Torsional Alfven waves in stratified and expanding magnetic flux tubes

TL;DR

This paper investigates how density stratification and magnetic field expansion influence torsional Alfven waves in magnetic flux tubes, revealing their opposite effects on wave properties through numerical analysis.

Contribution

It provides a detailed numerical study of the combined effects of density stratification and magnetic field expansion on torsional Alfven waves, which was not previously explored.

Findings

Density stratification increases wave frequencies.

Magnetic field expansion decreases wave frequencies.

The effects of stratification and expansion are opposite on wave oscillations.

Abstract

The effects of both density stratification and magnetic field expansion on torsional Alfven waves in magnetic flux tubes are studied. The frequencies, the period ratio P1/P2 of the fundamental and its first-overtone, and eigenfunctions of torsional Alfven modes are obtained. Our numerical results show that the density stratification and magnetic field expansion have opposite effects on the oscillating properties of torsional Alfven waves.