Magnetic helicity ejections and coronal activity

Nindos Alexander, anindos@cc.uoi.gr, University of Ioannina, Physics Department, Ioannina GR-45110, Greece

Abstract
Magnetic helicity is a quantity that describes the linkage and twistedness/shear in the magnetic field. It has the unique property that it is probably the only physical quantity which is approximately conserved even in resistive MHD on time scales less than the global diffusion time scale. Coronal mass ejections (CMEs) consist an important process through which accumulated helicity is removed from the corona. In this talk, I will review the role that magnetic helicity plays in the initiation of transient coronal activity, both flares and CMEs.