Unravelling tidal dissipation in gaseous giant planets

TL;DR

This paper investigates how different internal layers of gaseous giant planets contribute to tidal dissipation, emphasizing the importance of considering both core and envelope effects for accurate planetary evolution models.

Contribution

It provides a detailed comparison of tidal dissipation in the core and envelope of gaseous giants, highlighting the dominant role of core viscoelasticity in certain cases.

Findings

Core dissipation can dominate in Jupiter-like planets.

Fluid envelope dissipation is significant but secondary.

Complete models are essential for accurate tidal evolution understanding.

Abstract

Tidal dissipation in planetary interiors is one of the key physical mechanisms that drive the evolution of star-planet and planet-moon systems. New constraints are now obtained both in the Solar and exoplanetary systems. Tidal dissipation in planets is intrinsically related to their internal structure. In particular, fluid and solid layers behave differently under tidal forcing. Therefore, their respective dissipation reservoirs have to be compared. In this letter, we compute separately the contributions of the potential dense rocky/icy core and the convective fluid envelope of gaseous giant planets, as a function of core size and mass. We then compare the associated dissipation reservoirs, by evaluating the frequency-average of the imaginary part of the Love numbers $k^2_2$ in each region. In the case of Jupiter and Saturn-like planets, we show that the viscoelastic dissipation in the core could dominate the turbulent friction acting on tidal inertial waves in the envelope. However, the fluid dissipation would not be negligible. This demonstrates that it is necessary to build complete models of tidal dissipation in planetary interiors from their deep interior to their surface without any arbitrary a-priori.