Bibcode
Guennou, C.; Rachmeler, Laurel; Seaton, Daniel; Auchère, Frédéric
Bibliographical reference
Frontiers in Astronomy and Space Sciences, Volume 3, id.14 (2016)
Advertised on:
5
2016
Citations
9
Refereed citations
9
Description
We report on an exceptional large-scale coronal pseudostreamer/cavity
system in the southern polar region of the solar corona that was visible
for approximately a year starting in February 2014. It is unusual to see
such a large closed-field structure embedded within the open polar
coronal hole. We investigate this structure to document its formation,
evolution and eventually its shrinking process using data from both the
PROBA2/SWAP and SDO/AIA EUV imagers. In particular, we used EUV
tomography to find the overall shape and internal structure of the
pseudostreamer and to determine its 3D temperature and density structure
using DEM analysis. We found that the cavity temperature is extremely
stable with time and is essentially at a similar or slightly hotter
temperature than the surrounding pseudostreamer. Two regimes in cavity
thermal properties were observed: during the first 5 months of
observation, we found lower density depletion and highly multi-thermal
plasma, while after the pseudostreamer became stable and slowly shrank,
the depletion was more pronounced and the plasma was less multithermal.
As the thermodynamic properties are strongly correlated with the
magnetic structure, these results provide constraints on both the
trigger of CMEs and the processes that maintain cavities stability for
such a long lifetime.