XMM-Newton X-Ray Observations of the Unusual Wolf–Rayet Star WR 66

Abstract

Abstract We summarize results of an XMM-Newton X-ray observation of the WN8h-type Wolf–Rayet star WR 66 which shows unusual 3.5–4.1 hr optical variations. One possible explanation is a compact companion (cc) which, if present, could give rise to luminous X-ray emission. WR 66 was marginally detected and its inferred X-ray luminosity (L x ) is orders of magnitude below that expected from wind accretion onto a neutron star, but is comparable to that of the WN8h stars WR 16 and WR 124. If luminous X-ray emission from an accreting WR+cc system is present then it is absorbed and escapes detection. Other explanations of the faintly detected X-ray emission of WN8h stars are not ruled out.