Layered semi-convection and tides in giant planet interiors

TL;DR

This paper investigates how layered semi-convection in giant planet interiors can significantly enhance tidal dissipation, potentially explaining observed high dissipation rates in Jupiter and Saturn.

Contribution

It provides the first detailed analysis of tidal dissipation mechanisms in layered semi-convective regions of giant planets.

Findings

Tidal dissipation rates are significantly higher in layered semi-convective regions.

Enhanced dissipation occurs especially in the sub-inertial frequency range.

Layered semi-convection could explain the high tidal dissipation observed in Jupiter and Saturn.

Abstract

Layered semi-convection could operate in giant planets, potentially explaining the constraints on the heavy elements distribution in Jupiter deduced recently from Juno observations, and contributing to Saturn's luminosity excess or the abnormally large radius of some hot Jupiters. This is a state consisting of density staircases, in which convective layers are separated by thin stably stratified interfaces. The efficiency of tidal dissipation in a planet depends strongly on its internal structure. It is crucial to improve our understanding of the mechanisms driving this dissipation, since it has important consequences to predict the long-term evolution of any planetary system. In this work, our goal is to study the resulting tidal dissipation when internal waves are excited by other bodies (such as the moons of giant planets) in a region of layered semi-convection. We find that the rates of tidal dissipation can be significantly enhanced in a layered semi-convective medium compared to a uniformly convective medium, especially in the astrophysically relevant sub-inertial frequency range. Thus, layered semi-convection is a possible candidate to explain high tidal dissipation rates recently observed in Jupiter and Saturn.