Solar flares, microflares, nanoflares, and coronal heating

Abstract

Solar flare occurrence follows a power-law distribution against total flare energy W: d N/d W ∼ W-α with an index α ∼ 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. © 1991 Kluwer Academic Publishers.