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T.G. Forbes (Univ. of New Hampshire)
The mechanism which causes sudden eruptions in the solar atmosphere remains controversial. However, there is some consensus that the most energetic eruptions are powered by the sudden release of magnetic energy associated with currents flowing in the corona. Of the various mechanism which have been suggested, most involve the disappearance of a stable equilibrium as a result of the slow evolution of the photospheric magnetic field. This disappearance may be due to a loss of ideal-MHD equilibrium or stability such as occurs in the kink mode, or to a loss of resistive-MHD equilibrium as a result of magnetic reconnection. Mechanisms involving gravitational processes have also been considered. Many of the proposed mechanisms are based on configurations containing a flux rope imbedded in a magnetic arcade, or a highly sheared arcade which has flux-rope-like properties. Application of the MHD virial theorem to such configurations implies that the key property which allows them to lose equilibrium, or stability, is the inverse polarity of the magnetic field created by the presence of the flux rope.
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Bulletin of the American Astronomical Society, 34
© 2002. The American Astronomical Soceity.