Resonant absorption in complicated plasma configurations: Applications to multistranded coronal loop oscillations

Jaume Terradas, Invio Arregui, Ramon Oliver, Jose L Ballester, Jesse Andries, Marcel Goossens

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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 Alfvenic 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 Alfven frequency. We find that the mechanism of mode conversion, due to the coupling between fast and Alfven 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.
Original languageEnglish
Pages (from-to)1611 - 1620
Number of pages10
JournalThe Astrophysical Journal
Issue number2
Publication statusPublished - 2008
Externally publishedYes

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