Abstract
Propagating kink waves have been observed in many magnetic waveguides in the solar atmosphere, like coronal magnetic loops, spicules, and fine structures of prominences. There are also observational evidences that these waves are damped. At present resonant absorption is considered as the most likely candidate for explaining this damping. First the attenuation of propagating kink waves due to resonant absorption was studied using the simplest model with a straight magnetic tube and the density only varying in the radial direction. Later a more advanced model with the density also varying along the tube was used. It was shown that the variation of the wave amplitude along the tube is determined by the combined effect of resonant damping and the longitudinal density variation. In our article we extend the analysis of resonant damping of propagating kink waves to take into account the magnetic loop expansion. We also consider non-stationary magnetic tubes to model, for example, cooling coronal loops.
Highlights
Propagating kink waves have been observed in many magnetic waveguides in the solar atmosphere, like coronal magnetic loops (Tomczyk et al, 2007; Tomczyk and McIntosh, 2009), spicules (De Pontieu et al, 2007; He J. et al, 2009; He J.-S. et al, 2009), fine structures of prominences (Okamoto et al, 2007), and in filament threads (Lin et al, 2007, 2009)
We study the resonant damping of kink waves propagating along a magnetic tube with the density varying along the tube
In this article we studied the kink wave propagation along an expanding magnetic tube with the density varying along the tube and in time
Summary
Propagating kink waves have been observed in many magnetic waveguides in the solar atmosphere, like coronal magnetic loops (Tomczyk et al, 2007; Tomczyk and McIntosh, 2009), spicules (De Pontieu et al, 2007; He J. et al, 2009; He J.-S. et al, 2009), fine structures of prominences (Okamoto et al, 2007), and in filament threads (Lin et al, 2007, 2009). Soler et al (2011c) investigated the propagation and resonant absorption of kink waves in a magnetic tube with the density varying both. All papers cited above used the theory of resonant damping that can be called classical In this theory the wave amplitude decays exponentially with the distance from the place where it is driven. This result is based on the assumption that a propagating kink wave is an eigenmode of the linearized dissipative magnetohydrodynamics (MHD).
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