Flares and surges due to magnetic cancellation Original Research Article

A flare associated with magnetic cancellation and small pre-flare activity is analyzed. X-ray and H α emission was strongest at the canceling site and principal energy release occurred near the canceling site. However, small flare emission was observed also far from the canceling site and the overall structure of the active region was largely changed after the flare. Therefore, even this flare driven by small scale cancellation had an extension and influence over the active region. In the pre-flare phase, many small loop brightenings were observed at the canceling site. Associating with the brightening, expansion of the active region was observed and suggests a change of loop connectivity at the foot-point and contribution for energy build-up due to cancellation. 3D extrapolation with various alpha values shows that the bright loop near the canceling site was highly non-potential.