Two-dimensional simulations of solar-like models with artificially enhanced luminosity: Impact on internal gravity waves
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 (IGW). We perform two-dimensional simulations of solar-like stars with the fully compressible MUltidimensional Stellar Implicit Code (MUSIC). 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 of the stellar luminosity yields a decrease of the bulk convective turnover timescale and an increase of 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 10^4, 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 thus interpret with caution studies of IGW based on hydrodynamical simulations with artificially enhanced luminosity.