H(alpha) and Hard X-Ray Observations of a Two-Ribbon Flare Associated with a Filament Eruption

We perform a multiwavelength study of a two-ribbon flare on 2002 September 29 and its associated filament eruption, observed simultaneously in the H(alpha) line by a ground-based imaging spectrograph and in hard X-rays by RHESSI. The flare ribbons contain several H(alpha)-bright kernels that show different evolutionary behaviors. In particular, we find two kernels that may be the footpoints of a loop. A single hard X-ray source appears to cover these two kernels and to move across the magnetic neutral line. We explain this as a result of the merging of two footpoint sources that show gradually asymmetric emission owing to an asymmetric magnetic topology of the newly reconnected loops. In one of the H(alpha) kernels, we detect a continuum enhancement at the visible wavelength. By checking its spatial and temporal relationship with the hard X-ray emission, we ascribe it to electron-beam precipitation. In addition, we derive the line-of-sight velocity of the filament plasma based on the Doppler shift of the filament-caused absorption in the H(alpha) blue wing. The filament shows rapid acceleration during the impulsive phase. These observational features are in principal consistent with the general scenario of the canonical two-ribbon flare model.