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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.
| CCD photometry and astrometry for visual double and multiple stars of the HIPPARCOS catalogue III. CCD photometry and differential astrometry for 253 southern ``intermediate'' systems
We present new astrometric and photometric data for 253 visual doublestars of the ``intermediate'' class, i.e. with angular separations inthe range 1 to 15 arcsec. The multi-colour observations were obtained in1992-94 as part of the ESO Key Programme ``Visual Double Stars''performed at La Silla Observatory (Chile). Differential magnitudes andcolours have been secured in a systematic way while component magnitudesand colour indices have been determined in the V and I passbands of theCousins standard system in good photometric conditions only. Internaland mean external errors are smaller than respectively 0.01 mag and afew hundreths of a magnitude (typically less than 0.03 mag). Relativepositions are obtained as a by-product with internal errors of the orderof 0.006 arcsec in angular separation (corresponding to pixel width x0.02) and 0.07 degr in position angle. Final accuracies are thoroughlydiscussed: we illustrate the overall excellent quality of the data andestimate the quality degradation for angular separations barely largerthan the width of the seeing disk. Based on observations made at LaSilla (ESO, Chile, Key Programme 7-009-49K).
| MK spectral classifications for southern OB stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1977ApJS...35..111G&db_key=AST
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Osservazione e dati astrometrici
| Costellazione: | Scorpione |
| Ascensione retta: | 17h30m39.43s |
| Declinazione: | -43°03'42.5" |
| Magnitudine apparente: | 8.834 |
| Distanza: | 10000000 parsec |
| Moto proprio RA: | 0.4 |
| Moto proprio Dec: | -17.2 |
| B-T magnitude: | 8.844 |
| V-T magnitude: | 8.835 |
Cataloghi e designazioni:
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