Does magnetic field impact tidal dynamics inside the convective zone of low-mass stars along their evolution?

TL;DR

This study investigates how magnetic fields in low-mass stars influence the dissipation of tidal waves within their convective zones, revealing that magnetic effects mainly impact wave dissipation rather than excitation, which affects star-planet interaction models.

Contribution

The paper provides the first detailed analysis of the magnetic influence on tidal wave dissipation in low-mass stars across their evolution using stellar models and scaling laws.

Findings

Magnetic fields have little effect on tidal wave excitation in nearly-circular hot-Jupiter systems.

Magnetic fields significantly influence the dissipation of tidal waves.

A full magneto-hydrodynamical approach is necessary for accurate modeling.

Abstract

The dissipation of the kinetic energy of wave-like tidal flows within the convective envelope of low-mass stars is one of the key physical mechanisms that shapes the orbital and rotational dynamics of short-period exoplanetary systems. Although low-mass stars are magnetically active objects, the question of how the star's magnetic field impacts large-scale tidal flows and the excitation, propagation and dissipation of tidal waves still remains open. Our goal is to investigate the impact of stellar magnetism on the forcing of tidal waves, and their propagation and dissipation in the convective envelope of low-mass stars as they evolve. We have estimated the amplitude of the magnetic contribution to the forcing and dissipation of tidally induced magneto-inertial waves throughout the structural and rotational evolution of low-mass stars (from M to F-type). For this purpose, we have used detailed grids of rotating stellar models computed with the stellar evolution code STAREVOL. The amplitude of dynamo-generated magnetic fields is estimated via physical scaling laws at the base and the top of the convective envelope. We find that the large-scale magnetic field of the star has little influence on the excitation of tidal waves in the case of nearly-circular orbits and coplanar hot-Jupiter planetary systems, but that it has a major impact on the way waves are dissipated. Our results therefore indicate that a full magneto-hydrodynamical treatment of the propagation and dissipation of tidal waves is needed to properly assess the impact of star-planet tidal interactions throughout the evolutionary history of low-mass stars hosting short-period massive planets.