Chaotic Excitation and Tidal Damping in the GJ 876 System

Abhijit Puranam, Konstantin Batygin
(Submitted on 23 Feb 2018)

The M-dwarf GJ 876 is the closest known star to harbor a multi-planetary system. With three outer planets locked in a chaotic Laplace-type resonance and an appreciably eccentric short-period Super-Earth, this system represents a unique exposition of extrasolar planetary dynamics. A key question that concerns the long-term evolution of this system, and the fate of close-in planets in general, is how the significant eccentricity of the inner-most planet is maintained against tidal circularization on timescales comparable to the age of the universe. Here, we employ stochastic secular perturbation theory and N-body simulations to show that the orbit of the inner-most planet is shaped by a delicate balance between extrinsic chaotic forcing and tidal dissipation. As such, the planet’s orbital eccentricity represents an indirect measure of its tidal quality factor. Based on the system’s present-day architecture, we estimate that the extrasolar Super-Earth GJ 876d has a tidal Q~10,000-100,000 – a value characteristic of solar system gas giants.

Comments:    6 pages, 5 figures, accepted to AJ
Subjects:    Earth and Planetary Astrophysics (astro-ph.EP)
Cite as:    arXiv:1802.08385 [astro-ph.EP] (or arXiv:1802.08385v1 [astro-ph.EP] for this version)
Submission history
From: Konstantin Batygin
[v1] Fri, 23 Feb 2018 04:47:04 GMT (423kb,D)
https://arxiv.org/abs/1802.08385