The Nonlinear Breakup of the Sun’s Toroidal Field
There are good reasons for believing that the sun has a strong toroidal magnetic field in the stably-stratified region of convective overshoot sandwiched between the radiative zone and convective zone proper. We have modelled the magnetic field in this region by studying the behaviour of a layer of uniform field embedded in a sub-adiabatic atmosphere. Since the field can support extra mass, such a configuration is top-heavy and instabilities of the Rayleigh-Taylor type can occur. By numerical integration of the 2-dimensional compressible MHD equations we have followed the evolution of this instability into the nonlinear regime. The initial buoyancy-driven instability of the magnetic field gives rise to strong shearing motions, thereby exciting secondary Kelvin-Helmholtz instabilities which wrap the gas into regions of intense vorticity. The somewhat surprising subsequent motions are determined primarily by the strong interactions between vortices.
KeywordsConvection Zone Magnetic Layer Toroidal Field Random Initial Condition Magnetic Buoyancy
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- SPIEGEL, E.A. 1987 Hydrostatic adjustment time for the solar subconvective layer. In The Internal Solar Angular Velocity, eds. B.R. Durney and S. Sofia (D.Reidel), 321–327.Google Scholar