATAN PEMAHAMAN KONSEP HIMPUNAN MELALUI MIND MAPPING KELAS VII SMP

    Directory of Open Access Journals (Sweden)

    Dewi Arfiyanti

    2017-06-01

    Full Text Available The kind of this research is classroom action reseach (CAS. This research was conducted to 34 student in the VII.D class of SMP. The aim of this research is to describe understanding concept of set through mind mapping. The data collected is the result of observation, mind mapping and finals tes of the cycle. There are six indicators to decide sub topic, keyword, color design, supporting data and material of sets in assessing mind mapping. The result of mind mapping shows that students can produce picture and write the keywords, Supporting data in the form of notation and Venn diagram. Students comprehended sets concept and finished contextual problem by using Venn diagram. Jenis penelitian ini adalah Penelitian Tindakan Kelas (PTK. Penelitian ini dilaksanakan pada kelas VII. D SMP berjumlah 34 siswa. Tujuan penelitian ini adalah mendiskripsikan peningkatkan pemahaman konsep himpunan melalui mind mapping. Data yang dikumpulkan yaitu data observasi, hasil mind mapping dan tes akhir siklus. Penilaian mind mapping ada enam indikator yaitu menentukan sub topik, menentukan cabang sub topik, kata kunci, desain warna, data pendukung, dan materi himpunan. Berdasarkan hasil mind mapping menunjukkan siswa telah menghasilkan gambar dengan menuliskan kata kunci, data pendukung berupa notasi dan diagram Venn. Siswa memahami konsep himpunan dan menyelesaikan masalah kontekstual dengan diagram Venn.

  9. Star Formation in IC 348

    Science.gov (United States)

    Herbst, W.

    2008-12-01

    A review of work on the small, compact, nearby young cluster IC 348 is given. This region is particularly important because it is well surveyed at a variety of wavelengths and intermediate in nature between dense clusters and loose associations. Its earliest type star is B5 and it contains a few hundred stellar members as well as some brown dwarfs, protostars, Herbig-Haro objects and starless sub-mm cores. The total mass of its components is ˜90 M_⊙, most of which is in the form of pre-main sequence stars. Perhaps the biggest challenge to work on the cluster is the relatively high and variable extinction (A_v=3D1-7 mag). Studies to date have provided particularly valuable insights into the initial mass function, disk lifetimes, stellar rotation properties, X-ray properties, outflows and substructure of the cluster. Results on the stellar component include the following: 1) the initial mass function matches that for field stars in the stellar and brown dwarf regimes, 2) the fraction of stars with disks is probably normal for the cluster's age, 3) the rotation properties match those of the Orion Nebula Cluster and are significantly different, in the sense of slower rotation, than NGC 2264, 4) the X-ray properties of the stars appear normal for T Tauri stars. There is a ridge of high extinction that lies ˜10 arcmin (0.9 pc in projection) to the southwest of IC 348 and contains about a dozen Class 0 and I protostars as well as some Herbig Haro objects and sub-mm cores. This region, which also contains the "Flying Ghost Nebula" and the well-studied object HH 211, clearly signals that star formation in this part of the Perseus dark clouds is not yet finished. An extensive kinematical study involving both proper motions and radial velocities for the 400 members of the cluster would be most desirable.

  10. Imagining Ferdinand VII, a Catholic and felon King | Imaginando a Fernando VII, rey católico y felón

    National Research Council Canada - National Science Library

    Gregorio Alonso

    2015-01-01

    The public image of King Ferdinand VII (1784-1833) was built through a process of exaltation and sacralization as a result of the Napoleonic invasion of the Iberian Peninsula that started in the fall of 1807...

  11. A Correlation Study of the Minnesota Teacher Attitude Inventory and Kerlinger's ES-VII.

    Science.gov (United States)

    Padgett, Harry G.

    The Minnesota Teacher Attitude Inventory (MTAI) and Kerlinger's ES-VII are instruments which examine both the individual's general educational philosophy and his ideas of practice. A study was designed to investigate (1) the common variance in the Difference score of the 150-item MTAI and the D score of Kerlinger's 30-item ES-VII with respect to…

  12. Aristóteles y las series causales infinitas en Física VII y VIII

    Directory of Open Access Journals (Sweden)

    Alberto Ross

    2013-11-01

    Full Text Available The aim of this paper is to show that we have at least two different arguments that prove the First Motor's existence. Even though there are coincidences between Physics VII 1 and VIII 5, their arguments are not identical. Physics VII argue the impossibility of an infinite movement in a finite time and VIII 5 the necessity of a "principal" cause.

  13. 20 CFR Appendix Vii to Subpart C... - “Old-Law” Contribution and Benefit Base

    Science.gov (United States)

    2010-04-01

    ... Appendix VII to Subpart C of Part 404 Employees' Benefits SOCIAL SECURITY ADMINISTRATION FEDERAL OLD-AGE, SURVIVORS AND DISABILITY INSURANCE (1950- ) Computing Primary Insurance Amounts Pt. 404, Subpt. C, App. VII... appendix IV). This is the contribution and benefit base that would have been effective under the Social...

  14. Underuse of Title VII Funding for Indian Education in Arizona, Nevada, and Utah

    Science.gov (United States)

    West Comprehensive Center at WestEd, 2015

    2015-01-01

    Title VII provides funding for the education of American Indian/Alaska Native students based on a formula grant available to school districts, charter schools, and local education agencies (LEAs). This report explores why some eligible schools and districts do not apply for federal Title VII, potentially resulting in American Indian/Alaska Native…

  15. 77 FR 5396 - Recordkeeping and Reporting Requirements Under Title VII, the ADA, and GINA

    Science.gov (United States)

    2012-02-03

    ... GINA protects job applicants, current and former employees, labor union members, and apprentices and... more employees, employment agencies, labor unions, and joint labor-management training programs, as... recordkeeping requirements under title VII of the Civil Rights Act of 1964 (Title VII) and the Americans with...

  16. Classifying TDSS Stellar Variables

    Science.gov (United States)

    Amaro, Rachael Christina; Green, Paul J.; TDSS Collaboration

    2017-01-01

    The Time Domain Spectroscopic Survey (TDSS), a subprogram of SDSS-IV eBOSS, obtains classification/discovery spectra of point-source photometric variables selected from PanSTARRS and SDSS multi-color light curves regardless of object color or lightcurve shape. Tens of thousands of TDSS spectra are already available and have been spectroscopically classified both via pipeline and by visual inspection. About half of these spectra are quasars, half are stars. Our goal is to classify the stars with their correct variability types. We do this by acquiring public multi-epoch light curves for brighter stars (rclassifications and parameters in the Catalina Surveys Periodic Variable Star Catalog. Variable star classifications include RR Lyr, close eclipsing binaries, CVs, pulsating white dwarfs, and other exotic systems. The key difference between our catalog and others is that along with the light curves, we will be using TDSS spectra to help in the classification of variable type, as spectra are rich with information allowing estimation of physical parameters like temperature, metallicity, gravity, etc. This work was supported by the SDSS Research Experience for Undergraduates program, which is funded by a grant from Sloan Foundation to the Astrophysical Research Consortium.

  17. The Birth of Massive Stars and Star Clusters

    OpenAIRE

    Tan, Jonathan C.

    2005-01-01

    In the present-day universe, it appears that most, and perhaps all, massive stars are born in star clusters. It also appears that all star clusters contain stars drawn from an approximately universal initial mass function, so that almost all rich young star clusters contain massive stars. In this review I discuss the physical processes associated with both massive star formation and with star cluster formation. First I summarize the observed properties of star-forming gas clumps, then address...

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

    Energy Technology Data Exchange (ETDEWEB)

    Musella, Ilaria; Ripepi, Vincenzo; Marconi, Marcella, E-mail: ilaria@na.astro.it, E-mail: ripepi@na.astro.it, E-mail: marcella@na.astro.it [INAF, Osservatorio Astronomico di Capodimonte, I-8013 Napoli (Italy); and others

    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. 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.

  19. Photometric Variability of Four Coronally Active Stars

    Indian Academy of Sciences (India)

    Author Affiliations. J. C. Pandey1 K. P. Singh2 R. Sagar1 3 S. A. Drake4. State Observatory, Naini Tal 263 129, India. Tata Institute of Fundamental Research, Mumbai, India. Indian Institute of Astrophysics, Bangalore, India. Code 668, LHEA, NASA/Goddard Space Flight Center, Greenbelt, MD 20771, USA.

  20. Stellar laboratories. VII. New Kr iv - vii oscillator strengths and an improved spectral analysis of the hot, hydrogen-deficient DO-type white dwarf RE 0503-289

    Science.gov (United States)

    Rauch, T.; Quinet, P.; Hoyer, D.; Werner, K.; Richter, P.; Kruk, J. W.; Demleitner, M.

    2016-05-01

    Context. For the spectral analysis of high-resolution and high signal-to-noise (S/N) spectra of hot stars, state-of-the-art non-local thermodynamic equilibrium (NLTE) model atmospheres are mandatory. These are strongly dependent on the reliability of the atomic data that is used for their calculation. Aims: New Kr iv-vii oscillator strengths for a large number of lines enable us to construct more detailed model atoms for our NLTE model-atmosphere calculations. This enables us to search for additional Kr lines in observed spectra and to improve Kr abundance determinations. Methods: We calculated Kr iv-vii oscillator strengths to consider radiative and collisional bound-bound transitions in detail in our NLTE stellar-atmosphere models for the analysis of Kr lines that are exhibited in high-resolution and high S/N ultraviolet (UV) observations of the hot white dwarf RE 0503-289. Results: We reanalyzed the effective temperature and surface gravity and determined Teff = 70000 ± 2000 K and log (g/ cm s-2) = 7.5 ± 0.1. We newly identified ten Kr v lines and one Kr vi line in the spectrum of RE 0503-289. We measured a Kr abundance of -3.3 ± 0.3 (logarithmic mass fraction). We discovered that the interstellar absorption toward RE 0503-289 has a multi-velocity structure within a radial-velocity interval of -40 km s-1National Commission for Astronomy.Tables A.9-A.12 are only available via the German Astrophysical Virtual Observatory (GAVO) service TOSS (http://dc.g-vo.org/TOSS).

  1. Spectral Properties and Variability of BIS objects

    Science.gov (United States)

    Gaudenzi, S.; Nesci, R.; Rossi, C.; Sclavi, S.; Gigoyan, K. S.; Mickaelian, A. M.

    2017-10-01

    Through the analysis and interpretation of newly obtained and of literature data we have clarified the nature of poorly investigated IRAS point sources classified as late type stars, belonging to the Byurakan IRAS Stars catalog. From medium resolution spectroscopy of 95 stars we have strongly revised 47 spectral types and newly classified 31 sources. Nine stars are of G or K types, four are N carbon stars in the Asymptotic Giant Branch, the others being M-type stars. From literature and new photometric observations we have studied their variability behaviour. For the regular variables we determined distances, absolute magnitudes and mass loss rates. For the other stars we estimated the distances, ranging between 1.3 and 10 kpc with a median of 2.8 kpc from the galactic plane, indicating that BIS stars mostly belong to the halo population.

  2. Temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from USCGC POLAR STAR in the Arctic Ocean from 2002-08-19 to 2002-09-23 (NODC Accession 0115588)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0115588 includes discrete sample and profile data collected from USCGC POLAR STAR in the Arctic Ocean from 2002-08-19 to 2002-09-23. These data...

  3. Search of Short-Period Pulsating Variables(I

    Directory of Open Access Journals (Sweden)

    Chulhee Kim

    1996-06-01

    Full Text Available CCD differential photometry was carried out for seven stars in the "New Catalogue of Suspected Variable Stars" in order to discover new short-period pulsating variables such as low and high amplitude δ Scuti stars and RR Lyrae stars. It was found that NSV1132, NSV3031, and NSV5119 are RRs, Irregular, and low amplitude δ Scuti type variables respectively.

  4. Unexplained Brightening of Unusual Star

    Science.gov (United States)

    1997-01-01

    compact objects), both high- and low-luminosity X-ray sources , and cataclysmic variables (double stars whose light `flickers'). The kinds and numbers of these objects in cluster cores constrain the complex and as yet incompletely understood formation channels, most of which involve encounters with binaries. Many of the above exotic objects are strong emitters of ultraviolet light. The globular cluster 47 Tucanae 47 Tucanae is an impressive globular cluster that is visible with the naked eye from the southern hemisphere. It is one of the closest (distance 15,000 lightyears) and heaviest (total mass about 1 million solar masses) in our Galaxy. It contains about 1 million stars and the member stars have been intensively studied for decades. The observed structure of 47 Tucanae indicates that it is now approaching its ultimate fate during a core collapse phase. There are five known low-luminosity X-ray sources in the core of this cluster, eleven millisecond pulsars, many blue stragglers, and a centrally concentrated population of eclipsing binary stars. The observations support the idea that the population of primordial binaries in this cluster has been heavily modified by stellar encounters. The HST observations In late 1996, the group of astronomers obtained time to observe the central area of 47 Tucanae with the Hubble Space Telescope and the second Wide Field and Planetary Camera (WFPC2). During a period of more than 4 hours, a total of 15 CCD exposures were obtained through an ultraviolet filter (transmission near 3000 A), showing the thousands of individual stars in this densely populated region. Caption to ESO PR Photo 03/97 [GIF, 57k] When inspecting this material, it immediately became clear that one of the stars had undergone a substantial brightening in the course of these observations. In fact, its brightness increased by as much as 2.1 magnitudes, that is a factor of seven, in less than one hour; see the photos that accompany this Press Release. By the end of

  5. Coagulation factor VII, serum-triglycerides and the R/Q353 polymorphism: Differences between older men and women

    NARCIS (Netherlands)

    Mennen, L.I.; Maat, M.P.M. de; Schouten, E.G.; Kluft, C.; Jong, P.T.V.M. de; Hofman, A.; Grobbee, D.E.

    1997-01-01

    Coagulation factor VII activity (FVII:C) is a risk indicator for cardiovascular disease. It is related to serum-triglycerides and the R/Q353 polymorphism (alleles R and Q) in the gene coding for factor VII is strongly associated with factor VU[. The association of serum-triglycerides with factor VII

  6. File list: ALL.Brs.50.AllAg.MDA-MB-175-VII [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available ALL.Brs.50.AllAg.MDA-MB-175-VII hg19 All antigens Breast MDA-MB-175-VII SRX647704 h...ttp://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/ALL.Brs.50.AllAg.MDA-MB-175-VII.bed ...

  7. File list: Oth.Brs.05.AllAg.MDA-MB-175-VII [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Oth.Brs.05.AllAg.MDA-MB-175-VII hg19 TFs and others Breast MDA-MB-175-VII SRX647704... http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Oth.Brs.05.AllAg.MDA-MB-175-VII.bed ...

  8. File list: Oth.Brs.20.AllAg.MDA-MB-175-VII [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Oth.Brs.20.AllAg.MDA-MB-175-VII hg19 TFs and others Breast MDA-MB-175-VII SRX647704... http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Oth.Brs.20.AllAg.MDA-MB-175-VII.bed ...

  9. File list: Oth.Brs.50.AllAg.MDA-MB-175-VII [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Oth.Brs.50.AllAg.MDA-MB-175-VII hg19 TFs and others Breast MDA-MB-175-VII SRX647704... http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Oth.Brs.50.AllAg.MDA-MB-175-VII.bed ...

  10. File list: ALL.Brs.05.AllAg.MDA-MB-175-VII [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available ALL.Brs.05.AllAg.MDA-MB-175-VII hg19 All antigens Breast MDA-MB-175-VII SRX647704 h...ttp://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/ALL.Brs.05.AllAg.MDA-MB-175-VII.bed ...

  11. File list: Oth.Brs.10.AllAg.MDA-MB-175-VII [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Oth.Brs.10.AllAg.MDA-MB-175-VII hg19 TFs and others Breast MDA-MB-175-VII SRX647704... http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Oth.Brs.10.AllAg.MDA-MB-175-VII.bed ...

  12. File list: ALL.Brs.10.AllAg.MDA-MB-175-VII [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available ALL.Brs.10.AllAg.MDA-MB-175-VII hg19 All antigens Breast MDA-MB-175-VII SRX647704 h...ttp://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/ALL.Brs.10.AllAg.MDA-MB-175-VII.bed ...

  13. UXOR Hunting among Algol Variables

    Science.gov (United States)

    Poxon, M.

    2015-06-01

    The class of variable typified by UX Orionis (UXORs or UXors) are young stars characterised by aperiodic or semiperiodic fades from maximum. This has led to several of the class being formerly catalogued as Algol-type eclipsing binaries (EAs), which can show superficially similar light variations. With this in view, I propose a campaign to search for more UX Ori type stars.

  14. A Case of Aplasia Cutis Congenita, Type VII

    Science.gov (United States)

    Lee, Joung Sun; Lee, Jee Bum; Kim, Seong Jin; Won, Young Ho

    2008-01-01

    Aplasia cutis congenita (ACC) is a rare congenital defect in which localized or widespread areas of the skin are absent at birth. In the majority of cases, it is limited to the scalp especially on the vertex although other areas of the body may also be involved. Other congenital malformations can be associated with ACC. We present herein the case of a new born male with unilateral absence of skin on the extensor surface of the right lower leg. There was no associated malformation or skin disease such as blistering or nail abnormailty. According to the classification outlined by Frieden, the condition was diagnosed as type VII aplasia cutis congenita. The treatment of this large ulcer was conservative, wet dressing and prophylactic topical antibiotics. On follow up after 2 years showed that the patient was nearly cured of the ulcer and had only minimal scar formation. PMID:27303163

  15. On the distribution of visual double stars

    Directory of Open Access Journals (Sweden)

    Angelov T.

    1998-01-01

    Full Text Available An integrated distribution function is derived for visual double stars according to the magnitude difference Δm between the components. For this purpose the author uses a sample of 1626 double stars with Δm ∈ [0m − 4m]. The increment of the descriptive distribution function for an arbitrary increment of the variable Δm is also determined.

  16. The effect of neonatal gene therapy on skeletal manifestations in mucopolysaccharidosis VII dogs after a decade.

    Science.gov (United States)

    Xing, Elizabeth M; Knox, Van W; O'Donnell, Patricia A; Sikura, Tracey; Liu, Yuli; Wu, Susan; Casal, Margret L; Haskins, Mark E; Ponder, Katherine P

    2013-06-01

    Mucopolysaccharidosis (MPS) VII is a lysosomal storage disease due to deficient activity of β-glucuronidase (GUSB), and results in glycosaminoglycan accumulation. Skeletal manifestations include bone dysplasia, degenerative joint disease, and growth retardation. One gene therapy approach for MPS VII involves neonatal intravenous injection of a gamma retroviral vector expressing GUSB, which results in stable expression in liver and secretion of enzyme into blood at levels predicted to be similar or higher to enzyme replacement therapy. The goal of this study was to evaluate the long-term effect of neonatal gene therapy on skeletal manifestations in MPS VII dogs. Treated MPS VII dogs could walk throughout their lives, while untreated MPS VII dogs could not stand beyond 6 months and were dead by 2 years. Luxation of the coxofemoral joint and the patella, dysplasia of the acetabulum and supracondylar ridge, deep erosions of the distal femur, and synovial hyperplasia were reduced, and the quality of articular bone was improved in treated dogs at 6 to 11 years of age compared with untreated MPS VII dogs at 2 years or less. However, treated dogs continued to have osteophyte formation, cartilage abnormalities, and an abnormal gait. Enzyme activity was found near synovial blood vessels, and there was 2% as much GUSB activity in synovial fluid as in serum. We conclude that neonatal gene therapy reduces skeletal abnormalities in MPS VII dogs, but clinically-relevant abnormalities remain. Enzyme replacement therapy will probably have similar limitations long-term. Copyright © 2013 Elsevier Inc. All rights reserved.

  17. The Effect of Neonatal Gene Therapy on Skeletal Manifestations in Mucopolysaccharidosis VII Dogs after a Decade

    Science.gov (United States)

    Xing, Elizabeth M.; Knox, Van W.; O'Donnell, Patricia A.; Sikura, Tracey; Liu, Yuli; Wu, Susan; Casal, Margret L.; Haskins, Mark E.; Ponder, Katherine P.

    2013-01-01

    Mucopolysaccharidosis (MPS) VII is a lysosomal storage disease due to deficient activity of β-glucuronidase (GUSB), and results in glycosaminoglycan accumulation. Skeletal manifestations include bone dysplasia, degenerative joint disease, and growth retardation. One gene therapy approach for MPS VII involves neonatal intravenous injection of a gamma retroviral vector expressing GUSB, which results in stable expression in liver and secretion of enzyme into blood at levels predicted to be similar or higher to enzyme replacement therapy. The goal of this study was to evaluate the long-term effect of neonatal gene therapy on skeletal manifestations in MPS VII dogs. Treated MPS VII dogs could walk throughout their lives, while untreated MPS VII dogs could not stand beyond 6 months and were dead by 2 years. Luxation of the coxofemoral joint and the patella, dysplasia of the acetabulum and supracondylar ridge, deep erosions of the distal femur, and synovial hyperplasia were reduced, and the quality of articular bone was improved in treated dogs at 6 to 11 years of age compared with untreated MPS VII dogs at 2 years or less. However, treated dogs continued to have osteophyte formation, cartilage abnormalities, and an abnormal gait. Enzyme activity was found near synovial blood vessels, and there was 2% as much GUSB activity in synovial fluid as in serum. We conclude that neonatal gene therapy reduces skeletal abnormalities in MPS VII dogs, but clinically-relevant abnormalities remain. Enzyme replacement therapy will probably have similar limitations long-term. PMID:23628461

  18. The impact of Title VII on general and pediatric dental education and training.

    Science.gov (United States)

    Ng, Man Wai; Glassman, Paul; Crall, James

    2008-11-01

    The authors describe the impact of the Title VII, Section 747 Training in Primary Care Medicine and Dentistry (Title VII) grant program on the development, growth, and expansion of general and pediatric dentistry residency programs in the United States. They first briefly review the legislative history of the Title VII program as it pertains to dental education, followed by a historical overview of dental education in the United States, including a description of the differences between dental and medical education and the routes to professional practice. The authors then present an extensive assessment of the role of the Title VII grant program in building general and pediatric dental training capacity, diversifying the dental workforce, providing outreach and service to underserved and vulnerable populations, stimulating innovations in dental education, and engaging collaborative and interdisciplinary training with medicine. Finally, the authors call for broadening the scope of the Title VII program to allow for predoctoral training (dental student education) and faculty development in general and pediatric dentistry. In doing so, the Title VII program can more effectively address current and future challenges in dental education, dentist workforce, and disparities in oral health and access to care.This article is part of a theme issue of Academic Medicine on the Title VII health professions training programs.

  19. Tissue Factor–Factor VII Complex as a Key Regulator of Ovarian Cancer Phenotypes

    Directory of Open Access Journals (Sweden)

    Shiro Koizume

    2015-01-01

    Full Text Available Tissue factor (TF is an integral membrane protein widely expressed in normal human cells. Blood coagulation factor VII (fVII is a key enzyme in the extrinsic coagulation cascade that is predominantly secreted by hepatocytes and released into the bloodstream. The TF–fVII complex is aberrantly expressed on the surface of cancer cells, including ovarian cancer cells. This procoagulant complex can initiate intracellular signaling mechanisms, resulting in malignant phenotypes. Cancer tissues are chronically exposed to hypoxia. TF and fVII can be induced in response to hypoxia in ovarian cancer cells at the gene expression level, leading to the autonomous production of the TF–fVII complex. Here, we discuss the roles of the TF–fVII complex in the induction of malignant phenotypes in ovarian cancer cells. The hypoxic nature of ovarian cancer tissues and the roles of TF expression in endometriosis are discussed. Arguments will be extended to potential strategies to treat ovarian cancers based on our current knowledge of TF–fVII function.

  20. 'Polaris, Mark Kummerfeldt's Star, and My Star.'

    Science.gov (United States)

    McLure, John W.

    1984-01-01

    In most astronomy courses, descriptions of stars and constellations reveal the western European origins of the astronomers who named them. However, it is suggested that a study of non-western views be incorporated into astronomy curricula. Descriptions of various stars and constellations from different cultures and instructional strategies are…

  1. ENERGY STAR Certified Computers

    Data.gov (United States)

    U.S. Environmental Protection Agency — Certified models meet all ENERGY STAR requirements as listed in the Version 6.1 ENERGY STAR Program Requirements for Computers that are effective as of June 2, 2014....

  2. ENERGY STAR Certified Boilers

    Data.gov (United States)

    U.S. Environmental Protection Agency — Certified models meet all ENERGY STAR requirements as listed in the Version 3.0 ENERGY STAR Program Requirements for Boilers that are effective as of October 1,...

  3. ENERGY STAR Certified Dehumidifiers

    Data.gov (United States)

    U.S. Environmental Protection Agency — Certified models meet all ENERGY STAR requirements as listed in the Version 3.0 ENERGY STAR Program Requirements for Dehumidifiers that are effective as of October...

  4. ENERGY STAR Certified Displays

    Data.gov (United States)

    U.S. Environmental Protection Agency — Certified models meet all ENERGY STAR requirements as listed in the Version 7.0 ENERGY STAR Program Requirements for Displays that are effective as of July 1, 2016....

  5. Autonomous Star Tracker Algorithms

    DEFF Research Database (Denmark)

    Betto, Maurizio; Jørgensen, John Leif; Kilsgaard, Søren

    1998-01-01

    Proposal, in response to an ESA R.f.P., to design algorithms for autonomous star tracker operations.The proposal also included the development of a star tracker breadboard to test the algorithms performances.......Proposal, in response to an ESA R.f.P., to design algorithms for autonomous star tracker operations.The proposal also included the development of a star tracker breadboard to test the algorithms performances....

  6. Star operations and Pullbacks

    OpenAIRE

    Fontana, Marco; Park, Mi Hee

    2003-01-01

    In this paper we study the star operations on a pullback of integral domains. In particular, we characterize the star operations of a domain arising from a pullback of ``a general type'' by introducing new techniques for ``projecting'' and ``lifting'' star operations under surjective homomorphisms of integral domains. We study the transfer in a pullback (or with respect to a surjective homomorphism) of some relevant classes or distinguished properties of star operations such as $v-, t-, w-, b...

  7. Iron Abundance in the Prototype PG 1159 Star, GW Vir Pulsator PG 1159-035, and Related Objects

    Science.gov (United States)

    Werner, K.; Rauch, T.; Kruk, J. W.; Kurucz, R. L.

    2011-01-01

    We performed an iron abundance determination of the hot, hydrogen deficient post-AGB star PG 1159-035. which is the prototype of the PG 1159 spectral class and the GW Vir pulsators, and of two related objects (PG 1520+525, PG 1144+005), based on the first detection of Fe VIII lines in stellar photospheres. In another PG 1159 star. PG 1424+535. we detect Fe VII lines. In all four stars, each within T(sub eff) = 110,000-150,000 K, we find a solar iron abundance. This result agrees with our recent abundance analysis of the hottest PG 1159 stars (T(sub eff) = 150,000-200,000 K) that exhibit Fe x lines. On the whole, we find that the PG 1159 stars are not significantly iron deficient, in contrast to previous notions.

  8. America's Star Libraries

    Science.gov (United States)

    Lyons, Ray; Lance, Keith Curry

    2009-01-01

    "Library Journal"'s new national rating of public libraries, the "LJ" Index of Public Library Service, identifies 256 "star" libraries. It rates 7,115 public libraries. The top libraries in each group get five, four, or three Michelin guide-like stars. All included libraries, stars or not, can use their scores to learn from their peers and improve…

  9. Superfluid neutron stars

    OpenAIRE

    Langlois, David

    2001-01-01

    Neutron stars are believed to contain (neutron and proton) superfluids. I will give a summary of a macroscopic description of the interior of neutron stars, in a formulation which is general relativistic. I will also present recent results on the oscillations of neutron stars, with superfluidity explicitly taken into account, which leads in particular to the existence of a new class of modes.

  10. Rotating Stars in Relativity

    Directory of Open Access Journals (Sweden)

    Stergioulas Nikolaos

    2003-01-01

    Full Text Available Rotating relativistic stars have been studied extensively in recent years, both theoretically and observationally, because of the information they might yield about the equation of state of matter at extremely high densities and because they are considered to be promising sources of gravitational waves. The latest theoretical understanding of rotating stars in relativity is reviewed in this updated article. The sections on the equilibrium properties and on the nonaxisymmetric instabilities in f-modes and r-modes have been updated and several new sections have been added on analytic solutions for the exterior spacetime, rotating stars in LMXBs, rotating strange stars, and on rotating stars in numerical relativity.

  11. Rotating Stars in Relativity

    Directory of Open Access Journals (Sweden)

    Nikolaos Stergioulas

    1998-06-01

    Full Text Available Because of the information they can yield about the equation of state of matter at extremely high densities and because they are one of the more possible sources of detectable gravitational waves, rotating relativistic stars have been receiving significant attention in recentyears. We review the latest theoretical and numerical methods for modeling rotating relativistic stars, including stars with a strong magnetic field and hot proto-neutron stars. We also review nonaxisymmetric oscillations and instabilities in rotating stars and summarize the latest developments regarding the gravitational wave-driven (CFS instability in both polar and axial quasi-normal modes.

  12. Nuclear physics of stars

    CERN Document Server

    Iliadis, Christian

    2015-01-01

    Most elements are synthesized, or ""cooked"", by thermonuclear reactions in stars. The newly formed elements are released into the interstellar medium during a star's lifetime, and are subsequently incorporated into a new generation of stars, into the planets that form around the stars, and into the life forms that originate on the planets. Moreover, the energy we depend on for life originates from nuclear reactions that occur at the center of the Sun. Synthesis of the elements and nuclear energy production in stars are the topics of nuclear astrophysics, which is the subject of this book

  13. A high fat meal activates blood coagulation factor VII in rats

    DEFF Research Database (Denmark)

    Olsen, Aage K; Bladbjerg, Else M; Hansen, Axel K

    2002-01-01

    In humans, high fat meals cause postprandial activation of blood coagulation factor VII (FVII), but human studies have not provided definite evidence for a prothrombotic effect of dietary FVII activation. An animal model would be an attractive way to pursue this question and therefore we tested...... the LEW/Mol rat. We gavaged 3 mL of a fat emulsion (n = 42) or 3 mL isotonic glucose (n = 42). Blood was sampled by heart puncture 2, 4 and 6 h (n = 14/group at each time) after the fat/glucose load. Furthermore, blood was sampled from 16 untreated rats to determine the baseline levels. Triglyceride....../L), and FVIIa was significantly raised at 4 h (54 U/L) and 6 h (58 U/L) compared with baseline (29 U/L). No postprandial changes in FVIIc, FVIIam and TAT were observed. Glucose administration did not affect any variable. We conclude that the LEW/Mol rat is a promising model for use in future studies...

  14. Glycine substitutions in the triple-helical region of type VII collagen result in a spectrum of dystrophic epidermolysis bullosa phenotypes and patterns of inheritance

    Energy Technology Data Exchange (ETDEWEB)

    Christiano, A.M.; McGrath, J.A.; Uitto, J. [Thomas Jefferson Univ., Philadelphia, PA (United States); Kong Chong Tan [National Skin Centre (Singapore)

    1996-04-01

    The dystrophic forms of epidermolysis bullosa (DEB) are characterized by fragility of the skin and mucous membranes. DEB can be inherited in either an autosomal dominant or autosomal recessive pattern, and the spectrum of clinical severity is highly variable. The unifying diagnostic hallmark of DEB is abnormalities in the anchoring fibrils, which consist of type VII collagen, and recently, mutations in the corresponding gene, COL7A1, have been disclosed in a number of families. In this study, we report six families with glycine substitution mutations in the triple-helical region of type VII collagen. Among the six families, two demonstrated a mild phenotype, and the inheritance of the mutation was consistent with the dominantly inherited form of DEB. In the four other families, the mutation was silent in the heterozygous state but, when present in the homozygous state, or combined with a second mutation, resulted in a recessively inherited DEB phenotype. Type VII collagen is, therefore, unique among the collagen genes, in that different glycine substitutions can be either silent in heterozygous individuals or result in a dominantly inherited DEB. Inspection of the locations of the glycine substitutions along the COL7A1 polypeptide suggests that the consequences of these mutations, in terms of phenotype and pattern of inheritance, are position independent. 29 refs., 4 figs., 2 tabs.

  15. Biological and phylogenetic characterization of a genotype VII Newcastle disease virus from Venezuela: Efficacy of vaccination

    Science.gov (United States)

    Here we describe the characterization a virulent genotype VII Newcastle disease virus (NDV) from Venezuela and evaluate the efficacy of heterologous genotype commercial vaccination under field and controlled rearing conditions. Biological pathotyping and molecular analysis were applied. Results sh...

  16. Use of recombinant activated factor VII in a case of severe postpartum haemorrhage.

    Science.gov (United States)

    Verre, M; Bossio, F; Mammone, A; Piccirillo, M; Tancioni, F; Varano, M

    2006-02-01

    We describe the case of a 24 year old woman, affected by haemorrhagic shock due to post-partum uterine atony, who underwent an emergency hysterectomy with persistent postoperative bleeding, successfully treated with recombinant activated factor VII (Novoseven).

  17. Viis raamatutäit poola näidendeid / Riina Mägi

    Index Scriptorium Estoniae

    Mägi, Riina, 1957-

    2006-01-01

    Tõlkija Hendrik Lindepuult ilmus viies tõlkekogumik poola dramaturgia tippteoseid tutvustavast sarjast. Seekord said kaante vahele Tadeusz Rozewiczi näidendid "Valge abielu", "Lõks" ja "Vana naine haub"

  18. Spectrophotometry of Symbiotic Stars

    Science.gov (United States)

    Boyd, David

    2017-06-01

    Symbiotic stars are fascinating objects - complex binary systems comprising a cool red giant star and a small hot object, often a white dwarf, both embedded in a nebula formed by a wind from the giant star. UV radiation from the hot star ionises the nebula producing a range of emission lines. These objects have composite spectra with contributions from both stars plus the nebula and these spectra can change on many timescales. Being moderately bright, they lend themselves well to amateur spectroscopy. This paper describes the symbiotic star phenomenon, shows how spectrophotometry can be used to extract astrophysically useful information about the nature of these systems, and gives results for three symbiotic stars based on the author's observations.

  19. Physics of Eclipsing Binaries: Heartbeat Stars and Tidally Induced Pulsations

    Science.gov (United States)

    Hambleton, K.; Degroote, P.; Conroy, K.; Bloemen, S.; Kurtz, D.; Thompson, S. E.; Fuller, J.; Giammarco, J.; Pablo, H.; Prša, A.

    2013-02-01

    Heartbeat stars are a relatively new class of eccentric ellipsoidal variable first discovered by Kepler. An overview of the current field is given with details of some of the interesting objects identified in our current Kepler sample of 135 heartbeats stars. Three objects that have recently been or are undergoing detailed study are described along with suggestions for further avenues of research. We conclude by discussing why heartbeat stars are an interesting new tool to study tidally induced pulsations and orbital dynamics.

  20. Pulsating stars in SuperWASP

    Science.gov (United States)

    Holdsworth, Daniel L.

    2017-09-01

    SuperWASP is one of the largest ground-based surveys for transiting exoplanets. To date, it has observed over 31 million stars. Such an extensive database of time resolved photometry holds the potential for extensive searches of stellar variability, and provide solid candidates for the upcoming TESS mission. Previous work by e.g. [15], [5], [12] has shown that the WASP archive provides a wealth of pulsationally variable stars. In this talk I will provide an overview of the SuperWASP project, present some of the published results from the survey, and some of the on-going work to identify key targets for the TESS mission.

  1. Rapid variability of blazar 3C 279 during flaring states in 2013-2014 with joint FERMI-LAT, NuSTAR, swift, and ground-based multi-wavelength observations

    DEFF Research Database (Denmark)

    Hayashida, M.; Nalewajko, K.; Madejski, G. M.

    2015-01-01

    We report the results of a multiband observing campaign on the famous blazar 3C 279 conducted during a phase of increased activity from 2013 December to 2014 April, including first observations of it with NuSTAR. The γ-ray emission of the source measured by Fermi-LAT showed multiple distinct flar...

  2. Prevalence of collagen VII-specific autoantibodies in patients with autoimmune and inflammatory diseases

    OpenAIRE

    Licarete Emilia; Ganz Susanne; Recknagel Martin J; Di Zenzo Giovanni; Hashimoto Takashi; Hertl Michael; Zambruno Giovanna; Hundorfean Gheorghe; Mudter Jonas; Neurath Markus F; Bruckner-Tuderman Leena; Sitaru Cassian

    2012-01-01

    Abstract Background Autoimmunity to collagen VII is typically associated with the skin blistering disease epidermolysis bullosa acquisita (EBA), but also occurs occasionally in patients with systemic lupus erythematosus or inflammatory bowel disease. The aim of our present study was to develop an accurate immunoassay for assessing the presence of autoantibodies against collagen VII in large cohorts of patients and healthy donors. Methods Based on in silico antigenic analysis and previous wetl...

  3. Histopathologic changes of the ear in canine models of mucopolysaccharidosis types I and VII.

    Science.gov (United States)

    Hordeaux, J; Deniaud, J; Bemelmans, I; Bertrand, L; Moreau, S; Amiaud, J; Wyers, M; Cherel, Y; Colle, M-A

    2011-05-01

    Mucopolysaccharidosis (MPS) types I and VII are inborn errors of metabolism caused by mutation of enzymes involved in glycosaminoglycan catabolism, which leads to intralysosomal accumulation of glycosaminoglycans. In children, severe forms of MPS I and VII are characterized by somatic and neurologic manifestations, including a poorly understood hearing loss. The purpose of this study is to describe the age-related histopathologic changes of the ear in spontaneous canine models of MPS I and VII. Pathologic changes in the ear were assessed in MPS I and VII dogs ranging from 1.6 to 9.3 months of age. Paraffin-embedded sections of the whole ear and Epon-embedded semithin sections of the cochlea were examined. The following lesions were blindly scored in the middle and inner ear: inflammation, cells vacuolization, thickening of osseous and membranous structures, perivascular vacuolated macrophages infiltration, and bone resorption. All dogs had lysosomal storage within cells of tympanic membrane, ossicles, tympanic bone and mucosa, cochlear bone, spiral ligament, limbus, and stria vascularis. The MPS I dogs mainly had progressive cochlear lesions. The MPS VII dogs had severe and early middle ear lesions, including chronic otitis media and bone resorption. The MPS I dog only partially recapitulates the pathology seen in humans; specifically, the dog model lacks inflammatory middle ear disease. In contrast, the MPS VII dog has severe inflammatory middle ear disease similar to that reported in the human. In conclusion, the canine MPS VII model appears to be a good model to study MPS VII-related deafness.

  4. The Trigeminal (V) and Facial (VII) Cranial Nerves: Head and Face Sensation and Movement

    OpenAIRE

    Sanders, Richard D

    2010-01-01

    There are close functional and anatomical relationships between cranial nerves V and VII in both their sensory and motor divisions. Sensation on the face is innervated by the trigeminal nerves (V) as are the muscles of mastication, but the muscles of facial expression are innervated mainly by the facial nerve (VII) as is the sensation of taste. This article briefly reviews the anatomy of these cranial nerves, disorders of these nerves that are of particular importance to psychiatry, and some ...

  5. Massive Star Burps, Then Explodes

    Science.gov (United States)

    2007-04-01

    event was a complete surprise," added Alex Filippenko, leader of the UC Berkeley/Keck supernova group and a member of NASA'S Swift team. "It opens up a fascinating new window on how some kinds of stars die." All the observations suggest that the supernova's blast wave took only a few weeks to reach the shell of material ejected two years earlier, which did not have time to drift very far from the star. As the wave smashed into the ejecta, it heated the gas to millions of degrees, hot enough to emit copious X-rays. The Swift satellite saw the supernova continue to brighten in X-rays for 100 days, something that has never been seen before in a supernova. All supernovae previously observed in X-rays have started off bright and then quickly faded to invisibility. "You don't need a lot of mass in the ejecta to produce a lot of X-rays," notes Immler. Swift's ability to monitor the supernova's X-ray rise and decline over six months was crucial to his team's mass determination. But he adds that Chandra's sharp resolution enabled his group to resolve the supernova from a bright X-ray source that appears in the field of view of Swift's X-ray Telescope. "We could not have made this measurement without Chandra," says Immler, who will submit his team's paper next week to the Astrophysical Journal. "The synergy between Swift's fast response and its ability to observe a supernova every day for a long period, and Chandra's high spatial resolution, is leading to a lot of interesting results." Foley and his colleagues, whose paper appears in the March 10 Astrophysical Journal Letters, propose that the star recently transitioned from a Luminous Blue Variable (LBV) star to a Wolf-Rayet star. An LBV is a massive star in a brief but unstable phase of stellar evolution. Similar to the 2004 eruption, LBVs are prone to blow off large amounts of mass in outbursts so extreme that they are frequently mistaken for supernovae, events dubbed "supernova impostors." Wolf-Rayet stars are hot, highly

  6. Anisotropic models for compact stars

    Energy Technology Data Exchange (ETDEWEB)

    Maurya, S.K.; Dayanandan, Baiju [University of Nizwa, Department of Mathematical and Physical Sciences, College of Arts and Science, Nizwa (Oman); Gupta, Y.K. [Jaypee Institute of Information Technology University, Department of Mathematics, Noida, Uttar Pradesh (India); Ray, Saibal [Government College of Engineering and Ceramic Technology, Department of Physics, Kolkata, West Bengal (India)

    2015-05-15

    In the present paper we obtain an anisotropic analog of the Durgapal and Fuloria (Gen Relativ Gravit 17:671, 1985) perfect fluid solution. The methodology consists of contraction of the anisotropic factor Δ with the help of both metric potentials e{sup ν} and e{sup λ}. Here we consider e{sup λ} the same as Durgapal and Fuloria (Gen Relativ Gravit 17:671, 1985) did, whereas e{sup ν} is as given by Lake (Phys Rev D 67:104015, 2003). The field equations are solved by the change of dependent variable method. The solutions set mathematically thus obtained are compared with the physical properties of some of the compact stars, strange star as well as white dwarf. It is observed that all the expected physical features are available related to the stellar fluid distribution, which clearly indicates the validity of the model. (orig.)

  7. Linear Isentropic Oscillations of Stars Theoretical Foundations

    CERN Document Server

    Smeyers, Paul

    2010-01-01

    The study of stellar oscillations is the preeminent way to investigate the stability of stars and to interpret their variability. The theory of the linear, isentropic oscillations of isolated gaseous stars, and thus of compressible spherically symmetric equilibrium configurations, has largely been developed from the viewpoint of the hypothesis of the physical radial pulsations of stars. Written for doctoral students and researchers, this monograph aims to provide a systematic and consistent survey of the fundamentals of the theory of free, linear, isentropic oscillations in spherically symmetric, gaseous equilibrium stars. The first part of the book presents basic concepts and equations, the distinction between spheroidal and toroidal normal modes, the solution of Poisson’s differential equation for the perturbation of the gravitational potential, and Hamilton’s variational principle. The second part is devoted to the possible existence of waves propagating in the radial direction, the origin and classifi...

  8. GANGGUAN CEMAS PADA MAHASISWA SEMESTER I DAN VII PROGRAM STUDI PENDIDIKAN DOKTER FAKULTAS KEDOKTERAN UNIVERSITAS UDAYANA

    Directory of Open Access Journals (Sweden)

    Dyah Chandratika

    2015-05-01

    Full Text Available Penting untuk dilakukan penelitian mengenai gangguan cemas pada mahasiswa kedokteran karena tingginya tingkat stres mahasiswa terutama pada tahun pertama perkuliahan. Tujuan penelitian ini adalah untuk mengetahui prevalensi dan perbedaan skor  gangguan  cemas  pada mahasiswa  semester  I dan  VII serta untuk  mengetahui perbedaan skor gangguan cemas antara mahasiswa laki-laki dan perempuan di Fakultas Kedokteran Universitas Udayana. Desain penelitian ini adalah cross sectional analitik. Pengambilan sampel dilakukan secara random sampling. Sampel mengisi identitas, kuesioner L-MMPI, kuesioner Hamilton Anxiety Rating Scale (HARS. Kemudian dihitung prevalensi gangguan cemas tiap kelompok serta data dianalisis menggunakan uji t-independen. Terdapat 15 orang (25,0% mahasiswa semester I dan 7 orang (11,7% mahasiswa semester VII yang mengalami gangguan cemas. Dari hasil uji t-independen antara skor gangguan cemas mahasiswa semester I dan VII diperoleh nilai p = 0,001 (<0,05. Sedangkan diperoleh p = 0,080 antara mahasiswa laki-laki dan perempuan pada semester I dan p = 0,744 antara mahasiswa laki-laki dan perempuan pada semester VII. Prevalensi gangguan cemas pada mahasiswa semester I yaitu 25,0% sedangkan 11,7% pada mahasiswa semester VII. Terdapat perbedaan bermakna antara skor gangguan cemas mahasiswa semester I dan VII. Tidak ditemukan perbedaan bermakna skor gangguan cemas antara laki-laki dan perempuan.   

  9. Detection of type VII collagen autoantibodies before onset of bullous systemic lupus erythematosus

    Science.gov (United States)

    Grabell, Daniel A.; Matthews, Loderick A.; Yancey, Kim B.; Chong, Benjamin F.

    2016-01-01

    Importance Anti-type VII collagen autoantibodies are often detectable in patients with bullous systemic lupus erythematosus (BSLE); however their timing of appearance preceding onset of disease is unknown. Observations We report the case of a 50-year-old female with a history of systemic lupus erythematosus who presented with vesicles and bullae around her lips, trunk, axillae, arms, and thighs. Histologic analysis as well as immunofluorescence and immunoblot studies confirmed the diagnosis of BSLE. Immunoblotting and ELISA studies of the patient’s serum obtained three months prior to the onset of BSLE showed presence of anti-type VII collagen autoantibodies. Levels of anti-type VII collagen IgG increased after bullous lesions appeared. Within one month after initiating dapsone and increasing the dose of prednisone, skin lesions promptly resolved. A year after onset of BSLE, her anti-type VII collagen IgG decreased below levels observed prior to the inception of her bullous lesions. Conclusions and Relevance This study shows that anti-type VII collagen autoantibodies can precede the clinical appearance of BSLE. The subsequent increase and decrease in the levels of circulating anti-type VII collagen autoantibodies, which mirrored skin disease activity, support a potential role in their initiation of disease. PMID:25671758

  10. VARIABLES IN GLOBULAR CLUSTER NGC 5024

    Energy Technology Data Exchange (ETDEWEB)

    Safonova, M.; Stalin, C. S., E-mail: rita@iiap.res.in, E-mail: stalin@iiap.res.in [Indian Institute of Astrophysics, Koramangala, Bangalore 560 034 (India)

    2011-12-15

    We present the results of a commissioning campaign to observe Galactic globular clusters for the search of microlensing events. The central 10' Multiplication-Sign 10' region of the globular cluster NGC 5024 was monitored using the 2 m Himalayan Chandra Telescope in R-band for a period of about 8 hr on 2010 March 24. Light curves were obtained for nearly 10,000 stars using a modified Differential Image Analysis technique. We identified all known variables within our field of view and revised the periods and status of some previously reported short-period variables. We report about 70 new variable sources and present their equatorial coordinates, periods, light curves, and possible types. Out of these, 15 are SX Phe stars, 10 are W UMa-type stars, and 14 are probable RR Lyrae stars. Nine of the newly discovered SX Phe stars and one eclipsing binary belong to the blue straggler star population.

  11. Massive Star and Star Cluster Formation

    OpenAIRE

    Tan, Jonathan C.

    2006-01-01

    I review the status of massive star formation theories: accretion from collapsing, massive, turbulent cores; competitive accretion; and stellar collisions. I conclude the observational and theoretical evidence favors the first of these models. I then discuss: the initial conditions of star cluster formation as traced by infrared dark clouds; the cluster formation timescale; and comparison of the initial cluster mass function in different galactic environments.

  12. Star-Branched Polymers (Star Polymers)

    KAUST Repository

    Hirao, Akira

    2015-09-01

    The synthesis of well-defined regular and asymmetric mixed arm (hereinafter miktoarm) star-branched polymers by the living anionic polymerization is reviewed in this chapter. In particular, much attention is being devoted to the synthetic development of miktoarm star polymers since 2000. At the present time, the almost all types of multiarmed and multicomponent miktoarm star polymers have become feasible by using recently developed iterative strategy. For example, the following well-defined stars have been successfully synthesized: 3-arm ABC, 4-arm ABCD, 5-arm ABCDE, 6-arm ABCDEF, 7-arm ABCDEFG, 6-arm ABC, 9-arm ABC, 12-arm ABC, 13-arm ABCD, 9-arm AB, 17-arm AB, 33-arm AB, 7-arm ABC, 15-arm ABCD, and 31-arm ABCDE miktoarm star polymers, most of which are quite new and difficult to synthesize by the end of the 1990s. Several new specialty functional star polymers composed of vinyl polymer segments and rigid rodlike poly(acetylene) arms, helical polypeptide, or helical poly(hexyl isocyanate) arms are introduced.

  13. Dark stars: a review.

    Science.gov (United States)

    Freese, Katherine; Rindler-Daller, Tanja; Spolyar, Douglas; Valluri, Monica

    2016-06-01

    Dark stars are stellar objects made (almost entirely) of hydrogen and helium, but powered by the heat from dark matter annihilation, rather than by fusion. They are in hydrostatic and thermal equilibrium, but with an unusual power source. Weakly interacting massive particles (WIMPs), among the best candidates for dark matter, can be their own antimatter and can annihilate inside the star, thereby providing a heat source. Although dark matter constitutes only [Formula: see text]0.1% of the stellar mass, this amount is sufficient to power the star for millions to billions of years. Thus, the first phase of stellar evolution in the history of the Universe may have been dark stars. We review how dark stars come into existence, how they grow as long as dark matter fuel persists, and their stellar structure and evolution. The studies were done in two different ways, first assuming polytropic interiors and more recently using the MESA stellar evolution code; the basic results are the same. Dark stars are giant, puffy (∼10 AU) and cool (surface temperatures  ∼10 000 K) objects. We follow the evolution of dark stars from their inception at  ∼[Formula: see text] as they accrete mass from their surroundings to become supermassive stars, some even reaching masses  >[Formula: see text] and luminosities  >[Formula: see text], making them detectable with the upcoming James Webb Space Telescope. Once the dark matter runs out and the dark star dies, it may collapse to a black hole; thus dark stars may provide seeds for the supermassive black holes observed throughout the Universe and at early times. Other sites for dark star formation may exist in the Universe today in regions of high dark matter density such as the centers of galaxies. The current review briefly discusses dark stars existing today, but focuses on the early generation of dark stars.

  14. Technetium (VII) fixation in synthetic oxides under aerobic conditions; Fijacion de tecnecio (VII) en oxidos sinteticos en condiciones aerobicas

    Energy Technology Data Exchange (ETDEWEB)

    Arizpe M, L. G. [Instituto Tecnologico de Toluca, Av. Tecnologico s/n, Fraccionamiento La Virgen, 52149 Metepec, Estado de Mexico (Mexico); Badillo A, V. E., E-mail: letygame_06@hotmail.com [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

    2012-10-15

    The retention of fission products as the technetium in different materials to observe the behavior of anionic species, present in the spent fuel, is of vital importance in the evaluation of the safety of a radioactive waste storage. The radionuclide {sup 99}Tc is one of the fission products of long half life of 2.11 X 10{sup 5} years, which could be liberated in the underground waters that surround to a geologic warehouse of high level wastes, in the chemical form TcO{sub 4}{sup -}, which prevails in aerated solutions since is extremely soluble. In this work was evaluated the use of synthetic oxides as potential adsorbents of the radioactive technetium and to study the importance of the superficial properties of these solids in the radionuclide migration. Two synthetic oxides were studied, the titanium and aluminium oxide. The results demonstrate that the retention of Tc (VII) under aerobic conditions of the solution is worthless in the interval of studied ph of 4 at 9 for both solids; however when the ph of the solution diminishes to ph values of 3, important kD are obtained in the case of the titanium oxide, what shows the importance of the surface properties of these oxides to interpret the radionuclide retention. (Author)

  15. Delayed hypertrophic differentiation of epiphyseal chondrocytes contributes to failed secondary ossification in mucopolysaccharidosis VII dogs.

    Science.gov (United States)

    Peck, Sun H; O'Donnell, Philip J M; Kang, Jennifer L; Malhotra, Neil R; Dodge, George R; Pacifici, Maurizio; Shore, Eileen M; Haskins, Mark E; Smith, Lachlan J

    2015-11-01

    Mucopolysaccharidosis (MPS) VII is a lysosomal storage disorder characterized by deficient β-glucuronidase activity, which leads to the accumulation of incompletely degraded glycosaminoglycans (GAGs). MPS VII patients present with severe skeletal abnormalities, which are particularly prevalent in the spine. Incomplete cartilage-to-bone conversion in MPS VII vertebrae during postnatal development is associated with progressive spinal deformity and spinal cord compression. The objectives of this study were to determine the earliest postnatal developmental stage at which vertebral bone disease manifests in MPS VII and to identify the underlying cellular basis of impaired cartilage-to-bone conversion, using the naturally-occurring canine model. Control and MPS VII dogs were euthanized at 9 and 14 days-of-age, and vertebral secondary ossification centers analyzed using micro-computed tomography, histology, qPCR, and protein immunoblotting. Imaging studies and mRNA analysis of bone formation markers established that secondary ossification commences between 9 and 14 days in control animals, but not in MPS VII animals. mRNA analysis of differentiation markers revealed that MPS VII epiphyseal chondrocytes are unable to successfully transition from proliferation to hypertrophy during this critical developmental window. Immunoblotting demonstrated abnormal persistence of Sox9 protein in MPS VII cells between 9 and 14 days-of-age, and biochemical assays revealed abnormally high intra and extracellular GAG content in MPS VII epiphyseal cartilage at as early as 9 days-of-age. In contrast, assessment of vertebral growth plates and primary ossification centers revealed no significant abnormalities at either age. The results of this study establish that failed vertebral bone formation in MPS VII can be traced to the failure of epiphyseal chondrocytes to undergo hypertrophic differentiation at the appropriate developmental stage, and suggest that aberrant processing of Sox9 protein

  16. Isolated Neutron Stars

    Directory of Open Access Journals (Sweden)

    Popov S.

    2010-10-01

    Full Text Available Several aspects related to astrophysics of isolated neutron stars are discussed. We start with an introduction into the “new zoo” of young isolated neutron stars. In addition to classical radio pulsars, now we know several species (soft gamma-ray repeators, anomalous X-ray pulsars, central compact objects in supernova remnants, close-by cooling neutron stars - aka “Magnificent seven”, - RRATs, and some others. All these types are briefly discussed. In the second lecture a description of magneto-rotational evolution of neutron stars is given. Finally, in the third lecture we discuss population synthesis of isolated neutron stars. In some details we discuss population synthesis of young isolated radio pulsars and young close-by cooling neutron stars.

  17. Dietary changes in fasting levels of factor VII coagulant activity (FVII:C) are accompanied by changes in factor VII protein and other vitamin K-dependent proteins

    DEFF Research Database (Denmark)

    Bladbjerg, Else-Marie; Tholstrup, T; Marckmann, P

    1995-01-01

    The mechanisms behind dietary effects on fasting coagulant activity of factor VII (FVII:C) are not clarified. In the present study of 15 young volunteers, two experimental diets differing in composition of saturated fatty acids (C18:0 [diet S] or C12:0 + C14:0 [diet ML]) were served for 3 weeks...

  18. The Theatre of stars

    Science.gov (United States)

    Cavedon, M.; Peri, F.

    Planetariums are special instruments in education and didactics of Astronomy and Astrophysics. Since 1930 the Planetarium of Milan, the most important planetarium in Italy, has played a fundamental role in outreach to the public. Italian tradition always preferred didactics in ``live'' lessons. Now technology expands the potential of the star projector and the theatre of stars is a real window on the universe, where you can travel among the stars and galaxies, to reach the boundaries of space and time.

  19. Why Stars Matter

    OpenAIRE

    Ajay K. Agrawal; John McHale; Alex Oettl

    2014-01-01

    The growing peer effects literature pays particular attention to the role of stars. We decompose the causal effect of hiring a star in terms of the productivity impact on: 1) co-located incumbents and 2) new recruits. Using longitudinal university department-level data we report that hiring a star does not increase overall incumbent productivity, although this aggregate effect hides offsetting effects on related (positive) versus unrelated (negative) colleagues. However, the primary impact co...

  20. Interacting binary stars

    CERN Document Server

    Sahade, Jorge; Ter Haar, D

    1978-01-01

    Interacting Binary Stars deals with the development, ideas, and problems in the study of interacting binary stars. The book consolidates the information that is scattered over many publications and papers and gives an account of important discoveries with relevant historical background. Chapters are devoted to the presentation and discussion of the different facets of the field, such as historical account of the development in the field of study of binary stars; the Roche equipotential surfaces; methods and techniques in space astronomy; and enumeration of binary star systems that are studied

  1. Strange Nonchaotic Stars

    Science.gov (United States)

    Lindner, John F.; Kohar, Vivek; Kia, Behnam; Hippke, Michael; Learned, John G.; Ditto, William L.

    2015-08-01

    Exploiting the unprecedented capabilities of the planet-hunting Kepler space telescope, which stared at 150 000 stars for four years, we discuss recent evidence that certain stars dim and brighten in complex patterns with fractal features. Such stars pulsate at primary and secondary frequencies whose ratios are near the famous golden mean, the most irrational number. A nonlinear system driven by an irrational ratio of frequencies is generically attracted toward a “strange” behavior that is geometrically fractal without displaying the “butterfly effect” of chaos. Strange nonchaotic attractors have been observed in laboratory experiments and have been hypothesized to describe the electrochemical activity of the brain, but a bluish white star 16 000 light years from Earth in the constellation Lyra may manifest, in the scale-free distribution of its minor frequency components, the first strange nonchaotic attractor observed in the wild. The recognition of stellar strange nonchaotic dynamics may improve the classification of these stars and refine the physical modeling of their interiors. We also discuss nonlinear analysis of other RR Lyrae stars in Kepler field of view and discuss some toy models for modeling these stars.References: 1) Hippke, Michael, et al. "Pulsation period variations in the RRc Lyrae star KIC 5520878." The Astrophysical Journal 798.1 (2015): 42.2) Lindner, John F., et al. "Strange nonchaotic stars." Phys. Rev. Lett. 114, 054101 (2015)

  2. Covering tree with stars

    DEFF Research Database (Denmark)

    Baumbach, Jan; Guo, Jian-Ying; Ibragimov, Rashid

    2013-01-01

    We study the tree edit distance problem with edge deletions and edge insertions as edit operations. We reformulate a special case of this problem as Covering Tree with Stars (CTS): given a tree T and a set of stars, can we connect the stars in by adding edges between them such that the resulting...... tree is isomorphic to T? We prove that in the general setting, CST is NP-complete, which implies that the tree edit distance considered here is also NP-hard, even when both input trees having diameters bounded by 10. We also show that, when the number of distinct stars is bounded by a constant k, CTS...

  3. Covering tree with stars

    DEFF Research Database (Denmark)

    Baumbach, Jan; Guo, Jiong; Ibragimov, Rashid

    2015-01-01

    We study the tree edit distance problem with edge deletions and edge insertions as edit operations. We reformulate a special case of this problem as Covering Tree with Stars (CTS): given a tree T and a set of stars, can we connect the stars in by adding edges between them such that the resulting...... tree is isomorphic to T? We prove that in the general setting, CST is NP-complete, which implies that the tree edit distance considered here is also NP-hard, even when both input trees having diameters bounded by 10. We also show that, when the number of distinct stars is bounded by a constant k, CTS...

  4. ENERGY STAR Unit Reports

    Data.gov (United States)

    Department of Housing and Urban Development — These quarterly Federal Fiscal Year performance reports track the ENERGY STAR qualified HOME units that Participating Jurisdictions record in HUD's Integrated...

  5. Providing culturally competent care: residents in HRSA Title VII funded residency programs feel better prepared.

    Science.gov (United States)

    Green, Alexander R; Betancourt, Joseph R; Park, Elyse R; Greer, Joseph A; Donahue, Elizabeth J; Weissman, Joel S

    2008-11-01

    The Health Resources and Services Administration (HRSA) funds primary care residency programs through its Title VII training grants, with a goal of ensuring a well-prepared, culturally competent physician workforce. The authors sought to determine whether primary care residents in Title VII-funded training programs feel better prepared than those in nonfunded programs to provide care to culturally diverse patients. The authors analyzed data from a national mailed survey of senior resident physicians conducted in 2003-2004. Of 1,467 randomly selected family medicine, internal medicine, and pediatrics residents, 866 responded--403 in Title VII-funded programs and 463 in nonfunded programs (response rate = 59%). The survey included 28 Likert-response questions about residents' preparedness and perceived skills to provide cross-cultural care, sociodemographics, and residency characteristics. Residents in Title VII-funded programs were more likely than others to report being prepared to provide cross-cultural care across all 8 measures (odds ratio [OR] = 1.54-2.61, P experience related to cross-cultural care (e.g., role models, cross-cultural training, and attitudes of attending physicians) accounted for many of the differences in self-reported preparedness and skills. Senior residents in HRSA Title VII-funded primary care residency training programs feel better prepared than others to provide culturally competent care. This may be partially explained by better cross-cultural training experiences in HRSA Title VII-funded programs.This article is part of a theme issue of Academic Medicine on the Title VII health professions training programs.

  6. Factor VII R353Q genetic polymorphism is associated with altered warfarin sensitivity among CYP2C9 *1/*1 carriers.

    Science.gov (United States)

    Mlynarsky, Liat; Bejarano-Achache, Idit; Muszkat, Mordechai; Caraco, Yoseph

    2012-05-01

    Warfarin responsiveness is characterized by marked interindividual variability. A major portion of this variability is attributed to CYP2C9 and VKORC1 polymorphisms, but almost 50% is still unaccounted for. This paper reports the first prospective study on the association between factor VII R353Q polymorphism and warfarin responsiveness during induction. Genotyping for factor VII R353Q and 323D/I polymorphisms was performed in a cohort consisting of 374 patients (198 CYP2C9*1/*1) treated with warfarin who were prospectively followed from warfarin initiation. Compared with *1/*1-R/R and *1/*1-R/Q genotype carriers, *1/*1-Q/Q homozygotes achieved higher International Normalized Ratio (INR) values while consuming lower warfarin doses. The greater sensitivity was illustrated by 82.1% higher Warfarin Sensitivity Index During Induction (WSIDI) (0.14 ± 0.11 vs. 0.08 ± 0.50 mg⁻¹ Mann-Whitney, P = 0.043). Multiple regression analysis consisting of both genetic and nongenetic factors explained 26% of WSIDI variability, with R353Q genetic polymorphism having a modest yet significant effect and accounting for 1.7% of the overall variability. Moreover, the incidence of overanticoagulation (i.e., INR > 4) was 6.94-fold higher among *1/*1-Q/Q vs. *1/*1-R/R&R/Q carriers during warfarin induction (Pearson chi-square, P = 0.005). These findings were not accounted for by a chance difference in the distribution of VKORC1 genotypes. Analysis of these parameters among the entire cohort, including CYP2C9*2 and CYP2C9*3 variant allele carriers, did not reach statistical significance. Warfarin responsiveness during induction was unrelated to factor VII 323D/I genetic polymorphism. The response to warfarin during induction is influenced by factor VII R353Q polymorphism. The prospective use of this polymorphism, along with CYP2C9 and VKORC1, may enhance the accuracy of warfarin loading. However, the impact of R353Q polymorphism on overall warfarin response is subtle, and it is therefore

  7. Horizontal Branch stars as AmFm/HgMn stars

    OpenAIRE

    Michaud, G.; Richer, J.

    2008-01-01

    Recent observations and models for horizontal branch stars are briefly described and compared to models for AmFm stars. The limitations of those models are emphasized by a comparison to observations and models for HgMn stars.

  8. Strategi Peningkatan Kualitas Pelayanan Jasa Transportasi Kereta Api (Studi Pada PT. Kereta Api Indonesia (Persero) Dearah Operasi VII Madiun)

    OpenAIRE

    Tri Juliyanto, Ilham

    2015-01-01

    : Quality Improvement Strategy Railway Transportation Services (Studi pada PT. Kereta Api Indonesia (Persero) Daerah Operasi VII Madiun). This research intended to discover the strategic which applied by PT. KAI DAOP VII Madiun for increasing the quality of service in train transportation, supporting factor and inhibiting factor strategic in increase of quality of service of PT. KAI DAOP VII Madiun. In this research, uses descriptive research with qualitative approach and use analysis method ...

  9. How animals follow the stars.

    Science.gov (United States)

    Foster, James J; Smolka, Jochen; Nilsson, Dan-Eric; Dacke, Marie

    2018-01-31

    Throughout history, the stars have provided humans with ever more information about our world, enabling increasingly accurate systems of navigation in addition to fuelling some of the greatest scientific controversies. What information animals have evolved to extract from a starry sky and how they do so, is a topic of study that combines the practical and theoretical challenges faced by both astronomers and field biologists. While a number of animal species have been demonstrated to use the stars as a source of directional information, the strategies that these animals use to convert this complex and variable pattern of dim-light points into a reliable 'stellar orientation' cue have been more difficult to ascertain. In this review, we assess the stars as a visual stimulus that conveys directional information, and compare the bodies of evidence available for the different stellar orientation strategies proposed to date. In this context, we also introduce new technologies that may aid in the study of stellar orientation, and suggest how field experiments may be used to characterize the mechanisms underlying stellar orientation. © 2018 The Author(s).

  10. Circumstellar carbonaceous material associated with late-type dusty WC Wolf-Rayet stars

    NARCIS (Netherlands)

    Chiar, JE; Tielens, AGGM

    2001-01-01

    We have studied the 5-8.5 mum infrared spectra of the late-type Wolf-Rayet stars WR 118, WR 112, and WR 104, the WN star WR 147, the B5 hypergiant Cygnus OB2 No. 12, and the Galactic center luminous blue variable Pistol Star using the Short Wavelength Spectrometer on the Infrared Space Observatory.

  11. Four Star School Awards: Key Factors that Predict High Performance among Indiana School Corporations

    Science.gov (United States)

    Veracco, Lawrence H.

    2009-01-01

    The purpose of this study was to analyze the Four Star status of Indiana school corporations in order to determine if certain variables currently existing among school corporations could be predictive of Four Star status. Differences in Four Star status were examined with respect to school corporation size, school corporation average teacher…

  12. Merging strangeon stars

    Science.gov (United States)

    Lai, Xiao-Yu; Yu, Yun-Wei; Zhou, En-Ping; Li, Yun-Yang; Xu, Ren-Xin

    2018-02-01

    The state of supranuclear matter in compact stars remains puzzling, and it is argued that pulsars could be strangeon stars. What would happen if binary strangeon stars merge? This kind of merger could result in the formation of a hyper-massive strangeon star, accompanied by bursts of gravitational waves and electromagnetic radiation (and even a strangeon kilonova explained in the paper). The tidal polarizability of binary strangeon stars is different from that of binary neutron stars, because a strangeon star is self-bound on the surface by the fundamental strong force while a neutron star by the gravity, and their equations of state are different. Our calculation shows that the tidal polarizability of merging binary strangeon stars is favored by GW170817. Three kinds of kilonovae (i.e., of neutron, quark and strangeon) are discussed, and the light curve of the kilonova AT 2017 gfo following GW170817 could be explained by considering the decaying strangeon nuggets and remnant star spin-down. Additionally, the energy ejected to the fireball around the nascent remnant strangeon star, being manifested as a gamma-ray burst, is calculated. It is found that, after a prompt burst, an X-ray plateau could follow in a timescale of 102 ‑ 103 s. Certainly, the results could be tested also by further observational synergies between gravitational wave detectors (e.g., Advanced LIGO) and X-ray telescopes (e.g., the Chinese HXMT satellite and eXTP mission), and especially if the detected gravitational wave form is checked by peculiar equations of state provided by the numerical relativistical simulation.

  13. Study of star formation in NGC 1084

    Science.gov (United States)

    Ramya, S.; Sahu, D. K.; Prabhu, T. P.

    2007-10-01

    We present UBVRI broad-band, Hα narrow-band photometry of the star-forming complexes in the infrared bright galaxy NGC 1084. Results of medium-resolution spectroscopy of some of the brighter complexes are also discussed. Spectroscopic data are used to better estimate the internal reddening within the galaxy which is found to be highly variable and to calculate metallicity which is close to the solar value. A diagnostic diagram identifies the shocked regions within this galaxy. The narrow-band Hα flux and its equivalent width are used to determine the star formation rates of the complexes and the distribution of ages. Star formation rates for a few of the complexes are found to be as high as 0.5Msolar yr-1. The star-forming complexes lie in the age range 3 to 6.5 Myr. A U - B versus V - I colour-colour mixed population model created using the Starburst99 model colours is used to estimate the ages of the stellar populations present within these regions. Using this technique, it is found that the star formation in NGC 1084 has taken place in a series of short bursts over the last 40 Myr or so. It is proposed that the likely trigger for enhanced star formation is merger with a gas-rich dwarf galaxy.

  14. Learning from Pulsating Stars: Progress over the Last Century (Abstract)

    Science.gov (United States)

    Smith, H.

    2016-12-01

    (Abstract only) Scarcely more than a century has elapsed since it began to be widely accepted that pulsation plays an important role in the variability of stars. During that century pulsating stars have been used as tools to explore a variety of astrophysical questions, including the determination of distances to other galaxies, the testing of timescales of evolution through the HR diagram, and the identification of the ages and star formation histories of stellar populations. Among the significant early milestones along this investigative path are Henrietta Leavitt's discovery of a relation between the periods and luminosities of Cepheids, Harlow Shapley's proposal that all Cepheids are pulsating stars, and Arthur Stanley Eddington's use of the observed period change of d Cephei to constrain its power source. Today our explorations of pulsating stars are bolstered by long observational histories of brighter variables, surveys involving unprecedentedly large numbers of stars, and improved theoretical analyses. This talk will review aspects of the history and our current understanding of pulsating stars, paying particular attention to RR Lyrae, d Scuti, and Cepheid variables. Observations by AAVSO members have provided insight into several questions regarding the behavior of these stars.

  15. Star Trek in the Schools

    Science.gov (United States)

    Journal of Aerospace Education, 1977

    1977-01-01

    Describes specific educational programs for using the Star Trek TV program from kindergarten through college. For each grade level lesson plans, ideas for incorporating Star Trek into future classes, and reports of specific programs utilizing Star Trek are provided. (SL)

  16. Hadrons in compact stars

    Indian Academy of Sciences (India)

    volving Bose–Einstein condensates of antikaons within relativistic models. Also, the structures of non-rotating neutron stars are calculated using this EoS. 2. Hadrons in cold and dense medium. At normal nuclear matter density, neutron star matter mainly consists of neutrons, protons and electrons. The particle population is ...

  17. ENERGY STAR Certified Telephones

    Science.gov (United States)

    Certified models meet all ENERGY STAR requirements as listed in the Version 3.0 ENERGY STAR Program Requirements for Telephony (cordless telephones and VoIP telephones) that are effective as of October 1, 2014. A detailed listing of key efficiency criteria are available at http://www.energystar.gov/index.cfm?c=phones.pr_crit_phones

  18. Science Through ARts (STAR)

    Science.gov (United States)

    Kolecki, Joseph; Petersen, Ruth; Williams, Lawrence

    2002-01-01

    Science Through ARts (STAR) is an educational initiative designed to teach students through a multidisciplinary approach to learning. This presentation describes the STAR pilot project, which will use Mars exploration as the topic to be integrated. Schools from the United Kingdom, Japan, the United States, and possibly eastern Europe are expected to participate in the pilot project.

  19. STAR FORMATION IN TWO LUMINOUS SPIRAL GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Hunter, Deidre A.; Ashburn, Allison; Wright, Teresa [Lowell Observatory, 1400 West Mars Hill Road, Flagstaff, AZ 86001 (United States); Elmegreen, Bruce G. [IBM T. J. Watson Research Center, P.O. Box 218, Yorktown Heights, NY 10598 (United States); Rubin, Vera C. [Carnegie Institution of Washington, 5241 Broad Branch Road NW, Washington, DC 20015 (United States); Józsa, Gyula I. G.; Struve, Christian [ASTRON (Netherlands Organisation for Scientific Research NWO), Oude Hoogeveensedijk 4, 7991-PD Dwingeloo (Netherlands)

    2013-10-01

    We examined star formation in two very luminous (M{sub V} = –22 to –23) Sc-type spiral galaxies, NGC 801 and UGC 2885, using ultra-deep Hα images. We combine these Hα images with UBV and Two-Micron All-Sky Survey JHK images and H I maps to explore the star formation characteristics of disk galaxies at high luminosity. Hα traces star formation in these galaxies to 4-6 disk scale lengths, but the lack of detection of Hα further out is likely due to the loss of Lyman continuum photons. Considering gravitational instabilities alone, we find that the gas and stars in the outer regions are marginally stable in an average sense, but considering dissipative gas and radial and azimuthal forcing, the outer regions are marginally unstable to forming spiral arms. Star formation is taking place in spiral arms, which are regions of locally higher gas densities. Furthermore, we have traced smooth exponential stellar disks over four magnitudes in V-band surface brightness and 4-6 disk scale lengths, in spite of a highly variable gravitational instability parameter. Thus, gravitational instability thresholds do not seem relevant to the stellar disk. One possibility for creating an exponential disk is that the molecular cloud densities and star formation rates have exponential profiles and this fact forces the stellar disk to build up such a profile. Another possibility is that the stellar disk is continuously adjusted to an exponential shape regardless of the star formation profile, for example, through global dynamical processes that scatter stars. However, such scattering processes are only known to operate in spiral systems, in which case they cannot explain the same dilemma of smooth exponential disks observed in dwarf irregular galaxies.

  20. Neutron Stars: Formation and Structure

    OpenAIRE

    Kutschera, Marek

    1998-01-01

    A short introduction is given to astrophysics of neutron stars and to physics of dense matter in neutron stars. Observed properties of astrophysical objects containing neutron stars are discussed. Current scenarios regarding formation and evolution of neutron stars in those objects are presented. Physical principles governing the internal structure of neutron stars are considered with special emphasis on the possible spin ordering in the neutron star matter.

  1. Are Pulsars Bare Strange Stars?

    Science.gov (United States)

    Xu, R. X.; Qiao, G. J.; Zhang, B.

    It is believed that pulsars are neutron stars or strange stars with crusts. However we suggest here that pulsars may be bare strange stars (i.e., strange stars without crust). Due to rapid rotation and strong emission, young strange stars produced in supernova explosions should be bare when they act as radio pulsars. Because of strong magnetic field, two polar-crusts would shield the polar caps of an accreting strange star. Such a suggestion can be checked by further observations.

  2. Magnetic Fields of Massive Stars

    OpenAIRE

    Lundin, Andreas

    2010-01-01

    This paper is an introduction to the subject of magnetic fields on stars, with a focus on hotter stars. Basic astrophysical concepts are explained, including: spectroscopy, stellar classification, general structure and evolution of stars. The Zeeman effect and how absorption line splitting  is used to detect and measure magnetic fields is explained. The properties of a prominent type of magnetic massive star, Ap-stars, are delved into. These stars have very stable, global, roughly dipolar mag...

  3. Technetium (VII) Co-precipitation with Framework Aluminosilicates

    Energy Technology Data Exchange (ETDEWEB)

    Harsh, James B. [Washington State Univ., Pullman, WA (United States); Dickson, Johnbull Otah [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Pierce, Eric M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Bargar, John [SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2015-07-13

    Technetium-99 (99Tc), a long-lived radionuclide, is one of the most widespread contaminants within the Hanford subsurface. At some depths, it is only extractable with strong acids, suggesting incorporation into a solid phase. We hypothesized that Tc may have coprecipitated with feldspathoid aluminosilicates under waste tanks that had leaked caustic solutions into the vadose zone. Our objectives were to determine if Tc could be incorporated into the feldspathoids cancrinite and sodalite and under what conditions coprecipitation could occur. Our hypothesis was that sodalite was more likely to incorporate and retain Tc. Our approach was to use known methods of feldspathoid formation in solutions resembling those in Hanford waste tanks contacting sediments in terms of major ion (Na, NO3, OH, Al(OH)4, and Si(OH)4 concentrations. In some cases, Al and Si were supplied from zeolite. We used perrhenate (ReO4) as a surrogate for pertechnetate (TcO4) to avoid the radioactivity. The major findings of this study were 1) ReO4 could be incorporated into either sodalite or cancrinite but the concentration in the solid was < 1% of the competing ion Cl, NO3, or NO2. 2) The small amount of ReO4 incorporated was not exchangeable with NO3 or NO2. 3) In sodalite, NO3 was highly preferred over ReO4 but significant Re-sodalite was formed when the mole fraction in solution (Re/Re+N) exceeded 0.8. 4) A nonlinear relation between the unit cell parameter and amount of Re incorporated suggested that a separate Re-sodalite phase was formed rather than a solid solution. 5) We determined that sodalite preference for sodalite in the presence of different anions increased with the ionic size of the competing anion: Cl < CO3 < NO3 < SO4 < MnO4 < WO4 and significant incorporation did not occur unless the difference in anion radii was less than 12%. 6) Re(VII) was not significantly reduced to Re(IV) under the conditions of this experiment and Re appeared to be a good surrogate for Tc under oxidizing

  4. Study of Stellar Clusters Containing Massive Stars

    Science.gov (United States)

    Costado, Teresa; Alfaro, E. J.; Delgado, A. J.; Djupvik, A. A.; Maíz Apellániz, J.

    2013-06-01

    Most stars form in clusters, but the percentage of stars born in dense stellar systems is currently matter of controversy and depends very much on the own definition of cluster. The cluster definition and hence the morphologies of individual clusters appear to vary significantly from region to region, as well as with age, which suggests that either, star formation in clusters is not universal and may depend on the local environment, or that all clusters form with the same morphology but early dynamical evolution quickly modifies the structure of the phase space distribution. In addition, young populated clusters containing massive stars are excellent labs for the study of the formation of the massive stellar component of the Galactic disk. Three main scenarios have been proposed for the formation of high-mass stars (M > 7-8 M_{⊙}): a) monolithic collapse of proto-stellar nuclei; b) competitive accretion inside the proto-cluster molecular cloud; and c) coalescence of proto-stellar nuclei and low-mass stars in very dense atmospheres. Both scientific questions: a) cluster formation and b) formation of high mass stars in clusters are intimately connected via the structural description of the phase space distribution of cluster stars and their Mass Function (MF). Models of static clusters with different initial spatial and kinematic distributions show how the spatial distribution dynamically evolves with time, allowing a characterization of their dynamical state from snapshots of their spatial distribution. Four are the main variables (and their distribution with mass and position) needed for a reliable characterization of the cluster dynamical state: a) Mass segregation parameter; b) Mapping of surface density for different ranges of masses; c) Q morphological parameter based on the minimum spanning tree graph and its variation with mass and cluster age, and d) MF of the cluster members. Two years ago, the Stellar System Group of IAA has begun an observational

  5. Rotating stars in relativity.

    Science.gov (United States)

    Paschalidis, Vasileios; Stergioulas, Nikolaos

    2017-01-01

    Rotating relativistic stars have been studied extensively in recent years, both theoretically and observationally, because of the information they might yield about the equation of state of matter at extremely high densities and because they are considered to be promising sources of gravitational waves. The latest theoretical understanding of rotating stars in relativity is reviewed in this updated article. The sections on equilibrium properties and on nonaxisymmetric oscillations and instabilities in f -modes and r -modes have been updated. Several new sections have been added on equilibria in modified theories of gravity, approximate universal relationships, the one-arm spiral instability, on analytic solutions for the exterior spacetime, rotating stars in LMXBs, rotating strange stars, and on rotating stars in numerical relativity including both hydrodynamic and magnetohydrodynamic studies of these objects.

  6. Neutron Stars and Pulsars

    CERN Document Server

    Becker, Werner

    2009-01-01

    Neutron stars are the most compact astronomical objects in the universe which are accessible by direct observation. Studying neutron stars means studying physics in regimes unattainable in any terrestrial laboratory. Understanding their observed complex phenomena requires a wide range of scientific disciplines, including the nuclear and condensed matter physics of very dense matter in neutron star interiors, plasma physics and quantum electrodynamics of magnetospheres, and the relativistic magneto-hydrodynamics of electron-positron pulsar winds interacting with some ambient medium. Not to mention the test bed neutron stars provide for general relativity theories, and their importance as potential sources of gravitational waves. It is this variety of disciplines which, among others, makes neutron star research so fascinating, not only for those who have been working in the field for many years but also for students and young scientists. The aim of this book is to serve as a reference work which not only review...

  7. How Stars Form

    Science.gov (United States)

    McKee, Christopher F.

    2017-01-01

    Stars are the atoms of the universe. The process by which stars form is at the nexus of astrophysics since they are believed to be responsible for the re-ionization of the universe, they created the heavy elements, they play a central role in the formation and evolution of galaxies, and their formation naturally leads to the formation of planets. Whereas early work on star formation was based on the assumption that it is a quiescent process, it is now believed that turbulence plays a dominant role. In this overview, I shall discuss the evolution of our understanding of how stars form and current ideas about the stellar initial mass function and the rate of star formation.

  8. Star spot location estimation using Kalman filter for star tracker.

    Science.gov (United States)

    Liu, Hai-bo; Yang, Jian-kun; Wang, Jiong-qi; Tan, Ji-chun; Li, Xiu-jian

    2011-04-20

    Star pattern recognition and attitude determination accuracy is highly dependent on star spot location accuracy for the star tracker. A star spot location estimation approach with the Kalman filter for a star tracker has been proposed, which consists of three steps. In the proposed approach, the approximate locations of the star spots in successive frames are predicted first; then the measurement star spot locations are achieved by defining a series of small windows around each predictive star spot location. Finally, the star spot locations are updated by the designed Kalman filter. To confirm the proposed star spot location estimation approach, the simulations based on the orbit data of the CHAMP satellite and the real guide star catalog are performed. The simulation results indicate that the proposed approach can filter out noises from the measurements remarkably if the sampling frequency is sufficient. © 2011 Optical Society of America

  9. Recombinant-activated factor VII in patients with uncontrolled bleeding: A retrospective observational analysis

    Directory of Open Access Journals (Sweden)

    Said D Abuhasna

    2012-01-01

    Full Text Available Background: Factor VIIa (recombinant has an off-label use to control life-threatening bleeding that is refractory to other measures and was shown to decrease transfusion requirements. Objective: The primary objective of this study was to assess the safety and effectiveness of factor VIIa (recombinant on blood transfusion requirements and coagulation parameters when used in patients whose bleeding was uncorrected by other means. The pharmacoeconomic impact for any discrepancy from our protocol was evaluated. Secondary outcomes included 4-hour and 28-day mortality, as well as safety of this agent in terms of thromboembolic complications. Materials and Methods: We retrospectively evaluated patients who received recombinant-activated factor VII (rFVIIa for uncontrolled bleeding from June 2008 to April 2011. The medical records of 33 patients were evaluated. Coagulation parameters and blood products were determined 24 hours before and 24 hours after administration of rFVIIa, and the results compared. Patients were also screened for any thromboembolic complications. Results: Administration of rFVIIa reduced blood transfusion requirements and improved coagulation parameters significantly (P<0.05. No thromboembolic complications were reported. Most of the dosing was consistent with those recommended in our institutional protocol, with discrepancies resulting in an average cost of $56 058. Moreover, pH was reported in only 67% of patients. All patients treated with rFVIIa survived up to 4 hours after receiving this agent, while the 28-day mortality was 24% (8/33. Conclusion: The use of rFVIIa appears to be safe and effective in promoting hemostasis, as evident from reducing transfusion requirements and improving the coagulation variables.

  10. Period Changes of 23 Field RR Lyrae Stars

    Directory of Open Access Journals (Sweden)

    Soo-Chang Rey

    1994-12-01

    Full Text Available The secular period behavior of 23 field RR Lyrae stars is studied in order to determine if the observed period changes could be attributed, at least in the mean, to stellar evolution. The sample of stars is subdivided into two Oosterhoff groups based on the metallicity and period-shift. Despite the small sample size, we found a distinct bias toward positive period changes in the group variables. The period changes of the group variables in globular clusters. This provides yet another support for the Lee, Demarque, and Zinn(1990 evolutionary models of RR Lyrae stars and their explanation of the Sandage period-shift effect.

  11. Monte Carlo simulation of star/linear and star/star blends with chemically identical monomers

    Energy Technology Data Exchange (ETDEWEB)

    Theodorakis, P E [Department of Materials Science and Engineering, University of Ioannina, 45110 Ioannina (Greece); Avgeropoulos, A [Department of Materials Science and Engineering, University of Ioannina, 45110 Ioannina (Greece); Freire, J J [Departamento de Ciencias y Tecnicas FisicoquImicas, Universidad Nacional de Educacion a Distancia, Facultad de Ciencias, Senda del Rey 9, 28040 Madrid (Spain); Kosmas, M [Department of Chemistry, University of Ioannina, 45110 Ioannina (Greece); Vlahos, C [Department of Chemistry, University of Ioannina, 45110 Ioannina (Greece)

    2007-11-21

    The effects of chain size and architectural asymmetry on the miscibility of blends with chemically identical monomers, differing only in their molecular weight and architecture, are studied via Monte Carlo simulation by using the bond fluctuation model. Namely, we consider blends composed of linear/linear, star/linear and star/star chains. We found that linear/linear blends are more miscible than the corresponding star/star mixtures. In star/linear blends, the increase in the volume fraction of the star chains increases the miscibility. For both star/linear and star/star blends, the miscibility decreases with the increase in star functionality. When we increase the molecular weight of linear chains of star/linear mixtures the miscibility decreases. Our findings are compared with recent analytical and experimental results.

  12. Star Cluster Structure from Hierarchical Star Formation

    Science.gov (United States)

    Grudic, Michael; Hopkins, Philip; Murray, Norman; Lamberts, Astrid; Guszejnov, David; Schmitz, Denise; Boylan-Kolchin, Michael

    2018-01-01

    Young massive star clusters (YMCs) spanning 104-108 M⊙ in mass generally have similar radial surface density profiles, with an outer power-law index typically between -2 and -3. This similarity suggests that they are shaped by scale-free physics at formation. Recent multi-physics MHD simulations of YMC formation have also produced populations of YMCs with this type of surface density profile, allowing us to narrow down the physics necessary to form a YMC with properties as observed. We show that the shallow density profiles of YMCs are a natural result of phase-space mixing that occurs as they assemble from the clumpy, hierarchically-clustered configuration imprinted by the star formation process. We develop physical intuition for this process via analytic arguments and collisionless N-body experiments, elucidating the connection between star formation physics and star cluster structure. This has implications for the early-time structure and evolution of proto-globular clusters, and prospects for simulating their formation in the FIRE cosmological zoom-in simulations.

  13. Binary stars: Mass transfer and chemical composition

    Science.gov (United States)

    Lambert, D. L.

    1982-01-01

    It is noted that mass exchange (and mass loss) within a binary system should produce observable changes in the surface chemical composition of both the mass losing and mass gaining stars as a stellar interior exposed to nucleosyntheses is uncovered. Three topics relating mass exchange and/or mass loss to nucleosynthesis are sketched: the chemical composition of Algol systems; the accretion disk of a cataclysmic variable fed by mass from a dwarf secondary star; and the hypothesis that classical Ba II giants result from mass transfer from a more evolved companion now present as a white dwarf.

  14. The effect of Simvastatin upon serum pseudocholinesterase and plasmatic factor VII.

    Science.gov (United States)

    Zdrenghea, D; Bodizs, G; Predescu, D; Oprea, M; Zdrenghea, M

    2002-01-01

    The statins have a moderate lowering effect upon triglycerides, one hypothesis suggesting an inhibitory effect upon liver VLDL synthesis. Because VLDL synthesis is related to other hepatic protein synthesis we studied the effect of Simvastatin upon serum cholinesterase activity and factor VII activity, which are also synthetized at hepatic level. 39 patients with ischaemic heart disease, proved by coronarography and moderate hypercholesterolaemia received for two months 20 mg Simvastatin (Zocor). The value of total Co, LDLCo, HDLCo, triglycerides, serum cholinesterase activity and factor VII activity were determined before and after treatment, by standard methods. Triglycerides were, together with total Co, significantly lowered during the two months treatment with Simvastatin, but the values of serum cholinesterase and factor VII activity were not significantly modified. This suggests that moderate doses of Simvastatin do not depress liver protein synthesis. Simvastatin does not lower the triglycerides level through depression of liver protein syntesis, other mechanisms being probably involved.

  15. Cross-reactivity of autoantibodies from patients with epidermolysis bullosa acquisita with murine collagen VII.

    Science.gov (United States)

    Csorba, Kinga; Sesarman, Alina; Oswald, Eva; Feldrihan, Vasile; Fritsch, Anja; Hashimoto, Takashi; Sitaru, Cassian

    2010-04-01

    The pathomechanism of antibody-mediated tissue damage in autoimmune diseases can be best studied in experimental models by passively transferring specific autoantibodies into animals. The reproduction of the disease in animals depends on several factors, including the cross-reactivity of patient autoantibodies with the animal tissue. Here, we show that autoantibodies from patients with epidermolysis bullosa acquisita (EBA), a subepidermal autoimmune blistering disease, recognize multiple epitopes on murine collagen VII. Indirect immunofluorescence microscopy revealed that EBA patients' IgG cross-reacts with mouse skin. Overlapping, recombinant fragments of murine collagen VII were used to characterize the reactivity of EBA sera and to map the epitopes on the murine antigen by ELISA and immunoblotting. The patients' autoantibody binding to murine collagen VII triggered pathogenic events as demonstrated by a complement fixing and an ex vivo granulocyte-dependent dermal-epidermal separation assay. These findings should greatly facilitate the development of improved disease models and novel therapeutic strategies.

  16. Planck early results. VII. The Early Release Compact Source Catalogue

    DEFF Research Database (Denmark)

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

    2011-01-01

    if they meet the high reliability criterion. The Planck ERCSC sources have known associations to stars with dust shells, stellar cores, radio galaxies, blazars, infrared luminous galaxies and Galactic interstellar medium features. A significant fraction of unclassified sources are also present in the catalogs...... the entire sky once and 60% of the sky a second time by Planck, thereby comprising the first high sensitivity radio/submillimetre observations of the entire sky. Four source detection algorithms were run as part of the ERCSC pipeline. A Monte-Carlo algorithm based on the injection and extraction....... In addition, two early release catalogs that contain 915 cold molecular cloud core candidates and 189 SZ cluster candidates that have been generated using multifrequency algorithms are presented. The entire source list, with more than 15 000 unique sources, is ripe for follow-up characterisation with Herschel...

  17. OPTICAL SPECTROSCOPY OF X-RAY-SELECTED YOUNG STARS IN THE CARINA NEBULA

    Energy Technology Data Exchange (ETDEWEB)

    Vaidya, Kaushar [Physics Department, Birla Institute of Technology and Science Pilani, Pilani 333031, Rajasthan (India); Chen, Wen-Ping; Lee, Hsu-Tai [Graduate Institute of Astronomy, National Central University, 300 Zhongda Road, Zhongli 32001, Taiwan (China)

    2015-12-15

    We present low-resolution optical spectra for 29 X-ray sources identified as either massive star candidates or low-mass pre-main-sequence (PMS) star candidates in the clusters Trumpler 16 and Trumpler 14 of the Carina Nebula. Spectra of two more objects (one with an X-ray counterpart, and one with no X-ray counterpart), not originally our targets, but found close (∼3″) to two of our targets, are presented as well. Twenty early-type stars, including an O8 star, seven B1–B2 stars, two B3 stars, a B5 star, and nine emission-line stars, are identified. Eleven T Tauri stars, including eight classical T Tauri stars (CTTSs) and three weak-lined T Tauri stars, are identified. The early-type stars in our sample are more reddened compared to the previously known OB stars of the region. The Chandra hardness ratios of our T Tauri stars are found to be consistent with the Chandra hardness ratios of T Tauri stars of the Orion Nebula Cluster. Most early-type stars are found to be nonvariable in X-ray emission, except the B2 star J104518.81–594217.9, the B3 star J104507.84–594134.0, and the Ae star J104424.76–594555.0, which are possible X-ray variables. J104452.20–594155.1, a CTTS, is among the brightest and the hardest X-ray sources in our sample, appears to be a variable, and shows a strong X-ray flare. The mean optical and near-infrared photometric variability in the V and K{sub s} bands, of all sources, is found to be ∼0.04 and 0.05 mag, respectively. The T Tauri stars show significantly larger mean variation, ∼0.1 mag, in the K{sub s} band. The addition of one O star and seven B1–B2 stars reported here contributes to an 11% increase of the known OB population in the observed field. The 11 T Tauri stars are the first ever confirmed low-mass PMS stars in the Carina Nebula region.

  18. Making star teams out of star players.

    Science.gov (United States)

    Mankins, Michael; Bird, Alan; Root, James

    2013-01-01

    Top talent is an invaluable asset: In highly specialized or creative work, for instance, "A" players are likely to be six times as productive as "B" players. So when your company has a crucial strategic project, why not multiply all that firepower and have a team of your best performers tackle it? Yet many companies hesitate to do this, believing that all-star teams don't work: Big egos will get in the way. The stars won't be able to work with one another. They'll drive the team Leader crazy. Mankins, Bird, and Root of Bain & Company believe it's time to set aside that thinking. They have seen all-star teams do extraordinary work. But there is a right way and a wrong way to organize them. Before you can even begin to assemble such a team, you need to have the right talent management practices, so you hire and develop the best people and know what they're capable of. You have to give the team appropriate incentives and leaders and support staffers who are stars in their own right. And projects that are ill-defined or small scale are not for all-star teams. Use them only for critical missions, and make sure their objectives are clear. Even with the right setup, things can still go wrong. The wise executive will take steps to manage egos, prune non-team-players, and prevent average coworkers from feeling completely undervalued. She will also invest a lot of time in choosing the right team Leader and will ask members for lots of feedback to monitor how that leader is doing.

  19. Massive runaway stars in the Large Magellanic Cloud

    Science.gov (United States)

    Gvaramadze, V. V.; Kroupa, P.; Pflamm-Altenburg, J.

    2010-09-01

    The origin of massive field stars in the Large Magellanic Cloud (LMC) has long been an enigma. The recent measurements of large offsets (˜ 100 km s-1) between the heliocentric radial velocities of some very massive (O2-type) field stars and the systemic LMC velocity provides a possible explanation of this enigma and suggests that the field stars are runaway stars ejected from their birthplaces at the very beginning of their parent cluster's dynamical evolution. A straightforward way to prove this explanation is to measure the proper motions of the field stars and to show that they are moving away from one of the nearby star clusters or OB associations. This approach is, however, complicated by the long distance to the LMC, which makes accurate proper motion measurements difficult. We used an alternative approach for solving the problem (first applied for Galactic field stars), based on the search for bow shocks produced by runaway stars. The geometry of detected bow shocks would allow us to infer the direction of stellar motion, thereby determining their possible parent clusters. In this paper we present the results of a search for bow shocks around six massive field stars that have been proposed as candidate runaway stars. Using archival Spitzer Space Telescope data, we found a bow shock associated with one of our programme stars, the O2 V((f*)) star BI 237, which is the first-ever detection of bow shocks in the LMC. Orientation of the bow shock suggests that BI 237 was ejected from the OB association LH 82 (located at ≃ 120 pc in projection from the star). A by-product of our search is the detection of bow shocks generated by four OB stars in the field of the LMC and an arc-like structure attached to the candidate luminous blue variable R81 (HD 269128). The geometry of two of these bow shocks is consistent with the possibility that their associated stars were ejected from the 30 Doradus star-forming complex. We discuss implications of our findings for the

  20. Pseudosynchronization of Heartbeat Stars

    Science.gov (United States)

    Zimmerman, Mara; Thompson, Susan E.; Hambleton, Kelly; Fuller, Jim; Shporer, Avi; Isaacson, Howard T.; Howard, Andrew; Kurtz, Donald

    2016-01-01

    A type of eccentric binary star that undergoes extreme dynamic tidal forces, known as Heartbeat stars, were discovered by the Kepler Mission. As the two stars pass through periastron, the tidal distortion causes unique brightness variations. Short period, eccentric binary stars, like these, are theorized to pseudosynchronize, or reach a rotational frequency that matches the weighted average orbital angular velocity of the system. This pseudosynchronous rate, as predicted by Hut (1981), depends on the binary's orbital period and eccentricity. We tested whether sixteen heartbeat stars have pseudosynchronized. We measure the rotation rate from obvious spot signatures in the light curve. We measure the eccentricity by fitting the light curve using PHOEBE and are actively carrying out a radial velocity monitoring program with Keck/HIRES in order to improve these orbital parameters. Our initial results show that while most heartbeat stars appear to have pseudosynchronized we find stars with rotation frequencies both longer and shorter than this rate. We thank the SETI Institute REU program, the NSF, and the Kepler Guest Observer Program for making this work possible.

  1. Dense Axion Stars.

    Science.gov (United States)

    Braaten, Eric; Mohapatra, Abhishek; Zhang, Hong

    2016-09-16

    If the dark matter particles are axions, gravity can cause them to coalesce into axion stars, which are stable gravitationally bound systems of axions. In the previously known solutions for axion stars, gravity and the attractive force between pairs of axions are balanced by the kinetic pressure. The mass of these dilute axion stars cannot exceed a critical mass, which is about 10^{-14}M_{⊙} if the axion mass is 10^{-4}  eV. We study axion stars using a simple approximation to the effective potential of the nonrelativistic effective field theory for axions. We find a new branch of dense axion stars in which gravity is balanced by the mean-field pressure of the axion Bose-Einstein condensate. The mass on this branch ranges from about 10^{-20}M_{⊙} to about M_{⊙}. If a dilute axion star with the critical mass accretes additional axions and collapses, it could produce a bosenova, leaving a dense axion star as the remnant.

  2. Cooling of Neutron Stars

    Directory of Open Access Journals (Sweden)

    Grigorian H.

    2010-10-01

    Full Text Available We introduce the theoretical basis for modeling the cooling evolution of compact stars starting from Boltzmann equations in curved space-time. We open a discussion on observational verification of different neutron star models by consistent statistics. Particular interest has the question of existence of quark matter deep inside of compact object, which has to have a specific influence on the cooling history of the star. Besides of consideration of several constraints and features of cooling evolution, which are susceptible of being critical for internal structure of hot compact stars we have introduced a method of extraction of the mass distribution of the neutron stars from temperature and age data. The resulting mass distribution has been compared with the one suggested by supernove simulations. This method can be considered as an additional checking tool for the consistency of theoretical modeling of neutron stars. We conclude that the cooling data allowed existence of neutron stars with quark cores even with one-flavor quark matter.

  3. Wavelengths and energy levels of Xe VII and Xe VIII obtained by collision-based spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Larsson, M.O. [Uppsala Univ. (Sweden). Dept. of Theoretical Physics; Gonzalez, A.M. [Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas (CIEMAT), Madrid (Spain). Inst. de Investigacion Basica; Hallin, R. [Uppsala Univ. (Sweden). Dept. of Theoretical Physics; Heijkenskjoeld, F. [Uppsala Univ. (Sweden). Dept. of Theoretical Physics; Hutton, R. [Lund Univ. (Sweden). Dept. of Physics; Langereis, A. [Uppsala Univ. (Sweden). Dept. of Theoretical Physics; Nystroem, B. [Lund Univ. (Sweden). Dept. of Physics; O`Sullivan, G. [University Coll., Dublin (Ireland). Dept. of Physics; Waennstroem, A. [Uppsala Univ. (Sweden). Dept. of Theoretical Physics

    1995-01-01

    The Xe VII and Xe VIII spectra have been investigated by collision-based spectroscopy. The radiation emitted following electron capture by 10q keV Xe{sup q+} ions (q = 6-8) impinging on a He (Ar) gas target has, with some exceptions, been recorded in the 350-8000 (1200-2500) A wavelength region. The xenon ions were provided by the Uppsala University ECR ion source. Many of the observed, previously unreported spectral lines have been identified. In total, nine new energy levels of Xe VII and Xe VIII have been established, of which two are tentative. The analysis was supported by Hartree-Fock calculations. (orig.).

  4. Dove sta andando l'analisi musicale? Riflessioni sul VII EuroMac

    Directory of Open Access Journals (Sweden)

    Mario Baroni

    2014-01-01

    Full Text Available Come tutti i lettori della Rivista ormai sapranno, si è svolto a Roma dal 29 settembre al 2 ottobre di quest’anno, presso il Conservatorio di S. Cecilia, il settimo convegno europeo di analisi musicale (VII European Music Analysis Conference ossia VII EuroMac. Nel convegno, organizzato dal GATM e diretto da Giorgio Sanguinetti, sono state presentate 197 relazioni e svolti otto laboratori. Tutti i materiali sono stati riassunti in un volume (Programme and Abstract Book, Iter Edizioni di Subiaco curato da Egidio Pozzi e Antonio Cascelli.

  5. Entropy Production of Stars

    Directory of Open Access Journals (Sweden)

    Leonid M. Martyushev

    2015-06-01

    Full Text Available The entropy production (inside the volume bounded by a photosphere of main-sequence stars, subgiants, giants, and supergiants is calculated based on B–V photometry data. A non-linear inverse relationship of thermodynamic fluxes and forces as well as an almost constant specific (per volume entropy production of main-sequence stars (for 95% of stars, this quantity lies within 0.5 to 2.2 of the corresponding solar magnitude is found. The obtained results are discussed from the perspective of known extreme principles related to entropy production.

  6. Hyperons in neutron stars

    Directory of Open Access Journals (Sweden)

    Tetsuya Katayama

    2015-07-01

    Full Text Available Using the Dirac–Brueckner–Hartree–Fock approach, the properties of neutron-star matter including hyperons are investigated. In the calculation, we consider both time and space components of the vector self-energies of baryons as well as the scalar ones. Furthermore, the effect of negative-energy states of baryons is partly taken into account. We obtain the maximum neutron-star mass of 2.08M⊙, which is consistent with the recently observed, massive neutron stars. We discuss a universal, repulsive three-body force for hyperons in matter.

  7. Infrared spectroscopy of stars

    Science.gov (United States)

    Merrill, K. M.; Ridgway, S. T.

    1979-01-01

    This paper reviews applications of IR techniques in stellar classification, studies of stellar photospheres, elemental and isotopic abundances, and the nature of remnant and ejected matter in near-circumstellar regions. Qualitative IR spectral classification of cool and hot stars is discussed, along with IR spectra of peculiar composite star systems and of obscured stars, and IR characteristics of stellar populations. The use of IR spectroscopy in theoretical modeling of stellar atmospheres is examined, IR indicators of stellar atmospheric composition are described, and contributions of IR spectroscopy to the study of stellar recycling of interstellar matter are summarized. The future of IR astronomy is also considered.

  8. Pulsating stars in ω Centauri. Near-IR properties and period-luminosity relations

    Directory of Open Access Journals (Sweden)

    Navarrete Camila

    2017-01-01

    Full Text Available ω Centauri (NGC 5139 contains many variable stars of different types, including the pulsating type II Cepheids, RR Lyrae and SX Phoenicis stars. We carried out a deep, wide-field, near-infrared (IR variability survey of ω Cen, using the VISTA telescope. We assembled an unprecedented homogeneous and complete J and KS near-IR catalog of variable stars in the field of ω Cen. In this paper we compare optical and near-IR light curves of RR Lyrae stars, emphasizing the main differences. Moreover, we discuss the ability of near-IR observations to detect SX Phoenicis stars given the fact that the amplitudes are much smaller in these bands compared to the optical. Finally, we consider the case in which all the pulsating stars in the three different variability types follow a single period-luminosity relation in the near-IR bands.

  9. Contact activation and factor VII after the use of an activated prothrombin complex concentrate (FEIBA) in hemophiliacs with inhibitors.

    Science.gov (United States)

    Mariani, G; Bouma, B N; Mazzucconi, M G; Avvisati, G; Di Nucci, G D; Corrao, D; Mandelli, F

    1983-08-01

    Administration of a brand of activated prothrombin complex concentrate (FEIBA) to hemophiliacs with high-titre inhibitor to factor VIII, induced a shortening of the prothrombin time and thrombotest clotting time. This effect stems partly from the presence in the concentrate of high amounts of activated factor VII (alpha-VII a) which indeed after the infusion, were detected in the plasma of Hemophiliacs. The attained levels of factor alpha-VII a were shown to be proportional to the dose of concentrate administered. This form of activated factor VII was not generated as a result of activation of the contact activation mechanism, since after the infusion of the concentrate no changes were detected in the components of this system. The infused factor VII was indeed present in an activated form and this was further substantiated by the infusion of the concentrate in factor VII deficient patients. These observations suggest that factor alpha-VII a is not generated in vivo and thus is of exogenous origin. The clinical effect may well be due to the presence of this form of activated factor VII; in this context the alternative pathway involving factors IX and X should be implicated.

  10. 40 CFR Appendix Vii to Part 266 - Health-Based Limits for Exclusion of Waste-Derived Residues*

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 26 2010-07-01 2010-07-01 false Health-Based Limits for Exclusion of Waste-Derived Residues* VII Appendix VII to Part 266 Protection of Environment ENVIRONMENTAL PROTECTION...-Based Limits for Exclusion of Waste-Derived Residues* Metals—TCLP Extract Concentration Limits...

  11. Dietary effects on coagulation factor VII vary across genotypes of the R/Q353 polymorphism in elderly people

    NARCIS (Netherlands)

    Mennen, L.I.; Maat, M.P.M. de; Schouten, E.G.; Kluft, C.; Witteman, J.C.M.; Hofman, A.; Grobbee, D.E.

    1998-01-01

    The objective of this study was to evaluate the association of factor VII with dietary factors while also considering the R/Q353 polymorphism. Nutrition is an important determinant of coagulation factor VII, which is also genetically determined by the R/Q353 polymorphism. High levels of coagulation

  12. ESEA Title VII Bilingual/Bicultural Education Program; Programa de Educacion Bilingue/Bicultural 1975-1976.

    Science.gov (United States)

    Milwaukee Public Schools, WI. Dept. of Educational Research and Program Assessment.

    This is the annual evaluation report of the Title VII components of the Milwaukee Bilingual/Bicultural Education Program funded by Title I and Title VII of the Elementary and Secondary Education Act of 1967 and the Milwaukee Public Schools. The results of the 1975-76 assessment of pupil progress toward achievement of the program's academic and…

  13. Effects of different progestin regimens in hormone replacement therapy on blood coagulation factor VII and tissue factor pathway inhibitor

    DEFF Research Database (Denmark)

    Bladbjerg, E-M; Skouby, S O.; Andersen, L F

    2002-01-01

    BACKGROUND: Long-term hormone replacement therapy (HRT) reduces cardiovascular risk, but an early increased risk was reported in women with coronary heart disease. In such women the arterial intima can express tissue factor, and changes in coagulation factor VII (factor VII) and tissue factor...

  14. Periodic Variations in DQ Herculis Stars - CYC2HIGH

    Science.gov (United States)

    Bless, Robert

    1992-06-01

    The DQ Herculis Stars are cataclysmic variables showing rapid, strictly periodic luminosity variations at either optical or X-ray wavelengths, and usually both. The periods range from 33 sec in AE AQR through 71 sec in DQ Her to 18690 sec in TV Col. The cataclysmic variables are all close binary stars consisting of a late-type star transferring mass to its companion white dwarf star. The white dwarf in the DQ Her stars is magnetized. The periodicities of the DQ Her stars are caused by rotation of the magnetized, acreting white dwarf. We propose to observe the DQ Her stars at ultraviolet wavelengths using the high speed photometer on the space telescope. The purpose of the observations is to investigate the physics of accretion onto compact stars. Revision History: Received on RPS 9/1/89; Added to SCCS 9/5/89 RPSS V7.2 remote & local; Typos corrected; Added data-fmt - SALM 9/7/89 Updated text - SALM 9/28/89; Moved 5 targ to cycle 2 - SALM 2/12/90 Switched 1 targ in cycles 1 & 2 - SALM

  15. Observational Effects of Strange Stars

    OpenAIRE

    Lu, T.

    1998-01-01

    In this talk, after briefly reviewing some historical remarks concerning strange stars, the achievements in physics and dynamical behavior of strange stars are discussed. Especially, various observational effects in distinguishing strange stars from neutron stars such as mechanical effects, cooling effects, phase transition and related interesting phenomena are stressed.

  16. Short-Period Binary Stars: Observations, Analyses, and Results

    CERN Document Server

    Milone, Eugene F; Hobill, David W

    2008-01-01

    Short-period binaries run the gamut from widely separated stars to black-hole pairs; in between are systems that include neutron stars and white dwarfs, and partially evolved systems such as tidally distorted and over-contact systems. These objects represent stages of evolution of binary stars, and their degrees of separation provide critical clues to how their evolutionary paths differ from that of single stars. The widest and least distorted systems provide astronomers with the essential precise data needed to study all stars: mass and radius. The interactions of binary star components, on the other hand, provide a natural laboratory to observe how the matter in these stars behaves under different and often varying physical conditions. Thus, cataclysmic variables with and without overpoweringly strong magnetic fields, and stars with densities from that found in the Sun to the degenerate matter of white dwarfs and the ultra-compact states of neutron stars and black holes are all discussed. The extensive inde...

  17. Antimicrobial peptide scolopendrasin VII, derived from the centipede Scolopendra subspinipes mutilans, stimulates macrophage chemotaxis via formyl peptide receptor 1.

    Science.gov (United States)

    Park, Yoo Jung; Lee, Ha Young; Jung, Young Su; Park, Joon Seong; Hwang, Jae Sam; Bae, Yoe-Sik

    2015-08-01

    In this study, we report that one of the antimicrobial peptides scolopendrasin VII, derived from Scolopendra subspinipes mutilans, stimulates actin polymerization and the subsequent chemotactic migration of macrophages through the activation of ERK and protein kinase B (Akt) activity. The scolopendrasin VII-induced chemotactic migration of macrophages is inhibited by the formyl peptide receptor 1 (FPR1) antagonist cyclosporine H. We also found that scolopendrasin VII stimulate the chemotactic migration of FPR1-transfected RBL-2H3 cells, but not that of vector-transfected cells; moreover, scolopendrasin VII directly binds to FPR1. Our findings therefore suggest that the antimicrobial peptide scolopendrasin VII, derived from Scolopendra subspinipes mutilans, stimulates macrophages, resulting in chemotactic migration via FPR1 signaling, and the peptide can be useful in the study of FPR1-related biological responses.

  18. Interferometric star tracker Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Optical Physics Company (OPC) proposes to develop a high accuracy version of its interferometric star tracker capable of meeting the milli-arcsecond-level pointing...

  19. Principles of star formation

    CERN Document Server

    Bodenheimer, Peter H

    2011-01-01

    Understanding star formation is one of the key fields in present-day astrophysics. This book treats a wide variety of the physical processes involved, as well as the main observational discoveries, with key points being discussed in detail. The current star formation in our galaxy is emphasized, because the most detailed observations are available for this case. The book presents a comparison of the various scenarios for star formation, discusses the basic physics underlying each one, and follows in detail the history of a star from its initial state in the interstellar gas to its becoming a condensed object in equilibrium. Both theoretical and observational evidence to support the validity of the general evolutionary path are presented, and methods for comparing the two are emphasized. The author is a recognized expert in calculations of the evolution of protostars, the structure and evolution of disks, and stellar evolution in general. This book will be of value to graduate students in astronomy and astroph...

  20. Sounds of a Star

    Science.gov (United States)

    2001-06-01

    Acoustic Oscillations in Solar-Twin "Alpha Cen A" Observed from La Silla by Swiss Team Summary Sound waves running through a star can help astronomers reveal its inner properties. This particular branch of modern astrophysics is known as "asteroseismology" . In the case of our Sun, the brightest star in the sky, such waves have been observed since some time, and have greatly improved our knowledge about what is going on inside. However, because they are much fainter, it has turned out to be very difficult to detect similar waves in other stars. Nevertheless, tiny oscillations in a solar-twin star have now been unambiguously detected by Swiss astronomers François Bouchy and Fabien Carrier from the Geneva Observatory, using the CORALIE spectrometer on the Swiss 1.2-m Leonard Euler telescope at the ESO La Silla Observatory. This telescope is mostly used for discovering exoplanets (see ESO PR 07/01 ). The star Alpha Centauri A is the nearest star visible to the naked eye, at a distance of a little more than 4 light-years. The new measurements show that it pulsates with a 7-minute cycle, very similar to what is observed in the Sun . Asteroseismology for Sun-like stars is likely to become an important probe of stellar theory in the near future. The state-of-the-art HARPS spectrograph , to be mounted on the ESO 3.6-m telescope at La Silla, will be able to search for oscillations in stars that are 100 times fainter than those for which such demanding observations are possible with CORALIE. PR Photo 23a/01 : Oscillations in a solar-like star (schematic picture). PR Photo 23b/01 : Acoustic spectrum of Alpha Centauri A , as observed with CORALIE. Asteroseismology: listening to the stars ESO PR Photo 23a/01 ESO PR Photo 23a/01 [Preview - JPEG: 357 x 400 pix - 96k] [Normal - JPEG: 713 x 800 pix - 256k] [HiRes - JPEG: 2673 x 3000 pix - 2.1Mb Caption : PR Photo 23a/01 is a graphical representation of resonating acoustic waves in the interior of a solar-like star. Red and blue

  1. Catch a Star 2008!

    Science.gov (United States)

    2007-10-01

    ESO and the European Association for Astronomy Education have just launched the 2008 edition of 'Catch a Star', their international astronomy competition for school students. Now in its sixth year, the competition offers students the chance to win a once-in-a-lifetime trip to ESO's flagship observatory in Chile, as well as many other prizes. CAS logo The competition includes separate categories - 'Catch a Star Researchers' and 'Catch a Star Adventurers' - to ensure that every student, whatever their level, has the chance to enter and win exciting prizes. In teams, students investigate an astronomical topic of their choice and write a report about it. An important part of the project for 'Catch a Star Researchers' is to think about how ESO's telescopes such as the Very Large Telescope (VLT) or future telescopes such as the Atacama Large Millimeter/submillimeter Array (ALMA) and the European Extremely Large Telescope (E-ELT) could contribute to investigations of the topic. Students may also include practical activities such as observations or experiments. For the artistically minded, 'Catch a Star' also offers an artwork competition, 'Catch a Star Artists'. Last year, hundreds of students from across Europe and beyond took part in 'Catch a Star', submitting astronomical projects and artwork. "'Catch a Star' gets students thinking about the wonders of the Universe and the science of astronomy, with a chance of winning great prizes. It's easy to take part, whether by writing about astronomy or creating astronomically inspired artwork," said Douglas Pierce-Price, Education Officer at ESO. As well as the top prize - a trip to ESO's Very Large Telescope in Chile - visits to observatories in Austria and Spain, and many other prizes, can also be won. 'Catch a Star Researchers' winners will be chosen by an international jury, and 'Catch a Star Adventurers' will be awarded further prizes by lottery. Entries for 'Catch a Star Artists' will be displayed on the web and winners

  2. STAR: Copperhead interface

    OpenAIRE

    Cahill, Thomas Everett

    1981-01-01

    Approved for public release; distribution is unlimited This thesis provides the general design logic for a computer representation of the Field Artillery's precision guided munition- Copperhead. The design has been specifically structured to enable its integration into the Simulation of Tactical Alternative Responses (STAR) model. (STAR is a stochastic force-on-force combat simulation.) Routines and events are developed which portray the target identification, target selection, firing a...

  3. Characterizing bursty star formation

    Science.gov (United States)

    Emami, Najmeh

    2018-01-01

    An ongoing area of research in galaxy evolution is the efficiency of star formation as a function of galaxy halo mass. At low mass, it is believed that supernova feedback can expel gas from the galaxy and shut down star formation. However, there are still significant uncertainties in how the momentum/energy of the supernova couple with the gas and the efficiency with which it drives winds. Particularly uncertain are the parameters of the resulting bursts of star formation —amplitudes, durations, and periods — with important implications for interpreting observations of dwarf galaxies. Some hydrodynamical simulations predict order of magnitude bursts (and quenching) on very short (indicators of dwarf galaxies (H-alpha and ultraviolet luminosities) that trace star formation on different time scales (~5 Myr and ~20 Myr, respectively), as well as their relation to the average galaxies of similar stellar mass, to better constrain the parameters of the star formation bursts. We find that the burst amplitude increases with decreasing stellar mass, with amplitudes ranging two orders of magnitude at stellar masses of 10^7. We also find that the star formation is quenched very rapidly, with e-folding times less than 10 Myr in galaxies with stellar masses less than 10^(7.5). We conclude by comparing our results to recent hydrodynamical simulations and discussing the effects of stochastic sampling of the stellar initial mass function.

  4. NuSTAR discovery of a luminosity dependent cyclotron line energy in Vela X-1

    DEFF Research Database (Denmark)

    Fuerst, Felix; Pottschmidt, Katja; Wilms, Joern

    2014-01-01

    We present NuSTAR observations of Vela X-1, a persistent, yet highly variable, neutron star high-mass X-ray binary (HMXB). Two observations were taken at similar orbital phases but separated by nearly a year. They show very different 3-79 keV flux levels as well as strong variability during each...

  5. Collapsing Enormous Stars

    Science.gov (United States)

    Kohler, Susanna

    2015-09-01

    One of the big puzzles in astrophysics is how supermassive black holes (SMBHs) managed to grow to the large sizes weve observed in the very early universe. In a recent study, a team of researchers examines the possibility that they were formed by the direct collapse of supermassive stars.Formation MysterySMBHs billions of times as massive as the Sun have been observed at a time when the universe was less than a billion years old. But thats not enough time for a stellar-mass black hole to grow to SMBH-size by accreting material so another theory is needed to explain the presence of these monsters so early in the universes history. A new study, led by Tatsuya Matsumoto (Kyoto University, Japan), poses the following question: what if supermassive stars in the early universe collapsed directly into black holes?Previous studies of star formation in the early universe have suggested that, in the hot environment of these primordial times, stars might have been able to build up mass much faster than they can today. This could result in early supermassive stars roughly 100,000 times more massive than the Sun. But if these early stars end their lives by collapsing to become massive black holes in the same way that we believe massive stars can collapse to form stellar-mass black holes today this should result in enormously violent explosions. Matusmoto and collaborators set out to model this process, to determine what we would expect to see when it happens!Energetic BurstsThe authors modeled the supermassive stars prior to collapse and then calculated whether a jet, created as the black hole grows at the center of the collapsing star, would be able to punch out of the stellar envelope. They demonstrated that the process would work much like the widely-accepted collapsar model of massive-star death, in which a jet successfully punches out of a collapsing star, violently releasing energy in the form of a long gamma-ray burst (GRB).Because the length of a long GRB is thought to

  6. Coexistence of Factor VII Deficiency and Hereditary Spastic Paraplegia in Two Siblings

    Directory of Open Access Journals (Sweden)

    Hortensia De la Corte-Rodriguez

    2016-01-01

    Full Text Available We present the case of two patients aged 12 years and 7 years who were referred to our hospital for factor VII deficiency inherited in an autosomal recessive pattern, who had suffered from previous multiple joint haemarthroses. They presented with fine motor symptoms and difficulty in walking. During physical examination we observed neurological symptoms (general hypotonia, muscular hypotrophy, exaggerated tendon reflexes, pes cavus, and spastic gait. Given that the symptoms were not justified by the deficiency of coagulation factor VII and on suspicion of hereditary spastic paraplegia (HSP, tests were carried out. Findings from the tests confirmed the diagnosis of HSP (axonal degeneration of the central motor pathway and pyramidal tracts, further complicated by mixed neuropathy. This disease was also inherited in an autosomal recessive pattern with no direct genetic association with factor VII deficiency. Neurological symptoms had gone unnoticed due to a history of multiple joint haemarthrosis; musculoskeletal examination led to a satisfactory differential diagnosis. Haematological prophylaxis was commenced with rFVIIa at 30 mcg/kg, three days per week. A rehabilitation programme was prescribed so that the patient could remain independent for as long as possible, based on orthosis, physiotherapy, and occupational therapy. Response to treatment is currently satisfactory and no new bleeding has presented. As far as we are aware, the coexistence of these two diseases (factor VII deficiency and HSP has not been previously reported in the literature.

  7. Contribution of coagulation factor VII R353Q polymorphism to the ...

    African Journals Online (AJOL)

    Hanan Azzam

    2016-12-05

    Dec 5, 2016 ... a b s t r a c t. Background: Elevated factor VII (FVII) level is a risk factor for thromboembolic disorders. It was reported that the FVII R353Q polymorphism is associated with variation in plasma FVII levels, where Q allele car- ..... and von Willebrand factor: the CHARGE (Cohorts for Heart and Aging Research.

  8. PENGARUH KUALITAS SISTEM DAN INFORMASI TERHADAP KEPUASAN PEMAKAI SISTEM ERP PADA PT TELKOM DIVRE VII MAKASSAR

    OpenAIRE

    ARRESKI, DWI FITRA

    2014-01-01

    2014 Penelitian ini bertujuan untuk menganalisis pengaruh kualitas sistem dan informasi terhadap kepuasan pemakai sistem ERP pada PT Telkom Divre VII Makassar. Pengumpulan data dilakukan dengan menggunakan kuesioner yang diberikan kepada 132 responden sebagai pengguna sistem ERP. Data diolah dengan menggunakan analisis regresi berganda. Temuan penelitian menunjukkan bahwa kualitas sistem memiliki pengaruh positif terhadap ...

  9. Strangers No More: All Workers are Entitled to "Just Cause" Protection under Title VII.

    Science.gov (United States)

    Blumrosen, Alfred W.

    1978-01-01

    Examines the work of administrative agencies and courts in processing discrimination claims under Title VII (equal employment opportunity) of the Civil Rights Act of 1964, concluding that the common law rule of employer discretion has been superseded by the principle of just cause in personnel decisions. (MF)

  10. Factor VII-activating protease : Unraveling the release and regulation of dead cell nuclear damps

    NARCIS (Netherlands)

    Marsman, G.

    2017-01-01

    Upon inflammation, uncleared dying cells are an important source of pro-inflammatory damage-associated molecular patterns (DAMPs). Major DAMPs are histones and double-stranded DNA, which together form chromatin. Factor VII-activating protease (FSAP) is activated upon contact with dead cells, and its

  11. Presidendi teenetemärgi pälvis viis spordiinimest

    Index Scriptorium Estoniae

    2008-01-01

    Vt. ka Linnaleht : Tartu 7. veebr., lk. 7. Eesti riigile osutatud teenete eest pälvisid president Toomas Hendrik Ilveselt teenetemärgi viis spordieluga seotud inimest: jalgpallikoondise ekstreenerid Jelle Goes ja Arno Pijpers, kergejõustikutreener Vésteinn Hafsteinsson, sõudetreener Tatjana Jaanson ning spordielu edendaja Nora Kutti. Juuresoleval fotol Jelle Goes

  12. Investigating the air oxidation of V(II) ions in a vanadium redox flow battery

    Science.gov (United States)

    Ngamsai, Kittima; Arpornwichanop, Amornchai

    2015-11-01

    The air oxidation of vanadium (V(II)) ions in a negative electrolyte reservoir is a major side reaction in a vanadium redox flow battery (VRB), which leads to electrolyte imbalance and self-discharge of the system during long-term operation. In this study, an 80% charged negative electrolyte solution is employed to investigate the mechanism and influential factors of the reaction in a negative-electrolyte reservoir. The results show that the air oxidation of V(II) ions occurs at the air-electrolyte solution interface area and leads to a concentration gradient of vanadium ions in the electrolyte solution and to the diffusion of V(II) and V(III) ions. The effect of the ratio of the electrolyte volume to the air-electrolyte solution interface area and the concentrations of vanadium and sulfuric acid in an electrolyte solution is investigated. A higher ratio of electrolyte volume to the air-electrolyte solution interface area results in a slower oxidation reaction rate. The high concentrations of vanadium and sulfuric acid solution also retard the air oxidation of V(II) ions. This information can be utilized to design an appropriate electrolyte reservoir for the VRB system and to prepare suitable ingredients for the electrolyte solution.

  13. 78 FR 36011 - Region VII Regulatory Fairness Board; Federal Regulatory Enforcement Fairness Hearing

    Science.gov (United States)

    2013-06-14

    ... ADMINISTRATION Region VII Regulatory Fairness Board; Federal Regulatory Enforcement Fairness Hearing AGENCY: U.S... Business Regulatory Fairness Board. SUMMARY: The (SBA) Office of the National Ombudsman is issuing this notice to announce the location, date and time of the Regional Small Business Regulatory Fairness hearing...

  14. Last Hired, First Fired Seniority, Layoffs, and Title VII: Questions of Liability and Remedy

    Science.gov (United States)

    Joseph, Ellen R.

    1975-01-01

    The severe economic downturn since the fall of 1973 has focused attention on the consequences of layoffs for the groups intended by Congress to benefit from the employment opportunity policies of Title VII of the Civil Rights Act of 1964. Layoffs have disproportionately affected minority or women employees. (LBH)

  15. Page 1 396 R. D. Desai and (Miss) W. M. Vakil (VII) and its alcoholic ...

    Indian Academy of Sciences (India)

    (VII) and its alcoholic solution gave a red coloration with ferric chloride. (yield 42 per cent). (Found: C, 647; H, 46; CH, Os requires C, 65.0;. H, 4.5 per cent). The sodium bicarbonate solution, on acidification, gave an acid which is described below. Hydrolysis of methyl 2:4-dihydroxy-3-benzoyl-5-acetylbenzoate to 2:4-.

  16. Eesti lavastus "Põrgu wärk" võitis Balti teatrifestivalil viis auhinda

    Index Scriptorium Estoniae

    2006-01-01

    Balti teatrifestivalil "OmaDraama 2006" nähtud etendustest said viis auhinda eestlased - Mart Kivastik näidendi "Põrgu Wärk" eest, Hendrik Toompere lavastuse eest, Harriet Toompere naisosatäitmise eest, Jan Uuspõld Wiiralti kehastamise eest ning Margus Prangel Tuglase osa eest

  17. "Põrgu wärk" võitis Balti teatrifestivalil viis auhinda

    Index Scriptorium Estoniae

    2006-01-01

    Balti teatrifestivalil "OmaDraama 2006" nähtud etendustest said viis auhinda eestlased - Mart Kivastik näidendi "Põrgu Wärk" eest, Hendrik Toompere lavastuse eest, Harriet Toompere naisosatäitmise eest, Jan Uuspõld Wiiralti kehastamise eest ning Margus Prangel Tuglase osa eest. Ka teistest festivalil auhinnasaajatest

  18. Three-dimensional ultrasonography for visualization of muscular anomalies in type VI and VII radial polydactyly.

    Science.gov (United States)

    Saito, Susumu; Ueda, Maho; Takahashi, Natsuko; Kawakatsu, Motohisa; Suzuki, Shigehiko

    2016-04-01

    To describe a technique and its clinical applications of three-dimensional ultrasonography to type VI and VII radial polydactyly for identification of potential muscular anomalies. Ultrasonographic examinations were performed at an out-patient department without sedation or an operative room prior to surgery. The palm was scanned in the transverse direction using a 18-MHz linear transducer under speed regulation at 3 mm/s. Sequential images acquired at 0.2 mm intervals were converted into volume data. After validation of the technique, patients with a radial polydactyly in association with triphalangism (type VII) or with polydactylies of metacarpal duplication (type VI) were included for the examination. Five hands of five patients, one with type VI and four with type VII, were included the study. All the patients were male and the ages at examination ranged from 7 months to 2 years. Of the five patients, four examinations were performed at an out-patient department without sedation and one was under anesthesia just prior to surgery. The muscular abnormalities identified were mal-positions of the thenar muscles in a type VI case and a deficiency of the abductor pollicis brevis muscle in a type VII case with a delta phalanx in the ulnar part. Three-dimensional ultrasound technique could be an aid to plan strategies in radial polydactyly if intrinsic muscular anomalies are suspected to be involved.

  19. Fernando VII against the journalists. Litigations by the State Lawsuit Commission

    Directory of Open Access Journals (Sweden)

    Beatriz Sánchez Hita

    2017-09-01

    Full Text Available This paper deals with the documents associated to the litigations against editors and journalists stored in the State Lawsuit Commission (Madrid, Spain. These files illustrate the persecution of those who tried to create a pro-constitutional public opinion, the aspects which were received as important affronts by Fernando VII and the defendants’ strategies to be penalized as less as possible.

  20. Vittorio De Sica viis meistritööd / Aare Ermel

    Index Scriptorium Estoniae

    Ermel, Aare, 1957-2013

    2008-01-01

    DVD-st "Vittorio De Sica Masterpiece Collection", kus on peal itaalia filmirežissööri Vittorio De Sica viis teost: "Jalgratavargad" ("Ladri di biciclette", 1948), "Ime Milanos" ("Miraclo a milano", 1951), "Umberto D." (1952), "Eile täna, homme" ("Ieri, oggi, domani", 1963), "Ajatu filmikunst" ("Cinema senza tempo: Cosi e la vita", 2001)

  1. Plasma fibrinogen and factor VII concentrations in adults after prenatal exposure to famine

    NARCIS (Netherlands)

    Roseboom, T. J.; van der Meulen, J. H.; Ravelli, A. C.; Osmond, C.; Barker, D. J.; Bleker, O. P.

    2000-01-01

    To assess the effect of maternal malnutrition during different stages of gestation on plasma concentrations of fibrinogen and factor VII, we investigated 725 people, aged 50 years, born around the time of the Dutch famine 1944-5. After adjustment for sex, plasma fibrinogen concentrations differed by

  2. Hormone therapy affects plasma measures of factor VII-activating protease in younger postmenopausal women

    DEFF Research Database (Denmark)

    Mathiasen, Jørn Sidelmann; Skouby, S.O.; Vitzthum, F.

    2010-01-01

    Objectives Current reviews indicate that hormone therapy (HT) has a protective role in coronary heart disease (CHD) in younger postmenopausal women, whereas HT contributes to CHD in older women Factor VII-activating protease (FSAP) is a serine protease that accumulates in unstable atherosclerotic...

  3. Factor VII-activating protease in patients with acute deep venous thrombosis

    DEFF Research Database (Denmark)

    Sidelmann, Johannes J; Vitzthum, Frank; Funding, Eva

    2008-01-01

    Factor VII-activating protease (FSAP) is involved in haemostasis and inflammation. FSAP cleaves single chain urokinase-type plasminogen activator (scu-PA). The 1601GA genotype of the 1601G/A polymorphism in the FSAP gene leads to the expression of a FSAP variant with reduced ability to activate scu...

  4. Synthesis and characterization of 18F-labeled active site inhibited factor VII (ASIS)

    DEFF Research Database (Denmark)

    Erlandsson, Maria; Nielsen, Carsten Haagen; Jeppesen, Troels Elmer

    2015-01-01

    Activated factor VII blocked in the active site with Phe-Phe-Arg-chloromethyl ketone (active site inhibited factor VII (ASIS)) is a 50-kDa protein that binds with high affinity to its receptor, tissue factor (TF). TF is a transmembrane glycoprotein that plays an important role in, for example......, thrombosis, metastasis, tumor growth, and tumor angiogenesis. The aim of this study was to develop an 18F-labeled ASIS derivative to assess TF expression in tumors. Active site inhibited factor VII was labeled using N-succinimidyl-4-[18F]fluorobenzoate, and the [18F]ASIS was purified on a PD-10 desalting...... column. The radiochemical yield was 25 ± 6%, the radiochemical purity was >97%, and the pseudospecific radioactivity was 35 ± 9 GBq/µmol. The binding efficacy was evaluated in pull-down experiments, which monitored the binding of unlabeled ASIS and [18F]ASIS to TF and to a specific anti-factor VII...

  5. Association of protein Z and factor VII gene polymorphisms with risk ...

    Indian Academy of Sciences (India)

    Abstract. Protein Z (PZ) and factor (F) VII are two important factors in the clotting pathway which have similar structure, linked function and nearby gene sites. The aims of this study were to investigate whether the common variants of PZ and FVII genes are associated with the risk of cerebral hemorrhage (CH) and to explore ...

  6. What history tells us VII. Twenty-five years ago: the production of ...

    Indian Academy of Sciences (India)

    2006-11-13

    Nov 13, 2006 ... Home; Journals; Journal of Biosciences; Volume 31; Issue 5. What history tells us VII. Twenty-five years ago: the production of mouse embryonic stem cells. Michel Morange. Series Volume 31 Issue 5 December 2006 pp 537-541. Fulltext. Click here to view fulltext PDF. Permanent link:

  7. Contribution of coagulation factor VII R353Q polymorphism to the ...

    African Journals Online (AJOL)

    Aim of the study: Is to investigate the contribution of factor VII R353Q gene polymorphism to the risk of thrombotic disorders development (venous and arterial) in a group of Egyptian patients. Subjects and methods: This study was conducted on 310 subjects: 110 acute myocardial infarction (AMI) patients, 108 deep venous ...

  8. Dos Idiomas, Un Mundo. Dual Language Project. Title VII Biennial Evaluation Report, 1995-97.

    Science.gov (United States)

    Ernest, Harishini M.; Gonzalez, Rosa M.

    This is an evaluation of the first 2 years of a 5-year comprehensive Bilingual Education grant funded by Title VII Part A of the Improving America's Schools Act of 1994 in the Austin Independent School District (AISD) (Texas). The grant awarded to the AISD funds a program of Developmental Bilingual Education at two elementary schools where more…

  9. PEMBELAJARAN MENULIS PARAGRAF DESKRIPSI BERBASIS MIND MAPPING PADA SISWA KELAS VII SMP LABORATORIUM UNDIKSHA

    Directory of Open Access Journals (Sweden)

    Ida Bagus Putrayasa

    2015-10-01

    Full Text Available Tujuan penelitian ini untuk mendeskripsikan: (1 pembelajaran menulis paragraf deskripsi dengan model mind mapping pada siswa kelas VII SMP Laboratorium Undiksha Singaraja, (2 kemampuan siswa kelas VII SMP Laboratorium Undiksha Singaraja dalam pembelajaran menulis paragraf deskripsi dengan mind mapping. Rancangan yang digunakan dalam penelitian ini adalah penelitian deskriptif kualitatif. Yang menjadi subjek dalam penelitian ini adalah guru dan siswa kelas VII SMP Laboratorium Undiksha. Objek dalam penelitian ini adalah pembelajaran paragraf deskripsi dengan model mind mapping. Metode yang digunakan untuk mengumpulkan data adalah metode observasi dan metode tes. Data yang terkumpul dianalisis dengan metode analisis deskriptif kualitatif dan deskriptif kuantitatif. Hasilnya menunjukkan bahwa (1 Pembelajaran menulis paragraf deskripsi dengan model mind mapping yang dilakukan guru sudah sesuai dengan teori yang ada. (2 Kemampuan siswa kelas VII SMP Laboratorium Undiksha dalam menulis paragraf deskripsi tergolong baik. Skor yang diperoleh adalah 78,13. Walaupun skor yang diperoleh sudah mencapai kategori baik, tampaknya kinerja guru perlu ditingkatkan lagi dengan memberikan latihan-latihan yang lebih intensif, baik dalam membuat mind mapping maupun pengembangannya menjadi paragraf, sehingga tercapai hasil yang maksimal.

  10. Page 1 Exoenission 757 (vii) EE emission can occur continuously ...

    Indian Academy of Sciences (India)

    pulling rod coupled to a linear variable differential transformer (LVDT) for measuring the displacement and thereby the strain rate. Strain at a constant rate is applied at intervals, causing EE in bursts. The vacuum chamber (UHVC) is equipped with a ion-gun. (IG) for in-situ cleaning of the sample surface. No stimulation unit ...

  11. Prevalence of collagen VII-specific autoantibodies in patients with autoimmune and inflammatory diseases.

    Science.gov (United States)

    Licarete, Emilia; Ganz, Susanne; Recknagel, Martin J; Di Zenzo, Giovanni; Hashimoto, Takashi; Hertl, Michael; Zambruno, Giovanna; Hundorfean, Gheorghe; Mudter, Jonas; Neurath, Markus F; Bruckner-Tuderman, Leena; Sitaru, Cassian

    2012-04-04

    Autoimmunity to collagen VII is typically associated with the skin blistering disease epidermolysis bullosa acquisita (EBA), but also occurs occasionally in patients with systemic lupus erythematosus or inflammatory bowel disease. The aim of our present study was to develop an accurate immunoassay for assessing the presence of autoantibodies against collagen VII in large cohorts of patients and healthy donors. Based on in silico antigenic analysis and previous wetlab epitope mapping data, we designed a chimeric collagen VII construct containing all collagen VII epitopes with higher antigenicity. ELISA was performed with sera from patients with EBA (n = 50), Crohn's disease (CD, n = 50), ulcerative colitis (UC, n = 50), bullous pemphigoid (BP, n = 76), and pemphigus vulgaris (PV, n = 42) and healthy donors (n = 245). By ELISA, the receiver operating characteristics analysis yielded an area under the curve of 0.98 (95% CI: 0.9638-1.005), allowing to set the cut-off at 0.32 OD at a calculated specificity of 98% and a sensitivity of 94%. Running the optimized test showed that serum IgG autoantibodies from 47 EBA (94%; 95% CI: 87.41%-100%), 2 CD (4%; 95% CI: 0%-9.43%), 8 UC (16%; 95% CI: 5.8%-26%), 2 BP (2.63%; 95% CI: 0%-6.23%), and 4 PV (9.52%; 95% CI: 0%-18.4%) patients as well as from 4 (1.63%; 95% CI: 0%-3.21%) healthy donors reacted with the chimeric protein. Further analysis revealed that in 34%, 37%, 16% and 100% of sera autoantibodies of IgG1, IgG2, IgG3, and IgG4 isotype, respectively, recognized the recombinant autoantigen. Using a chimeric protein, we developed a new sensitive and specific ELISA to detect collagen specific antibodies. Our results show a low prevalence of collagen VII-specific autoantibodies in inflammatory bowel disease, pemphigus and bullous pemphigoid. Furthermore, we show that the autoimmune response against collagen VII is dominated by IgG4 autoantibodies. The new immunoassay should prove a useful tool for clinical and translational

  12. Prevalence of collagen VII-specific autoantibodies in patients with autoimmune and inflammatory diseases

    Directory of Open Access Journals (Sweden)

    Licarete Emilia

    2012-04-01

    Full Text Available Abstract Background Autoimmunity to collagen VII is typically associated with the skin blistering disease epidermolysis bullosa acquisita (EBA, but also occurs occasionally in patients with systemic lupus erythematosus or inflammatory bowel disease. The aim of our present study was to develop an accurate immunoassay for assessing the presence of autoantibodies against collagen VII in large cohorts of patients and healthy donors. Methods Based on in silico antigenic analysis and previous wetlab epitope mapping data, we designed a chimeric collagen VII construct containing all collagen VII epitopes with higher antigenicity. ELISA was performed with sera from patients with EBA (n = 50, Crohn's disease (CD, n = 50, ulcerative colitis (UC, n = 50, bullous pemphigoid (BP, n = 76, and pemphigus vulgaris (PV, n = 42 and healthy donors (n = 245. Results By ELISA, the receiver operating characteristics analysis yielded an area under the curve of 0.98 (95% CI: 0.9638-1.005, allowing to set the cut-off at 0.32 OD at a calculated specificity of 98% and a sensitivity of 94%. Running the optimized test showed that serum IgG autoantibodies from 47 EBA (94%; 95% CI: 87.41%-100%, 2 CD (4%; 95% CI: 0%-9.43%, 8 UC (16%; 95% CI: 5.8%-26%, 2 BP (2.63%; 95% CI: 0%-6.23%, and 4 PV (9.52%; 95% CI: 0%-18.4% patients as well as from 4 (1.63%; 95% CI: 0%-3.21% healthy donors reacted with the chimeric protein. Further analysis revealed that in 34%, 37%, 16% and 100% of sera autoantibodies of IgG1, IgG2, IgG3, and IgG4 isotype, respectively, recognized the recombinant autoantigen. Conclusions Using a chimeric protein, we developed a new sensitive and specific ELISA to detect collagen specific antibodies. Our results show a low prevalence of collagen VII-specific autoantibodies in inflammatory bowel disease, pemphigus and bullous pemphigoid. Furthermore, we show that the autoimmune response against collagen VII is dominated by IgG4 autoantibodies. The new immunoassay should

  13. The Fundamental Properties of Young Stars

    Science.gov (United States)

    Czekala, Ian

    Accurate knowledge of the fundamental properties of stars--mass, temperature, and luminosity--is key to our understanding of stellar evolution. In particular, empirical measurements of stellar mass are difficult to make and are generally limited to stars that dynamically interact with a companion (e.g., eclipsing or astrometric binaries), a precious but ultimately small sample. We developed a technique that uses the rotation of the protoplanetary disk--a consequence of the star formation process still present around many pre-main sequence stars--to measure the stellar mass. To establish the absolute accuracy of this technique, in ALMA Cycle 1/2 we observed the few circumbinary disks around double-lined spectroscopic binary stars, enabling an independent confirmation of the total stellar mass. This comparison with radial-velocity results demonstrates that the disk-based dynamical mass technique can reliably achieve precise measurements of stellar mass on the order of 2-5%, clearing the way for widespread application of this technique to measure the masses of single stars. We discuss our calibration in the context of two sources, AK Sco and DQ Tau. Second, we developed novel statistical techniques for spectroscopic inference. Young stars exhibit rich and variable spectra; although interesting phenomena in their own right, accretion veiling and star spots complicate the retrieval of accurate photospheric properties. The subtraction of an imperfect model from a continuously sampled spectrum introduces covariance between adjacent datapoints (pixels) into the residual spectrum. For the high signal-to-noise data with large spectral range that is commonly employed in stellar astrophysics, that covariant structure can lead to dramatically underestimated parameter uncertainties (and, in some cases, biases). We construct a likelihood function that accounts for the structure of the covariance matrix, utilizing the machinery of Gaussian process kernels. This framework

  14. Super Star Clusters

    Science.gov (United States)

    O'Connell, R. W.

    1994-05-01

    Super star clusters represent an extreme in the star formation process. They are very luminous, compact objects with L_V > 10(6) L_{V,sun} and diameters = 100 times higher than normal OB associations and clusters in ``giant H II regions''. Prior to HST about a dozen such objects had been identified in nearby galaxies, but at ground-based resolution they are nearly point sources. We review recent HST observations of individual super star clusters in NGC 1140, 1569, and 1705. They have half-light radii of only 2--3.5 pc, and some show evidence of substructure which should be resolvable with the repaired HST. After allowing for age differences, the surface brightness of NGC 1569-A is over 65 times higher than the core of 30 Doradus in the LMC and 1200 times higher than the mean rich LMC star cluster. In some cases, the energy released by the clusters into their surroundings is sufficient to drive galaxy-wide winds. Their properties make super star clusters good analogues of young globular clusters. In some, though not all, cases super star clusters appear to form in the aftermath of a merger or accretion event. The most impressive examples are the clusters detected by HST in NGC 1275 and 7252, one of which has the extraordinary luminosity ~ 6 times 10(8) L_{V,sun}. M82 affords a nearby view of a post-interaction system. HST imaging has identified over 80 super star clusters in its central regions with mean luminosities of ~ 3 times 10(6) L_{V,sun}. Their close packing and signs of interaction with the well-known supernova-driven wind suggest that they do not evolve independently. Super cluster evolution in starbursts is probably a collective phenomenon.

  15. Structural study on 2,2'-(methylimino)bis(N,N-dioctylacetamide) complex with Re(VII)O4- and Tc(VII)O4- by 1H NMR, EXAFS, and IR spectroscopy.

    Science.gov (United States)

    Saeki, Morihisa; Sasaki, Yuji; Nakai, Ayaka; Ohashi, Akira; Banerjee, Dipanjan; Scheinost, Andreas C; Foerstendorf, Harald

    2012-05-21

    The structures of the complex of 2,2'-(methylimino)bis(N,N-dioctylacetamide) (MIDOA) with M(VII)O(4)(-) (M = Re and Tc), which were prepared by liquid-liquid solvent extraction, were investigated by using (1)H nuclear magnetic resonance (NMR), extended X-ray absorption fine structure (EXAFS), and infrared (IR) spectroscopy. The (1)H NMR spectra of the complex of MIDOA with Re(VII)O(4)(-) prepared in the organic solution suggest the transfer of a proton from aqueous to organic solution and the formation of the H(+)MIDOA ion. The EXAFS spectra of the complexes of H(+)MIDOA with Re(VII)O(4)(-) and Tc(VII)O(4)(-) show only the M-O coordination of the aquo complexes, suggesting that the chemical state of M(VII)O(4)(-) was unchanged during the extraction process. The results from (1)H NMR and EXAFS, therefore, provide evidence of M(VII)O(4)(-)···H(+)MIDOA complex formation in the organic solution. The IR spectra of Re(VII)O(4)(-)···H(+)MIDOA and Tc(VII)O(4)(-)···H(+)MIDOA were analyzed based on the structures and the IR spectra that were calculated at the B3LYP/cc-pVDZ level. Comparison of the observed and calculated IR spectra demonstrates that an intramolecular hydrogen bond is formed in H(+)MIDOA, and the M(VII)O(4)(-) ion interacts with H(+)MIDOA through multiple C-H(n)···O hydrogen bonds.

  16. Genetic diversity of the genotype VII Newcastle disease virus: identification of a novel VIIj sub-genotype.

    Science.gov (United States)

    Xue, Cong; Cong, Yanlong; Yin, Renfu; Sun, Yixue; Ding, Chan; Yu, Shengqing; Liu, Xiufan; Hu, Shunlin; Qian, Jing; Yuan, Qianliang; Yang, Mingxi; Wang, Chunfeng; Ding, Zhuang

    2017-02-01

    Newcastle disease (ND) is a highly contagious disease of poultry caused by Newcastle disease virus (NDV). Multiple genotypes of NDV have been circulating worldwide and NDV is continuously evolving, resulting into more diversity. Of multiple viral genotypes, VII is particularly important given that it had been associated with most recent ND outbreaks worldwide. In this study, an epidemiological investigation performed in northeastern China during 2014-2015 showed that 11 genotype VII isolates amounted to 55 percent in a total number of NDV isolates. Therefore, to evaluate the genetic diversity worldwide and epidemiological distribution in China of genotype VII NDV, a phylogenetic analysis based on the 1255 complete F gene sequences showed that VII is the most predominant genotype worldwide. A further detailed characterization on genotype VII was conducted based on the 477 complete F gene sequences from 11 isolates and 466 reference viruses available in GenBank. The results demonstrated that VII can be further divided into 8 sub-genotypes (VIIb, VIId-VIIj), indicating its complex genetic diversity. It is worthy of note that the isolation rate of VIIj is increasing recently. It emphasizes the necessity to pay close attention to the epidemiological dynamic of genotype VII NDV and highlights the importance of vaccination program.

  17. Oxidation of triclosan by permanganate (Mn(VII)): importance of ligands and in situ formed manganese oxides.

    Science.gov (United States)

    Jiang, Jin; Pang, Su-Yan; Ma, Jun

    2009-11-01

    Experiments were conducted to examine permanganate (Mn(VII); KMnO(4)) oxidation of the widely used biocide triclosan (one phenolic derivative) in aqueous solution at pH values of 5-9. Under slightly acidic conditions, the reactions displayed autocatalysis, suggesting the catalytic role of in situ formed MnO(2). This was further supported by the promoting effects of the addition of preformed MnO(2) colloids on Mn(VII) oxidations of triclosan and two other selected phenolics (i.e., phenol and 2,4-dichlorophenol), as well as p-nitrophenol which otherwise showed negligible reactivity toward Mn(VII) and MnO(2) colloids, respectively. Surprisingly, phosphate buffer significantly enhanced Mn(VII) oxidation of triclosan, as well as phenol and 2,4-dichlorophenol over a wide pH range. Further, several other selected ligands (i.e., pyrophosphate, EDTA, and humic acid) also exerted oxidation enhancement, supporting a scenario where highly active aqueous manganese intermediates (Mn(INT)(aq)) formed in situ upon Mn(VII) reduction might be stabilized to a certain extent in the presence of ligands and subsequently involved in further oxidation of target phenolics, whereas without stabilizing agents Mn(INT)(aq) autodecomposes or disproportionates spontaneously. The effectiveness of Mn(VII) for the oxidative removal of triclosan in natural water and wastewater was confirmed. Their background matrices were also found to accelerate Mn(VII) oxidation of phenolics.

  18. Pulsating stars in SuperWASP

    Directory of Open Access Journals (Sweden)

    Holdsworth Daniel L.

    2017-01-01

    Full Text Available SuperWASP is one of the largest ground-based surveys for transiting exoplanets. To date, it has observed over 31 million stars. Such an extensive database of time resolved photometry holds the potential for extensive searches of stellar variability, and provide solid candidates for the upcoming TESS mission. Previous work by e.g. [15], [5], [12] has shown that the WASP archive provides a wealth of pulsationally variable stars. In this talk I will provide an overview of the SuperWASP project, present some of the published results from the survey, and some of the on-going work to identify key targets for the TESS mission.

  19. A SECOND NEUTRON STAR IN M4?

    Energy Technology Data Exchange (ETDEWEB)

    Kaluzny, J.; Rozanska, A.; Rozyczka, M.; Krzeminski, W. [Nicolaus Copernicus Astronomical Center, Bartycka 18, 00-716 Warsaw (Poland); Thompson, Ian B. [Observatories of the Carnegie Institution of Washington, 813 Santa Barbara Street, Pasadena, CA 91101 (United States)

    2012-05-01

    We show that the optical counterpart of the X-ray source CX 1 in M4 is a {approx}20th magnitude star, located in the color-magnitude diagram on (or very close to) the main sequence of the cluster, and exhibiting sinusoidal variations of the flux. We find the X-ray flux to be also periodically variable, with X-ray and optical minima coinciding. Stability of the optical light curve, lack of UV-excess, and unrealistic mean density resulting from period-density relation for semidetached systems speak against the original identification of CX 1 as a cataclysmic variable. We argue that the X-ray active component of this system is a neutron star (probably a millisecond pulsar).

  20. Circulation of Stars

    Science.gov (United States)

    Boitani, P.

    2016-01-01

    Since the dawn of man, contemplation of the stars has been a primary impulse in human beings, who proliferated their knowledge of the stars all over the world. Aristotle sees this as the product of primeval and perennial “wonder” which gives rise to what we call science, philosophy, and poetry. Astronomy, astrology, and star art (painting, architecture, literature, and music) go hand in hand through millennia in all cultures of the planet (and all use catasterisms to explain certain phenomena). Some of these developments are independent of each other, i.e., they take place in one culture independently of others. Some, on the other hand, are the product of the “circulation of stars.” There are two ways of looking at this. One seeks out forms, the other concentrates on the passing of specific lore from one area to another through time. The former relies on archetypes (for instance, with catasterism), the latter constitutes a historical process. In this paper I present some of the surprising ways in which the circulation of stars has occurred—from East to West, from East to the Far East, and from West to East, at times simultaneously.

  1. New insight into the physics of atmospheres of early type stars

    Science.gov (United States)

    Lamers, H. J. G. L. M.

    1981-01-01

    The phenomenon of mass loss and stellar winds from hot stars are discussed. The mass loss rate of early type stars increases by about a factor of 100 to 1000 during their evolution. This seems incompatible with the radiation driven wind models and may require another explanation for the mass loss from early type stars. The winds of early type stars are strongly variable and the stars may go through active phases. Eclipses in binary systems by the stellar winds can be used to probe the winds. A few future IUE studies are suggested.

  2. Pseudane-VII Isolated from Pseudoalteromonas sp. M2 Ameliorates LPS-Induced Inflammatory Response In Vitro and In Vivo

    Directory of Open Access Journals (Sweden)

    Mi Eun Kim

    2017-11-01

    Full Text Available The ocean is a rich resource of flora, fauna, food, and biological products. We found a wild-type bacterial strain, Pseudoalteromonas sp. M2, from marine water and isolated various secondary metabolites. Pseudane-VII is a compound isolated from the Pseudoalteromonas sp. M2 metabolite that possesses anti-melanogenic activity. Inflammation is a response of the innate immune system to microbial infections. Macrophages have a critical role in fighting microbial infections and inflammation. Recent studies reported that various compounds derived from natural products can regulate immune responses including inflammation. However, the anti-inflammatory effects and mechanism of pseudane-VII in macrophages are still unknown. In this study, we investigated the anti-inflammatory effects of pseudane-VII. In present study, lipopolysaccharide (LPS-induced nitric oxide (NO production was significantly decreased by pseudane-VII treatment at 6 μM. Moreover, pseudane-VII treatment dose-dependently reduced mRNA levels of pro-inflammatory cytokines including inos, cox-2, il-1β, tnf-α, and il-6 in LPS-stimulated macrophages. Pseudane-VII also diminished iNOS protein levels and IL-1β secretion. In addition, Pseudane-VII elicited anti-inflammatory effects by inhibiting ERK, JNK, p38, and nuclear factor (NF-κB-p65 phosphorylation. Consistently, pseudane-VII was also shown to inhibit the LPS-stimulated release of IL-1β and expression of iNOS in mice. These results suggest that pseudane-VII exerted anti-inflammatory effects on LPS-stimulated macrophage activation via inhibition of ERK, JNK, p38 MAPK phosphorylation, and pro-inflammatory gene expression. These findings may provide new approaches in the effort to develop anti-inflammatory therapeutics.

  3. Radio stars observed in the LAMOST spectral survey

    Science.gov (United States)

    Zhang, Li-Yun; Yue, Qiang; Lu, Hong-Peng; Han, Xian-Ming L.; Zhang, Yong; Shi, Jian-Rong; Wang, Yue-Fei; Hou, Yong-Hui; Zi-Huang, Cao

    2017-09-01

    Radio stars have attracted astronomers’ attention for several decades. To better understand the physics behind stellar radio emissions, it is important to study their optical behaviors. The LAMOST survey provides a large database for researching stellar spectroscopic properties of radio stars. In this work, we concentrate on their spectroscopic properties and infer physical properties from their spectra, such as stellar activity and variability. We mined big data from the LAMOST spectral survey Data Release 2 (DR2), published on 2016 June 30, by cross-matching them with radio stars from FIRST and other surveys. We obtained 783 good stellar spectra with high signal to noise ratio for 659 stars. The criteria for selection were positional coincidence within 1.5‧‧ and LAMOST objects classified as stars. We calculated the equivalent widths (EWs) of the Ca ii H&K, Hδ, Hγ, Hβ, Hα and Ca ii IRT lines by integrating the line profiles. Using the EWs of the Hα line, we detected 147 active stellar spectra of 89 objects having emissions above the Hα continuum. There were also 36 objects with repeated spectra, 28 of which showed chromospheric activity variability. Furthermore, we found 14 radio stars emitting noticeably in the Ca ii IRT lines. The low value of the EW8542/EW8498 ratio for these 14 radio stars possibly alludes to chromospheric plage regions.

  4. Stars a very short introduction

    CERN Document Server

    King, Andrew

    2012-01-01

    Stars: A Very Short Introduction looks at how stars live, producing all the chemical elements beyond helium, and how they die, leaving remnants such as black holes. Every atom of our bodies has been part of a star. Our very own star, the Sun, is crucial to the development and sustainability of life on Earth. Understanding stars is key to understanding the galaxies they inhabit, the existence of planets, and the history of our entire Universe. This VSI explores the science of stars, the mechanisms that allow them to form, the processes that allow them to shine, and the results of their death.

  5. Lithium in LMC carbon stars

    OpenAIRE

    Hatzidimitriou, D.; Morgan, D. H.; Cannon, R. D.; Croke, B. F. W.

    2003-01-01

    Nineteen carbon stars that show lithium enrichment in their atmospheres have been discovered among a sample of 674 carbon stars in the Large Magellanic Cloud. Six of the Li-rich carbon stars are of J-type, i.e. with strong 13C isotopic features. No super-Li-rich carbon stars were found. The incidence of lithium enrichment among carbon stars in the LMC is much rarer than in the Galaxy, and about five times more frequent among J-type than among N-type carbon stars. The bolometric magnitudes of ...

  6. Variability of young stellar objects: Accretion, disks, outflows, and magnetic activity

    Science.gov (United States)

    Stelzer, B.

    2015-06-01

    Variability is a key characteristic of young stars. Two major origins may be distinguished: a scaled-up version of the magnetic activity seen on main-sequence stars and various processes related to circumstellar disks, accretion, and outflows.

  7. The Physical Nature of Subdwarf A Stars: White Dwarf Impostors

    Science.gov (United States)

    Brown, Warren R.; Kilic, Mukremin; Gianninas, A.

    2017-04-01

    We address the physical nature of subdwarf A-type (sdA) stars and their possible link to extremely low mass (ELM) white dwarfs (WDs). The two classes of objects are confused in low-resolution spectroscopy. However, colors and proper motions indicate that sdA stars are cooler and more luminous, and thus larger in radius, than published ELM WDs. We demonstrate that surface gravities derived from pure hydrogen models suffer a systematic ˜1 dex error for sdA stars, likely explained by metal line blanketing below 9000 K. A detailed study of five eclipsing binaries with radial velocity orbital solutions and infrared excess establishes that these sdA stars are metal-poor ≃1.2 M ⊙ main sequence stars with ≃0.8 M ⊙ companions. While WDs must exist at sdA temperatures, only ˜1% of a magnitude-limited sdA sample should be ELM WDs. We conclude that the majority of sdA stars are metal-poor A-F type stars in the halo, and that recently discovered pulsating ELM WD-like stars with no obvious radial velocity variations may be SX Phe variables, not pulsating WDs.

  8. The Physical Nature of Subdwarf A Stars: White Dwarf Impostors

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Warren R. [Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States); Kilic, Mukremin; Gianninas, A., E-mail: wbrown@cfa.harvard.edu, E-mail: kilic@ou.edu, E-mail: alexg@nhn.ou.edu [Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, 440 W. Brooks Street, Norman, OK, 73019 (United States)

    2017-04-10

    We address the physical nature of subdwarf A-type (sdA) stars and their possible link to extremely low mass (ELM) white dwarfs (WDs). The two classes of objects are confused in low-resolution spectroscopy. However, colors and proper motions indicate that sdA stars are cooler and more luminous, and thus larger in radius, than published ELM WDs. We demonstrate that surface gravities derived from pure hydrogen models suffer a systematic ∼1 dex error for sdA stars, likely explained by metal line blanketing below 9000 K. A detailed study of five eclipsing binaries with radial velocity orbital solutions and infrared excess establishes that these sdA stars are metal-poor ≃1.2 M {sub ⊙} main sequence stars with ≃0.8 M {sub ⊙} companions. While WDs must exist at sdA temperatures, only ∼1% of a magnitude-limited sdA sample should be ELM WDs. We conclude that the majority of sdA stars are metal-poor A–F type stars in the halo, and that recently discovered pulsating ELM WD-like stars with no obvious radial velocity variations may be SX Phe variables, not pulsating WDs.

  9. Yttrium in the peculiar A and B stars

    Energy Technology Data Exchange (ETDEWEB)

    Allen, M.S.

    1977-04-01

    Spectroscopic analyses of 18 late B and early A stars have been conducted by use of 2.4 A mm/sup -1/ blue plate region spectra from the Dominion Astrophysical Observatory. The physical characteristics of the stellar atmospheres have been determined and abundances calculated for iron, strontium, yttrium, and zirconium with an LTE spectrum synthesis algorithm. Included in the sample were nine mercury-manganese stars; for some of these, previous studies have indicated abundance excesses of yttrium over both strontium and zirconium in violation of the systematics of neutron-addition nucleosynthesis. No such anomalous excess was expected for the nine control stars, which included normal, Am, and Ap spectrum variable stars.The present work failed to confirm the anomalous yttrium abundance pattern in any star in the sample. The following conclusions were drawn from the detailed abundance results for the Hg-Mn stars: (i) their Sr-Y-Zr abundances are all enhanced relative to the star content; (ii) the relative Sr-Y-Zr abundance patterns are frequently nonsolar in these stars; (iii) but they are not demonstrably nonnuclear; (iv) the prediction of the radiative diffusion theory of element separation for yttrium relative to its neighbors for the appropriate stellar mass range is still to be clearly established, but does not appear promising.

  10. Giant star seismology

    Science.gov (United States)

    Hekker, S.; Christensen-Dalsgaard, J.

    2017-06-01

    The internal properties of stars in the red-giant phase undergo significant changes on relatively short timescales. Long near-uninterrupted high-precision photometric timeseries observations from dedicated space missions such as CoRoT and Kepler have provided seismic inferences of the global and internal properties of a large number of evolved stars, including red giants. These inferences are confronted with predictions from theoretical models to improve our understanding of stellar structure and evolution. Our knowledge and understanding of red giants have indeed increased tremendously using these seismic inferences, and we anticipate that more information is still hidden in the data. Unraveling this will further improve our understanding of stellar evolution. This will also have significant impact on our knowledge of the Milky Way Galaxy as well as on exo-planet host stars. The latter is important for our understanding of the formation and structure of planetary systems.

  11. Dynamical Boson Stars

    Directory of Open Access Journals (Sweden)

    Steven L. Liebling

    2012-05-01

    Full Text Available The idea of stable, localized bundles of energy has strong appeal as a model for particles. In the 1950s, John Wheeler envisioned such bundles as smooth configurations of electromagnetic energy that he called geons, but none were found. Instead, particle-like solutions were found in the late 1960s with the addition of a scalar field, and these were given the name boson stars. Since then, boson stars find use in a wide variety of models as sources of dark matter, as black hole mimickers, in simple models of binary systems, and as a tool in finding black holes in higher dimensions with only a single Killing vector. We discuss important varieties of boson stars, their dynamic properties, and some of their uses, concentrating on recent efforts.

  12. Collapse of axion stars

    Energy Technology Data Exchange (ETDEWEB)

    Eby, Joshua [Department of Physics, University of Cincinnati,2600 Clifton Ave, Cincinnati, OH, 45221 (United States); Fermi National Accelerator Laboratory,P.O. Box 500, Batavia, IL, 60510 (United States); Leembruggen, Madelyn; Suranyi, Peter; Wijewardhana, L.C.R. [Department of Physics, University of Cincinnati,2600 Clifton Ave, Cincinnati, OH, 45221 (United States)

    2016-12-15

    Axion stars, gravitationally bound states of low-energy axion particles, have a maximum mass allowed by gravitational stability. Weakly bound states obtaining this maximum mass have sufficiently large radii such that they are dilute, and as a result, they are well described by a leading-order expansion of the axion potential. Heavier states are susceptible to gravitational collapse. Inclusion of higher-order interactions, present in the full potential, can give qualitatively different results in the analysis of collapsing heavy states, as compared to the leading-order expansion. In this work, we find that collapsing axion stars are stabilized by repulsive interactions present in the full potential, providing evidence that such objects do not form black holes. In the last moments of collapse, the binding energy of the axion star grows rapidly, and we provide evidence that a large amount of its energy is lost through rapid emission of relativistic axions.

  13. Dynamical boson stars

    Science.gov (United States)

    Liebling, Steven L.; Palenzuela, Carlos

    2017-11-01

    The idea of stable, localized bundles of energy has strong appeal as a model for particles. In the 1950s, John Wheeler envisioned such bundles as smooth configurations of electromagnetic energy that he called geons, but none were found. Instead, particle-like solutions were found in the late 1960s with the addition of a scalar field, and these were given the name boson stars. Since then, boson stars find use in a wide variety of models as sources of dark matter, as black hole mimickers, in simple models of binary systems, and as a tool in finding black holes in higher dimensions with only a single Killing vector. We discuss important varieties of boson stars, their dynamic properties, and some of their uses, concentrating on recent efforts.

  14. Heavy Metal Stars

    Science.gov (United States)

    2001-08-01

    La Silla Telescope Detects Lots of Lead in Three Distant Binaries Summary Very high abundances of the heavy element Lead have been discovered in three distant stars in the Milky Way Galaxy . This finding strongly supports the long-held view that roughly half of the stable elements heavier than Iron are produced in common stars during a phase towards the end of their life when they burn their Helium - the other half results from supernova explosions. All the Lead contained in each of the three stars weighs about as much as our Moon. The observations show that these "Lead stars" - all members of binary stellar systems - have been more enriched with Lead than with any other chemical element heavier than Iron. This new result is in excellent agreement with predictions by current stellar models about the build-up of heavy elements in stellar interiors. The new observations are reported by a team of Belgian and French astronomers [1] who used the Coude Echelle Spectrometer on the ESO 3.6-m telescope at the La Silla Observatory (Chile). PR Photo 26a/01 : A photo of HD 196944 , one of the "Lead stars". PR Photo 26b/01 : A CES spectrum of HD 196944 . The build-up of heavy elements Astronomers and physicists denote the build-up of heavier elements from lighter ones as " nucleosynthesis ". Only the very lightest elements (Hydrogen, Helium and Lithium [2]) were created at the time of the Big Bang and therefore present in the early universe. All the other heavier elements we now see around us were produced at a later time by nucleosynthesis inside stars. In those "element factories", nuclei of the lighter elements are smashed together whereby they become the nuclei of heavier ones - this process is known as nuclear fusion . In our Sun and similar stars, Hydrogen is being fused into Helium. At some stage, Helium is fused into Carbon, then Oxygen, etc. The fusion process requires positively charged nuclei to move very close to each other before they can unite. But with increasing

  15. Dynamical boson stars.

    Science.gov (United States)

    Liebling, Steven L; Palenzuela, Carlos

    2017-01-01

    The idea of stable, localized bundles of energy has strong appeal as a model for particles. In the 1950s, John Wheeler envisioned such bundles as smooth configurations of electromagnetic energy that he called geons, but none were found. Instead, particle-like solutions were found in the late 1960s with the addition of a scalar field, and these were given the name boson stars. Since then, boson stars find use in a wide variety of models as sources of dark matter, as black hole mimickers, in simple models of binary systems, and as a tool in finding black holes in higher dimensions with only a single Killing vector. We discuss important varieties of boson stars, their dynamic properties, and some of their uses, concentrating on recent efforts.

  16. Atomic diffusion in stars

    CERN Document Server

    Michaud, Georges; Richer, Jacques

    2015-01-01

    This book gives an overview of atomic diffusion, a fundamental physical process, as applied to all types of stars, from the main sequence to neutron stars. The superficial abundances of stars as well as their evolution can be significantly affected. The authors show where atomic diffusion plays an essential role and how it can be implemented in modelling.  In Part I, the authors describe the tools that are required to include atomic diffusion in models of stellar interiors and atmospheres. An important role is played by the gradient of partial radiative pressure, or radiative acceleration, which is usually neglected in stellar evolution. In Part II, the authors systematically review the contribution of atomic diffusion to each evolutionary step. The dominant effects of atomic diffusion are accompanied by more subtle effects on a large number of structural properties throughout evolution. One of the goals of this book is to provide the means for the astrophysicist or graduate student to evaluate the importanc...

  17. Really Hot Stars

    Science.gov (United States)

    2003-04-01

    Spectacular VLT Photos Unveil Mysterious Nebulae Summary Quite a few of the most beautiful objects in the Universe are still shrouded in mystery. Even though most of the nebulae of gas and dust in our vicinity are now rather well understood, there are some which continue to puzzle astronomers. This is the case of a small number of unusual nebulae that appear to be the subject of strong heating - in astronomical terminology, they present an amazingly "high degree of excitation". This is because they contain significant amounts of ions, i.e., atoms that have lost one or more of their electrons. Depending on the atoms involved and the number of electrons lost, this process bears witness to the strength of the radiation or to the impact of energetic particles. But what are the sources of that excitation? Could it be energetic stars or perhaps some kind of exotic objects inside these nebulae? How do these peculiar objects fit into the current picture of universal evolution? New observations of a number of such unusual nebulae have recently been obtained with the Very Large Telescope (VLT) at the ESO Paranal Observatory (Chile). In a dedicated search for the origin of their individual characteristics, a team of astronomers - mostly from the Institute of Astrophysics & Geophysics in Liège (Belgium) [1] - have secured the first detailed, highly revealing images of four highly ionized nebulae in the Magellanic Clouds, two small satellite galaxies of our home galaxy, the Milky Way, only a few hundred thousand light-years away. In three nebulae, they succeeded in identifying the sources of energetic radiation and to eludicate their exceptional properties: some of the hottest, most massive stars ever seen, some of which are double. With masses of more than 20 times that of the Sun and surface temperatures above 90 000 degrees, these stars are truly extreme. PR Photo 09a/03: Nebula around the hot star AB7 in the SMC. PR Photo 09b/03: Nebula near the hot Wolf-Rayet star BAT99

  18. General Relativity&Compact Stars

    Energy Technology Data Exchange (ETDEWEB)

    Glendenning, Norman K.

    2005-08-16

    Compact stars--broadly grouped as neutron stars and white dwarfs--are the ashes of luminous stars. One or the other is the fate that awaits the cores of most stars after a lifetime of tens to thousands of millions of years. Whichever of these objects is formed at the end of the life of a particular luminous star, the compact object will live in many respects unchanged from the state in which it was formed. Neutron stars themselves can take several forms--hyperon, hybrid, or strange quark star. Likewise white dwarfs take different forms though only in the dominant nuclear species. A black hole is probably the fate of the most massive stars, an inaccessible region of spacetime into which the entire star, ashes and all, falls at the end of the luminous phase. Neutron stars are the smallest, densest stars known. Like all stars, neutron stars rotate--some as many as a few hundred times a second. A star rotating at such a rate will experience an enormous centrifugal force that must be balanced by gravity or else it will be ripped apart. The balance of the two forces informs us of the lower limit on the stellar density. Neutron stars are 10{sup 14} times denser than Earth. Some neutron stars are in binary orbit with a companion. Application of orbital mechanics allows an assessment of masses in some cases. The mass of a neutron star is typically 1.5 solar masses. They can therefore infer their radii: about ten kilometers. Into such a small object, the entire mass of our sun and more, is compressed.

  19. Stellar laboratories. III. New Ba v, Ba vi, and Ba vii oscillator strengths and the barium abundance in the hot white dwarfs G191-B2B and RE 0503-289

    Science.gov (United States)

    Rauch, T.; Werner, K.; Quinet, P.; Kruk, J. W.

    2014-06-01

    Context. For the spectral analysis of high-resolution and high-signal-to-noise (S/N) spectra of hot stars, state-of-the-art non-local thermodynamic equilibrium (NLTE) model atmospheres are mandatory. These are strongly dependent on the reliability of the atomic data that is used for their calculation. Aims: Reliable Ba v-vii oscillator strengths are used to identify Ba lines in the spectra of the DA-type white dwarf G191-B2B and the DO-type white dwarf RE 0503-289 and to determine their photospheric Ba abundances. Methods: We newly calculated Ba v-vii oscillator strengths to consider their radiative and collisional bound-bound transitions in detail in our NLTE stellar-atmosphere models for the analysis of Ba lines exhibited in high-resolution and high-S/N UV observations of G191-B2B and RE 0503-289. Results: For the first time, we identified highly ionized Ba in the spectra of hot white dwarfs. We detected Ba vi and Ba vii lines in the Far Ultraviolet Spectroscopic Explorer (FUSE) spectrum of RE 0503-289. The Ba vi/Ba vii ionization equilibrium is well reproduced with the previously determined effective temperature of 70 000 K and surface gravity of log g = 7.5. The Ba abundance is 3.5 ± 0.5 × 10-4 (mass fraction, about 23 000 times the solar value). In the FUSE spectrum of G191-B2B, we identified the strongest Ba vii line (at 993.41 Å) only, and determined a Ba abundance of 4.0 ± 0.5 × 10-6 (about 265 times solar). Conclusions: Reliable measurements and calculations of atomic data are a pre-requisite for stellar-atmosphere modeling. Observed Ba vi-vii line profiles in two white dwarfs' (G191-B2B and RE 0503-289) far-ultraviolet spectra were well reproduced with our newly calculated oscillator strengths. This allowed to determine the photospheric Ba abundance of these two stars precisely. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for

  20. Thomas Hinsley Astbury: from an English market town schoolroom to the internal constitution of the stars

    CERN Document Server

    Shears, Jeremy

    2012-01-01

    T. H. Astbury (1858-1922) was for many years the much-respected headmaster of a boys' junior school in the English market town of Wallingford. By night he was a dedicated amateur astronomer who enjoyed observing meteors, variable stars and many other objects. He began to search few new variable stars, his first discovery being the bright Cepheid variable, RT Aurigae. This, along with his discovery of 4 other variable stars, brought him to attention of some of the most famous professional astronomers of the age, including Herbert Hall Turner, Frank Dyson and Arthur Eddington.