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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.
| New identifications for blue objects towards the Galactic center: post-AGB stars, Be/disk stars and others
As part of a programme to investigate spatial variations in the Galacticchemical composition, we have been searching for normal B-type stars andA-type supergiants near the Galactic center. During this search we havefound eleven peculiar stars, and in some cases performed detailedabundance analyses of them which suggest that they may be at a post-AGBevolutionary stage. The A-type post-AGB candidates show [Fe/H]=-1.0 to-2.0, and [O/Fe] ~ +1.4, typical of the post-AGB abundance patternsdiscussed in the literature. One star, LS 3591 (=SAO 243756), has alsobeen examined recently by Oudmaijer (1996); its spectrum appears to bechanging very rapidly, which may indicate erratic mass loss or theincipient formation of a planetary nebula. A B-type post-AGB candidate,LS 4950, has a similar spectrum to a well studied post-AGB star, LSIV-12 111. However, an examination of the line strengths and elementalabundances of LS 4950 show that it is peculiar for both a Population II,post-AGB, B-type star and for a normal, Population I, B-type supergiant.Two other B-type stars, LS 4825 and LS 5112, are either post-AGB starsnear the Galactic center or normal B-type supergiants lying well beyondthe Galactic center. In addition, several Be-type stars have been newly(or more clearly) identified from our spectra. Tables 12, 13, 14, 15 andAppendices A,B are only available in electronic form at CDS viaanonymous ftp to: cdsarc.u-strasbg.fr(130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| 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.
| A spectroscopic database for Stephenson-Sanduleak Southern Luminous Stars
A database of published spectral classifications for objects in theStepenson-Sanduleak Luminous Stars in the Southern Milky Way catalog hasbeen compiled from the literature. A total of 6182 classifications for2562 stars from 139 sources are incorporated.
| The calibration of the Stromgren photometric system for A, F and early G supergiants. I - The observational data
An empirical calibration of the Stromgren uvby-beta photometric systemfor the A, F, and early G supergiants is being derived. This paperexplains the observational program and the photometric reductiontechniques used and presents a catalog of new Stromgren photometry forover 600 A, F, and G supergiants.
| UBV-/H-beta/ photometry of luminous stars between L equals 335 deg and L equals 6 deg
Results are reported for photoelectric UBV and H-beta photometry of 316luminous OB stars and early-type supergiants in the region between 335and 6 deg galactic longitude. UBV magnitudes for the 316 stars and betaindexes for 37 of them are presented. Absolute magnitudes, distances,and color excesses are determined for the 161 stars with measured betaindexes or known MK spectral types. The results are discussed in termsof the spiral structure of the Galaxy. From the data obtained forprogram stars assumed to be cluster members, distances are derived forthe open clusters NGC 6167 (1.7 kpc), NGC 6193 (1.3 kpc), Hogg 22 (2.0kpc), NGC 6231 (1.9 kpc), and Tr 27 (1.6 kpc).
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| Takýmyýldýz: | Akrep |
| Sað Açýklýk: | 17h39m28.84s |
| Yükselim: | -37°21'52.7" |
| Görünürdeki Parlaklýk: | 8.45 |
| Uzaklýk: | 763.359 parsek |
| özdevim Sað Açýklýk: | -0.1 |
| özdevim Yükselim: | -2.4 |
| B-T magnitude: | 9.518 |
| V-T magnitude: | 8.539 |
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