SOLAR-FLARES, MICROFLARES, NANOFLARES, AND CORONAL HEATING

Solar flare occurrence follows a power-law distribution against total flare energy W: [GRAPHICS] with an index alpha approximately 1.8 as determined by several studies. This implies (a) that microflares must have a different, steeper distribution if they are energetically significant, and (b) there must be a high-energy cutoff of the observed distribution. We identify the distinct 'soft' distribution needed for coronal heating, if such a distribution exists, with Parker's nanoflares.