期刊
ASTRONOMY & ASTROPHYSICS
卷 580, 期 -, 页码 -出版社
EDP SCIENCES S A
DOI: 10.1051/0004-6361/201526472
关键词
hydrodynamics; waves; celestial mechanics; planet-star interactions; stars: evolution; stars: rotation
资金
- Programme National de Planetologie (CNRS/INSU)
- CoRoT-CNES grant at Service d'Astrophysique (CEA-Saclay)
Context. Since 1995, more than 1500 exoplanets have been discovered around a wide variety of host stars (from M- to A-type stars). Tidal dissipation in stellar convective envelopes is an important factor that shapes the orbital architecture of short-period systems. Aims. Our objective is to understand and evaluate how tidal dissipation in the convective envelope of low-mass stars (from M to F types) depends on their mass, evolutionary stage, and rotation. Methods. Using a simplified two-layer assumption, we analytically compute the frequency-averaged tidal dissipation in the convective envelope. This dissipation is due to the conversion into heat of the kinetic energy of tidal non-wavelike/equilibrium flow and inertial waves because of the viscous friction applied by turbulent convection. Using grids of stellar models allows us to study the variation of the dissipation as a function of stellar mass and age on the pre-main sequence and on the main sequence for stars with masses ranging from 0.4 to 1.4 M-circle dot. Results. During their pre-main sequence, all low-mass stars have an increase in the frequency-averaged tidal dissipation for a fixed angular velocity in their convective envelope until they reach a critical aspect and mass ratios (respectively alpha = R-c/R-s and beta = M-c/M-s, where R-s, M-s, R-c, and M-c are the star's radius and mass and its radiative core's radius and mass). Next, the dissipation evolves on the main sequence to an asymptotic value that is highest for 0.6 M-circle dot K-type stars and that then decreases by several orders of magnitude with increasing stellar mass. Finally, the rotational evolution of low-mass stars strengthens the importance of tidal dissipation during the pre-main sequence for star-planet and multiple star systems. Conclusions. As shown by observations, tidal dissipation in stars' convection zones varies over several orders of magnitude as a function of stellar mass, age, and rotation. We demonstrate that i) it reaches a maximum value on the pre-main sequence for all stellar masses and ii) on the main sequence and at fixed angular velocity, it is at a maximum for 0.6 M-circle dot K-type stars and decreases with increasing mass.
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