Abstract

Moffat Clumps as the Source of X-rays from Single Wolf-Rayet Stars

Kenneth Gayley (Univ. of Iowa)

Wolf-Rayet stars in colliding-wind binaries can produce X-ray spectra that are surprisingly similar to putatively single Wolf-Rayet stars. At first it was suggested this may be because wind-wind collisions are less efficient at making X-rays than originally thought. Recently the opposite explanation has been offered, that all X-rays from Wolf-Rayet winds might be from wind collisions, perhaps involving unseen companions. Here I consider the possibility that single and binary Wolf-Rayet winds have separate identities as X-ray sources, but the spectra have similar attributes because both involve a non-negligible fraction of the wind passing through ~1000 km/s shocks at fairly large distances from the star. In the case of single Wolf-Rayet stars, the presence of the shocks may involve encounters with the slowest accelerating tail of a distribution of Moffat clumps.