Coronal Cavity Survey: Morphological Clues to Eruptive Magnetic Topologies

B C Forland,J B Dove,Y Fan,S E Gibson,L A Rachmeler

doi:10.1007/s11207-013-0361-1

Abstract

We present a survey on coronal prominence cavities conducted using 19 months of data from the Atmospheric Imaging Assembly (AIA) instrument aboard the Solar Dynamics Observatory (SDO) satellite. 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. We find that cavities with a teardrop-shaped morphology are more likely to erupt, and we discuss the implications of this morphology for magnetic topologies associated with CME models. We provide the full details of the survey for broad scientific use as supplemental material.

Highlights

IntroductionCommonly observed in association with prominences ( known as filaments), possess clearly defined boundaries implying a self-contained organized magnetic system
Coronal cavities, commonly observed in association with prominences, possess clearly defined boundaries implying a self-contained organized magnetic system
Characterizing coronal magnetic structures is helpful for understanding the magnetic field of the corona as a whole; since cavities are often seen in association with coronal mass ejections (CMEs), a better understanding of their structure and evolution helps illuminate pre-CME magnetic field configurations (Engvold, 1989; Hudson et al, 1999; Low and Hundhausen, 1995; Gibson et al, 2006; Maricic, Vršnak, and Rosa, 2009; Régnier, Walsh, and Alexander, 2011)

Summary

Introduction

Commonly observed in association with prominences ( known as filaments), possess clearly defined boundaries implying a self-contained organized magnetic system. Using the Coronal Multi-channel Polarimeter (CoMP), it is possible to obtain information about the direction of the underlying magnetic fields (Tomczyk et al, 2008). This is complicated by the fact that the corona is optically thin; forward modeling of specific magnetic field topologies has been demonstrated as an effective means of enabling interpretation of the CoMP observations of cavities (Dove et al, 2011; Rachmeler, Casini, and Gibson, 2012; Rachmeler et al, 2013; Bak-Steslicka et al, 2013)

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