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Dissipation of longitudinal oscillations in stratified non-isothermal hot coronal loops

Erdelyi, R., Luna-Cardozo, M. and Mendoza-Briceno, C.A. (2008) Dissipation of longitudinal oscillations in stratified non-isothermal hot coronal loops. Solar Physics, 252 (2). pp. 305-319. ISSN 1573-093X

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Abstract

We investigate the damping of longitudinal (i.e., slow or acoustic) waves in nonisothermal, hot (T≥ 5.0 MK), gravitationally stratified coronal loops. Motivated by SOHO/SUMER and Yohkoh/SXT observations, and by taking into account a range of dissipative mechanisms such as thermal conduction, compressive viscosity, radiative cooling, and heating, the nonlinear governing equations of one-dimensional hydrodynamics are solved numerically for standing-wave oscillations along a magnetic field line. A semicircular shape is chosen to represent the geometry of the coronal loop. It was found that the decay time of standing waves decreases with the increase of the initial temperature, and the periods of oscillations are affected by the different initial footpoint temperatures and loop lengths studied by the numerical experiments. In general, the period of oscillation of standing waves increases and the damping time decreases when the parameter that characterises the temperature at the apex of the loop increases for a fixed footpoint temperature and loop length. A relatively simple second-order scaling polynomial between the damping time and the parameter determining the apex temperature is found. This scaling relation is proposed to be tested observationally. Because of the lack of a larger, statistically relevant number of observational studies of the damping of longitudinal (slow) standing oscillations, it can only be concluded that the numerically predicted decay times are well within the range of values inferred from Doppler shifts observed by SUMER in hot coronal loops.

Item Type: Article
Copyright, Publisher and Additional Information: © 2008 Springer. This is an author produced version of a paper published in 'Solar Physics'. Uploaded 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)
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Depositing User: Mrs Megan Hobbs
Date Deposited: 25 Mar 2010 13:11
Last Modified: 07 Jun 2010 11:10
Published Version: http://dx.doi.org/10.1007/s11207-008-9274-9
Status: Published
Publisher: Springer
Identification Number: 10.1007/s11207-008-9274-9
URI: http://eprints.whiterose.ac.uk/id/eprint/10526

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