HR: 1330h
AN: SH22A-0189    [PDF]
TI: Statistical Study of Hard X-ray Footpoint Region
AU: * Sato, J
EM: sato@solar.isas.ac.jp
AF: ISAS, 3-1-1 Yoshinodai, Sagamihara, 2298510 Japan
AB: We show statistical characteristics of hard X-ray footpoint sources derived from THE YOHKOH FLARE IMAGE CATALOGUE. We use many hard X-ray images over the whole YOHKOH mission period (1991/08 - 2001/12) and the study is concentrated on following two points. 1) Average height of hard X-ray footpoint sources in the four HXT(Hard X-ray Telescope) energy bands (14-23, 23-33, 33-53, 53-93 keV). 2) Spectral characteristics of hard X-ray footpoint sources. We mainly revealed that A) the hard X-ray emission comes from just above the H$\alpha$ emitting region and the accelerated electrons loose their energy within 1000 km length leading to the high density around footpoints, and that B) Many hard X-ray footpoint sources show a broken power-law spectrum with very hard spectrum in the low energy range (20-30 keV), suggesting a cut off energy of accelerated electrons is around 20 keV - 30 keV at least.
DE: 7507 Chromosphere
DE: 7519 Flares
DE: 7554 X rays, gamma rays, and neutrinos
SC: SPA - Solar and Heliospheric Physics [SH]
MN: 2003 Fall Meeting