Astronomy and Astrophysics – Astrophysics
Scientific paper
2006-04-03
Astrophys.J.655:1157-1165,2007
Astronomy and Astrophysics
Astrophysics
Changed content: 24 pages, 3 figures, accepted for publication in ApJ
Scientific paper
10.1086/510345
Angular momentum transport by internal magnetic fields is an important ingredient for stellar interior models. In this paper we critically examine the basic heuristic assumptions in the model of the Tayler-Spruit dynamo, which describes how a pinch-type instability of a toroidal magnetic field in differentially rotating stellar radiative zones may result in large-scale fluid motion. We agree with prior published work both on the existence of the instability and its nearly horizontal geometry for perturbations. However, the approximations in the original Acheson dispersion relation are valid only for small length scales, and we disagree that the dispersion relation can be extrapolated to horizontal length scales of order the radius of the star. We contend that dynamical effects, in particular angular momentum conservation, limit the maximum horizontal length scale. We therefore present transport coefficients for chemical mixing and angular momentum redistribution by magnetic torques that are significantly different from previous published values. The new magnetic viscosity is reduced by 2 to 3 orders of magnitude compared to the old one, and we find that magnetic angular momentum transport by this mechanism is very sensitive to gradients in the mean molecular weight. The revised coefficients are more compatible with empirical constraints on the timescale of core-envelope coupling in young stars than the previous ones. However, solar models including only this mechanism possess a rapidly rotating core, in contradiction with helioseismic data. (abridged)
Denissenkov Pavel A.
Pinsonneault Marc
No associations
LandOfFree
A Revised Prescription for the Tayler-Spruit Dynamo: Magnetic Angular Momentum Transport in Stars does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with A Revised Prescription for the Tayler-Spruit Dynamo: Magnetic Angular Momentum Transport in Stars, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and A Revised Prescription for the Tayler-Spruit Dynamo: Magnetic Angular Momentum Transport in Stars will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-500573