Spin dynamics of close-in planets exhibiting large transit timing variations

J.-B. Delisle (1) , A. Correia (2, 1) , A. Leleu (1) , P. Robutel (1)

1 IMCCE - Institut de Mécanique Céleste et de Calcul des Ephémérides
2 Department of Physics

We study the spin evolution of close-in planets in compact multi-planetary systems. The rotation period of these planets is often assumed to be synchronous with the orbital period due to tidal dissipation. Here we show that planet-planet perturbations can drive the spin of these planets into non-synchronous or even chaotic states. In particular, we show that the transit timing variation (TTV) is a very good probe to study the spin dynamics, since both are dominated by the perturbations of the mean longitude of the planet. We apply our model to KOI-227 b and Kepler-88 b, which are both observed undergoing strong TTVs. We also perform numerical simulations of the spin evolution of these two planets. We show that for KOI-227 b non-synchronous rotation is possible, while for Kepler-88 b the rotation can be chaotic.

Mots clés: celestial mechanics; planets and satellites: general

Domaines: Astrophysique [astro-ph]

J.-B. Delisle, A. Correia, A. Leleu, P. Robutel. Spin dynamics of close-in planets exhibiting large transit timing variations. Astronomy and Astrophysics - A&A, 2017, 605, pp.A37. ⟨10.1051/0004-6361/201730755⟩. ⟨hal-02238858⟩