On the relative luminosities of the stars in the Wolf-Rayet binary V444 Cygni.

Abstract

A new spectroscopic estimate of the luminosity ratio q=L_WR_/L_O6_ is obtained from the dilution of the absorption lines of the O6V-III component in the WR eclipsing binary V444 Cygni (WN5+O6). We find q=0.60+/-0.06 for the range λλ4000-6000A and q=0.56+/-0.13 from IUE spectra. This clearly indicates that the light of the O6 dominates the combined light of V444 Cyg. This result is in strong contradiction with the value q=3.1 derived from the light curve solution for V444 Cyg (model with T_eff_=40000K for the O-star component) by Hamann & Schwarz (1992), but agrees with the light curve solutions obtained previously by Cherepashchuk (1975) and Cherepashchuk et al. (1984). The discrepancy can be explained if the model of a homogeneous extended atmosphere for WR stars applied by Hamann & Schwarz for the determination of q from the emission lines of He I and He II is not applicable. Clumpy structure of WR winds proposed in earlier papers (Cherepashchuk et al. 1984; Moffat et al. 1988) should be more applicable.