Helical motion of magnetic flux tubes in the solar atmosphere

TL;DR

This paper investigates how transverse kink pulses in magnetic flux tubes, excited by photospheric granulation, propagate and superimpose to produce helical motions, contributing to solar atmospheric heating and wind acceleration.

Contribution

It introduces a model explaining helical motions in flux tubes due to superimposed kink pulses, linking wave dynamics to solar atmospheric heating.

Findings

Superposition of kink pulses causes helical flux tube motions.

Wakes oscillate at the kink cut-off frequency and decay over time.

Pulses carry enough energy to heat the solar atmosphere and drive the solar wind.

Abstract

Photospheric granulation may excite transverse kink pulses in anchored vertical magnetic flux tubes. The pulses propagate upwards along the tubes with the kink speed, while oscillating wakes are formed behind the wave front in a stratified atmosphere. The wakes oscillate at the kink cut-off frequency of stratified medium and gradually decay in time. When two or more consecutive kink pulses with different polarizations propagate in the same thin tube, then the wakes corresponding to different pulses may superimpose. The superposition sets up helical motions of magnetic flux tubes in the photosphere/chromosphere as seen by recent Hinode movies. The energy carried by the pulses is enough to heat the solar chrmosphere/corona and accelerate the solar wind.