Bibcode
DOI
Terradas, J.; Arregui, I.; Oliver, R.; Ballester, J. L.; Andries, J.; Goossens, M.
Referencia bibliográfica
The Astrophysical Journal, Volume 679, Issue 2, pp. 1611-1620.
Fecha de publicación:
6
2008
Revista
Número de citas
79
Número de citas referidas
78
Descripción
We study the excitation and damping of transverse oscillations in a
multistranded model of a straight line-tied coronal loop. The transverse
geometry of our equilibrium configuration is quite irregular and more
realistic than the usual cylindrical loop model. By numerically solving
the time-dependent ideal magnetohydrodynamic equations in two
dimensions, we show how the global motion of the whole bundle of
strands, excited by an external disturbance, is converted into localized
Alfvénic motions due to the process of resonant absorption. This
process produces the attenuation of the transverse oscillations. At any
location in the structure, two dominant frequencies are found: the
frequency of the global mode or quasi-mode, and the local Alfvén
frequency. We find that the mechanism of mode conversion, due to the
coupling between fast and Alfvén waves, is not compromised by the
complicated geometry of the model. We also show that it is possible to
have energy conversion not only at the external edge of the composite
loop, but also inside the structure. The implications of these results
and their relationship with the observations are discussed.