OPTICAL SPECTROSCOPY OF INHOMOGENEITIES IN THE WINDS OF WOLF-RAYET STARS

Recent high quality spectra in the wavelength range 5300-6000 Angstrom of 9 WR stars of different subtypes are presented to study the intrinsic variability of the WR winds. These data clearly show variable subpeaks superimposed on the emission lines of all stars. The global level of variability of the lines decreases while more subpeaks are seen for stars with taster winds. The spectroscopic variations are associated to the presence of perturbations in the stellar winds. An inhomogeneity model is developed to study the dynamic and the physical characteristics of the wind perturbations. In the case of HD193793, for which more structures have been detected, a comparison with the general velocity law gives beta > 3. The internal velocity dispersion is larger in the direction of propagation than perpendicular to it. A histogram of the flux of the inhomogeneities indicates it larger number of wind structures with small flux. A power law fitted to the flux histogram of each stars gives an average exponent which is compatible with the one seen for giant molecular clouds where supersonic turbulence prevails. The physical representation of the WR winds and the origin of the perturbations is questioned.