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Magnetic Pinching of Hyperbolic Flux Tubes: I. Basic Estimations

V. S. Titov·K. Galsgaard·T. Neukirch
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Abstract

The concept of hyperbolic flux tubes (HFTs) is a generalization of the concept of separator field lines for coronal magnetic fields with a trivial magnetic topology. An effective mechanism of a current layer formation in HFTs is proposed. This mechanism is called magnetic pinching and it is caused by large-scale shearing motions applied to the photospheric feet of HFTs in a way as if trying to twist the HFT. It is shown that in the middle of an HFT such motions produce a hyperbolic flow that causes an exponentially fast growth of the current density in a thin force-free current layer. The magnetic energy associated with the current layer that is built up over a few hours is sufficient for a large flare. Other implications of HFT pinching for solar flares are discussed as well.

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V. S. Titov, K. Galsgaard, T. Neukirch. 2002-10-04. Magnetic Pinching of Hyperbolic Flux Tubes: I. Basic Estimations. https://doi.org/10.1086/344799

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