Ultraviolet high-resolution spectroscopy of the X-ray binary SK 160/SMC X-1.
Howarth, I. D.; Hammerschlag-Hensberge, G.; Kallman, T. R.
Netherlands, United States, United Kingdom
Abstract
High-resolution IUE spectra of Sk 160, the optical counterpart of the X-ray source SMC X-1, show substantial variations with orbital phase of the resonance P Cygni profiles. These variations are ascribed to the changing ionization state in the stellar wind caused by the X-rays emitted by the companion, as suggested by Hatchett and McCray and first established for the galactic X-ray binary Vela X-1. Furthermore, the profile observed during X-ray eclipse differs significantly from profiles of similar stars in the absence of X-ray ionization.