The resonant damping of fast magnetohydrodynamic oscillations in a system of two coronal slabs 

Inigo Arregui Submitted: 20070809 04:38
Observations of transversal 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 by
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 transversal 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
surfacelike oscillations, while sausage bodylike 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.
Authors: Inigo Arregui, Jaume Terradas, Ramon Oliver, Jose Luis Ballester
Projects:

Publication Status: Submitted
Last Modified: 20070810 11:00


