Magnetic Pinching of Hyperbolic Flux Tubes: I. Basic Estimations
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.
Cite
@article{arxiv.astro-ph/0208112,
title = {Magnetic Pinching of Hyperbolic Flux Tubes: I. Basic Estimations},
author = {V. S. Titov and K. Galsgaard and T. Neukirch},
journal= {arXiv preprint arXiv:astro-ph/0208112},
year = {2007}
}
Comments
31 pages, 12 figures, accepted to Astrophysical Journal, added typos in Eq. (A9) and new comments to Sections 2 and 7, references updated