{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,5]],"date-time":"2026-02-05T13:06:28Z","timestamp":1770296788352,"version":"3.49.0"},"reference-count":23,"publisher":"MDPI AG","issue":"3","license":[{"start":{"date-parts":[[2023,3,2]],"date-time":"2023-03-02T00:00:00Z","timestamp":1677715200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100003981","name":"Agenzia Spaziale Italiana","doi-asserted-by":"publisher","award":["2018-16-HH.0"],"award-info":[{"award-number":["2018-16-HH.0"]}],"id":[{"id":"10.13039\/501100003981","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Symmetry"],"abstract":"<jats:p>The bright solar corona entirely consists of closed magnetic loops rooted in the photosphere. Photospheric motions are important drivers of magnetic stressing, which eventually leads to energy release into heat. These motions are chaotic and obviously different from one footpoint to the other, and in fact, there is strong evidence that loops are finely stranded. One may also expect strong transient variations along the field lines, but at a glance, coronal loops ever appear more or less uniformly bright from one footpoint to the other. We aim to understand how much coronal loops can preserve their own symmetry against asymmetric boundary motions that are expected to occur at loop footpoints. We investigate this issue by time-dependent 2.5D MHD modelling of a coronal loop, including its rooting and beta-variation in the photosphere. We assume that the magnetic flux tube is stressed by footpoint rotation but also that the rotation has a different pattern from one footpoint to the other. In this way, we force strong asymmetries because we expect independent evolution along different magnetic strands. We found that until the Alfv\u00e9n crossing-travel time relative to the entire loop length is much lower than the twisting period, the loop\u2019s evolution depends only on the relative velocity between the boundaries, and the symmetry is efficiently preserved. We conclude that the very high Alfv\u00e9n velocities that characterise the coronal environment can explain why coronal loops can maintain a very high degree of symmetry even when they are subjected to asymmetric photospheric motions for a long time.<\/jats:p>","DOI":"10.3390\/sym15030627","type":"journal-article","created":{"date-parts":[[2023,3,2]],"date-time":"2023-03-02T04:57:38Z","timestamp":1677733058000},"page":"627","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":7,"title":["Asymmetric Twisting of Coronal Loops"],"prefix":"10.3390","volume":"15","author":[{"given":"Gabriele","family":"Cozzo","sequence":"first","affiliation":[{"name":"Dipartimento di Fisica & Chimica, Universit\u00e0 di Palermo, Piazza del Parlamento 1, I-90134 Palermo, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5274-515X","authenticated-orcid":false,"given":"Paolo","family":"Pagano","sequence":"additional","affiliation":[{"name":"Dipartimento di Fisica & Chimica, Universit\u00e0 di Palermo, Piazza del Parlamento 1, I-90134 Palermo, Italy"},{"name":"INAF-Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, I-90134 Palermo, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9882-1020","authenticated-orcid":false,"given":"Antonino","family":"Petralia","sequence":"additional","affiliation":[{"name":"INAF-Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, I-90134 Palermo, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Fabio","family":"Reale","sequence":"additional","affiliation":[{"name":"Dipartimento di Fisica & Chimica, Universit\u00e0 di Palermo, Piazza del Parlamento 1, I-90134 Palermo, Italy"},{"name":"INAF-Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, I-90134 Palermo, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2023,3,2]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1","DOI":"10.12942\/lrsp-2014-4","article-title":"Coronal loops: Observations and modeling of confined plasma","volume":"11","author":"Reale","year":"2014","journal-title":"Living Rev. 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