Ýçindekiler
Görüntüler
Resim Yükleyin
DSS Images Other Images
Ýlgili Makaleler
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 optical positions and proper motions of late type stars associated with SiO masers
The 33 cm astrograph of the Bordeaux Observatory has been used to derivewith respect to AGK3 reference stars, accurate positions of late typevariable stars variable stars associated with strong SiO maser emission.It is suggested that selected maser stars can be used to link theHIPPARCOS system and the VLBI extragalactic reference frame. The propermotions of the program (SiO) and reference stars are derived and, forthe program stars, are compared to the McCormick catalog of propermotions.
| UBV photometry for southern OB stars
New UBV photometry of 1227 OB stars in the southern Milky Way ispresented. For 1113 of these stars, MK spectral types have been reportedpreviously in a comprehensive survey to B = 10.0 mag.
| On the 4430 A interstellar band - A visual classification
A system of visual classification of the strength of the interstellarband 4430 A has been developed, based on spectra taken at spectralclassification dispersion. The intensity of the band was divided into 8main classes, defined by a group of selected standard stars. The systemwas applied to 1,111 southern OB stars contained in the catalog ofspectral types by Garrison, Hiltner, and Schild (1977). The mean errorin the classification was estimated to be plus or minus 1 class.Equivalent widths were measured for 100 stars; an excellent correlationwith the visual estimations was obtained. A calibration between thesetwo parameters is given.
| 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
|
Yeni bir Makale Öner
Ýlgili Baðlantýlar
Yeni Bir Baðlantý Öner
sonraki gruplarýn üyesi:
|
Gözlemler ve gökölçümü verileri
| Takýmyýldýz: | Buyuk Kopek |
| Sað Açýklýk: | 07h23m02.78s |
| Yükselim: | -25°31'17.0" |
| Görünürdeki Parlaklýk: | 9.232 |
| özdevim Sað Açýklýk: | -6.9 |
| özdevim Yükselim: | 2 |
| B-T magnitude: | 9.516 |
| V-T magnitude: | 9.256 |
Kataloglar ve belirtme:
|
