Coronal cavity survey: Morphological clues to eruptive magnetic topologies

Coronal cavities are elliptical regions of rarefied density lying above and around prominences. They can be long-lived (weeks to months) but are often observed to eventually erupt as part of a coronal mass ejection (CME).

We determine morphological properties of the cavities both by qualitatively assessing their shape, and quantitatively fitting them with ellipses. We demonstrate consistency between these two approaches, and find that fitted ellipses are taller than they are wide for almost all cavities studied, in agreement with an earlier analysis of white-light cavities. We examine correlations between cavity shape, aspect ratio, and propensity for eruption.