Evidence for the flare trigger site and three-dimensional reconnection in multiwavelength observations of a solar flare

Based on a multiwavelength data set and a topological model for the magneti c field, we argue that a M1.9 hare which occurred on 1993 May shows evidenc e of three-dimensional coronal reconnection in a spine-fan configuration. I mages from the Transition Region and Coronal Explorer allow the detailed ex amination of the structures involved in the flare and preflare in the 171 A ngstrom (1 MK) EUV passband and the Ly alpha (10,000-20,000 K) passband. Yo hkoh Hard X-ray Telescope maps the position of nonthermal electron precipit ation and the Soft X-ray Telescope reveals preflare and flare heating on la rge and small scales. While the flare appears to be driven by changes in sm all-scale field close to the photosphere, near the interface between strong opposite magnetic polarities, the result is the disruption of large-scale field. We demonstrate how this observed activity on large and small scales, along with many other aspects of the flare, suggests a qualitative explana tion in the three-dimensional reconfiguration of coronal magnetic field, fo llowing a small-scale flux cancellation at the photosphere.