Modeling the effects of a lightbridge on oscillations in a solar pore

Abstract

Solar pores are ideal magnetic structures for wave propagation and transport of energy radially-outwards across the upper layers of the solar atmosphere. We aim to model the excitation and propagation of magnetohydrodynamic waves in a pore with a lightbridge modelled as two interacting magnetic flux tubes separated by a thin, weaker field, layer. We solve the three-dimensional MHD equations numerically and calculate the circulation as a measure of net torsional motion. We find that the interaction between flux tubes results in the natural excitation of propagating torsional Alfv\'{e}n waves, but find no torsional waves in the model with a single flux tube. The torsional Alfv\'{e}n waves propagate with wave speeds matching the local Alfv\'en speed where wave amplitude peaks.