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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.
| 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.
| 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.
| The warped distribution of young stars in the southern Milky Way
From a sample presented by Reed containing OB stars with a heliocentricdistance greater than 5kpc, we have selected those stars with agalactocentric azimuth between 240 deg and 275 deg, i.e. in the regionof the maximum warp in the southern hemisphere. Only nine stars havethese characteristics, but they permit a first, unambiguous detection ofthe southern stellar warp in the Milky Way. This seems to be as large asthe gaseous warp, and does not present evidence of twisting of the lineof nodes. Flaring of the stellar distribution with respect to thecentroid of the HI warp is also noticeable.
| Distant (r greater than 5 kpc) OB stars in the galaxy
Distances and reddenings have been computed from UBV Beta photometry for1042 stars in the Stephenson and Sanduleak (1971) Catalog of LuminousStars in the Southern Milky Way ('LS' Catalog). The local spiral featureis likely a continuous feature toward Puppis at l approximately equals240 deg, and the Carina feature apparently extends to a distance of some10 kpc from the Sun. Detailed information is presented for 73 LS starsthat appear to be at least 5 kpc from the Sun. Of these, three (LS 1329,2419, and 2598) are close to 1.5 kpc below the galactic plane, and one,LS 607, may be ideally suited as a distant rotation-curve point.Radial-velocity and spectroscopic data would be valuable for theseobjects.
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