Are There Stellar Winds in the Hot Stars of M31?
Massey, Philip; Bianchi, L.; Hutchings, J. B.
Canada, United States, Italy
Abstract
Results are reported of 16 hr exposures with the IUE satellite of two stars in M31. Ground-based spectra indicate these stars to be of type about O6 and WN 7. The UV spectra have good signal but are conspicuously different from Galactic stars of their type. Specifically, no line emission is seen in either star, resonance absorption lines are very weak and indicate low outflow velocities in the O star, there appear to be shifted narrow lines normally attributed to the ISM, and either the UV continuum is 'cooler' than the optical, or the UV extinction law is steeper than Galactic. All of these indicate unexpected global differences between the Galaxy and M31.