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Astron. Astrophys. 322, 320-328 (1997)


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Angular momentum transport by internal waves in the solar interior

Jean-Paul Zahn 1, Suzanne Talon 1 and José Matias 1, 2

1 Département d'Astrophysique Stellaire et Galactique, Observatoire de Paris, Section de Meudon, F-92195 Meudon, France
2 Centro de Astrofísica, Universidade do Porto, Rua do Campo Alegre 823, 415 Porto, Portugal (zahn@obspm.fr, talon@obspm.fr, Jose.Matias@mail.telepac.pt)

Received 6 September 1996 / Accepted 20 November 1996

Abstract

The internal gravity waves of low frequency which are emitted at the base of the solar convection zone are able to extract angular momentum from the radiative interior. We evaluate this transport with some simplifying assumptions: we ignore the Coriolis force, approximate the spectrum of turbulent convection by the Kolmogorov law, and couple this turbulence to the internal waves through their pressure fluctuations, following Press (1981) and García López & Spruit (1991). The local frequency of an internal wave varies with depth in a differentially rotating star, and it can vanish at some location, thus leading to enhanced damping (Goldreich & Nicholson 1989). It is this dissipation mechanism only that we take into account in the exchange of momentum between waves and stellar rotation. The flux of angular momentum is then an implicit function of depth, involving the local rotation rate and an integral representing the cumulative effect of radiative dissipation. We find that the efficiency of this transport process is rather high: it operates on a timescale of [FORMULA] years, and is probably responsible for the flat rotation profile which has been detected through helioseismology.

Key words: Hydrodynamics – turbulence – Sun: interior: rotation – stars: interiors: rotation

Send offprint requests to: Jean-Paul Zahn

© European Southern Observatory (ESO) 1997

Online publication: June 30, 1998

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