Preprint typeset using LATEX style emulateapj v. 5/2/11 RECURRENT EXPLOSIVE ERUPTIONS AND THE “SIGMOID-TO-ARCADE ” TRANSFORMATION IN THE SUN DRIVEN BY DYNAMICAL MAGNETIC FLUX EMERGENCE.

We report on three-dimensional (3D) MHD simulations of recurrent mini CME-like eruptions in a small active region (AR), which is formed by the dynamical emergence of a twisted (not kink unstable) flux tube from the solar interior. The eruptions are developed as a result of repeated formation and expulsion of new flux ropes due to continous emergence and reconnection of sheared fieldlines along the polarity inversion line (PIL) of the AR. The acceleration of the eruptions is triggered by tether-cutting reconnection at the current sheet underneath the erupting field. We find that each explosive eruption is followed by reformation of a sigmoidal structure and a subsequent “sigmoid-to-flare arcade ” transformation in the AR. These results might have implications for recurrent CMEs and eruptive sigmoids/flares observations and theoretical studies. Subject headings: Sun: activity — Sun: magnetic topology 1