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dc.contributor.authorMackay, Duncan Hendry
dc.contributor.authorDeVore, C. Richard
dc.contributor.authorAntiochos, Spiro
dc.contributor.authorYeates, Anthony Robinson
dc.identifier.citationMackay , D H , DeVore , C R , Antiochos , S & Yeates , A R 2018 , ' Magnetic helicity condensation and the solar cycle ' , Astrophysical Journal , vol. 869 , no. 1 , 62 .
dc.identifier.otherPURE: 256867264
dc.identifier.otherPURE UUID: a802d6f1-38e7-49ea-a41d-8d3a4e60efcc
dc.identifier.otherScopus: 85058571622
dc.identifier.otherORCID: /0000-0001-6065-8531/work/58055460
dc.identifier.otherWOS: 000453051300005
dc.description.abstractSolar 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 (2013). 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, which 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 x 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 x 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.
dc.relation.ispartofAstrophysical Journalen
dc.rights© 2018, American Astronomical Society. This work has been made available online in accordance with the publisher's policies. This is the final published version of the work, which was originally published at
dc.subjectSun: activityen
dc.subjectSun: coronaen
dc.subjectSun: magnetic fieldsen
dc.subjectQB Astronomyen
dc.subjectQC Physicsen
dc.titleMagnetic helicity condensation and the solar cycleen
dc.typeJournal articleen
dc.contributor.sponsorScience & Technology Facilities Councilen
dc.contributor.sponsorScience & Technology Facilities Councilen
dc.contributor.sponsorThe Leverhulme Trusten
dc.description.versionPublisher PDFen
dc.contributor.institutionUniversity of St Andrews. Applied Mathematicsen
dc.description.statusPeer revieweden

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