Formation of Hot Jupiters through Secular Chaos and Dynamical Tides. (arXiv:1901.05006v1 [astro-ph.EP])
<a href="http://arxiv.org/find/astro-ph/1/au:+Teyssandier_J/0/1/0/all/0/1">Jean Teyssandier</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lai_D/0/1/0/all/0/1">Dong Lai</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Vick_M/0/1/0/all/0/1">Michelle Vick</a>
The population of giant planets on short-period orbits can potentially be
explained by some flavours of high-eccentricity migration. In this paper we
investigate one such mechanism involving “secular chaos”, in which secular
interactions between at least three giant planets push the inner planet to a
highly eccentric orbit, followed by tidal circularization and orbital decay. In
addition to the equilibrium tidal friction, we incorporate dissipation due to
dynamical tides that are excited inside the giant planet. Using the method of
Gaussian rings to account for planet-planet interactions, we explore the
conditions for extreme eccentricity excitation via secular chaos and the
properties of hot Jupiters formed in this migration channel. Our calculations
show that once the inner planet reaches a sufficiently large eccentricity,
dynamical tides quickly dissipate the orbital energy, producing an eccentric
warm Jupiter, which then decays in semi-major axis through equilibrium tides to
become a hot Jupiter. Dynamical tides help the planet avoid tidal disruption,
increasing the chance of forming a hot Jupiter, although not all planets
survive the process. We find that the final orbital periods generally lie in
the range of 2-3 days, somewhat shorter than those of the observed hot Jupiter
population. We couple the planet migration to the stellar spin evolution to
predict the final spin-orbit misalignments. The distribution of the
misalignment angles we obtain shows a lack of retrograde orbits compared to
observations. Our results suggest that high-eccentricity migration via secular
chaos can only account for a fraction of the observed hot Jupiter population.
The population of giant planets on short-period orbits can potentially be
explained by some flavours of high-eccentricity migration. In this paper we
investigate one such mechanism involving “secular chaos”, in which secular
interactions between at least three giant planets push the inner planet to a
highly eccentric orbit, followed by tidal circularization and orbital decay. In
addition to the equilibrium tidal friction, we incorporate dissipation due to
dynamical tides that are excited inside the giant planet. Using the method of
Gaussian rings to account for planet-planet interactions, we explore the
conditions for extreme eccentricity excitation via secular chaos and the
properties of hot Jupiters formed in this migration channel. Our calculations
show that once the inner planet reaches a sufficiently large eccentricity,
dynamical tides quickly dissipate the orbital energy, producing an eccentric
warm Jupiter, which then decays in semi-major axis through equilibrium tides to
become a hot Jupiter. Dynamical tides help the planet avoid tidal disruption,
increasing the chance of forming a hot Jupiter, although not all planets
survive the process. We find that the final orbital periods generally lie in
the range of 2-3 days, somewhat shorter than those of the observed hot Jupiter
population. We couple the planet migration to the stellar spin evolution to
predict the final spin-orbit misalignments. The distribution of the
misalignment angles we obtain shows a lack of retrograde orbits compared to
observations. Our results suggest that high-eccentricity migration via secular
chaos can only account for a fraction of the observed hot Jupiter population.
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