• DOI:10.3847/1538-3881/aab09f
• Corpus ID: 54009668

Chaotic Excitation and Tidal Damping in the GJ 876 System

@article{Puranam2018ChaoticEA,
  title={Chaotic Excitation and Tidal Damping in the GJ 876 System},
  author={Abhijit Puranam and Konstantin Batygin},
  journal={The Astronomical Journal},
  year={2018},
  volume={155}
}

• A. Puranam, K. Batygin
• Published 23 February 2018
• Physics, Geology
• The Astronomical Journal

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 876 d has a tidal Q ∼ 104–105, a value characteristic of solar system gas giants.