Browsing by Author "Zahn, Jean-Paul"
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- Angular momentum transport by internal waves in the solar interiorPublication . Zahn, Jean-Paul; Talon, Suzanne; Matias, JoséThe 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 Garc´ıa L´opez & 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 107 years, and is probably responsible for the flat rotation profile which has been detected through helioseismology.
- Angular momentum transport in the sun through meridian circulationPublication . Matias, José; Zahn, Jean-PaulWe investigated the transport of angularmomentum in the radiative interior of the Sun through the mecanism describ by ZAhn (1992), namely the meridian circulation driven by the solar wind and the turbulance caused by the shear instabilities due to the differential rotation.
- Internal waves and angular momentum transport in the sunPublication . Zahn, Jean-Paul; Talon, Suzanne; Matias, JoséThe low frequency gravity waves emitted at the base of the solar convection zone are able to extract angularmomentumfrom the radiative interior.
- Lithium depletion in the sunPublication . Morel, P.; Provost, J.; Berthomieu, G; Matias, José; Zahn, Jean-PaulPhysical properties of non-standard solar models including pre-main sequence phase, penetrative convention and microscopic diffusion are presented.We emphasize on 7Li depletion.