Evidence for the Flare Trigger Site and Three‐Dimensional Reconnection in Multiwavelength Observations of a Solar Flare

Abstract

Based on a multiwavelength data set and a topological model for the magnetic field, the authors argue that a M1.9 flare which occurred on 1993 May 3 shows evidence of three-dimensional coronal reconnection in a spine-fan configuration. Images from the Transition Region and Coronal Explorer allow the detailed examination of the structures involved in the flare and preflare in the 171 AA (1 MK) EUV passband and the Ly alpha (10-20 kK) passband. Yohkoh Hard X-ray Telescope maps the position of nonthermal electron precipitation and the Soft X-ray Telescope reveals preflare and flare heating on large and small scales. While the flare appears to be driven by changes in small-scale field close to the photosphere, near the interface between strong opposite magnetic polarities, the result is the disruption of large-scale field. The authors demonstrate how this observed activity on large and small scales, along with many other aspects of the flare, suggests a qualitative explanation in the three-dimensional reconfiguration of coronal magnetic field, following a small-scale flux cancellation at the photosphere.