Competition between gravity waves excited by convection and tides in stars that host a companion

Asteroseismology has become a powerful diagnostic tool in stellar astrophysics, offering unprecedented insights into the internal structures and dynamics of stars. Through the analysis of stellar oscillation modes, it enables the precise characterisation of stellar interiors across a wide range of stellar masses and evolutionary phases, from the main sequence to the white dwarf phase. At the same time, the number of close stellar and planetary companions discovered throughout all stellar evolutionary phases has increased significantly, raising key questions about the interplay between stellar evolution and binarity. In this study we investigated the competition between gravity waves excited by internal convection and those excited by tides in stars that host a companion. By modelling the energy and angular momentum luminosities transported by internal gravity waves stochastically excited by convection and by tides, we sought to quantify their relative contributions and identify the main parameters that govern their efficiency. We computed the energy and angular momentum luminosities transported by both types of waves for a range of stellar masses and evolutionary stages, with a particular focus on understanding how the presence of a companion influences the angular momentum transport and the induced rotational evolution of the radiative layers of the host star. The competition between the two excitation mechanisms is sensitive to the mass and orbital properties of the companion, as well as the internal structure of the host star. We find that for a Jupiter-mass companion, the stochastic excitation dominates over tidal excitation during all evolutionary phases. Only for close-in stellar companions around late-type stars does the tidal excitation become more efficient. The presence of a companion is unlikely to significantly alter the internal angular momentum transport in the radiative layers of the host star, simplifying the modelling of angular momentum transport driven by internal gravity waves in stars that host a companion.