Giagkiozis, I., Fedun, V., Erdélyi, R. et al. (1 more author) (2015) Axisymmetric Modes in Magnetic Flux Tubes with Internal and External Magnetic Twist. Astrophysical Journal, 810 (1). ISSN 0004-637X
Abstract
© 2015. The American Astronomical Society. All rights reserved. Observations suggest that twisted magnetic flux tubes are ubiquitous in the Sun's atmosphere. The main aim of this work is to advance the study of axisymmetric modes of magnetic flux tubes by modeling both twisted internal and external magnetic fields, when the magnetic twist is weak. In this work, we solve the derived wave equations numerically assuming that the twist outside the tube is inversely proportional to the distance from its boundary. We also study the case of a constant magnetic twist outside the tube and solve these equations analytically. We show that the solution for a constant twist outside the tube is a good approximation for the case where the magnetic twist is proportional to , namely, the error is in all cases less than . The solution is in excellent agreement with solutions to simpler models of twisted magnetic flux tubes, i.e., without external magnetic twist. It is shown that axisymmetric Alfvén waves are naturally coupled with magnetic twist as the azimuthal component of the velocity perturbation is nonzero. We compared our theoretical results with observations and comment on what the Doppler signature of these modes is expected to be. Lastly, we argue that the character of axisymmetric waves in twisted magnetic flux tubes can lead to false positives in identifying observations with axisymmetric Alfvén waves.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2015 The American Astronomical Society. Reproduced in accordance with the publisher's self-archiving policy. |
Dates: |
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Institution: | The University of Sheffield |
Academic Units: | The University of Sheffield > Faculty of Engineering (Sheffield) > Department of Automatic Control and Systems Engineering (Sheffield) The University of Sheffield > Faculty of Science (Sheffield) > School of Mathematics and Statistics (Sheffield) |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 07 Oct 2015 14:48 |
Last Modified: | 29 Mar 2018 01:20 |
Published Version: | http://dx.doi.org/10.1088/0004-637X/810/1/53 |
Status: | Published |
Publisher: | American Astronomical Society |
Refereed: | Yes |
Identification Number: | 10.1088/0004-637X/810/1/53 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:90262 |