HighEnergy Flare Explosions Driven by 3DIMENSIONAL XType Current Loop Coalescence
Abstract
We present a model for highenergy solar flare explosions driven by 3dimensional Xtype current loop coalescence. The 3dimensional Xtype current loop coalescence, where two crossed fluxtubes interact at one point, is a fundamentally new process as compared to the 1D and 2D cases studied earlier. This process is studied by a firstorder approach of the relevant variables near the point of coalescence; it appears to yield reliable information in a sufficiently large area around this point. It is shown that, following a strong plasma collapse due to the pinch effect, a pointlike plasma explosion can be driven while fast magnetosonic shock waves can also be excited. We found that the conditions in the area producing the remarkable flare bursts of 21 May, 1984 were indeed such that the many flare spikes could have been due to 3D explosive Xtype current loop coalescence. We also show, by studying the conditions of shock formation in a gamma ray flare, that the time delay of γrays from the impulsive phase could be the time needed for the shock formation in the flaring region. We draw some general conclusions on the question why certain flares do emit γrays in the MeV energy range, and why other, apparently important and energetic flares, do not. We accentuate the fact that a welldeveloped highenergy flare has three phases of particle acceleration.
 Publication:

Solar Physics
 Pub Date:
 August 1991
 DOI:
 10.1007/BF00152652
 Bibcode:
 1991SoPh..134..329S
 Keywords:

 Coalescing;
 Plasma Currents;
 Solar Flares;
 Gamma Rays;
 Mathematical Models;
 Plasma Heating;
 Shock Waves;
 Solar Magnetic Field;
 Solar Oscillations;
 Solar Physics