Stellar winds of massive stars in M31

Abstract

We have obtained the first UV high resolution spectra of hot luminous stars in M31 with the FOS on Hubble Space Telescope. The spectra, combined with optical spectroscopic and photometric observations, enable us to study their stellar winds and photospheric parameters. We derive mass-loss rates and velocity laws from the wind line profiles, with the SEI method, as well as information on abundances. The wind lines and photospheric spectra are compared with galactic stars of the same spectral type. The spectra analyzed so far indicate that the stars have mass—loss rates comparable or slightly lower than galactic stars of the same spectral type, but possibly different velocity laws in their winds. The spectra of two stars are discussed here.