A model for solar coronal mass ejections

We propose a new model for the initiation of a solar coronal mass ejection (CME). The model agrees with two properties of CMEs and eruptive flares tha t have proved to be very difficult to explain with previous models: (1) ver y low-lying magnetic field lines, down to the photospheric neutral line, ca n open toward infinity during an eruption; and (2) the eruption is driven s olely by magnetic free energy stored in a closed, sheared arcade. Consequen tly, the magnetic energy of the closed state is well above that of the post eruption open state. The key new feature of our model is that CMEs occur in multipolar topologies in which reconnection between a sheared arcade and n eighboring flux systems triggers the eruption. In this "magnetic breakout" model, reconnection removes the unsheared field above the low-lying, sheare d core flux near the neutral line, thereby allowing this core flux to burst open. We present numerical simulations that demonstrate our model can acco unt for the energy requirements for CMEs. We discuss the implication of the model for CME/flare prediction.