Two-dimensional simulations of solar-like models with artificially enhanced luminosity. II. Impact on internal gravity waves

TL;DR

This study investigates how artificial enhancements of luminosity in 2D stellar simulations affect internal gravity waves, revealing significant impacts on wave properties and emphasizing caution in interpreting such simulation results.

Contribution

It provides a detailed analysis of the effects of artificially increased luminosity and thermal diffusivity on stellar interior dynamics and internal gravity waves in 2D models.

Findings

Higher luminosity decreases convective turnover timescale.

Increased luminosity raises the characteristic frequency of internal wave excitation.

Enhanced luminosity results in higher energy in high-frequency waves.

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.