Volume 644, December 2020
|Number of page(s)||14|
|Section||Planets and planetary systems|
|Published online||04 December 2020|
Tidal evolution of the Pluto–Charon binary
CFisUC, Department of Physics, University of Coimbra,
2 ASD, IMCCE, Observatoire de Paris, PSL Université, 77 Av. Denfert-Rochereau, 75014 Paris, France
Accepted: 26 October 2020
A giant collision is believed to be at the origin of the Pluto–Charon system. As a result, the initial orbit and spins after impact may have substantially differed from those observed today. More precisely, the distance at periapse may have been shorter, subsequently expanding to its current separation by tides raised simultaneously on the two bodies. Here we provide a general 3D model to study the tidal evolution of a binary composed of two triaxial bodies orbiting a central star. We apply this model to the Pluto–Charon binary, and notice some interesting constraints on the initial system. We observe that when the eccentricity evolves to high values, the presence of the Sun prevents Charon from escaping because of Lidov-Kozai cycles. However, for a high initial obliquity for Pluto or a spin-orbit capture of Charon’s rotation, the binary eccentricity is damped very efficiently. As a result, the system can maintain a moderate eccentricity throughout its evolution, even for strong tidal dissipation on Pluto.
Key words: planets and satellites: dynamical evolution and stability / minor planets, asteroids: individual: Pluto / minor planets, asteroids: individual: Charon
© ESO 2020
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