A ROSAT Survey of Contact Binary Stars

Abstract

Contact binary stars are common variable stars which are all believed to emit relatively large fluxes of x-rays. In this work we combine a large new sample of contact binary stars derived from the ROTSE-I telescope with x-ray data from the ROSAT All-Sky Survey (RASS) to estimate the x-ray volume emissivity of contact binary stars in the galaxy. We obtained x-ray fluxes for 140 contact binaries from the RASS, as well as 2 additional stars observed by the XMM-Newton observatory. From these data we confirm the emission of x-rays from all contact binary systems, with typical luminosities of approximately 1.0 x 10^30 erg s^-1. Combining calculated luminosities with an estimated contact binary space density, we find that contact binaries do not have strong enough x-ray emission to account for a significant portion of the galactic x-ray background.

19 pages, 5 figures, accepted by AJ

References in corpus (4)

• Wide-field millimagnitude photometry with HAT: A Tool for Extra-solar Planet Detection
• Northern Sky Variability Survey (NSVS): Public data release
• A Catalog of 1022 Bright Contact Binary Stars
• The 7.5 Magnitude Limit Sample of Bright Short-Period Binary Stars. I. How Many Contact Binaries Are There?

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• Astrophysics in 2006
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• Classification of low-luminosity stellar X-ray sources in the field of the Draco dwarf spheroidal galaxy