The Magnetic Structure of Solar Prominence Cavities: New Observational Signature Revealed by Coronal Magnetometry
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
* : Corresponding author
Avenue Circulaire 3, 1180 Brussels -
Belgium
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.