Authors: Joel Dahlin (University of Maryland, College Park)

A major unsolved problem in solar physics is understanding what determines whether a solar flare remains confined or becomes eruptive. In particular, the influence of the magnetic structure of the flaring region and its surrounding magnetic topology has not yet been fully understood. Identifying the key factors that govern flare eruptivity is critical for predicting major solar eruptions and their resulting space weather impacts. We present new three-dimensional MHD simulations that illustrate three distinct pathways for a solar eruption to ‘fail’. For each scenario explored, the active region hosting the flare contains a magnetic null that plays an important role in the flare confinement. However, the nature of the interaction between the magnetic null and would-be eruptive structure differs for each case, producing distinct results ranging from the formation of a stable flux rope to the generation of a large-scale coronal loop jet. We show how despite the ‘failure’ of these events, the magnetic stress is not destroyed, but rather redistributed over a large volume and find that when subjected to further driving, ongoing the accumulation of this magnetic stress eventually leads to a successful eruption (albeit after many preceding confined events). We discuss the key factors for flare confinement identified from these investigations and discuss the implications of these results for understanding and predicting flare eruptivity.