The Magnetic Topology of Coronal Mass Ejection Sources

In an attempt to test current initiation models of coronal mass ejections(CMEs), with an emphasis on the magnetic breakout model, we inspect themagnetic topology of the sources of 26 CME events in the context of theirchromospheric and coronal response in an interval of approximately nine hoursaround the eruption onset. First, we perform current-free (potential)extrapolations of photospheric magnetograms to retrieve the key topologicalingredients, such as coronal magnetic null points. Then we compare thereconnection signatures observed in the high cadence and high spatialresolution of the Transition Region And Coronal Explorer (TRACE) images withthe location of the relevant topological features. The comparison reveals thatonly seven events can be interpreted in terms of the breakout model, whichrequires a multi-polar topology with pre-eruption reconnection at a coronalnull. We find, however, that a larger number of events (twelve) can not beinterpreted in those terms. No magnetic null is found in six of them. Sevenother cases remain difficult to interpret. We also show that there are nosystematic differences between the CME speed and flare energies of events underdifferent interpretations.Comment: Accepted for publication in Ap