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How common envelope binary interactions change the life of stars and planets

by Orsola De Marco (Macquarie University, Sydney, AU)

Dec 13, 2012 from 02:00 PM to 05:00 PM

Where Seminars' room, floor -1, via Ranzani 1

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An expanding giant star may engulf a nearby stellar or substellar
companion. The common envelope phase that follows, fundamentally alters
the evolution of both stars in the system by reducing the orbital
separation and leading to a merger (such as V838 Mon or V1309 Sco), or a
compact binary (e.g., novae, type Ia supernova progenitors, X-ray
binaries). Frequencies and physical properties of all compact, evolved
binaries depend sensitively on the poorly understood common envelope
phase. We have developed 3- dimensional, hydrodynamic common envelope
simulations between a red giant branch star and a range of companions.
Comparing the modelled ejected masses and final separations with
observations, we revisit our understanding of the common envelope
efficiency, a parameter on which predictions such as supernova type Ia
rates sensitively rest. Finally, we bring our results to bear on the
surprising result that some planets can survive a common envelope phase
with their mother star.