Flare morphologies and coronal field configurations

Abstract

Chromospheric flares are the footpoints of closed coronal field lines. In this paper we present different flare morphologies from observations and examine the implied coronal field configurations above the flaring region. Flares are grouped according to the number of ribbons, from unresolved compact point-like flare to four-ribbon flares. Quiet region flares having characteristics all their own are also presented here.

We find that compact, unresolved point-like flares have two distinct footpoints when viewed in offband Hα. The footpoints of some of the compact flares also show increased separation as a function of time.

Unlike large two-ribbon flares, the ribbons of many small and/or short-lived two-ribbon flares usually have no measurable separation of ribbons.

Multiple-ribbon (three or more ribbon) flares consist of two or more pairs of two-ribbons, or two or more sets of field lines. Parity of the ribbons in multiple-ribbon flares, or the lack of it, depends on the magnetic makeup of the locale of the ribbons.

Flares in old quiet regions resulting from sudden filament eruptions show discrete small patches of emissions reflecting the ‘spottiness’ of decayed and dispersed field of quiet region.