Two-dimensional simulations of solar-like models with artificially enhanced luminosity

II. Impact on internal gravity waves

¹ University of Exeter, Physics and Astronomy, EX4 4QL Exeter, UK
e-mail: al598@exeter.ac.uk
² École Normale Supérieure, Lyon, CRAL (UMR CNRS 5574), Université de Lyon, France
³ Department of Physics and Astronomy, Georgia State University, Atlanta, GA 30303, USA
⁴ Centre for Fusion, Space and Astrophysics, Department of Physics, University of Warwick, Coventry CV4 7AL, UK
⁵ Institut de Recherche en Astrophysique et Planétologie, CNRS, UPS, CNES, Toulouse, France
⁶ AIM, CEA, CNRS, Universités Paris et Paris-Saclay, 91191 Gif-sur-Yvette, Cedex, France

Received: 2 November 2021
Accepted: 24 January 2022

Abstract

Artificially increasing the luminosity and the thermal diffusivity of a model is a common tactic adopted in hydrodynamical simulations of stellar convection. In this work, we analyse the impact of these artificial modifications on the physical properties of stellar interiors and specifically on internal gravity waves. We perform two-dimensional simulations of solar-like stars with the MUSIC code. We compare three models with different luminosity enhancement factors to a reference model. The results confirm that properties of the waves are impacted by the artificial enhancement of the luminosity and thermal diffusivity. We find that an increase in the stellar luminosity yields a decrease in the bulk convective turnover timescale and an increase in the characteristic frequency of excitation of the internal waves. We also show that a higher energy input in a model, corresponding to a larger luminosity, results in higher energy in high frequency waves. Across our tests with the luminosity and thermal diffusivity enhanced together by up to a factor of 10⁴, our results are consistent with theoretical predictions of radiative damping. Increasing the luminosity also has an impact on the amplitude of oscillatory motions across the convective boundary. One must use caution when interpreting studies of internal gravity waves based on hydrodynamical simulations with artificially enhanced luminosity.