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Common Proper Motion Search for Faint Companions Around Early-Type Field Stars – Progress Report

Huélamo, N.; Foellmi, C.; Chauvin, G. +5 more

The multiplicity of early-type stars is still not well established. The derived binary fraction is different for individual star forming regions, suggesting a connection with the age and the environment conditions. The few studies that have investigated this connection do not provide conclusive results. To fill in this gap, we started the first de…

Absolute Magnitudes of Be Stars Based on Hipparcos Parallaxes

Zhang, P.; Chen, P. S.; Liu, C. Q.

The absolute visual magnitudes of 457 Be stars are determined from Hipparcos parallaxes, subsequently the mean absolute visual magnitudes of Be stars for luminosity classes III, IV and V are obtained. The new Mv calibration is compared with existing calibrations. It is found that Be stars are generally brighter than B stars of the corresponding sp…

Dense Spot Coverage and Polar Caps on SV Cam

Jeffers, S. V.; Barnes, J. R.; Aufdenberg, J. P. +1 more

We have used spectrophotometric data from nine Hubble Space Telescope orbits to eclipse-map the primary component of the RS CVn binary SV Cam. From these observations and its HIPPARCOS parallax we find that the surface flux in the eclipsed low-latitude region is about 30 % lower than computed from the best fitting PHOENIX model atmosphere. This fl…

Late-type X-ray Emitting Binaries in the Solar Neighborhood and in Star Forming Regions

Alcalá, Juan M.; Covino, Elvira; Frasca, Antonio +3 more

We present a spectroscopic and photometric follow-up of binary stars, discovered in a sample of X-ray sources, aimed at a deep characterization of the stellar X-ray population in the solar neighborhood and in Star Forming Regions (SFRs). The sources have been selected from the RasTyc sample, obtained by the cross-correlation between the ROSAT all-…

The Spatial Distribution of W UMa-Type Stars

Ogloza, Waldemar; Zakrzewski, Bartlomiej

The aim of this project is to study the spatial distribution of contact binaries and to compare the sample from the project of study the W UMa-type stars, with existing databases such as Hipparcos, GCVS or ASAS (ESA, 1997; GCVS, 2005; Pojmanski, 2002).