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Author(s): Wei, Xing; Goodman, Jeremy J.

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Abstract: We investigate the interaction of differential rotation and a misaligned magnetic field. The incompressible magnetohydrodynamic equations are solved numerically for a free-decay problem. In the kinematic limit, differential rotation annihilates the non-axisymmetric field on a timescale proportional to the cube root of magnetic Reynolds number (Rm), as predicted by Radler. Nonlinearly, the outcome depends upon the initial energy in the non-axisymmetric part of the field. Sufficiently weak fields approach axisymmetry as in the kinematic limit; some differential rotation survives across magnetic surfaces, at least on intermediate timescales. Stronger fields enforce uniform rotation and remain non-axisymmetric. The initial field strength that divides these two regimes does not follow the scaling Rm(-1/3) predicted by quasi-kinematic arguments, perhaps because our Rm is never sufficiently large or because of reconnection. We discuss the possible relevance of these results to tidal synchronization and tidal heating of close binary stars, particularly double white dwarfs.
Publication Date: 10-Jun-2015
Electronic Publication Date: 5-Jun-2015
Citation: Wei, Xing, Goodman, Jeremy. (2015). ON OBLIQUELY MAGNETIZED AND DIFFERENTIALLY ROTATING STARS. ASTROPHYSICAL JOURNAL, 806 (10.1088/0004-637X/806/1/50
DOI: doi:10.1088/0004-637X/806/1/50
ISSN: 0004-637X
EISSN: 1538-4357
Type of Material: Journal Article
Journal/Proceeding Title: ASTROPHYSICAL JOURNAL
Version: Final published version. Article is made available in OAR by the publisher's permission or policy.

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