Aims. We investigate impulsive excitation mechanisms of the first harmonic fast magnetoacoustic kink mode of vertical oscillations in a solar coronal loop which is approximated either by a straight slab or by a curved arcade slab.
Methods. We solve numerically the full set of nonlinear ideal two-dimensional magnetohydrodynamic equations and analyze temporal and spatial wave signatures to infer characteristic features such as waveperiods and node positions.
Results. We show that an initial velocity pulse that is located off-centrally excites the first harmonic and fundamental modes, which result in a movement of the node around the loop apex. These results are verified by the analytical findings for an elastic string.
Conclusions. As the fundamental mode acquires more energy than its first harmonic, this explains why the latter is so rarely detected within a coronal loop.
Authors: A. Wasiljew, K. Murawski
Publication Status: in press
Last Modified: 2009-02-10 08:30