Spin-orbit coupling and chaotic rotation for circumbinary bodies. Application to the small satellites of the Pluto-Charon system [EPA]

http://arxiv.org/abs/1506.06733


Circumbinary bodies are objects that orbit around a more massive binary system. Here we show that, contrarily to the classical two-body problem, circumbinary bodies in planar quasi-circular orbits can present stable non-synchronous rotation. Denoting $n_b$ and $n$ the orbital mean motion of the binary and of the circumbinary body, respectively, there is an entirely new family of spin-orbit resonances at the frequencies $n\pm k\nu/2$, where $\nu = n_b – n$, and $k$ is an integer. In addition, when the natural rotational libration frequency has the same magnitude as $\nu$, the individual resonances overlap and the rotation becomes chaotic. We apply these results to the small satellites in the Pluto-Charon system. We conclude that the rotation of Nix and Styx can be chaotic, and that the rotation of Hydra and Kerberos is stable but not necessarily synchronous.

Read this paper on arXiv…

A. Correia, A. Leleu and P. Robutel
Tue, 23 Jun 15
25/67

Comments: 5 pages, 4 figures, 1 appendix, submitted to Astronomy & Astrophysics