Dimitri Veras, Christopher A. Tout
Extrasolar planets and belts of debris orbiting post-main-sequence single
stars may become unbound as the evolving star loses mass. In multiple star
systems, the presence or co-evolution of the additional stars can significantly
complicate the prospects for orbital excitation and escape. Here, we
investigate the dynamical consequences of multi-phasic, nonlinear mass loss and
establish a criterion for a system of any stellar multiplicity to retain a
planet whose orbit surrounds all of the parent stars. For single stars which
become white dwarfs, this criterion can be combined with the Chandrasekhar
Limit to establish the maximum allowable mass loss rate for planet retention.
We then apply the criterion to circumbinary planets in evolving binary systems
over the entire stellar mass phase space. Through about 10^5 stellar
evolutionary track realizations, we characterize planetary ejection prospects
as a function of binary separation, stellar mass and metallicity. This
investigation reveals that planets residing at just a few tens of AU from a
central concentration of stars are susceptible to escape in a wide variety of
multiple systems. Further, planets are significantly more susceptible to
ejection from multiple star systems than from single star systems for a given
system mass. For system masses greater than about 2 Solar masses, multiple star
systems represent the greater source of free-floating planets.
View original:
http://arxiv.org/abs/1202.3139
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