Accretion-Induced Collimated Fast Wind Model for Eta Carinae

Abstract

I propose a scenario to account for the fast polar outflow detected to be blown by Eta Carinae in 2000. The scenario accounts also for the lack of this flow in 1998 and 1999. The scenario is based on the binary nature of Eta Carinae. The collision of the winds blown by the two stars, in particular near periastron passages, slows down about 5 per cent of the wind blown by Eta Carinae, i.e., the massive primary star, such that it stays bound to the system. I assume that most of this mass is accreted back through the equator by Eta Carinae during apastron passage, when its orbital velocity is much lower. The mass accretion rate of this backflowing material may become about 25 per cent of the wind's mass loss rate near apastron passages. If the backflowing matter has enough specific angular momentum it can form an accretion disk and may lead to the formation of a polar collimated fast wind (CFW) on top of the stellar wind.