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One-winged butterflies: mode selection for azimuthal magnetorotational instability by thermal convection

Published online by Cambridge University Press:  27 August 2024

Ashish Mishra
Affiliation:
Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstr. 400, D-01328 Dresden, Germany Center for Astronomy and Astrophysics, ER 3-2, TU Berlin, Hardenbergstr. 36, 10623 Berlin, Germany
George Mamatsashvili*
Affiliation:
Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstr. 400, D-01328 Dresden, Germany Abastumani Astrophysical Observatory, Abastumani 0301, Georgia
Martin Seilmayer
Affiliation:
Staatliche Studienakademie Bautzen, Löbauer Str. 1, 02625 Bautzen, Germany
Frank Stefani
Affiliation:
Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstr. 400, D-01328 Dresden, Germany
*
Email address for correspondence: g.mamatsashvili@hzdr.de

Abstract

The effects of thermal convection on turbulence in accretion discs, and particularly its interplay with the magnetorotational instability (MRI), are of significant astrophysical interest. Despite extensive theoretical and numerical studies, such an interplay has not been explored experimentally. We conduct linear analysis of the azimuthal version of MRI (AMRI) in the presence of thermal convection and compare the results with our experimental data published before. We show that the critical Hartmann number ($Ha$) for the onset of AMRI is reduced by convection. Importantly, convection breaks symmetry between $m = \pm 1$ instability modes ($m$ is the azimuthal wavenumber). This preference for one mode over the other makes the AMRI wave appear as a ‘one-winged butterfly’.

Type
JFM Rapids
Copyright
© The Author(s), 2024. Published by Cambridge University Press

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