Large scale coherent magnetohydrodynamic oscillations in a sunspot

Abstract

Although theoretically predicted, the simultaneous excitation of several resonant modes in sunspots has not been observed. Like any harmonic oscillator, a solar magnetic flux tube can support a variety of resonances, which constitute the natural response of the system to external forcing. Apart from a few single low order eigenmodes in small scale magnetic structures, several simultaneous resonant modes were not found in extremely large sunspots. Here we report the detection of the largest-scale coherent oscillations observed in a sunspot, with a spectrum significantly different from the Sun’s global acoustic oscillations, incorporating a superposition of many resonant wave modes. Magnetohydrodynamic numerical modeling agrees with the observations. Our findings not only demonstrate the possible excitation of coherent oscillations over spatial scales as large as 30–40 Mm in extreme magnetic flux regions in the solar atmosphere, but also paves the way for their diagnostic applications in other astrophysical contexts.

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Item Type:	Article
Authors/Creators:	Stangalini, M. Verth, G. Fedun, V. https://orcid.org/0000-0002-0893-7346 Aldhafeeri, A.A. Jess, D.B. Jafarzadeh, S. Keys, P.H. Fleck, B. Terradas, J. Murabito, M. Ermolli, I. Soler, R. Giorgi, F. MacBride, C.D.
Copyright, Publisher and Additional Information:	© 2022 The Author(s). This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.
Dates:	Published: 25 January 2022 Published (online): 25 January 2022 Accepted: 6 January 2022
Institution:	The University of Sheffield
Academic Units:	The University of Sheffield > Faculty of Engineering (Sheffield) > Department of Automatic Control and Systems Engineering (Sheffield)
Funding Information:	Funder Grant number European Commission - HORIZON 2020 739500 Science and Technology Facilities Council ST/V000977/1 The Royal Society IE170301; IES\R1\191114
Depositing User:	Symplectic Sheffield
Date Deposited:	07 Feb 2022 10:37
Last Modified:	07 Feb 2022 10:37
Status:	Published
Publisher:	Springer Nature
Refereed:	Yes
Identification Number:	10.1038/s41467-022-28136-8
Related URLs:	PubMed URL
Open Archives Initiative ID (OAI ID):	oai:eprints.whiterose.ac.uk:183288

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Large scale coherent magnetohydrodynamic oscillations in a sunspot

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