Direct evidence that twisted flux tube emergence creates solar active regions

MacTaggart, D. , Prior, C., Raphaldini, B., Romano, P. and Guglielmino, S.L. (2021) Direct evidence that twisted flux tube emergence creates solar active regions. Nature Communications, 12, 6621. (doi: 10.1038/s41467-021-26981-7)

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The magnetic nature of the formation of solar active regions lies at the heart of understanding solar activity and, in particular, solar eruptions. A widespread model, used in many theoretical studies, simulations and the interpretation of observations, is that the basic structure of an active region is created by the emergence of a large tube of pre-twisted magnetic field. Despite plausible reasons and the availability of various proxies suggesting the accuracy of this model, there has not yet been a methodology that can clearly and directly identify the emergence of large pre-twisted magnetic flux tubes. Here, we present a clear signature of the emergence of pre-twisted magnetic flux tubes by investigating a robust topological quantity, called magnetic winding, in solar observations. This quantity detects the emerging magnetic topology despite the significant deformation experienced by the emerging magnetic field. Magnetic winding complements existing measures, such as magnetic helicity, by providing distinct information about field line topology, thus allowing for the direct identification of emerging twisted magnetic flux tubes.

Item Type:Articles
Additional Information:D.M., C.P. and B.R. welcome support from the US Air Force Office for Scientific Research (AFOSR): grant number FA8655-20-1-7032. S.L.G. and P.R. welcome support from the Italian MIUR-PRIN grant 2017APKP7T "Circumterrestrial environment: Impact of Sun-Earth Interaction" and by the Istituto Nazionale di Astrofisica (INAF). This research received funding from the European Union’s Horizon 2020 Research and Innovation program under grant agreements No 824135 (SOLARNET) and No 729500 (PRE-EST). Numerical calculations were performed using the ARCHIE-WeSt High Performance Computer ( based at the University of Strathclyde and the DiRAC Extreme Scaling service at the University of Edinburgh, operated by the Edinburgh Parallel Computing Centre on behalf of the STFC DiRAC HPC Facility ( This equipment was funded by BEIS capital funding via STFC capital grant ST/R00238X/1 and STFC DiRAC Operations grant ST/R001006/1. DiRAC is part of the National e-Infrastructure.
Glasgow Author(s) Enlighten ID:Mactaggart, Dr David
Authors: MacTaggart, D., Prior, C., Raphaldini, B., Romano, P., and Guglielmino, S.L.
College/School:College of Science and Engineering > School of Mathematics and Statistics > Mathematics
Journal Name:Nature Communications
Publisher:Nature Research
ISSN (Online):2041-1723
Copyright Holders:Copyright © 2021 The Authors
First Published:First published in Nature Communications 12: 6621
Publisher Policy:Reproduced under a Creative Commons License
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Data DOI:10.5525/gla.researchdata.1197

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
311487Predicting solar eruptions via magnetic windingDavid MactaggartUS Air Force (USAF)FA8655-20-1-7032M&S - Mathematics