PHOTOMETRIC-DETERMINATION OF ORBITAL INCLINATIONS AND MASS-LOSS RATESFOR WOLF-RAYET STARS IN WR+O BINARIES

We analyze the atmospheric ''eclipse'' light curves of all 13 short-pe riod (P<30(d)) Galactic binary WR+O systems with solved orbits, exclud ing the 3 known photospheric eclipsers. Some of the light curves are b ased on newly obtained data; others are taken from the literature. Mos t of the 13 WR+O systems show V-shaped dips in their light curves. Whe n accurate orbital ephemerides are available, maximum light attenuatio n is reached when the O star passes farthest behind the WR star. The d ips can be explained by phase-dependent electron scattering opacity of O-star light by WR-wind material, which to good approximation can be assumed to be expanding spherically symmetrically from the WR star, as the O star orbits. A simple model is derived for the light curves, wh ose shapes lead to an estimate of the orbital inclinations. The values obtained agree reasonably well with those from polarimetry or from co mpanion spectra. For a given orbit and inclination, the depth of the d ip leads to an estimate for the mass loss rate of the WR star. We deri ve masses and mass loss rates, based on photometry, for i and M and sp ectroscopy for M sin(3)i, for most of the 13 WR stars. These are brief ly discussed in the context of stellar evolution. (C) 1996 American As tronomical Society.