# Onset of Nonlinear Internal Gravity Waves in Intermediate-Mass Stars

## TL;DR

This paper investigates how internal gravity waves in stars' radiative zones become nonlinear, influenced by stellar parameters, and explores their potential role in angular momentum transport and mixing.

## Contribution

It introduces a criterion to determine when IGW become nonlinear in non-rotating stars, considering effects of radiative diffusion and density stratification based on stellar models.

## Key findings

- Nonlinear wave energies increase with stellar mass.
- Generation spectrum, convective velocities, and stratification influence wave nonlinearity.
- Trends vary with metallicity and age depending on the wave generation spectrum.

## Abstract

Internal gravity waves (IGW) propagate in the radiation zones of all stars. During propagation, their amplitudes are affected by two main features: radiative diffusion and density stratification. We have studied the implications of these two features on waves traveling within the radiative zones of non-rotating stars with stellar parameters obtained from the one dimensional stellar evolution code, MESA. As a simple measure of induced wave dynamics, we define a criterion to see if waves can become nonlinear and if so, under what conditions. This was done to understand the role IGW may play in angular momentum transport and mixing within stellar interiors. We find that the IGW generation spectrum, convective velocities and the strength of density stratification all play major roles in whether waves become nonlinear. With increasing stellar mass, there is an increasing trend in nonlinear wave energies. The trends with different metallicities and ages depend on the generation spectrum.