A study of ultraviolet spectra of zeta Aur/VV CEP systems. II. Mass loss of supergiants in zeta Aur, 32 CYG and 31 Cyg.

Abstract

This paper describes a method for the determination of mass loss rates of red giants in spectroscopic eclipsing binaries. A non-spherical, three-dimensional line transfer code has been applied to investigate the wind and mass loss of the K supergiants in ζ Aur, 32 Cyg and 31 Cyg. The authors compare theoretical line profiles with IUE observations of Fe II, Si II and S II resonance lines at various binary phases. The wind velocities lie in the range 40 - 80 km s^-1 while the microturbulence is of the order of 20 - 30 km s^-1. In a first approximation no detectable asymmetry in the K giant wind envelope was observed. The mass loss rates of ζ Aur, 32 Cyg and 31 Cyg are 0.63×10^-8, 2.8×10^-8 and ⪆10^-8 M_sun; yr^-1 respectively with an error bar of roughly a factor of three.