Hague, A. and Erdelyi, R. (2016) Buoyancy-driven Magnetohydrodynamic Waves. Astrophysical Journal , 828 (2). 88. ISSN 0004-637X
Abstract
Turbulent motions close to the visible solar surface may generate low-frequency internal gravity waves (IGWs) that propagate through the lower solar atmosphere. Magnetic activity is ubiquitous throughout the solar atmosphere, so it is expected that the behavior of IGWs is to be affected. In this article we investigate the role of an equilibrium magnetic field on propagating and standing buoyancy oscillations in a gravitationally stratified medium. We assume that this background magnetic field is parallel to the direction of gravitational stratification. It is known that when the equilibrium magnetic field is weak and the background is isothermal, the frequencies of standing IGWs are sensitive to the presence of magnetism. Here, we generalize this result to the case of a slowly varying temperature. To do this, we make use of the Boussinesq approximation. A comparison between the hydrodynamic and magnetohydrodynamic cases allows us to deduce the effects due to a magnetic field. It is shown that the frequency of IGWs may depart significantly from the Brunt–Väisälä frequency, even for a weak magnetic field. The mathematical techniques applied here give a clearer picture of the wave mode identification, which has previously been misinterpreted. An observational test is urged to validate the theoretical findings.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2016. The American Astronomical Society. Reproduced in accordance with the publisher's self-archiving policy. |
Keywords: | hydrodynamics; magnetohydrodynamics (MHD); Sun: atmosphere; Sun: oscillations; waves |
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) |
Funding Information: | Funder Grant number SCIENCE AND TECHNOLOGY FACILITIES COUNCIL ST/J001430/1 SCIENCE AND TECHNOLOGY FACILITIES COUNCIL ST/G002207/1 |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 08 Nov 2016 11:35 |
Last Modified: | 08 Nov 2016 11:35 |
Published Version: | https://doi.org/10.3847/0004-637X/828/2/88 |
Status: | Published |
Publisher: | IOP Publishing |
Refereed: | Yes |
Identification Number: | 10.3847/0004-637X/828/2/88 |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:106780 |