The Role of Magnetic Helicity in Coronal Heating

One of the greatest challenges in solar physics is understanding the heating of the Sun's corona. Most theories for coronal heating postulate that free energy in the form of magnetic twist/stress is injected by the photosphere into the corona where the free energy is converted into heat either...

Full description

Saved in:
Bibliographic Details
Published in:The Astrophysical journal 2019-09, Vol.883 (1), p.26
Main Authors: Knizhnik, K. J., Antiochos, S. K., Klimchuk, J. A., DeVore, C. R.
Format: Article
Language:English
Subjects:
Astrophysics
Channels
Computer simulation
Corona
Coronal heating
Coronal loops
Energy conservation
Energy dissipation
Free energy
Heating rate
Helicity
Mathematical models
Numerical simulations
Photosphere
Solar Physics
Sun: corona
Sun: general
Sun: magnetic fields
Wave dissipation
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:One of the greatest challenges in solar physics is understanding the heating of the Sun's corona. Most theories for coronal heating postulate that free energy in the form of magnetic twist/stress is injected by the photosphere into the corona where the free energy is converted into heat either through reconnection or wave dissipation. The magnetic helicity associated with the twist/stress, however, is expected to be conserved and appear in the corona. In previous works, we showed that the helicity associated with the small-scale twists undergoes an inverse cascade via stochastic reconnection in the corona and ends up as the observed large-scale shear of filament channels. Our "helicity condensation" model accounts for both the formation of filament channels and the observed smooth, laminar structure of coronal loops. In this paper, we demonstrate, using helicity- and energy-conserving numerical simulations of a coronal system driven by photospheric motions, that the model also provides a natural mechanism for heating the corona. We show that the heat generated by the reconnection responsible for the helicity condensation process is sufficient to account for the observed coronal heating. We study the role that helicity injection plays in determining coronal heating and find that, crucially, the heating rate is only weakly dependent on the net helicity preference of the photospheric driving. Our calculations demonstrate that motions with 100% helicity preference are least efficient at heating the corona; those with 0% preference are most efficient. We discuss the physical origins of this result and its implications for the observed corona.
ISSN:0004-637X
1538-4357
DOI:10.3847/1538-4357/ab3afd