Hard X-ray footpoint motion and acceleration mechanism

Abstract

An intense (X9.4/2B) flare, which occurred on 6 November 1997, was observed with the hard X-ray telescope on board Yohkoh . In the M2- (33 – 53 keV) and H-band (53 – 93 keV), This flare clearly show double footpoint sources during its impulsive phase. We have analyzed the locations and motions of these sources in detail. It is found that, at ∼ 11:53:06 UT, one of the footpoint sources in the M2-band moved to a new position earlier than the corresponding source in the H-band. The time-lag is about one second and the separation between the old and new positions is ∼ 5 arcsec. This happened between two major spikes in the time profile of hard X-ray intensity. This apparent motion might indicate that an epoch of energy release finished somewhere high in the corona and the next epoch started in another magnetic field system. This observation clearly shows that higher energy electrons precipitate into the footpoint region later . We try to interpret this particular phenomenon under the two assumptions, which are the direct precipitation model and the trap-and-precipitation model.