Enhanced Mixing in Magnetized Fingering Convection, and Implications for Red Giant Branch Stars

Harrington, Peter Z. and Garaud, Pascale (2019) Enhanced Mixing in Magnetized Fingering Convection, and Implications for Red Giant Branch Stars. The Astrophysical Journal, 870 (1). L5. ISSN 2041-8213

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Abstract

Double-diffusive convection has been well studied in geophysical contexts, but detailed investigations of the regimes characteristic of stellar or planetary interiors have only recently become feasible. As most astrophysical fluids are electrically conducting, it is possible that magnetic fields play a role in either enhancing or suppressing double-diffusive convection, but to date there have been no numerical investigations of such possibilities. Here we study the effects of a vertical background magnetic field (aligned with the gravitational axis) on the linear stability and nonlinear saturation of fingering (thermohaline) convection, through a combination of theoretical work and direct numerical simulations. We find that a vertical magnetic field rigidifies the fingers along the vertical direction, which has the remarkable effect of enhancing vertical mixing. We propose a simple analytical model for mixing by magnetized fingering convection, and argue that magnetic effects may help explain discrepancies between theoretical and observed mixing rates in low-mass red giant branch stars. Other implications of our findings are also discussed.

Item Type: Article
Subjects: GO for STM > Physics and Astronomy
Depositing User: Unnamed user with email support@goforstm.com
Date Deposited: 06 Jun 2023 07:14
Last Modified: 18 Sep 2023 10:34
URI: http://archive.article4submit.com/id/eprint/1005

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