Ruderman, M.S. (2003) The resonant damping of oscillations of coronal loops with elliptic crosssections. Astronomy and Astrophysics, 409 (1). pp. 287297. ISSN 14320746

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Abstract
Motivated by recent Transition Region and Coronal Explorer (TRACE) observations of damped oscillations in coronal loops, Ruderman & Roberts (2002), studied resonant damping of kink oscillations of thin straight magnetic tubes in a cold plasma. In their analysis, Ruderman & Roberts considered magnetic tubes with circular crosssections. We extend their analysis for magnetic tubes with elliptic crosssections. We find that there are two infinite sequences of the eigenfrequencies of the tube oscillations, {omega(nc)} and {omega(ns)}, n = 1,2,.... The eigenfrequencies {omega(nc)} and {omega(ns)} correspond to modes with 2n nodes at the tube boundary. In particular, omega(1c) and omega(1s) correspond to two kink modes. These modes are linearly polarized in the direction of the large and small axis of the tube elliptic crosssection respectively. The sequence {omega(nc)} is monotonically growing and {omega(ns)} monotonically decreasing, and they both tend to omega(k) as n > infinity, where omega(k) is the frequency of the kink mode of tubes with circular crosssections. In particular, omega(1c) < omega(k) < omega(1s). We calculate the decrements of the two kink modes and show that they are of the order of decrement of the kink mode of a tube with a circular crosssection.
Item Type:  Article 

Copyright, Publisher and Additional Information:  © ESO 2003. Reproduced with permission. 
Keywords:  magnethohydrodynamics (MHD), plasmas, Sun, corona, waves 
Institution:  The University of Sheffield 
Academic Units:  The University of Sheffield > Faculty of Science (Sheffield) > School of Mathematics and Statistics (Sheffield) 
Depositing User:  Repository Officer 
Date Deposited:  16 Nov 2006 
Last Modified:  07 Jun 2014 01:30 
Published Version:  http://dx.doi.org/10.1051/00046361:20031079 
Status:  Published 
Publisher:  EDP Sciences 
Refereed:  Yes 
Identification Number:  10.1051/00046361:20031079 
URI:  http://eprints.whiterose.ac.uk/id/eprint/1716 