Verwichte, E. (Erwin), Foullon, C. (Claire) and Nakariakov, Valery M.. (2006) Fast magnetoacoustic waves in curved coronal loops. II, Tunneling modes. Astronomy & Astrophysics, Vol.449 (No.2). pp. 769-779. ISSN 0004-6361

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Abstract

Aims. Fast magnetoacoustic waves in curved coronal loops are investigated and the role of lateral leakage in wave damping, which includes the mechanism of wave tunneling, is explored. Methods. A coronal loop is modeled as a curved, magnetic slab in the zero plasma-β limit. In this model and for an arbitrary piece-wise continuous power law equilibrium density profile, the wave equation governing linear vertically polarised fast magnetoacoustic waves is solved analytically. An associated dispersion relation is derived and the frequencies and eigenfunctions of the wave modes are characterised. Results. For some equilibria, the waves are shown to be all damped due to lateral leakage. It is demonstrated that waves either leak straight out into the external medium or have to overcome an evanescent barrier, which is linked to wave tunneling. The wave solutions consist of alternating vertically polarised kink and sausage branches. Fast kink oscillations may have a non-zero density perturbation when averaged across the loop. The calculated damping rate of fast magnetoacoustic kink oscillations is shown to be consistent with related numerical simulations and show that lateral leakage may explain the observed damping of (vertically polarised) fast magnetoacoustic kink oscillations.

Item Type:	Journal Article
Subjects:	Q Science > QB Astronomy
Divisions:	Faculty of Science > Physics
Library of Congress Subject Headings (LCSH):	Magnetohydrodynamics, Sun -- Loop prominences, Sun -- Corona, Solar oscillations
Journal or Publication Title:	Astronomy & Astrophysics
Publisher:	EDP Sciences
ISSN:	0004-6361
Date:	April 2006
Volume:	Vol.449
Number:	No.2
Page Range:	pp. 769-779
Identification Number:	10.1051/0004-6361:20054398
Status:	Peer Reviewed
Access rights to Published version:	Open Access
Funder:	Royal Society (Great Britain), Leverhulme Trust (LT), Particle Physics and Astronomy Research Council (Great Britain) (PPARC)
References:	Brady, C. S., & Arber, T. D. 2005, A&A, 438, 733 Brady, C. S., Verwichte, E., & Arber, T. D. 2006, A&A, 449, 389 Edwin, P. M., & Roberts, B. 1982, Sol. Phys., 76, 239 Edwin, P. M., & Roberts, B. 1983, Sol. Phys., 88, 179 Nakariakov, V. M., & Verwichte, E. 2005, Living Rev. Solar Phys., 2, 3, URL (2005-07-05) http://www.livingreviews.org/lrsp-2005-3 Roberts, B., Edwin, P. M., & Benz, A. O. 1984, ApJ, 279, 857 Verwichte, E., Foullon, C., & Nakariakov, V. M. 2006a, A&A, 446, 1139 Verwichte, E., Foullon, C., & Nakariakov, V. M. 2006b, A&A, submitted Wang, T. J., & Solanki, S. K. 2004, A&A, 421, L33
URI:	http://wrap.warwick.ac.uk/id/eprint/3562

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