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R. B. Hindsley (Naval Research Laboratory), V. V. Makarov (USRA/USNO), G. Torres (Harvard-Smithsonian Center for Astrophysics)
We have cross-referenced X-ray sources in the ROSAT All-Sky Survey Bright Source Catalog (RASS-BSC; Voges et al. 1999) and the Faint Source Catalog (RASS-FSC; Voges et al. 2000) with binary and multiple systems collected in the Tycho Double Star Catalogue (TDSC; Fabricius et al.2001) and with common proper motion (CPM) pairs found by us in the Tycho-2 catalog (H{ø}g et al. 2000). We consider only those likely physical pairs that could be resolved by the PSPC instrument of ROSAT, that is, with separations larger than 3 angular resolution limits. There are some 200 pairs in the TDSC for which one or both stars are X-ray emitters, and some 70 more wide CPM pairs. Only 8 pairs have both components detected by ROSAT (X-X pairs), while the rest have only one component detected, either primary (X-O) or secondary (O-X). It is found for the X-X pairs that most of the bluer components are harder in X-ray, similar to the result for T Tauri stars in Taurus (König et al. 2001). Primaries are often stronger sources, but not always. Most of the X components are solar type or later, with a few notable exceptions. We make a first attempt to investigate the nature of X-ray emission in field wide binaries, and see if their radiation characteristics comply with the X-ray luminosity function (XLF) in Galactic clusters and star forming regions.
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Bulletin of the American Astronomical Society, 34, #4
© 2002. The American Astronomical Soceity.