Birth and evolution of a dense coronal loop in a complex flare region
Abstract
Context: 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.
Aims: We develop a scenario using multiwavelength observations to explain the high coronal column density (≈1020 cm-2) present at the onset of the 14th April 2002 M3.7 hard X-ray event.
Methods: 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.
Results: 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 filled with 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 ≈50 keV.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- April 2007
- DOI:
- 10.1051/0004-6361:20065129
- Bibcode:
- 2007A&A...466..339B
- Keywords:
-
- Sun: activity;
- Sun: flares;
- Sun: radio radiation;
- Sun: X-rays;
- gamma rays