The Problem of V444 Cygni

Abstract

The authors have studied the changes of the spectrum of V444 Cygni (WN5+O6) shown on 13 high-resolution spectrograms obtained with the IUE. Evidence is found for an orbital-phase-dependent "third light" both in line and in continuum wavelengths. A model for the V444 Cygni system consisting of an O star with T_eff = 40,000K, R/R_sun; = 10, and a Wolf-Rayet star with T_eff = 30,000K, R/R_sun; = 9, will reproduce the energy curve observed from 1300 to 6000 Å. The authors describe a model Wolf-Rayet star possessing large, readily visible, magnetic field-supported plumes which envelop both stars. The emission-line spectrum from these plumes and stellar continuum light scattered by the plumes could explain the observed light curve distortions.