A systematic study of variability among OB-stars based on HIPPARCOS photometry
Context: Variability is a key factor for understanding the nature of themost massive stars, the OB stars. Such stars lie closest to the unstableupper limit of star formation. Aims: In terms of statistics, thedata from the HIPPARCOS satellite are unique because of time coverageand uniformity. They are ideal to study variability in this large,uniform sample of OB stars. Methods: We used statisticaltechniques to determine an independant threshold of variabilitycorresponding to our sample of OB stars, and then applied an automaticalgorithm to search for periods in the data of stars that are locatedabove this threshold. We separated the sample stars into 4 maincategories of variability: 3 intrinsic and 1 extrinsic. The intrinsiccategories are: OB main sequence stars (~2/3 of the sample), OBe stars(~10%) and OB Supergiant stars (~1/4).The extrinsic category refers toeclipsing binaries. Results: We classified about 30% of the wholesample as variable, although the fraction depends on magnitude level dueto instrumental limitations. OBe stars tend to be much more variable(≈80%) than the average sample star, while OBMS stars are belowaverage and OBSG stars are average. Types of variables include αCyg, β Cep, slowly pulsating stars and other types from the generalcatalog of variable stars. As for eclipsing binaries, there arerelatively more contact than detached systems among the OBMS and OBestars, and about equal numbers among OBSG stars.
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Pulkovo compilation of radial velocities for 35495 stars in a common system.
Not Available
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New Estimates of the Solar-Neighborhood Massive Star Birthrate and the Galactic Supernova Rate
The birthrate of stars of masses >=10 Msolar is estimatedfrom a sample of just over 400 O3-B2 dwarfs within 1.5 kpc of the Sunand the result extrapolated to estimate the Galactic supernova ratecontributed by such stars. The solar-neighborhood Galactic-plane massivestar birthrate is estimated at ~176 stars kpc-3Myr-1. On the basis of a model in which the Galactic stellardensity distribution comprises a ``disk+central hole'' like that of thedust infrared emission (as proposed by Drimmel and Spergel), theGalactic supernova rate is estimated at probably not less than ~1 normore than ~2 per century and the number of O3-B2 dwarfs within the solarcircle at ~200,000.
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Catalog of Galactic OB Stars
An all-sky catalog of Galactic OB stars has been created by extendingthe Case-Hamburg Galactic plane luminous-stars surveys to include 5500additional objects drawn from the literature. This work brings the totalnumber of known or reasonably suspected OB stars to over 16,000.Companion databases of UBVβ photometry and MK classifications forthese objects include nearly 30,000 and 20,000 entries, respectively.
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The 74th Special Name-list of Variable Stars
We present the Name-list introducing GCVS names for 3153 variable starsdiscovered by the Hipparcos mission.
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UBV beta Database for Case-Hamburg Northern and Southern Luminous Stars
A database of photoelectric UBV beta photometry for stars listed in theCase-Hamburg northern and southern Milky Way luminous stars surveys hasbeen compiled from the original research literature. Consisting of over16,000 observations of some 7300 stars from over 500 sources, thisdatabase constitutes the most complete compilation of such photometryavailable for intrinsically luminous stars around the Galactic plane.Over 5000 stars listed in the Case-Hamburg surveys still lackfundamental photometric data.
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Accurate Two-dimensional Classification of Stellar Spectra with Artificial Neural Networks
We present a solution to the long-standing problem of automaticallyclassifying stellar spectra of all temperature and luminosity classeswith the accuracy shown by expert human classifiers. We use the 15Angstroms resolution near-infrared spectral classification systemdescribed by Torres-Dodgen & Weaver in 1993. Using the spectrum withno manual intervention except wavelength registration, artificial neuralnetworks (ANNs) can classify these spectra with Morgan-Keenan types withan accuracy comparable to that obtained by human experts using 2Angstroms resolution blue spectra, which is about 0.5 types (subclasses)in temperature and about 0.25 classes in luminosity. Accuratetemperature classification requires a hierarchy of ANNs, whileluminosity classification is most successful with a single ANN. Wepropose an architecture for a fully automatic classification system.
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Vitesses radiales. Catalogue WEB: Wilson Evans Batten. Subtittle: Radial velocities: The Wilson-Evans-Batten catalogue.
We give a common version of the two catalogues of Mean Radial Velocitiesby Wilson (1963) and Evans (1978) to which we have added the catalogueof spectroscopic binary systems (Batten et al. 1989). For each star,when possible, we give: 1) an acronym to enter SIMBAD (Set ofIdentifications Measurements and Bibliography for Astronomical Data) ofthe CDS (Centre de Donnees Astronomiques de Strasbourg). 2) the numberHIC of the HIPPARCOS catalogue (Turon 1992). 3) the CCDM number(Catalogue des Composantes des etoiles Doubles et Multiples) byDommanget & Nys (1994). For the cluster stars, a precise study hasbeen done, on the identificator numbers. Numerous remarks point out theproblems we have had to deal with.
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Extinction law survey based on UV ANS photometry
The paper presents an extensive survey of interstellar extinction curvesderived from the ANS photometric measurements of early type starsbelonging to our Galaxy. This survey is more extensive and deeper thanany other one, based on spectral data. The UV color excesses aredetermined with the aid of 'artificial standards', a new techniqueproposed by the authors which allows the special check of Sp/L match ofa target and the selected standard. The results indicate that extinctionlaw changes from place to place.
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Absolute magnitudes of B emission line stars - Correlation between the luminosity excess and the effective temperature
A new determination of the visual absolute magnitude of Be stars iscarried out. For this, a new calibration of visual absolute magnitudesof B stars of luminosity classes, V, IV, and III is first obtained froma sample of 215 stars. The absolute luminosity excess in the visual isdetermined for a sample of 49 Be stars. It is found that this excess iscorrelated with the effective temperature of the underlying stars. Awell defined correlation between this excess and the emission in thefirst two Balmer lines is established. From these results, using asimple model of circumstellar envelope, it is inferred that the zones ofthe circumstellar envelope contributing to the emission in the continuumand in the lines have to be rather small. It is also deduced that theemission measure of the envelope is correlated with the temperature ofthe central star and that the irregular photometric variations of Bestars are an envelope-opacity phenomenon.
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The interstellar 217 NM band - A third catalogue of equivalent widths
A catalog of equivalent widths of the 217 nm interstellar absorptionband as well as other parameters characterizing the extinction curve inthe ultraviolet has been compiled for 790 O and B stars. A relativelytight correlation between the equivalent width of the 217 nm band andE(B-V) indicates that the absorber of this band is connected with thepopulation of larger interstellar grains responsible for the visualextinction. The parameter characterizing the amount of extinction in thefar UV is only weakly correlated with E(B-V), a result in accord withthe assumption that a second population of very small grains causes therapid increase of the far-UV extinction.
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Catalog of O-B stars observed with Tokyo Meridian Circle
A catalog of the O-B stars, selected from 'Blaauw-Parenago' list andRubin's catalog, has been compiled on the FK4 system by the observationsmade with Gautier 8-inch Meridian Circle at the Tokyo AstronomicalObservatory during the period, 1971 to 1979. It contains 1059 stars andwas compiled for the future establishment of high precision propermotions of O-B stars.
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Studies of luminous stars in nearby galaxies. I. Supergiants and O stars in the Milky Way.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1978ApJS...38..309H&db_key=AST
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Observations of diffuse interstellar features in the spectra of dust-embedded and field stars.
Abstract image available at:http://adsabs.harvard.edu/abs/1973A&A....26...17B
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La classification stellaire BCD : parametre caracteristique DU type spectral calibration EN magnitudes absolues.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1973A&A....23...69C&db_key=AST
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Photometric data for 139 supergiants.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1972AJ.....77..150F&db_key=AST
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A Comparison of the Luminosities of Perseus-Arm Stars in the Hγ and MK Systems
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1972ApJ...171..285C&db_key=AST
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Photoelectric measurements of the 6284 Angstroms diffuse interstellarline.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1972MNRAS.157..461M&db_key=AST
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Some Spectroscopic Characteristics of the OB Stars: an Investigation of the Space Distribution of Certain OB Stars and the Reference Frame of the Classification
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1971ApJS...23..257W&db_key=AST
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The space distribution and kinematics of supergiants
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1970AJ.....75..602H&db_key=AST
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Catalogue d'etoiles O et B.
Not Available
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Photoelectric 4430 A observations of 506 O, B and A stars.
Not Available
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Photoelectric observations of the intensity of the 4430 band in 147 O, B, and A stars in the Northern Milky Way.
Not Available
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Photoelectric observations of the intensity of the 4430 band in 147 O,B, and A stars in the Northern Milky Way
Not Available
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Troisième catalogue de l'Observatoire de Besançon comprenant 764 étoiles réduites à 1950, 0 sans mouvement propre et 326 étoiles FK3 pour l'époque moyenne d'observation
Not Available
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Stellar Radial Velocities in the Perseus Arm.
Abstract image available at:http://adsabs.harvard.edu/abs/1963ApJ...138.1002A
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Comparison of radial velocities of the OB-stars and Cepheids in the Perseus arm
Not Available
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Color Excesses from Six-Color Photometry of Supergiant Stars
Not Available
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Interstellar Absorption Lines in Distant Stars. I. Northern Milky way.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1957ApJ...125...42M&db_key=AST
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Six-color photometry of stars. VIII. The colors of 409 stars of different spectral types
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1956ApJ...123..440S&db_key=AST
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INHABITED SKY
