Magnetic helicity change rate associated with three X-class eruptive flares

Abstract

In this paper we have examined the temporal evolution of magnetic helicity change rate associated with three X-class eruptive flares that occurred on November 24, 2000. By analyzing a set of 1 minute cadence high-resolution magnetograms taken by Michelson Doppler Imager (MDI) on board Solar and Heliospheric Observatory (SOHO), we have determined the rates of magnetic helicity transport via horizontal photospheric motions. Then we have compared the impulsive variations of helicity injection rate with an initial eruption speed profile of a filament associated with a X1.8 flare. As a result, we have found (1) that the impulsive variations of magnetic helicity change rate were strongly correlated with only three X-class flarings, (2) that the eruption of the filament started about 10 minutes before the impulsive variation of the helicity change rate, and (3) that horizontal velocity kernels were located between Ha two flaring ribbons. Thus we suggest that the observed impulsive helicity change is not a cause of the eruptive solar flare but its result, i.e., photospheric response to the coronal field restructuring.