The Resonant Damping of Fast Magnetohydrodynamic Oscillations in a System of Two Coronal Slabs

Arregui, Iñigo; Terradas, Jaume; Oliver, Ramón; Luis Ballester, José
Referencia bibliográfica

The Astrophysical Journal, Volume 674, Issue 2, pp. 1179-1190.

Fecha de publicación:
2
2008
Número de autores
4
Número de autores del IAC
0
Número de citas
13
Número de citas referidas
13
Descripción
Observations of transverse coronal loop oscillations very often show the excitation and damping of oscillations in groups of coronal loops rather than in individual and isolated structures. We present results on the oscillatory properties (periods, damping rates, and spatial distribution of perturbations) for resonantly damped oscillations in a system of two inhomogeneous coronal slabs and compare them to the properties found in single-slab loop models. A system of two identical coronal loops is modeled, in Cartesian geometry, as being composed of two density enhancements. The linear magnetohydrodynamic (MHD) wave equations for oblique propagation of waves are solved, and the damping of the different solutions, due to the transverse inhomogeneity of the density profile, is computed. The physics of the obtained results is analyzed by an examination of the perturbed physical variables. We find that, due to the interaction between the loops, the normal modes of oscillation present in a single slab split into symmetric and antisymmetric oscillations when a system of two identical slabs is considered. The frequencies of these solutions may differ from the single slab results when the distance between the loops is of the order of a few slab widths. Oblique propagation of waves weakens this interaction, since solutions become more confined to the edges of the slabs. The damping is strong for surface-like oscillations, while sausage body-like solutions are unaffected. For some solutions, and small slab separations, the damping in a system of two loops differs substantially from the damping of a single loop.