Observations and Modelling of Condensation Formation at Coronal Hole Boundaries
Abstract
One of the primary mechanisms suggested for slow solar wind formation is interchange reconnection. This tool for leveraging closed-loop plasma into the heliosphere is believed to occur ubiquitously in the corona, but has few definitive observational characteristics. We present recent observations from SDO AIA and STEREO-A of frequent condensations in small null-point topologies. These structures, termed raining null-point topologies, result from decayed active regions bordering on or entirely within coronal holes. These structures may have unique S-Web fingerprints, aiding slow wind detection and prediction capability. Our observations clearly show condensation formation at the open-closed boundary, where interchange reconnection is widely believed to occur. The condensations take the form of coronal rain, catastrophically cooled plasma that is easy to track using remote observations; their formation on apparently newly-opened coronal flux tubes gives interchange reconnection a hallmark signature. We will also present 1D hydrodynamic models for how these condensations can form via interchange reconnection and thermal nonequilibrium. Due to the nature of these null-point topologies and their proximity to coronal holes, they share characteristics common to open-closed boundaries, pseudostreamers, and active regions. Coordination between Parker Solar Probe, DKIST, Solar Orbiter, etc. would provide a deeper understanding of these ideal targets, which encompass such useful signatures for slow wind investigation.
- Publication:
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Solar Heliospheric and INterplanetary Environment (SHINE 2019)
- Pub Date:
- May 2019
- Bibcode:
- 2019shin.confE..40M