LOW ATMOSPHERE RECONNECTIONS ASSOCIATED WITH AN ERUPTIVE SOLAR FLARE

Abstract

It has been a big mystery what drives lament eruptions and ares. We have studied in detail an X1.8 are and its associated lament eruption that occurred in NOAA Active Region 9236 on November 24, 2000. For this work we have analyzed high temporal (about 1 minute) and spatial (about 1 arcsec) resolution images taken by Michelson Doppler Imager (MDI) onboard the Solar and Heliospheric Observatory, H centerline and blue wing (?0.6 A) images from Big Bear Solar Observatory, and 1600 A UV images by the Transition Region and Corona Explorer (TRACE). We have found that there were several transient brightenings seen in H and, more noticeably in TRACE 1600 A images around the preeare phase. A closer look at the UV brightenings in 1600 A images reveals that they took place near one end of the erupting lament, and are a kind of jets supplying mass into the transient loops seen in 1600 A. These brightenings were also associated with canceling magnetic features (CMFs) as seen in the MDI magnetograms. The ux variations of these CMFs suggest that the ux cancellation may have been driven by the emergence of the new ux. For this event, we have estimated the ejection speeds of the lament ranging from 10 to 160 km s ?1 for the rst twenty minutes. It is noted that the initiation of the lament eruption (as deened by the rise speed less than 20 km s ?1) coincided with the preeare activity characterized by UV brightenings and CMFs. The speed of the associated LASCO CME can be well extrapolated from the observed lament speed and its direction is consistent with those of the disturbed UV loops associated with the preeare activity. Supposing the H/UV transient brightenings and the canceling magnetic features are due to magnetic reconnection in the low atmosphere, our results may be strong observational evidence supporting that the initiation of the lament eruption and the preeare phase of the associated are may be physically related to low-atmosphere magnetic reconnection.