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

Context. 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...

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Bibliographic Details
Published in:Astronomy and astrophysics (Berlin) 2019-11, Vol.631, p.A111
Main Authors: Astoul, A., Mathis, S., Baruteau, C., Gallet, F., Strugarek, A., Augustson, K. C., Brun, A. S., Bolmont, E.
Format: Article
Language:English
Subjects:
Amplitudes
Astronomical models
Astrophysics
Circular orbits
Energy dissipation
Excitation
Extrasolar planets
Kinetic energy
Low mass stars
Magnetic fields
Magnetism
magnetohydrodynamics (MHD)
Physics
planet-star interactions
Planetary evolution
Planetary systems
Propagation
Scaling laws
stars: evolution
stars: magnetic field
stars: rotation
Stellar evolution
Stellar magnetic fields
Stellar models
Stellar rotation
Tidal energy
Tidal flow
Tidal waves
Wave propagation
waves
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Summary:Context. 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. Aims. 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. Methods. 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. Results. 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.
ISSN:0004-6361
1432-0746
1432-0756
DOI:10.1051/0004-6361/201936477