IUE observations of phase-dependent variations in WN + O systems

Abstract

IUE observations of six WN + O Wolf-Rayet (W-R) systems are reported. The periodic variations in five of the systems are shown to result primarily from selective atmospheric eclipses of the O star continuum by the W-R wind. An optical depth distribution of the form tau inversely proportional to radius is suggested for radii greater than 14 solar radii. Phase-dependent variations in the C IV 1550 absorption components in V444 Cyg, HD 90657, and HD 211853 are interpreted as wind-wind collision effects.