Expanding Atmospheres in OB Supergiants--V: The Ultra-Violet Resonance Lines and Radiative Acceleration in the Orion Supergiants

Abstract

Line profiles are computed for the observed ultra-violet resonance lines in the Orion supergiants. Initial velocity and ion density distributions are deduced which lead to approximate numerical estimates of radiative acceleration processes affecting the entire atmospheric mass. Recomputation of the line profiles yields a very close fit with observation. A mass loss rate of $$10^{-6} M_{\odot} \,\text{yr}^{-1}$$ is deduced for these stars. Some general remarks are made on mass loss from early type supergiants.