engleski

Numerical Simulation of Coronal Waves Interacting with Coronal Holes. II. Dependence on Alfvén Speed Inside the Coronal Hole

We used our newly developed magnetohydrodynamic (MHD) code to perform 2.5D simulations of a fast-mode MHD wave interacting with coronal holes (CHs) of varying Alfvén speed that result from assuming different CH densities. We find that this interaction leads to effects like reflection, transmission, stationary fronts at the CH boundary, and the formation of a density depletion that moves in the opposite direction to the incoming wave. We compare these effects with regard to the different CH densities and present a comprehensive analysis of morphology and kinematics of the associated secondary waves. We find that the density value inside the CH influences the phase speed and the amplitude values of density and magnetic field for all different secondary waves. Moreover, we observe a correlation between the CH density and the peak values of the stationary fronts at the CH boundary. The findings of reflection and transmission on the one hand and the formation of stationary fronts caused by the interaction of MHD waves with CHs on the other hand strongly support the theory that largescale disturbances in the corona are fast-mode MHD waves.

magnetohydrodynamics (MHD) ; Sun: corona ; Sun: evolution ; waves

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