Hα and Hard X‐Ray Observations of a Two‐Ribbon Flare Associated with a Filament Eruption

We perform a multi-wavelength study of a two-ribbon flare on 2002 September29 and its associated filament eruption, observed simultaneously in the H-alphaline by a ground-based imaging spectrograph and in hard X-rays by RHESSI. Theflare ribbons contain several H-alpha bright kernels that show differentevolutional behaviors. In particular, we find two kernels that may be thefootpoints of a loop. A single hard X-ray source appears to cover these twokernels and to move across the magnetic neutral line. We explain this as aresult of the merging of two footpoint sources that show gradually asymmetricemission owing to an asymmetric magnetic topology of the newly reconnectedloops. In one of the H-alpha kernels, we detect a continuum enhancement at thevisible wavelength. By checking its spatial and temporal relationship with thehard X-ray emission, we ascribe it as being caused by electron beamprecipitation. In addition, we derive the line-of-sight velocity of thefilament plasma based on the Doppler shift of the filament-caused absorption inthe H-alpha blue wing. The filament shows rapid acceleration during theimpulsive phase. These observational features are in principal consistent withthe general scenario of the canonical two-ribbon flare model.Comment: 15 pages, 5 figures, accepted for publication in Ap