The Study of Ring-filament Eruption and CME in AR0588 on 2004 April 11

Using YNAO Hα,SOHO/EIT EUV,SOHO/MDI magnetic field and Nobeyama Radio Heliograph 17GHz observations,we studied the eruption of a ring-filament,a following C9.6 flare,and an associated partial halo CME occurring in AR0588 on 2004 April 11. The main results are as follows: (1) The erupted filament shaped as a closed ring in Hα. Before its eruption,the filament showed obvious activation stage,in which its west part first became thick followed by the appearance of a gap,and then slowly ascended towards southwest. During its major eruption,two bright bands taking root in the original eruption site appeared in EIT 195Å images. The two bands were possibly two legs of the erupting filament and their top,the erupting filament itself. It is clear that the filament plasma was heated during the eruption. (2) The filament eruption was accompanied by a C9.6 X-ray class two-ribbon flare. One flare ribbon located at the center of the erupted filament showing no motion,and the other was a ring-shaped ribbon surrounded the eruption filament with obvious separating motion. A post-flare loop were observed between the two ribbons at the late stage of the flare. (3) The filament eruption and flare were closely associated with a partial halo CME observed by the LASCO,which was a quick CME and consisted of three components:the bright front,the dark void,the bright core.