O-STAR WINDS IN THE MAGELLANIC CLOUDS AND THE MILKY-WAY - A MODIFIED EMPIRICAL-ANALYSIS OF UV P-CYGNI PROFILES

UV P-Cygni profiles of OB-stars in the Magellanic Clouds (observed wit h HST), and the galaxy (observed with IUE) are analyzed empirically us ing a line formation procedure similar to the one described by Lamers et al. (1987). The assumption of a constant microturbulence upsilon(tu rb) throughout the wind is dropped and replaced by a radially increasi ng turbulence parameter upsilon(turb)(upsilon), thus improving the fit for the emission peaks substantially, and at the same time avoiding t he need for a justification of extremely supersonic turbulence in the vicinity of the wind's sonic point. The Sobolev optical depth is deter mined iteratively at fixed velocities in the wind, which removes the b ias introduced by the choice of a specific parameterization function. Where it was possible and necessary a full photospheric spectrum was u sed to illuminate the wind line. The terminal velocities upsilon(infin ity) are are found to be largest in the Galaxy, smallest in the Small Magellanic Cloud, and intermediate or similar to galactic in the Large Cloud.