Tachocline Confinement by an Oscillatory Magnetic Field

Abstract

Helioseismic measurements indicate that the solar tachocline is very thin, its full thickness not exceeding 4% of the solar radius. The mechanism that inhibits differential rotation to propagate from the convective zone to deeper into the radiative zone is not known, though several propositions have been made. In this paper we demonstrate by numerical models and analytic estimates that the tachocline can be confined to its observed thickness by a poloidal magnetic field B_p of about one kilogauss, penetrating below the convective zone and oscillating with a period of 22 years, if the tachocline region is turbulent with a diffusivity of eta 10^10 cm^2/s (for a turbulent magnetic Prandtl number of unity). We also show that a similar confinement may be produced for other pairs of the parameter values (B_p, eta). The assumption of the dynamo field penetrating into the tachocline is consistent whenever eta>10^9 cm^2/s.

18 pages

Cited by in corpus (14)

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• Dynamics of the fast solar tachocline: I. Dipolar field
• The Dynamics of the Solar Radiative Zone
• Confinement of the solar tachocline by a cyclic dynamo magnetic field
• Some glimpses from helioseismology at the dynamics of the deep solar interior
• Dynamics of the fast solar tachocline: II. Migrating field
• A Consistent One-Dimensional Model for the Turbulent Tachocline
• On the possibility of a bimodal solar dynamo
• On the compatibility of a flux transport dynamo with a fast tachocline scenario
• Angular-momentum coupling through the tachocline
• An analytic interface dynamo over a shear layer of finite depth
• Stratified Resistive Tearing Instability
• Flux Transport Dynamo coupled with a Fast Tachocline Scenario
• Confinement of the Solar Tachocline by Dynamo Action in the Radiative Interior