Tidal dissipation due to inertial waves can explain the circularization periods of solar-type binaries

TL;DR

This paper shows that inertial wave dissipation in convective envelopes of solar-type stars can explain observed binary orbit circularization periods, emphasizing its importance over other mechanisms like equilibrium tides or gravity waves.

Contribution

It introduces a comprehensive model of tidal dissipation including inertial waves, demonstrating their key role in explaining binary orbit circularization across stellar evolution.

Findings

Inertial wave dissipation explains observed circularization periods.

Equilibrium tide and gravity wave dissipation are insufficient.

Inertial wave dissipation is effective during pre-main sequence and near synchronization.

Abstract

Tidal dissipation is responsible for circularizing the orbits and synchronizing the spins of solar-type close binary stars, but the mechanisms responsible are not fully understood. Previous work has indicated that significant enhancements to the theoretically-predicted tidal dissipation rates are required to explain the observed circularization periods ($P_\mathrm{circ}$) in various stellar populations, and their evolution with age. This was based partly on the common belief that the dominant mechanism of tidal dissipation in solar-type stars is turbulent viscosity acting on equilibrium tides in convective envelopes. In this paper we study tidal dissipation in both convection and radiation zones of rotating solar-type stars following their evolution. We study equilibrium tide dissipation, incorporating a frequency-dependent effective viscosity motivated by the latest hydrodynamical simulations, and inertial wave (dynamical tide) dissipation, adopting a frequency-averaged formalism that accounts for the realistic structure of the star. We demonstrate that the observed binary circularization periods can be explained by inertial wave (dynamical tide) dissipation in convective envelopes. This mechanism is particularly efficient during pre-main sequence phases, but it also operates on the main sequence if the spin is close to synchronism. The predicted $P_\mathrm{circ}$ due to this mechanism increases with main-sequence age in accord with observations. We also demonstrate that both equilibrium tide and internal gravity wave dissipation are unlikely to explain the observed $P_\mathrm{circ}$, even during the pre-main sequence, based on our best current understanding of these mechanisms. Finally, we advocate more realistic dynamical studies of stellar populations that employ tidal dissipation due to inertial waves.