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Magnetoacoustic Waves and the Kelvin–Helmholtz Instability in a Steady Asymmetric Slab: I: The Effects of Varying Density Ratios

Recent observations have shown that bulk flow motions in structured solar plasmas, most evidently in coronal mass ejections (CMEs), may lead to the formation of Kelvin–Helmholtz instabilities (KHIs). Analytical models are thus essential in understanding both how the flows affect the propagation of m...

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Autores principales: Barbulescu, M., Erdélyi, R.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Springer Netherlands 2018
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6438655/
https://www.ncbi.nlm.nih.gov/pubmed/30996491
http://dx.doi.org/10.1007/s11207-018-1305-6
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author Barbulescu, M.
Erdélyi, R.
author_facet Barbulescu, M.
Erdélyi, R.
author_sort Barbulescu, M.
collection PubMed
description Recent observations have shown that bulk flow motions in structured solar plasmas, most evidently in coronal mass ejections (CMEs), may lead to the formation of Kelvin–Helmholtz instabilities (KHIs). Analytical models are thus essential in understanding both how the flows affect the propagation of magnetohydrodynamic (MHD) waves, and what the critical flow speed is for the formation of the KHI. We investigate both these aspects in a novel way: in a steady magnetic slab embedded in an asymmetric environment. The exterior of the slab is defined as having different equilibrium values of the background density, pressure, and temperature on either side. A steady flow and constant magnetic field are present in the slab interior. Approximate solutions to the dispersion relation are obtained analytically and classified with respect to mode and speed. General solutions and the KHI thresholds are obtained numerically. It is shown that, generally, both the KHI critical value and the cut-off speeds for magnetoacoustic waves are lowered by the external asymmetry.
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spelling pubmed-64386552019-04-15 Magnetoacoustic Waves and the Kelvin–Helmholtz Instability in a Steady Asymmetric Slab: I: The Effects of Varying Density Ratios Barbulescu, M. Erdélyi, R. Sol Phys Article Recent observations have shown that bulk flow motions in structured solar plasmas, most evidently in coronal mass ejections (CMEs), may lead to the formation of Kelvin–Helmholtz instabilities (KHIs). Analytical models are thus essential in understanding both how the flows affect the propagation of magnetohydrodynamic (MHD) waves, and what the critical flow speed is for the formation of the KHI. We investigate both these aspects in a novel way: in a steady magnetic slab embedded in an asymmetric environment. The exterior of the slab is defined as having different equilibrium values of the background density, pressure, and temperature on either side. A steady flow and constant magnetic field are present in the slab interior. Approximate solutions to the dispersion relation are obtained analytically and classified with respect to mode and speed. General solutions and the KHI thresholds are obtained numerically. It is shown that, generally, both the KHI critical value and the cut-off speeds for magnetoacoustic waves are lowered by the external asymmetry. Springer Netherlands 2018-05-28 2018 /pmc/articles/PMC6438655/ /pubmed/30996491 http://dx.doi.org/10.1007/s11207-018-1305-6 Text en © The Author(s) 2018 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided 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.
spellingShingle Article
Barbulescu, M.
Erdélyi, R.
Magnetoacoustic Waves and the Kelvin–Helmholtz Instability in a Steady Asymmetric Slab: I: The Effects of Varying Density Ratios
title Magnetoacoustic Waves and the Kelvin–Helmholtz Instability in a Steady Asymmetric Slab: I: The Effects of Varying Density Ratios
title_full Magnetoacoustic Waves and the Kelvin–Helmholtz Instability in a Steady Asymmetric Slab: I: The Effects of Varying Density Ratios
title_fullStr Magnetoacoustic Waves and the Kelvin–Helmholtz Instability in a Steady Asymmetric Slab: I: The Effects of Varying Density Ratios
title_full_unstemmed Magnetoacoustic Waves and the Kelvin–Helmholtz Instability in a Steady Asymmetric Slab: I: The Effects of Varying Density Ratios
title_short Magnetoacoustic Waves and the Kelvin–Helmholtz Instability in a Steady Asymmetric Slab: I: The Effects of Varying Density Ratios
title_sort magnetoacoustic waves and the kelvin–helmholtz instability in a steady asymmetric slab: i: the effects of varying density ratios
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6438655/
https://www.ncbi.nlm.nih.gov/pubmed/30996491
http://dx.doi.org/10.1007/s11207-018-1305-6
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