Two-Dimensional Simulations of Internal Gravity Waves in The Radiation Zones of Intermediate-Mass Stars

TL;DR

This study uses two-dimensional hydrodynamical simulations to explore how internal gravity waves generated in the radiative zones of intermediate-mass stars propagate and interact, revealing nonlinear effects and matching observed wave spectra.

Contribution

It introduces detailed 2D non-linear simulations of IGWs in stars with realistic models, highlighting wave interactions and spectral properties consistent with observations.

Findings

Wave self-interaction observed with single wave forcing.

Non-linear triadic interactions occur with multiple wave forcing.

Surface wave spectra match observed power-law slopes.

Abstract

Intermediate-mass main sequence stars have large radiative envelopes overlying convective cores. This configuration allows internal gravity waves (IGWs) generated at the convective-radiative interface to propagate towards the stellar surface. The signatures of these waves can be observed in the photometric and spectroscopic data from stars. We have studied the propagation of these IGWs using two-dimensional fully-non-linear hydrodynamical simulations with realistic stellar reference states from the one-dimensional stellar evolution code, Modules for Stellar Astrophysics (MESA). When a single wave is forced, we observe wave self-interaction. When two waves are forced, we observe non-linear interaction (i.e. triadic interaction) between these waves forming waves at different wavelengths and frequencies. When a spectrum of waves similar to that found in numerical simulations is forced, we find that the surface IGW frequency slope is consistent with recent observations. This power law is similar to that predicted by linear theory for the wave propagation, with small deviations which can be an effect of nonlinearities. When the same generation spectrum is applied to 3 solar mass models at different stellar rotation and ages, the surface IGW spectrum slope is very similar to the generation spectrum slope.