We investigate the temporal evolution of impulsively generated perturbationsin a potential coronal arcade with an embedded loop. As the initialconfiguration we consider a coronal loop, represented by a density enhancement,which is unbounded in the ignorable direction of the arcade. The linearizedtime-dependent magnetohydrodynamic equations have been numerically solved infield-aligned coordinates and the time evolution of the initial perturbationshas been studied in the zero-beta approximation. For propagation constrained tothe plane of the arcade, the considered initial perturbations do not excitetrapped modes of the system. This weakness of the model is overcome by theinclusion of wave propagation in the ignorable direction. The inclusion ofperpendicular propagation produces two main results. First, damping by waveleakage is less efficient because the loop is able to act as a wave trap ofvertical oscillations. Second, the consideration of an inhomogeneous coronaenables the resonant damping of vertical oscillations and the energy transferfrom the interior of the loop to the external coronal medium.
Authors: S. Rial, I. Arregui, J. Terradas, R. Oliver, J. L. Ballester
Publication Status: submitted to apj
Last Modified: 2012-01-24 11:24