ON WINDS AND X-RAYS OF O-TYPE STARS

We investigate dependences between stellar wind and X-ray properties of the O-type stars. New IUE-based mass-loss rates and wind terminal velocities are obtained for 40 well-known, bright single stars or binaries. There is no evidence for enhanced mass loss from the binaries compared with the single stars. We suggest that a weak dependence between L(x) and M-upsilon-infinity found here for single stars at least partially accounts for the observed proportionality between L(x) and L(bol). Very tight, detached, massive binaries with kinetic energy of the wind exceeding 3 x 10(35) ergs s-1 (\M\ > 10(-7) M. yr-1) generate an excess X-ray flux which is in a qualitative agreement with simple theories of colliding stellar winds.