Solar Physics Division Meeting 2000, June 19-22
Session 2. Corona, Solar Wind, Flares, CMEs, Solar-stellar, Instrumentation, Other
Display, Chair: J. Krall, Monday-Thursday, June 19, 2000, 8:00am-6:00pm, Forum Ballroom

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[2.58] Energy Release in an Impulsive Flare

J. Qiu (BBSO/NJIT), H. Wang (NJIT/BBSO), V. B. Yurchyshyn (BBSO/NJIT), P. R. Goode (NJIT/BBSO), BBSO/NJIT Team

We analyze the multi-spectral observations on an impulsive short-lived flare event, and demonstrate that the flare consisted of several flaring components with different evolution profiles, morphologies, energy spectra, and magnetic configurations. These observations suggest that the magnetic energy was released in this event in several ways.

(1) Two hard X-ray components were observed by Yohkoh HXT. One component was brightened and reached its emission maximum more slowly than the other component by > 15 seconds, and the spectrum of the slow component was much softer than the fast component. The coordinated high resolution ground-based observations from Big Bear Solar Observatory (BBSO) further demonstrate that these two hard X-ray components were each co-aligned with complicated H\alpha and magnetic field structures. Therefore, the two hard X-ray components should come from different magnetic reconnection processes at different locations.

(2) Accompanying the flare, we find both hot and cool mass ejections. The cool mass ejection was related to the fast-varying non-thermal flare component, while the hot mass ejection was related to the flare component which exhibited a strong heating process. The hot mass ejection, or bright surge, also led to a long-lasting (for at least a few hours) bright EUV loop. Such observation offers a strong evidence that both pre-flare and post-flare heating of the chromospheric material occurred at the root of the bright surge.

(3) We study the magnetic field configurations of the flare components, and propose that both the non-thermal and thermal components of the flare, together with the cool and hot surges, were produced by the magnetic reconnection of the large scale over-lying open field lines with the low-lying magnetic loops, while the gradual and thermal flare components and bright surge were located in the area of magnetic quadrupolar structures where moving magnetic features and flux cancellation were observed. The observations suggest that the proper motions in the region of the quadrupolar structure may enhance electric current along the separatrix and neutral point, and produce heating via current dissipation in the quadrupolar areas in the lower atmosphere both before and after the fast reconnection occurred.

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