HR: 0830h
AN: SP11A-01    [Abstracts]
TI: Statistical Study of Rapid Penumbral Decay Associated with Flares
AU: * Chen, W
EM: wc35@njit.edu
AF: Center for Solar-Terrestrial Research, New Jersey Institute of Technology, 323 Martin Luther King Blvd, Newark, NJ 07102 United States
AU: Liu, C
EM: cl45@njit.edu
AF: Center for Solar-Terrestrial Research, New Jersey Institute of Technology, 323 Martin Luther King Blvd, Newark, NJ 07102 United States
AU: Wang, H
EM: haimin@flare.njit.edu
AF: Center for Solar-Terrestrial Research, New Jersey Institute of Technology, 323 Martin Luther King Blvd, Newark, NJ 07102 United States
AU: Wang, H
EM: haimin@flare.njit.edu
AF: Big Bear Solar Observatory, 40386 North Shore Lane, Big Bear City, CA 92314 United States
AB: We present results of statistical study of rapid penumbral decay associated with flares. In total, we investigated 402 events from 05/09/98 to 07/17/04, including 40 X-class, 173 M-class and 189 C-class flares. We show strong evidence that penumbral segments decayed rapidly and permanently right after many flares. The rapid changes, which can be identified in the time profiles of white-light(WL) mean intensity are permanent, not transient, thus are not due to flare emissions. Our study shows that penumbral decay is more likely to be detected when associated with large solar flares. The larger the flare magnitude, the stronger the penumbral decay is. For X-class flares, almost 50% events show distinct decay. But for M- and C-class flares, this percentage drops to 16% and 10%, respectively. For all the events that clear decay can be observed, we find that the locations of penumbral decay are associated with flare emissions and are connected by prominent TRACE post-flare loops. To explain these observations, we propose a reconnection picture in that the penumbral fields change from a highly inclined to a more vertical configuration, leading to penumbral decay.
DE: 7519 Flares
SC: Solar Physics Division - AAS [SP]
MN: 2005 Joint Assembly