The dynamics and observability of circularly polarized kink waves⋆

Context. Kink waves are routinely observed in coronal loops. Resonant absorption is a well-accepted mechanism that extracts energy from kink waves. Nonlinear kink waves are know to be affected by the Kelvin-Helmholtz instability. However, all previous numerical studies consider linearly polarized kink waves. Aims. We study the properties of circularly polarized kink waves on straight plasma cylinders, for both standing and propagating waves, and we compare them to the properties of linearly polarized kink waves. Methods. We used the code MPI-AMRVAC to solve the full 3D magnetohydrodynamic equations for a straight magnetic cylinder, excited by both standing and propagating circularly polarized kink (m  = 1) modes. Results. The damping due to resonant absorption is independent of the polarization state. The morphology or appearance of the induced resonant flow is different for the two polarizations; however, there are essentially no differences in the forward-modeled Doppler signals. For nonlinear oscillations, the growth rate of small scales is determined by the total energy of the oscillation rather than the perturbation amplitude. We discuss possible implications and seismological relevance.

Automated summary

This study investigates the properties of circularly polarized kink waves on straight plasma cylinders and compares them to linearly polarized kink waves. The research finds that the damping caused by resonant absorption is independent of the polarization state, although the morphology of the induced resonant flow differs for the two polarizations. There are no significant differences in the forward-modeled Doppler signals. Additionally, the growth rate of small scales in nonlinear oscillations is determined by the total energy of the oscillation, rather than the perturbation amplitude.