An explanation of observed trends in the X-ray emission from single Wolf-Rayet stars

The O and early B star winds show empirical correlations between X-ray (L-x ) and Bolometric (L-Bol) luminosity as well as wind properties such as wind momentum and wind kinetic energy. Wolf-Rayet stars do not. We discuss scal ing relations to qualitatively explain this lack of correlation among the W R winds and to quantitatively reproduce the observed ratio of X-ray luminos ities between the N-rich WN types and C-rich WC types. If (a) the filling f actor of hot X-ray emitting gas varies as ((M)over dot/v(infinity))(-1) for stars of different mass loss and terminal speed and (b) the ambient Wolf-R ayet wind component is optically thick to the hut gas X-rays, then a lack o f correlation between L-x and wind parameters is to be expected. The emerge nt X-ray emission then depends only on factors relating to relative abundan ces and ionization. The observed ratio L-X(WN)/L-X(WC) is consistent with o ur scaling analysis using typical WN and WC abundances.