Allcock, M., Shukhobodskaia, D., Zsámberger, N.K. et al. (1 more author) (2019) Magnetohydrodynamic waves in multi-layered asymmetric waveguides : solar magneto-seismology theory and application. Frontiers in Astronomy and Space Sciences, 6. 48.
Abstract
Diagnosing the solar atmospheric plasma is one of the major challenges in solar physics. Magnetohydrodynamic (MHD) waves, by means of applying the powerful concept of solar magneto-seismology (SMS), provide a tool to obtain diagnostic insight into the magnetized solar plasma in MHD waveguides. This paper provides a road-map of simple but applicable models of solar atmospheric waveguides in the framework of Cartesian geometry. We focus on exploiting the diagnostic potential of waveguide asymmetry and consider the effects of steady flow. In particular, the dispersion relation describing linear MHD wave propagation along a multi-layered MHD waveguide is derived. Aiming at lower solar atmospheric applications of SMS, the special case of a single magnetic slab embedded in an asymmetric magnetized plasma environment is revisited. As a proof of concept, the Amplitude Ratio Method is used to make a seismological estimate of the local Alfvén speed in several chromospheric fibrils that exhibit asymmetric oscillations. Absolute ratios of boundary oscillations between 1.29 and 3.42 are detected and, despite the significant errors expected, the local Alfvén speed estimates agree with previously derived estimates from magnetic field extrapolations. Finally, the effects of asymmetric shear flows present in these slab MHD waveguides are considered as a suitable model of Kelvin-Helmholtz instability initiation that is applicable, for example, to coronal mass ejection flanks.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2019 The Authors. This is an open-access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms. |
Keywords: | solar atmosphere; plasma; waves; magnetohydrodynamics (MHD); magnetic fields; magnetoseismology; fibrils; magnetic bright points |
Dates: |
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Institution: | The University of Sheffield |
Academic Units: | The University of Sheffield > Faculty of Science (Sheffield) > School of Mathematics and Statistics (Sheffield) |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 15 Aug 2019 10:24 |
Last Modified: | 15 Aug 2019 10:24 |
Status: | Published |
Publisher: | Frontiers Media SA |
Refereed: | Yes |
Identification Number: | 10.3389/fspas.2019.00048 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:149744 |