Braiding-induced Interchange Reconnection of the Magnetic Field and the Width of Solar Coronal Loops
Abstract
The random walk of the footpoints of coronal loops in the rapidly evolving solar granulation is expected to cause braiding of the field, which in turn should lead to a multitude of coronal reconnection events. Consequently, plasma volumes in coronal loops should repeatedly be spliced onto parts of other such loop structures within their lifetime in the corona. Both heat and plasma can thereby in effect be dispersed perpendicular to the field's guide direction, leading to an increase of loop width with time. I show that observed loop cross sections are consistent with this process for a reconnection-induced dispersal coefficient of 93+/-9 km2 s-1, which equals the dispersal coefficient that characterizes the granular random walk up to several hours. Loop width observations thus offer support for the hypothesis that granular braiding is countered statistically by frequent coronal reconnections, which in turn explains the general absence of entangled coronal field structures in high-resolution observations of the quiescent solar corona. This finding suggests that reconnection-enabled cross-field plasma dispersal needs to be included in models of coronal loop atmospheres.
- Publication:
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The Astrophysical Journal
- Pub Date:
- June 2007
- DOI:
- 10.1086/519455
- Bibcode:
- 2007ApJ...662L.119S
- Keywords:
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- Sun: Corona