Angular momentum redistribution by waves in the sun

Citation
P. Kumar et al., Angular momentum redistribution by waves in the sun, ASTROPHYS J, 520(2), 1999, pp. 859-870
Citations number
20
Categorie Soggetti
Space Sciences
Journal title
ASTROPHYSICAL JOURNAL
ISSN journal
0004637X → ACNP
Volume
520
Issue
2
Year of publication
1999
Part
1
Pages
859 - 870
Database
ISI
SICI code
0004-637X(19990801)520:2<859:AMRBWI>2.0.ZU;2-P
Abstract
We calculate the angular momentum transport by gravito-inertial-Alfven wave s and show that, so long as prograde and retrograde gravity waves are excit ed to roughly the same amplitude, the sign of angular momentum deposit in t he radiative interior of the Sun is such as to lead to an exponential growt h of any existing small radial gradient of rotation velocity just below the convection zone. This leads to formation of a strong thin shear layer (of thickness about 0.3% R.) near the top of the radiative zone of the Sun on a timescale of order 20 yr. When the magnitude of differential rotation acro ss this layer reaches about 0.1 mu Hz, the layer becomes unstable to shear instability and undergoes mixing, and the excess angular momentum deposited in the layer is returned to the convection zone. The strong shear in this layer generates a toroidal magnetic field which is also deposited in the co nvection zone when the layer becomes unstable. This could possibly start a new magnetic activity cycle seen at the surface.