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Efficient Common Envelope Ejection Through Dust Driven Winds

TYPEAstrophysics Seminar
Speaker:Hila Glanz
Time:All Day
Location:Lidow 620
Remark:M.Sc. seminar.

Common-envelope evolution (CEE) is the short-lived phase in the life of an interacting binary system during which two stars orbit inside a single shared envelope. Such evolution is thought to lead to the inspiral of the binary, the ejection of the extended envelope and the formation of a remnant short-period binary. However, detailed hydrodynamical models of CEE encounter major difficulties. They show that following the inspiral most of the envelope is not ejected; rather, it expands to larger separations where it still remains bound to the binary. Here we propose that dust-driven winds can be produced following the CEE, and these can evaporate the envelope, following similar processes as those operating in the ejection of the envelopes of asymptotic giant branch (AGB) stars. Stellar pulsations in such stars drive the outer envelope to large distances, where the material cools down to sufficiently low temperatures as to allow for dust condensation. Radiation pressure on the dust accelerates it, and through its coupling to the gas it drives winds which eventually completely erode the envelope. As we show, in CE binaries the inspiral phase can effectively replace the role of stellar pulsation and drive the CE expansion to scales comparable with those of AGB stars, where dust can condensate, and give rise to efficient mass-loss through dust-driven winds.