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Magnetic Helicity Condensation and the Solar Cycle

Mackay, Duncan H.; DeVore, C. Richard; Antiochos, Spiro K.; Yeates, Anthony R.

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Duncan H. Mackay

C. Richard DeVore

Spiro K. Antiochos


Solar filaments exhibit a global chirality pattern where dextral/sinistral filaments, corresponding to negative/positive magnetic helicity, are dominant in the northern/southern hemisphere. This pattern is opposite to the sign of magnetic helicity injected by differential rotation along east–west oriented polarity inversion lines, posing a major conundrum for solar physics. A resolution of this problem is offered by the magnetic helicity-condensation model of Antiochos. To investigate the global consequences of helicity condensation for the hemispheric chirality pattern, we apply a temporally and spatially averaged statistical approximation of helicity condensation. Realistic magnetic field configurations in both the rising and declining phases of the solar cycle are simulated. For the helicity-condensation process, we assume convective cells consisting of positive/negative vorticities in the northern/southern hemisphere that inject negative/positive helicity. The magnitude of the vorticity is varied as a free parameter, corresponding to different rates of helicity injection. To reproduce the observed percentages of dominant and minority filament chiralities, we find that a vorticity of magnitude 2.5 × 10−6 s−1 is required. This rate, however, is insufficient to produce the observed unimodal profile of chirality with latitude. To achieve this, a vorticity of at least 5 × 10−6 s−1 is needed. Our results place a lower limit on the small-scale helicity injection required to dominate differential rotation and reproduce the observed hemispheric pattern. Future studies should aim to establish whether the helicity injection rate due to convective flows and/or flux emergence across all latitudes of the Sun is consistent with our results.


Mackay, D. H., DeVore, C. R., Antiochos, S. K., & Yeates, A. R. (2018). Magnetic Helicity Condensation and the Solar Cycle. Astrophysical Journal, 869(1), Article 62.

Journal Article Type Article
Acceptance Date Oct 25, 2018
Online Publication Date Dec 12, 2018
Publication Date Dec 12, 2018
Deposit Date Dec 14, 2018
Publicly Available Date Jan 8, 2019
Journal Astrophysical Journal
Print ISSN 0004-637X
Publisher American Astronomical Society
Peer Reviewed Peer Reviewed
Volume 869
Issue 1
Article Number 62


Published Journal Article (8.8 Mb)

Copyright Statement
© 2018. The American Astronomical Society. All rights reserved

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