Ultraviolet, radio and X-ray observations of hybrid stars.

The Mg II profiles of hybrid stars (obtained from spectra available in the IUE Archives of the Univ. of Colorado RDAF) were reanalyzed. Radio observations of 3 hybrid stars (iota aur, theta Her and gamma Aq1) are presented and the available Einstein X-ray data on these stars are discussed. This observational material is compared with the properties of the HDR model for hybrids that could form both low- and high-velocity Mg II absorptions in the extending circumstellar envelope predicted no X ray emission. From the analysis it is conducted that interstellar absorption is sufficient to account for the observed low-velocity features, so that only the high-velocity absorptions are formed in the winds themselves. What makes the kinematics of hybrid stellar winds interesting are the observed high wind velocities (70 km to 140 km) compared to other G-K I III stars and not the supposed twin circumstellar absorptions.