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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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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The distribution of neutral hydrogen in the interstellar medium. 1: The data
We compile, from the existing literature, the largest sample to date(842 data points) of hydrogen column density measurements, N(H I), ofthe gas in the interstellar medium. We include only results obtainedfrom absorption measurements toward individual stars (594 in our sample)in an effort to construct a three-dimensional picture of theinterstellar gas. We derive hydrogen column densities toward a fractionof the stars in the sample from published column density measurements ofmetal ions. A three-dimensional physical model derived from this dataset will be presented in a companion paper. The observed stars spandistances from a few parsecs to a few thousand parsecs, and more thanhalf of the sample serves to describe the local interstellar mediumwithin a few hundred parsecs of the Sun. Hydrogen column densities rangefrom 1017 to 1022/sq cm. We describe here thevarious observational methods used to estimate the hydrogen columndensities and present the table with the stellar and hydrogen columndensity data. The provided table is intended as a global reference work,not to introduce new results.
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X-ray emission from hybrid-chromosphere stars
The observations of hybrid stars made by the Exosat X-ray satellite areconsidered, and emphasis is placed on the hybrid star alpha TrA.Attention is focused on the determination of the column density of IShydrogen toward the stars in order to interpret X-ray observations ofstellar coronal emission. The coronal properties of alpha TrA arediscussed as well as implications of the general coronal properties ofhybrid stars. An analysis of the X-ray data, in conjunction withtransition region properties of the star, shows that the X-ray emittingplasma is likely to have a temperature of at least 10 to the 6th K. TheX-ray luminosity of the star is calculated to be about 5 x 10 to the29th ergs/s over the 1-300 A spectral region and 7 x 10 to the 28thergs/s in the 0.2-4 keV energy range for N(H) = 5 x 10 to the 19th /sqcm and a temperature of 10 to the 6th K.
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Empirical temperature calibrations for early-type stars
Three temperature calibrations of suitable photometric quantities havebeen derived for O and B stars. A sample of 120 stars with reliableT(eff.) determinations has been used for establishing each calibration.The different calibrations have been critically discussed and compared.Temperature determinations for 1009 program stars have been obtainedwith an accuracy of the order of 10 percent.
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On the origin of intermediate-latitude OB stars
An attempt is made to trace the origin of early-type stars observed atappreciable distances from the galactic plane. Because uncertainties inthe proper motions make space motions and hence dynamical lifetimesrather inaccurate, a theory of oscillations normal to the plane has beenused to compute radial velocities for 138 intermediate-latitude OBstars. These theoretical values are then compared with the observedradial velocities, and it is found that the low-velocity stars wereprobably ejected from the plane some time after formation, while thehigh-velocity stars were ejected very soon after formation. Velocitiesof ejection perpendicular to the plane are computed and show a narrowdistribution with a mean absolute value of 7 km/s together with a spreadof velocities from about 40 to over 200 km/s. The data are in reasonableagreement with a 'sling' effect and 'runaway' origin for the stars inthe sample.
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H-beta photometry of southern early-type stars and galactic structure away from the plane
H-beta photoelectric photometry is reported for 165 early-type stars atintermediate and high galactic latitudes. The data are combined withearlier UBV and spectroscopic results to determine the stellar spacedistribution. Stars of type B2 and earlier, at distances of up to 1 kpcfrom the galactic plane, appear to follow spiral structure in the plane.The available material, particularly the derived color excesses, is usedto select a number of blue stars which may be subluminous.
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Equivalent widths and rotational velocities of southern early-type stars
Not Available
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UBV photometry of southern early-type stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1974MNRAS.168..451H&db_key=AST
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Radial velocities of Southern B stars determined at the Radcliffe Observatory.
Not Available
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INHABITED SKY
