The impact of rotation on the stochastic excitation of stellar acoustic modes in solar-like pulsators

¹ Université Paris-Saclay, Université Paris Cité, CEA, CNRS, AIM, Gif-sur-Yvette F-91191, France
² Ecole Polytechnique, Institut Polytechnique de Paris, Palaiseau, France
³ Institute of Science and Technology Austria (IST Austria), Am Campus 1, Klosterneuburg, Austria
⁴ Instituto de Astrofísica de Canarias (IAC), E-38205 La Laguna, Tenerife, Spain
⁵ Universidad de La Laguna (ULL), Departamento de Astrofísica, E-38206 La Laguna, Tenerife, Spain

^⋆ Corresponding author.

Received: 2 September 2024
Accepted: 12 February 2025

Abstract

Context. Recent observational results from asteroseismic studies show that an important fraction of solar-like stars do not present detectable stochastically excited acoustic oscillations. This non-detectability seems to correlate with a high rotation rate in the convective envelope and a high surface magnetic activity. At the same time, the properties of stellar convection are affected by rotation and magnetism.

Aims. We investigate the role of rotation in the excitation of acoustic modes in the convective envelope of solar-like stars, to evaluate its impact on the energy injected in the oscillations.

Methods. We derived theoretical prescriptions for the excitation of acoustic waves in the convective envelope of rotating solar-like stars. We adopted the rotating mixing-length Theory to model the influence of rotation on convection. We used the MESA stellar evolution code and the GYRE stellar oscillation code to estimate the power injected in the oscillations from our theoretical prescriptions.

Results. We demonstrate that the power injected in the acoustic modes is insensitive to rotation if a Gaussian time-correlation function is assumed, while it can decrease by up to 60% for a Lorentzian time-correlation function, for a 20 Ω_⊙ rotation rate. We show that the modification of the excitation rate by rotation depends not only on the rotation rate but also on the radial and angular orders of the considered oscillation mode. This result can allow for better constraints on the properties of stellar convection by studying observationally acoustic mode excitation.

Conclusions. These results demonstrate how important it is to take into account the modification of stellar convection by rotation when evaluating the amplitude of the stellar oscillations it stochastically excites. They open the path for understanding the large variety of observed acoustic-mode amplitudes at the surface of solar-like stars as a function of surface rotation rates.