Tidal dissipation in binary systems

TL;DR

This paper reviews the physical processes responsible for tidal dissipation in binary systems, focusing on viscous and radiative damping mechanisms, and compares theoretical predictions with observed orbital circularization data.

Contribution

It provides a comprehensive review of tidal dissipation mechanisms in binary systems and discusses recent developments and uncertainties in theoretical modeling.

Findings

Viscous dissipation dominates in stars with convection zones.

Radiative damping is key in stars with radiation zones.

Theoretical models are compared with observed binary orbital properties.

Abstract

To first approximation, a binary system conserves its angular momentum while it evolves to its state of minimum kinetic energy: circular orbit, all spins aligned, and components rotating in synchronism with the orbital motion. The pace at which this final state is achieved depends on the physical processes that are responsible for the dissipation of the tidal kinetic energy. For stars (or planets) with an outer convection zone, the dominant mechanism identified so far is the viscous dissipation acting on the equilibrium tide. For stars with an outer radiation zone, it is the radiative damping operating on the dynamical tide. After a brief presentation of the tides, I shall review these physical processes; I shall discuss the uncertainties of their present treatment, describe the latest developments, and compare the theoretical predictions with the observed properties concerning the orbital circularization of close binaries.