The UV resonance lines of zeta ¹ Sco.

Abstract

The IUE satellite has been used to obtain high-resolution UV spectrograms of the extreme B1 supergiant Zeta-1 Sco. The observed line spectrum was found to be dominated by conspicuous P Cygni profiles or strongly blueshifted circumstellar absorption lines of the resonance transitions of Al II, Mg II, Si II, C II, Al III, Si IV, C IV, and N V, and of Fe III multiplets originating from metastable lower states. The observed line profiles are compared with different models of the velocity field and ionization structure of the expanding envelope of Zeta-1 Sco.