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UBVRI polarimetry of the massive interacting binary SX Cassiopeiae: modeling the electron-scattering circumstellar envelope
Aims.We perform a study of the structure, density, and distribution ofionized circumstellar gas in the strongly interacting binary SX Cas. Methods: .We apply our new model codes for electron scattering incircumstellar matter to analyze a previously unpublished, extensivelinear polarization data set for SX Cas, collected during foursuccessive observing periods in 1981-84 at the Crimean AstrophysicalObservatory. These data are complemented by our polarizationobservations carried out in 2000 and 2005 with the KVA-60 telescope atLa Palma. Results: .A clear, phase-locked pattern of polarizationvariations over the 36.6-day orbital period is revealed in each season,showing significant 1st and 2nd harmonic Fourier components andpronounced effects in the U and B bands at the primary eclipse, when thehot component and the surrounding circumstellar matter are obscured bythe companion star. Seasonal variability is also found, but the majorfeatures of the polarization curves are well explained by a model withan extended scattering region on the trailing side of the accretingstar, where the stream from the companion hits the accretion disk. Nosignificant polarized flux is detected from the disk. We interpret thisas being due to multiple scattering and strong absorption effects in theoptically thick medium, which reduce the polarization of the lightemerging from the disk to low levels. The modeled scattering region isabove the orbital plane by about 10°, as seen from the center of themass gainer. We attribute this to dominant electron scattering takingplace on the upper side of an optically and geometrically thickaccretion disk seen at an inclination i ˜ 78° by theobserver.
| 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.
| Vitesses radiales. Catalogue WEB: Wilson Evans Batten. Subtittle: Radial velocities: The Wilson-Evans-Batten catalogue.
We give a common version of the two catalogues of Mean Radial Velocitiesby Wilson (1963) and Evans (1978) to which we have added the catalogueof spectroscopic binary systems (Batten et al. 1989). For each star,when possible, we give: 1) an acronym to enter SIMBAD (Set ofIdentifications Measurements and Bibliography for Astronomical Data) ofthe CDS (Centre de Donnees Astronomiques de Strasbourg). 2) the numberHIC of the HIPPARCOS catalogue (Turon 1992). 3) the CCDM number(Catalogue des Composantes des etoiles Doubles et Multiples) byDommanget & Nys (1994). For the cluster stars, a precise study hasbeen done, on the identificator numbers. Numerous remarks point out theproblems we have had to deal with.
| Optical observations of ultraviolet objects. II - Classification and photometry /l = 0 to 145 deg/
UBV photometry and MK spectral classification are presented for a sampleof stars originally selected as UV objects from satellite photometrywith the S2/68 experiment. Although most stars of the sample arespectroscopically normal, a number of hot, subluminous stars were alsofound. Radial velocities are given for some of the stars observed. It isproposed that the majority of the apparently normal early B stars athigh galactic latitudes which are not runaway stars are subluminousdisc-population analogues of horizontal branch B stars of Population II.
| Luminous stars in a region south of h and chi Persei. With 3 Figures in the Text
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| Takýmyýldýz: | Zincirli Prenses |
| Sað Açýklýk: | 00h13m46.21s |
| Yükselim: | +54°27'52.5" |
| Görünürdeki Parlaklýk: | 8.726 |
| Uzaklýk: | 684.932 parsek |
| özdevim Sað Açýklýk: | -4.4 |
| özdevim Yükselim: | -2.9 |
| B-T magnitude: | 8.587 |
| V-T magnitude: | 8.715 |
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