Fast MHD oscillations of a 3-dimensional prominence fibril

Free access article

Issue		A&A Volume 402, Number 2, May I 2003


Page(s)		781 - 789
Section		Diffuse matter in space
DOI		http://dx.doi.org/10.1051/0004-6361:20030285

A&A 402, 781-789 (2003)
DOI: 10.1051/0004-6361:20030285

Fast MHD oscillations of a 3-dimensional prominence fibril

A. J. Díaz, R. Oliver and J. L. Ballester

Departament de Física, Universitat de les Illes Balears, 07122 Palma de Mallorca, Spain
e-mail: toni@hubble.uib.es; ramon.oliver@uib.es; dfsjlb0@uib.es
(Received 23 December 2002 / Accepted 20 February 2003 )

Abstract
High-resolution observations of quiescent filaments point out that their fine structure is made of small-scale threads or fibrils. These fibrils can be represented as thin loops having cool tops, i.e. the prominence material, while the rest of the loop displays coronal temperatures. Then, the stacking of these thin loops in the vertical and horizontal directions gives place to the fine structure of filaments. On the other hand, two-dimensional, high-resolution observations of oscillations in filaments suggest that individual fibrils or groups of fibrils may oscillate independently with their own periods (Yi et al. 1991). Díaz et al. (2001, hereafter Paper I) studied the fast magnetohydrodynamic oscillations of a single and isolated slab prominence fibril using a two-dimensional model with no dependence in the y-direction. Here, we introduce a completely different approach which allows us to build up a 3-dimensional model for the fast magnetohydrodynamic oscillations of the fibril configuration used in Paper I. As compared to the results obtained in Paper I, two relevant new features appear; first of all, the cut-off frequency varies with the longitudinal wavenumber, so more modes can be trapped within the fibril; secondly, a much better confinement of the energy of the modes within the fibril appears, diminishing the leakage of energy towards neighbouring fibrils and so difficulting their mutual excitation.

Key words: Sun: oscillations -- Sun: magnetic fields -- Sun: corona -- Sun: prominences

Offprint request: A. J. Díaz, toni@hubble.uib.es

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