X-ray survey of Wolf-Rayet stars in the Magellanic Clouds
Abstract
Systematic X-ray surveys of Wolf-Rayet (WR) stars in our Galaxy are hampered by the heavy obscuration in the Galactic plane, which prohibits the detections of WR stars, and by the uncertain distances to individual WR stars, which result in poorly determined luminosities. These problems are mitigated in the Large and Small Magellanic Clouds (MCs), because foreground and internal extinctions are small and distances are known. We have used archival Chandra ACIS and ROSAT PSPC and HRI observations of 128 WR stars in the MCs to search for X-ray emission from these stars. About 25 per cent of the WR stars in this sample are detected with X-ray luminosities in the range 2×1032-2×1035 ergs s-1. The X-ray spectral analysis of the brightest WR stars reveals large absorption columns and high temperatures, similar to those seen in sources with colliding winds. The colliding-wind origin of the X-ray emission is further supported by the higher frequency of X-ray detections among WR stars in binary systems and by their higher X-ray luminosities compared to those of single WR stars. Among single WR stars, X-ray emission is mostly detected in WN6 stars, while single WC stars are not detected.
- Publication:
-
Massive Stars and High-Energy Emission in OB Associations
- Pub Date:
- November 2005
- Bibcode:
- 2005mshe.work...13G