Energy Release in Solar Flares,
STANFORD UNIV CA INST FOR PLASMA RESEARCH
Pagination or Media Count:
This report examines observational information concerning various phases of the solar-flare process a Recent evidence strongly suggests that the soft X-ray emission before and after the impulsive phase should be regarded as one process--the gradual phase. b Microwave and X-ray data indicate that the impulsive phase is comprised of a large number of similar bursts of energy release. c Large flares are usually preceded by filament eruptions, and it is possible tht the same process occurs on a smaller scale for smaller flares. We propose that most flares are initiated by the eruption of a filament. The eruption opens up magnetic field lines to form a large current sheet. This current sheet may persist as a coronal streamer, or it may immediately reconnect. Reconnection of this current sheet is responsible for the gradual phase of a flare. Since magnetic field at the photospheric level is concentrated into small knots of high field strength, the coronal magnetic field may be regarded as an aggregation of small flux tubes, each with an internal current, adjacent tubes being separated by current sheets. The gradual phase of a flare may leave the fine-scale current system undisturbed, in which case the flare has only a gradual phase.