A Catastrophic Flux Rope in a Quadrupole Magnetic Field for Coronal Mass Ejections

Abstract

We propose a flux-rope model for the initiation of flare-associated CMEs. The model triggers the eruption with a catastrophic loss of MHD equilibrium and then requires magnetic reconnection to sustain the eruption's acceleration. We carry out 2.5-dimensional time-dependent resistive MHD simulations, choosing the initial state such that a flux rope embedded in a quadrupole field is attached to the solar surface; we then increase the magnetic flux of the rope by two different amounts, thus obtaining two cases. One exhibits a gradual acceleration of the flux rope, whereas the other produces an immediate acceleration. In both cases, the maximum speed of the flux rope is representative of a fast CME. Thus, we conclude that the flux-rope dynamics depends on the intensity of the emergent magnetic flux. Our model does reproduce the three-component structure of CMEs.