AAS Meeting #194 - Chicago, Illinois, May/June 1999
Session 79. The Sun Close Up: Results from the TRACE Mission
Solar, Oral, Wednesday, June 2, 1999, 2:00-3:30pm, Continental Ballroom C

[Previous] | [Session 79] | [Next]

[79.07] Studies of Microflares and C5.2 Flare of September 27, 1998

H. Wang, J. Qiu, J. Chae, C. Lee, P. Goode (Big Bear Solar Obs., NJIT)

On September 27, 1998, Big Bear Solar Observatory (BBSO) and Transition Region and Coronal Explorer (TRACE) coordinated observations from 16:00 to 19:00 UT to study properties of microflares on AR NOAA #8340. Fortuitously, a C5.2 flare occurred at 16:30UT in this active region. H\alpha and magnetograph movies were obtained at BBSO; CIV 1550Å, FeIX 171Å, and FeXII 195Åmovies were obtained by TRACE; both with a cadence about 1 minute. In this paper, we concentrate on the study of magnetic properties of 70 CIV microflares, as well as their relationship to the C5.2 flare. We obtained the following results: (1) We found two kinds of microflares: (a) microflares of transient brightenings with a time scale of 1 to 5 minutes (impulsive events). 90% of the microflares are of this form. Most of the events in this category are associated with well defined magnetic neutral lines, although a few of them are not located near a neutral line; and (b) microflares lasting half an hour or longer (persistent events). Seven events in three clusters belong to this category. All three sites are associated with a dominant magnetic polarity plus a very small element of opposite polarity. (2) More than a third of the impulsive microflares occurred near the C5.2 flare site indicating that a local instability is responsible for both the C5.2 flare and microflares. This indirectly support the avalanche theory of flare energy release, which predicts that a big flare may be associated with many small flares. Based on the morphologies of those events, we postulate that the persistent events may be due to loop interaction; while impulsive events may be associated with sheared loop structure.

If the author provided an email address or URL for general inquiries, it is a s follows:

[Previous] | [Session 79] | [Next]