Instabilities in the Solar Tachocline

Scott Hopper (Newcastle University)

Wednesday 26th February 15:00-16:00 Maths 311B

Abstract

The solar tachocline is a thin region of strong shear located deep within the solar interior, which is largely stably stratified. It is thought to be the “seat” of the Sun’s magnetic field, and very likely subject to many hydrodynamic and magnetohydrodynamic instabilities such as magnetic buoyancy instability, magnetorotational instability and tearing instability. In this talk, we pay particular attention to the latter -- a resistive instability common in fluids that are highly electrically conductive and carry strong currents. We determine the effect of stable stratification on the tearing instability under the Boussinesq approximation, with a view to considering it in the tachocline. Our results generalise previous work that considered only specific parameter regimes, and we show that the length scale of the fastest growing mode depends non-monotonically on the stratification strength. We discuss the implications for tearing within the context of the solar tachocline.

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