Long-decay soft X-ray flares. 3

Twenty cases of LDE flares were analyzed with regard to the development of their morphology in the H-alpha line. It was found that LDE flares may be classed as: a) ''one-ribbon'' flares, in which the long-lasting H-alpha emission loops are arranged along the axis of the filament, or along its channel; b) two-ribbon flares, and c) three-ribbon flares which are a combination of the first two types. The system of central loops (SCL) of the three-ribbon flares is situated along the axis of the interribbon space and is a dynamic formation which cannot be mistaken for flare-loop tops. The repeated energy release which occurs in the lower part of the interribbon space indicates that the accumulation of energy, required for the formation of SCL and also for the trigger mechanism of the flare, is concentrated in the low structures (lower than 3.5-7.0 thousand kilometres). (author). 5 figs., 3 tabs., 46 refs