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Lookup NU author(s): Rathish Ratnasingam, Professor Tamara Rogers
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
© The Author(s) 2026. Published by Oxford University Press on behalf of Royal Astronomical Society. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited. Recent asteroseismic analysis of the main-sequence F star KIC 9244992 has revealed evidence for a strong, predominantly toroidal magnetic field in its deep radiative interior. Motivated by this result, we present three-dimensional anelastic magnetohydrodynamic simulations of a rotating 2 (Formula presented) main-sequence star to investigate whether such internal magnetic field strengths and geometries naturally arise in global stellar dynamo simulations for stars within a similar mass range. These simulations self-consistently generate magnetic fields with azimuthal components that dominate over radial components by factors of several near the peak of the Brunt–Väisälä frequency left behind as the core recedes. Moreover, these field strengths arise despite near-uniform, spherically-averaged, rotation from the near-core region to the surface. When the Reynolds number is greater than (Formula presented) 100 and the appropriate Rossby number is used, the resulting field strengths and geometrical properties are consistent with those inferred asteroseismically for KIC 9244992. These results indicate that a dominant toroidal field in the near-core region is a generic field configuration in core-convecting stars and should be considered in future asteroseismic inferences.
Author(s): Ratnasingam RP, Rogers TM
Publication type: Article
Publication status: Published
Journal: Monthly Notices of the Royal Astronomical Society
Year: 2026
Volume: 549
Issue: 4
Print publication date: 01/07/2026
Online publication date: 10/06/2026
Acceptance date: 05/06/2026
Date deposited: 29/06/2026
ISSN (print): 0035-8711
ISSN (electronic): 1365-2966
Publisher: Oxford University Press
URL: https://doi.org/10.1093/mnras/stag1107
DOI: 10.1093/mnras/stag1107
Data Access Statement: The data underlying this article will be shared on reasonable request to the corresponding authors.
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