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Numerical Simulations Confirm Wave-induced Shear Mixing in Stellar Interiors

Lookup NU author(s): Dr Ashlin Varghese, Rathish Ratnasingam, Professor Tamara Rogers

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This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).

Abstract

© 2025. The Author(s). Published by the American Astronomical Society. Internal gravity waves (IGWs) are thought to cause mixing in stellar interiors, a process that has been widely studied both theoretically and numerically. Our aim is to determine the physical mechanism responsible for the wave-induced mixing in stellar interiors. We compare the mixing profiles obtained from two-dimensional (2D) equatorial hydrodynamical and tracer particle simulations with theoretical predictions from R. J. Garcia Lopez & H. C. Spruit and J. P. Zahn (1992) on wave mixing due to wave-induced shear turbulence. Our results show that, despite not satisfying the vertical shear instability threshold, the mixing profiles from the simulations agree remarkably well with the theoretical predictions of both prescriptions, strongly suggesting that shear from IGWs plays an important role in mixing even at low shear rates. This agreement remains robust across different stellar masses, ages, rotation and simulation parameters. This provides an important step in providing realistic parameterisations for wave mixing in stellar structure and evolution models.

Publication metadata

Author(s): Varghese A, Ratnasingam RP, Ramirez-Galeano L, Mathis S, Rogers TM

Publication type: Article

Publication status: Published

Journal: Astrophysical Journal Letters

Year: 2025

Volume: 992

Issue: 1

Online publication date: 06/10/2025

Acceptance date: 20/09/2025

Date deposited: 20/10/2025

ISSN (print): 2041-8205

ISSN (electronic): 2041-8213

Publisher: American Astronomical Society

URL: https://doi.org/10.3847/2041-8213/ae09ae

DOI: 10.3847/2041-8213/ae09ae

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