The genesis of solar coronal mass ejections (CMEs) is both an intellectually intriguing, fundamental unsolved problem in plasma astrophysics, and a societally relevant subject critical to space weather prediction and mitigation. Dark coronal cavities surrounding cool, dense prominence material are observed within CMEs, but also as equilibrium states in the magnetically-dominated corona. Their plasma properties as observed in their quiescent phase provide clues to the nature of such equilibria and how they may ultimately be lost during CMEs.
July 22, 2002 observations of a polar crown filament and associated cavity. Clockwise from top left: HAO MLSO Mk4 white-light coronagraph; Big Bear Solar Observatory H-alpha; SOHO/EIT 284 Angstroms; SOHO/EIT 304 Angstroms.
From Gibson et al, 2006.
2008 Southern polar crown filament cavity (includes Whole Heliosphere Interval observations).
IHY Filament observing campaign: Activity in filaments and filament channels: First run --August 8-18 2007
1998-2004 White light cavity survey
"The calm before the storm: the link between quiescent cavities and coronal mass ejections", S. Gibson et al., ApJ, 641, 590, 2006
"Observing the unobservable? Modeling coronal cavity densities", J. Fuller et al., ApJ, 678, 515, 2008