Atmospheric Eclipses in the SMC Wolf-Rayet Eclipsing Binary HD 5980: The Heavy versus the Light Metal Abundance
Koenigsberger, G.; Auer, L. H.; Moffat, A. F. J.
Mexico, Canada, United States
Abstract
Phase-dependent variations in the IUE spectra of the SMC 19.6-day eclipsing binary system HD 5980 (WN4 + 07I) are discussed. The effects of selective atmospheric eclipses in the N, C, and He lines of HD 5980 are found to be similar to those observed in its Galactic counterpart, while the variations in the 1350-1490 A continuum region are virtually undetectable. It is suggested that this observation is a consequence of the lower initial abundance, particularly of the heavier elements in the SMC with respect to the Galaxy, combined with subsequent nuclear processing in the WR star interior.