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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.
| BVR Photometry of Northern Galactic Plane Luminous Stars
CCD-based BVR photometry of 90 stars listed in Volumes II, III, and IVof the Case-Hamburg Catalog of Luminous Stars in the Northern Milky Wayis reported. This research was performed at the Lowell Observatory 31inch telescope, which, under an agreement with Northern ArizonaUniversity and the NURO Consortium, is operated 60% of the time as theNational Undergraduate Research Observatory.
| 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.
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Gözlemler ve gökölçümü verileri
| Takýmyýldýz: | Yilan |
| Sað Açýklýk: | 18h00m26.84s |
| Yükselim: | -12°59'17.2" |
| Görünürdeki Parlaklýk: | 7.442 |
| Uzaklýk: | 1639.344 parsek |
| özdevim Sað Açýklýk: | -0.6 |
| özdevim Yükselim: | -9.2 |
| B-T magnitude: | 7.79 |
| V-T magnitude: | 7.471 |
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