MG II profile variations of zeta Aurigae.

Abstract

The authors have observed variations in the Mg II 2800 Å doublet of Zeta Aurigae. The Mg II profiles deviate from simple P-Cygni profiles in that they exhibit an absorption feature consistent with Chapman's (1981) interpretation of C IV absorption as evidence of a column of accretion onto the B star component of the binary. The authors find the opening angle of the shock cone, containing the accretion column to exceed 16° implying a stellar wind velocity of approximately 67 km s^-1, unless the H II region temperature is unusually high. The turbulence velocity of the wind then appears to be about 33 km s^-1, compared to values of order 10 km s^-1 previously determined closer to the K-star surface.