Solar Physics

, Volume 53, Issue 2, pp 305–345 | Cite as

An unstable arch model of a solar flare

  • Daniel S. Spicer


The theoretical consequences of assuming that a current flows along flaring arches consistent with a twist in the field lines of these arches are examined. It is found that a sequence of magneto-hydrodynamic (MHD) and resistive MHD instabilities driven by the assumed current (which we refer to as the toroidal current) can naturally explain most manifestations of a solar flare.

The principal flare instability in the proposed model is the resistive kink (or tearing mode in arch geometry) which plays the role of thermalizing some of the field energy in the arch and generating X-configured neutral points needed for particle acceleration. The difference between thermal and nonthermal flares is elucidated and explained, in part, by amplitude-dependent instabilities, generally referred to as overlapping resonances. We show that the criteria for the generation of flare shocks strongly depend on the magnitude and gradient steepness of the toroidal current, which also are found to determine the volume and rate of energy release. The resulting model is in excellent agreement with present observations and has successfully predicted several flare phenomena.


Flare Energy Release Field Line Current Flow Solar Flare 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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Copyright information

© D. Reidel Publishing Company 1977

Authors and Affiliations

  • Daniel S. Spicer
    • 1
    • 2
  1. 1.E. O. Hulburt Center for Space Research, U.S. Naval Research LaboratoryWashington, D.C.U.S.A.
  2. 2.Institute for Fluid Dynamics and Applied Mathematics, University of MarylandCollege ParkU.S.A.

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