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Astron. Astrophys. 342, 863-866 (1999)
Research Note
Leaky and resonantly damped flux tube modes reconsidered
H. Stenuit 1,
W.J. Tirry * 1,
R. Keppens 2 and
M. Goossens 1
1 Centre for Plasma Astrophysics, K.U. Leuven,
Celestijnenlaan 200B, B-3001 Heverlee, Belgium
2 FOM-Institute for Plasma Physics `Rijnhuizen', P.O.
Box 1207, 3430 BE Nieuwegein, The Netherlands
Received 20 April 1998 / Accepted 3 November 1998
Abstract
In this research note the results for the eigenfrequencies of the uniform and non-uniform magnetic flux tubes of Stenuit et al. (1998) are reconsidered. In that paper it is shown that the eigenfrequencies may have a damping rate due to two mechanisms causing a loss of energy. In non-uniform flux tubes the eigenmodes can be damped by resonant absorption. The other mechanism is leakage of wave energy into the surroundings, which can occur for both uniform and non-uniform flux tubes.
We point out that the dispersion relations obtained by Stenuit et al. are correct for leaky and undamped non-leaky modes, but are not correct for resonantly damped non-leaky modes.
Key words: Magnetohydrodynamics
(MHD) 
Sun:
oscillations
Sun:
photosphere
Sun: sunspots
* Research Assistant of the F.W.O.-Vlaanderen
Send offprint requests to: H. Stenuit
This article contains no SIMBAD objects.
Contents
- 1. Introduction
- 2. Mathematical approach
- 3. The physically relevant solution
- 4. Results: eigenfunctions and energy fluxes
- 5. The cubic mode: a mathematical artefact?
- 6. Conclusions
- References
© European Southern Observatory (ESO) 1999
Online publication: February 23, 1999
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