Tidal dissipation in giant planets containing regions of layered semi-convection

Context: Gravitational tidal interactions play an important role in the evolution of the orbits and spins of extrasolar planets, and in the migration of the satellites of Jupiter & Saturn. The mechanisms responsible for tidal dissipation are poorly understood, but it has been recognised that they will depend strongly on the internal structure of the planet. Recent observations from the Juno mission are consistent with giant planet interior models that contain gradients in heavy elements. These could be sufficient to inhibit ordinary convection, but allow double-diffusive convection. This is thought to produce a staircase-like profile for the density, in which convective layers are separated by very thin stably-stratified interfaces. The importance of such structures for tidal dissipation has not yet been explored.

Aims, Objectives & Applications: (i) to study the effects of layered semi-convection on the properties and propagation of waves in quasi-global models of giant planet interiors. (ii) to explore the efficiency of tidal dissipation in giant planets containing regions of layered semi-convection using a combination of analytical and numerical approaches. (iii) to understand the implications of these results for tidal evolution in the solar system and in extrasolar planetary systems.