The Magnetic Structure of Solar Prominence Cavities: New Observational Signature Revealed by Coronal Magnetometry
Urszula Bak-Steslicka  1, *@  , Sarah Gibson  2@  , Yuhong Fan  2@  , Christian Bethge  2@  , Blake Forland  2@  , Laurel Rachmeler  3@  
1 : Astronomical Institute, University of Wroclaw
Kopernika 11, 51-622 Wroclaw -  Poland
2 : National Center for Atmospheric Research  (NCAR)  -  Website
3080 Central Green Dr Boulder, CO, 80301 USA -  United States
3 : Royal Observatory of Belgium
Avenue Circulaire 3, 1180 Brussels -  Belgium
* : Corresponding author

The Coronal Multi-channel Polarimeter (CoMP) obtains daily full-Sun above-the-limb coronal observations in linear polarization, allowing for the first time a diagnostic of the coronal magnetic field direction in quiescent prominence cavities. We find that these cavities consistently possess a characteristic ``lagomorphic'' signature in linear polarization indicating twist or shear extending up into the cavity above the neutral line. We demonstrate that such a signature may be explained by a magnetic flux-rope model, a topology with implications for solar eruptions. We find corroborating evidence for a flux rope structure in the pattern of concentric rings within cavities seen in CoMP line-of-sight velocity. 


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