34th Solar Physics Division Meeting, June 2003
Session 16 Flares and Microflares II
Poster, Wednesday, June 18, 2003, 3:30-5:00pm, Mezzanine

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[16.11] Pre-flare Activity, Canceling Magnetic Features, and Filament Initiation associated with an X-class Flare

Y.-J. Moon (BBSO/NJIT, KAO), J. Chae (Chungnam Univ.), G. S. Choe (PPPL), H. Wang (BBSO/NJIT), Y. D. Park (KAO)

We have examined the relationship among pre-flare brightenings, canceling magnetic features (CMFs), and filament initiation associated with an X1.8 flare that occurred in NOAA AR 9236 on November 24, 2000. For this, we have inspected high temporal (about 1 minute) and spatial (about 1 arcsec) resolutions of SOHO/MDI, BBSO H\alpha, and TRACE 1600 Å~ UV images. Major results are as follows. First, these pre-flare brightenings are the most clearly seen in the TRACE 1600 Å~ images rather than in BBSO H\alpha with very weak corresponding features in SOHO/EIT images. Second, two major pre-flare brightenings near one of the filament footpoints are exactly located on CMFs seen in the MDI images. Third, recurrent small-scale TRACE UV eruptive events, which may be interpreted as upward outflows associated with the low atmosphere magnetic reconnection, took place just at the site of

the CMFs. Fourth, these CMFs show a common tendency of flux change: first flux emergence and then flux cancellation. Fifth, the abrupt UV enhancement of one major pre-flare brightening is responsible for the flare precursor in the GOES X-ray curve. It is very interesting to note that such an enhancement is coincident with the starting of the eruption, which is about 20 minutes earlier than the starting time of hard X-ray flaring. Our results support an idea that the low atmosphere reconnection, supported by CMFs and pre-flare brightenings, play important role in triggering the filament eruption.

This work has been supported by NASA grants NAG5-10894 and NAG5-7837, by a MURI grant of AFOSR, and by NRL M10104000059-01J000002500 of Korean government.

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