Theory of differential rotation and meridional circulation

Abstract

Meridional flow results from slight deviations from the thermal wind balance. The deviations are relatively large in the boundary layers near the top and bottom of the convection zone. Accordingly, the meridional flow attains its largest velocities at the boundaries and decreases inside the convection zone. The thickness of the boundary layers, where meridional flow is concentrated, decreases with rotation rate, so that an advection-dominated regime of dynamos is not probable in rapidly rotating stars. Angular momentum transport by convection and by the meridional flow produce differential rotation. The convective fluxes of angular momentum point radially inward in the case of slow rotation but change their direction to equatorward and parallel to the rotation axis as the rotation rate increases. The differential rotation of main-sequence dwarfs is predicted to vary mildly with rotation rate but increase strongly with stellar surface temperature. The significance of differential rotation for dynamos has the opposite tendency to increase with spectral type.

12 pages, 9 figures. To appear in the Proceedings of IAU Symp. 294 "Solar and Astrophysical Dynamos and Magnetic Activity"

References in corpus (7)

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• A theoretical model of the variation of the meridional circulation with the solar cycle
• Enhanced Rotational Mixing in the Radiative Zones of Massive Stars
• New Suns in the Cosmos II: Differential rotation in Kepler Sun-like stars
• A Theoretical Model of the Near Surface Shear Layer of the Sun
• Turbulence Closure for Mixing Length Theories
• Convective Differential Rotation in Stars and Planets I: Theory
• Magnetic field as a tracer for studying the differential rotation of the solar corona
• Forward Modeling Helioseismic Signatures of One- and Two-cell Meridional Circulation
• A theoretical estimate of the pole-equator temperature difference and a possible origin of the near-surface shear layer
• Meridional flow velocities on solar-like stars with known activity cycles