Orbital dynamics of Exomoons in Planetary Close Encounters

Yu-Cian Hong, Sean N. Raymond, Philip D. Nicholson, Jonathan I. Lunine
(Submitted on 18 Dec 2017)

Planet-planet scattering is the leading mechanism to explain the broad eccentricity distribution of observed giant exoplanets. Here we study the orbital stability of primordial giant planet moons in this scenario. We use N-body simulations including realistic oblateness and evolving spin evolution for the giant planets. We find that the vast majority (80-90% across all our simulations) of orbital parameter space for moons is destabilized. There is a strong radial dependence, as moons past 0.1 Hill radii are systematically removed. Closer-in moons on Galilean-moon-like orbits (< 0.04 Hill radii) have a good ( 20-40%) chance of survival. Destabilized moons may undergo a collision with the star or a planet, be ejected from the system, be captured by another planet, be ejected but still orbiting its free-floating host planet, or survive on heliocentric orbits as "planets." The survival rate of moons increases with the host planet mass but is independent of the planet's final (post-scattering) orbits. Based on our simulations we predict the existence of an abundant galactic population of free- floating (former) moons. Comments:    15 pages, 9 figures, 1 table, accepted for publication in ApJ
Subjects:    Earth and Planetary Astrophysics (astro-ph.EP)
Cite as:    arXiv:1712.06500 [astro-ph.EP]    (or arXiv:1712.06500v1 [astro-ph.EP] for this version)
Submission history
From: Yu-Cian Hong 
[v1] Mon, 18 Dec 2017 16:22:10 GMT (205kb,D)
https://arxiv.org/abs/1712.06500