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

TL;DR

This study models how lightbridges in solar pores excite torsional Alfvén waves through flux tube interactions, revealing wave propagation mechanisms in the solar atmosphere.

Contribution

It introduces a 3D MHD simulation of flux tube interactions in solar pores, demonstrating the natural excitation of torsional Alfvén waves.

Findings

Interaction between flux tubes excites torsional Alfvén waves.

Single flux tube models do not produce torsional waves.

Wave speeds match local Alfvén speeds at amplitude peaks.

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.