EDP Sciences
Free access
Issue
A&A
Volume 425, Number 1, October I 2004
Page(s) 229 - 242
Section Stellar structure and evolution
DOI http://dx.doi.org/10.1051/0004-6361:20040278


A&A 425, 229-242 (2004)
DOI: 10.1051/0004-6361:20040278

Transport and mixing in the radiation zones of rotating stars

I. Hydrodynamical processes
S. Mathis and J.-P. Zahn

LUTH, Observatoire de Paris, 92195 Meudon, France
    e-mail: [stephane.mathis;jean-paul.zahn]@obspm.fr

(Received 16 February 2004 / Accepted 3 June 2004 )

Abstract
The purpose of this paper is to improve the modelization of the rotational mixing which occurs in stellar radiation zones, through the combined action of the thermally driven meridional circulation and of the turbulence generated by the shear of differential rotation. The turbulence is assumed to be anisotropic, due to the stratification, with stronger transport in the horizontal directions than in the vertical. The main difference with the former treatments by Zahn (1992, A&A, 265, 115) and Maeder & Zahn (1998, A&A, 334, 1000) is that we expand here the departures from spherical symmetry to higher order, and include explicitly the differential rotation in latitude, to first order. This allows us to treat simultaneously the bulk of a radiation zone and its tachocline(s). Moreover, we take fully into account the non-stationarity of the problem, which will enable us to tackle the rapid phases of evolution. The system of partial differential equations, which govern the transport of angular momentum, heat and chemical elements, is written in a form which makes it ready to implement in a stellar evolution code. Here the effect of a magnetic field is deliberately ignored; it will be included in forthcoming papers.


Key words: turbulence -- stars: evolution -- stars: rotation




© ESO 2004