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Radiative damping of standing acoustic waves in solar coronal loops

Bradshaw, S.J. and Erdelyi, R. (2008) Radiative damping of standing acoustic waves in solar coronal loops. Astronomy & Astrophysics, 483 (1). pp. 301-309. ISSN 1432-0746

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Abstract

Context. A detailed understanding of the physical processes that determine the damping timescales of magneto-acoustic waves is essential to interpret diagnostic results from the application of solar magneto-seismology. Aims. The influence of the transition region and the importance of radiative emission, arising from equilibrium and non-equilibrium ionisation balances, for the damping timescale of the fundamental mode standing acoustic wave is investigated. Methods. An extensive numerical study, in the framework of the field-aligned hydrodynamic approximation, is carried out of the damping of the fundamental mode standing wave in a solar coronal loop, for a wide range of loop lengths and apex temperatures. Results. It was found that the radiative emission arising from a non-equilibrium ionisation balance will always act to reduce the damping timescale (in comparison to the equilibrium case) and may do so by up to ~10%. The physics of the transition region is most crucial in determining the magnitude of the reduction of the damping timescale when a non-equilibrium ionisation balance is properly accounted for. Conclusions. The methods of solar magneto-seismology, in particular the tools of coronal seismology, may be used to estimate loop lengths to a reasonable degree of accuracy, although estimates of the apex temperature are significantly less reliable, and one should use alternative (e.g. spectroscopic) diagnostics instead.

Item Type: Article
Copyright, Publisher and Additional Information: © ESO 2008. Reproduced in accordance with the publisher's self-archiving policy.
Academic Units: The University of Sheffield > Faculty of Science (Sheffield) > School of Mathematics and Statistics (Sheffield)
Depositing User: Mrs Megan Hobbs
Date Deposited: 16 Mar 2010 18:43
Last Modified: 08 Feb 2013 17:00
Published Version: http://dx.doi.org/10.1051/0004-6361:20079128
Status: Published
Publisher: EDP Sciences
Refereed: Yes
Identification Number: 10.1051/0004-6361:20079128
URI: http://eprints.whiterose.ac.uk/id/eprint/10523

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