TITLE: Accretion onto the Companion of Eta Carinae

SPEAKER: Amit Kashi, Technion – Israel Institute of Technology, Haifa, Israel

ABSTRACT: Eta Carinae is a unique massive binary star system in our Galaxy, presenting some basic undetermined parameters and open questions. Its 5.54 year periodicity in a very eccentric orbit is observed in all wavelengths. We identify the important physical processes that we expect to take place at periastron passage, and use these to explain observations. We use the standard parameters of the system and show that near periastron the secondary - the hotter less massive star - is very likely to accrete mass from the slow dense wind blown by the LBV primary. We examine a variety of observations that shed light on the orientation of the semi-major axis the binary system. We find that all of them support an orientation where for most of the time the secondary is behind the primary star. The secondary comes closer to the observer only for a short time near periastron passage, in its highly eccentric orbit.