HR: 1340h
AN: SH13A-0272    [Abstracts]
TI: Analysis of EUV Brightenings of Solar Flares
AU: * Su, Y
EM: ynsu@head.cfa.harvard.edu
AF: Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS 58, Cambridge, MA 02138 United States
AU: * Su, Y
EM: ynsu@head.cfa.harvard.edu
AF: Purple Mountain Observatory, 2 Bejing West Road, Nanjing, 210008 China
AU: Golub, L
EM: golub@head.cfa.harvard.edu
AF: Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS 58, Cambridge, MA 02138 United States
AU: Van Ballegooijen, A
EM: avanballegooijen@cfa.harvard.edu
AF: Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS 58, Cambridge, MA 02138 United States
AU: Gros, M
EM: MGROS@dapnia.cea.fr
AF: DSM/DAPNIA/Service d'Astrophysique, CEA Saclay, Gif-sur-Yvette, 91191 France
AB: An X17 class (GOES soft X-ray) two-ribbon solar flare occurred on 2003 October 28. EUV observations made by the Transition Region and Coronal Explorer (TRACE) show us that the two flare ribbons are initially composed of several discrete bright kernels. High time resolution hard X-ray (HXR) (E >150 KeV) data were obtained by the anticoincidence system (ACS) of the spectrometer SPI on board the ESA INTEGRAL satellite, and 8 spikes can be seen during the impulsive phase of the solar flare. The comparison of the evolution of EUV bright kernels and HXR light curves shows us that individual peaks in the HXR bursts are associated with peaks in the EUV light curves of individual bright kernels, which suggests that the EUV kernels result from direct energy deposition of the energetic particles accelerated in the flare. EUV bright kernels within the flare ribbons are tracked and identified as conjugate footpoints using a manual method. The co-alignment of TRACE/EUV and Hα images from Big Bear Solar Observatory (BBSO) using EIT and MDI data from SOHO allows us to obtain information about the ribbon's underlying magnetic inversion line. We find that the EUV conjugate footpoints start (3 minutes before the hard X-ray onset) at a position close to, but with a large separation along, the magnetic inversion line and evolve into straight across and far from the inversion line during the impulsive phase. We also made a statistical investigation of the two-ribbon flares observed by TRACE. We find that this progressive decrease in shear of footpoints is a common feature, which appears to indicate that the pre-flare magnetic field configuration of this kind of flare is highly sheared close to, and less sheared far from the magnetic inversion line.
DE: 7519 Flares
DE: 7524 Magnetic fields
DE: 7526 Magnetic reconnection (2723, 7835)
DE: 7549 Ultraviolet emissions
DE: 7554 X-rays, gamma rays, and neutrinos
SC: SPA-Solar and Heliospheric Physics [SH]
MN: Fall Meeting 2005