During the 14th/15th of April 2002, several flares occurred in NOAA active region complex 9893/9910. Two of these were previously interpreted as having anomalously high coronal column densities. We develop a scenario using multiwavelength observations to explain the high coronal column density (approx 1020cm-2) present at the onset of the 14th April 2002 M3.7 hard X-ray event.Prior to this event a series of flares occurred in close temporal and spatial proximity. We observe the sequence of flares in a multiwavelength regime from radio to hard X-rays. This allows us to study the particle acceleration and plasma evaporation in these events. The observations of these flares lead us to propose a sequence of reconnections between multiple systems of loops in a 3 dimensional field geometry. We suggest that the dense loops in the M3.7 event can be explained as being already filledwith plasma from the earlier events; these loops then themselves become unstable or reconnect leading to particle acceleration into an overdense coronal environment. We explore the possibility that a high-beta disruption is behind the instability of these dense loops, leading to the 14th April 2002 M3.7 event and the observation of hard X-rays in the corona at energies up to approx 50 keV.
Authors: L. Bone, J. C. Brown, L. Fletcher, A. Veronig and S. White
Publication Status: A&A (in press)
Last Modified: 2007-01-26 10:40