Magnetic evolution of a long-lived active region: The sources of magnetic helicity

MANDRINI, C.H.; DÉMOULIN, P.; VAN DRIEL-GESZTELYI, L.; THOMPSON, B.; PLUNKETT, S.P.; KHOVARI, ZS.; AULANIER, G.

Santiago de Chile

Workshop; Magnetic Fields across the Hertzsprung-Russell Diagram; 2001

An isolated active region (AR) was observed on the disk during seven solar rotations. We compute its coronal magnetic helicity and the helicity injected by differential rotation. Furthermore, using average values for the field and radius of magnetic clouds, we estimate the helicity which could be shedded via CMEs. We compare the three values to evaluate the importance of differential rotation relative to twisted flux emergence as a source of helicity for the coronal field and for CMEs.