Tidal interactions in rotating multiple stars and their impact on their evolution

TL;DR

This paper develops an analytical model of tidal gravito-inertial waves in rotating stars, revealing how resonant dissipation influences the orbital evolution of binary systems with complex, irregular dynamics.

Contribution

It introduces a local analytical approach to study tidal wave resonances in stellar interiors, linking internal properties to dissipation and orbital evolution.

Findings

Resonant tidal dissipation depends on rotation, stratification, and viscous properties.

Viscous dissipation causes erratic orbital evolution in binary systems.

Analytical expressions for resonance characteristics in stellar regimes.

Abstract

Tidal dissipation in stars is one of the key physical mechanisms that drive the evolution of binary and multiple stars. As in the Earth oceans, it corresponds to the resonant excitation of their eigenmodes of oscillation and their damping. Therefore, it strongly depends on the internal structure, rotation, and dissipative mechanisms in each component. In this work, we present a local analytical modeling of tidal gravito-inertial waves excited in stellar convective and radiative regions respectively. This model allows us to understand in details the properties of the resonant tidal dissipation as a function of the excitation frequencies, the rotation, the stratification, and the viscous and thermal properties of the studied fluid regions. Then, the frequencies, height, width at half-height, and number of resonances as well as the non-resonant equilibrium tide are derived analytically in asymptotic regimes that are relevant in stellar interiors. Finally, we demonstrate how viscous dissipation of tidal waves leads to a strongly erratic orbital evolution in the case of a coplanar binary system. We characterize such a non-regular dynamics as a function of the height and width of resonances, which have been previously characterized thanks to our local fluid model.