Planetary Architectures in Interacting Stellar Environments. (arXiv:2002.05727v1 [astro-ph.EP])

Planetary Architectures in Interacting Stellar Environments. (arXiv:2002.05727v1 [astro-ph.EP])
<a href="http://arxiv.org/find/astro-ph/1/au:+Wang_Y/0/1/0/all/0/1">Yi-Han Wang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Perna_R/0/1/0/all/0/1">Rosalba Perna</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Leigh_N/0/1/0/all/0/1">Nathan W. C. Leigh</a>

The discovery of Exoplanetary Systems has challenged some of the theories of
planet formation, which assume unperturbed evolution of the host star and its
planets. However, in star clusters the interactions with flyby stars and
binaries may be relatively common during the lifetime of a planetary system.
Here, via high-resolution $N$-body simulations of star-planet systems perturbed
by interlopers (stars and binaries), we explore the reconfiguration to the
planetary system due to the encounters. In particular, via an exploration
focused on the strong scattering regime, we derive the fraction of encounters
which result in planet ejections, planet transfers and collisions by the
interloper star/binary, as a function of the characteristics of the environment
(density, velocity dispersion), and for different masses of the flyby
star/binary. We find that binary interlopers can significantly increase the
cross section of planet ejections and collisions, while they only slightly
change the cross section for planet transfers. Therefore, in environments with
high binary fractions, floating planets are expected to be relatively common,
while in environments with low binary fractions, where the cross sections of
planet ejection and transfer are comparable, the rate of planet exchanges
between two stars will be comparable to the rate of production of free-floating
planets.

The discovery of Exoplanetary Systems has challenged some of the theories of
planet formation, which assume unperturbed evolution of the host star and its
planets. However, in star clusters the interactions with flyby stars and
binaries may be relatively common during the lifetime of a planetary system.
Here, via high-resolution $N$-body simulations of star-planet systems perturbed
by interlopers (stars and binaries), we explore the reconfiguration to the
planetary system due to the encounters. In particular, via an exploration
focused on the strong scattering regime, we derive the fraction of encounters
which result in planet ejections, planet transfers and collisions by the
interloper star/binary, as a function of the characteristics of the environment
(density, velocity dispersion), and for different masses of the flyby
star/binary. We find that binary interlopers can significantly increase the
cross section of planet ejections and collisions, while they only slightly
change the cross section for planet transfers. Therefore, in environments with
high binary fractions, floating planets are expected to be relatively common,
while in environments with low binary fractions, where the cross sections of
planet ejection and transfer are comparable, the rate of planet exchanges
between two stars will be comparable to the rate of production of free-floating
planets.

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