Comments on Binary Star Evolution and the Small Magellanic Cloud System HD 5980

Abstract

Studies of the effects that close binary stars may produce in the evolution of stellar populations are starting to suggest that the role of binary stars cannot be neglected when deducing the properties of starburst regions from population synthesis models. It is thus important to study massive binary systems such as HD 5980, located in the Small Magellanic Cloud young stellar cluster NGC 346, in this context. The Luminous Blue Variable type eruptions that the system has suffered suggest that it may be presenting the results of strong interaction effects due to tidal forces. Because of the eccentricity of the orbit and due to the oscillations that are excited in such a non-equilibrium configuration, its evolution is likely to be proceeding differently than predicted by models based on the assumption of an equilibrium configuration. In particular, standard models that assume Roche Lobe Overflow are not applicable.