| Issue |
A&A
Volume 528, April 2011
|
|
|---|---|---|
| Article Number | A79 | |
| Number of page(s) | 7 | |
| Section | Astrophysical processes | |
| DOI | https://doi.org/10.1051/0004-6361/201014449 | |
| Published online | 04 March 2011 | |
Stellar Mixing
IV. The angular momentum problem⋆
1 NASA, Goddard Institute for Space
Studies, New
York, NY 10025, USA
2 Department of Applied Physics and
Applied Mathematics, Columbia University, New York, NY
10027,
USA
e-mail: vmc13@columbia.edu
Received: 17 March 2010
Accepted: 10 October 2010
We present a formalism that provides the Reynolds stresses needed to solve the angular momentum equation. The traditional Reynolds stress model assumes that the only contribution comes from shear (a down-gradient flux), but this leads to an extraction of angular momentum from the interior that is far too small compared to what is required to explain the helio seismological data. An illustrative solution of the new Reynolds stress equations shows that the presence of vorticity in a stably stratified regime, such as the one in the radiative zone, contributes a new term to the angular momentum equation that has an up-gradient flux like the one provided by the IGW model (internal gravity waves). The time scale entailed by such a term may be of the same order of 107 yrs produced by the IGW model. It would be instructive to solve the new angular momentum equation together with the formalism developed in Paper III to study not only the solar angular momentum distribution vs. helio data, but also the evolution of elements such as 7Li and 4He. These results would allow a more quantitative assessment of the overall model.
The complete model yields Reynolds stresses that include differential rotation, unstable/stable stratification, double diffusion, radiative losses (arbitrary Peclet number), and meridional currents.
Key words: turbulence / diffusion / convection / hydrodynamics / methods: analytical / stars: rotation
© ESO, 2011
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