Spectral diagnostics of luminous blue supergiants

Abstract

The spectral analysis of the most luminous stars as individuals provides a unique tool for the determination of the properties of young populations in galaxies. Generally this requires hydrodynamic model atmospheres including the effects of spherical extension and stellar winds. Standard codes for this problem have now been developed by many groups. It is shown how the properties of the most luminous stars in different galaxies (temperature, gravity, radii, luminosity, masses, mass-loss rates, wind velocities, abundances) can be determined using spectral information from the UV to the IR. Recent results for O, B, A-supergiants in the Galaxy, LMC, SMC, M31, M33 and beyond the Local Group are presented. Special emphasis is given to the wind momentum - luminosity relationship as a tool for the determination of extragalactic distances out to the Virgo cluster of galaxies. (orig.)57 refs.Available from TIB Hannover: RR 4697(993) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman