Characterizing the propagation of gravity waves in 3D nonlinear simulations of solar-like stars

TL;DR

This paper uses 3D nonlinear simulations to analyze the excitation, propagation, and dissipation of gravity waves in the radiative zone of solar-like stars, revealing their complex behavior and energy distribution.

Contribution

It provides a detailed 3D analysis of internal gravity waves in stellar interiors, comparing simulations with linear theory and highlighting the importance of 3D effects.

Findings

Identification of wave propagation regions in 2D and 3D

Comparison of simulation results with linear raytracing theory

Discovery of non-uniform energy distribution depending on azimuthal wave number

Abstract

The revolution of helio- and asteroseismology provides access to the detailed properties of stellar interiors by studying the star's oscillation modes. Among them, gravity (g) modes are formed by constructive interferences between progressive internal gravity waves (IGWs), propagating in stellar radiative zones. Our new 3D nonlinear simulations of the interior of a solar-like star allows us to study the excitation, propagation, and dissipation of these waves. The aim of this article is to clarify our understanding of the behavior of IGWs in a 3D radiative zone and to provide a clear overview of their properties. We use a method of frequency filtering that reveals the path of {individual} gravity waves of different frequencies in the radiative zone. We are able to identify the region of propagation of different waves in 2D and 3D, to compare them to the linear raytracing theory and to distinguish between propagative and standing waves (g modes). We also show that the energy carried by waves is distributed in different planes in the sphere, depending on their azimuthal wave number. We are able to isolate individual IGWs from a complex spectrum and to study their propagation in space and time. In particular, we highlight in this paper the necessity of studying the propagation of waves in 3D spherical geometry, since the distribution of their energy is not equipartitioned in the sphere.