Tidal instability in stellar and planetary binary systems

M. Le Bars (1) , Laurent Lacaze (2) , S. Le Dizès (1) , P. Le Gal (1) , M. Rieutord (3)

1 IRPHE - Institut de Recherche sur les Phénomènes Hors Equilibre
2 IMFT - Institut de mécanique des fluides de Toulouse
3 LATT - Laboratoire Astrophysique de Toulouse-Tarbes

In this paper, we combine theoretical and experimental approaches to study the tidal instability in planetary liquid cores and stars. We demonstrate that numerous complex modes can be excited depending on the relative values of the orbital angular velocity Ω and of the spinning angular velocity Ω, except in a stable range characterized by Ω=Ω ɛ 2 [−1; 1/3]. Even if the tidal deformation is small, its subsequent instability - coming from a resonance process - may induce motions with large amplitude, which play a fundamental role at the planetary scale. This general conclusion is illustrated in the case of Jupiter's moon Io by a coupled model of synchronization, demonstrating the importance of energy dissipation by elliptical instability.

Mots clés: binary systems; synchronization; tidal/elliptical instability; Tides

Domaines: Mécanique des fluides [physics.class-ph]; Astrophysique [astro-ph]; Sciences de la Terre

M. Le Bars, Laurent Lacaze, S. Le Dizès, P. Le Gal, M. Rieutord. Tidal instability in stellar and planetary binary systems. Physics of the Earth and Planetary Interiors, 2010, 178 (1-2), pp.48-55. ⟨10.1016/j.pepi.2009.07.005⟩. ⟨hal-00601517⟩