On the relationship between coronal magnetic null points and solar eruptive events

One mechanism that has been proposed for initiating coronal mass ejections (CMEs) is the "breakout" model. For this model to account for CMEs, a coronal null point must be present prior to the eruption. The relationship between the existence of coronal null points and eruptive events is investigated using a collection of over 1800 vector magnetograms from the Imaging Vector Magnetograph at Haleakala. Each magnetogram is subjected to magnetic charge topology analysis, including determining the presence of coronal null points. It is found that the majority of events originate in regions above which no null point is found. However, a much larger fraction of active regions for which a coronal null point was found were the source of an eruption than active regions for which no null was found. The implications of these results for the breakout model are discussed.