Coronal Magnetic Structures, Coronal Mass Ejections

Formation and Evolution of Large-Scale Magnetic Funnels in the Solar Corona

May 2016


The existence of open coronal magnetic fields with peculiar geometry – large-scale magnetic funnels – can be attributed to three factors: (i) the presence of two or more corona holes of the same polarity (or pseudostreamers – PSs), (ii) specific configurations of closed magnetic field in the low corona up to 1.3 Rs (filament channels) and (iii) the presence of strong active regions in the vicinity of the pseudostreamer. The important property of magnetic funnels is their strongly non-monotonic expansion factor below 2 Rs. The case study presented here is a pseudostreamer near the equator, formed between two isolated coronal holes of the same polarity, and harboring a pair of twin filaments in its base. Following the evolution of these coronal holes we find that the PS topology changes when two coronal holes merged together. Using a potential field source-surface (PFSS) extrapolation to compute the coronal field from photospheric maps (SDO/HMI), we show that the funnel-like geometry of the open magnetic field changes to a regular one with monotonic expansion factor after the merging of coronal holes. The presence of coronal magnetic funnels becomes directly visible when sufficient plasma accumulates inside them: when the plasma density grows to become observable coronal cloud prominences appear in the corona. The plasma suspension at heights of 0.3 Rs coincides with the largest gradients in the field which naturally leads to a diamagnetic hypothesis for the force counteracting gravity. We study the evolution of the funnel-like open fields during several solar rotations and find a direct relation between funnels and the presence of coronal clouds at great heights in the solar corona.

Featured Publications

  2016 (1)
Rapid Reconnection and Field Line Topology. Parker, E.; and Rappazzo, A. In Gonzalez, W.; and Parker, E., editor(s), Astrophysics and Space Science Library, volume 427, pages 181, 2016.
doi   bibtex
  2015 (1)
Observations and Analysis of the Non-Radial Propagation of Coronal Mass Ejections Near the Sun. Liewer, P.; Panasenco, O.; Vourlidas, A.; and Colaninno, R. \solphys, 290: 3343-3364. November 2015.
doi   bibtex
  2014 (1)
Apparent Solar Tornado-Like Prominences. Panasenco, O.; Martin, S.; and Velli, M. \solphys, 289: 603-622. February 2014.
doi   bibtex

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