The outer layers of the beta Cephei stars BW VUL and sigma Sco.

Abstract

Mass loss rates for the Beta Cephei stars BW Vul and Sigma Sco have been derived from the C IV and Si IV resonance lines, which are formed in the outflowing layers. Assuming an ionization fraction log q(C IV) = -1.9, mass losses of 1.4 and 1.9 x 10 to the -9th solar mass/yr are predicted for BW Vul and Sigma Sco, respectively. In the case of BW Vul, variations of these lines during the pulsational cycle have given evidence for changes in ion density which cannot be explained by changes in mass density only. For Sigma Sco, the line profile variations are much smaller and no detailed interpretation has been attempted.