Properties of Remote Flare Ribbons Associated with Coronal Mass Ejections

Abstract

To understand the large-scale structure of flares and coronal mass ejections, we studied the motion and properties of remote flare ribbons of three major events: 2003 May 27 X1.3, 2000 November 24 X1.8, and 2000 November 25 X1.9 flares. The remote ribbons are in addition to the typical two-ribbon pairs in the flare cores. We found two common properties of these three events. First, the flare core occurs at the edge of a major sunspot, associated with flux emergence parallel to the edge. Such a flux emergence formed complicated magnetic channel structure. Second, three flare ribbons are visible for each event. The first two make up a typical two-ribbon structure near the flare core. The third ribbon (remote ribbon) moves away from the flare site at a speed between 30 and 100 km s-1, several times larger than the nominal two-ribbon separation speed of flares. It is interesting to note that for the 2000 November 25 event, the remote ribbon first moved away in the same manner as the other two events; it then retracted after the flare emission peaked. We compared such an expansion/retraction motion with a limb event observed on 2001 April 15. We interpret the observed motion of remote ribbons by the interaction between the erupting flux rope in the flare core region and the overlying large-scale magnetic fields. For the 2000 November 25 event, the overlying field and flare core fields interacted twice, during the outward and inward motions.