Polarisation of decayless kink oscillations of solar coronal loops

TL;DR

This study detects the polarisation of decayless kink oscillations in solar coronal loops using multi-viewpoint observations, providing insights into their excitation mechanisms and potential role in coronal heating.

Contribution

First simultaneous multi-viewpoint detection of decayless kink oscillation polarisation, linking it to steady flows that may contribute to coronal heating.

Findings

Detected horizontal or weakly oblique linear polarisation.

Supported steady flows as energy source for oscillations.

Enhanced understanding of oscillation excitation mechanisms.

Abstract

Decayless kink oscillations of plasma loops in the solar corona may contain an answer to the enigmatic problem of solar and stellar coronal heating. The polarisation of the oscillations gives us a unique information about their excitation mechanisms and energy supply. However, unambiguous determination of the polarisation has remained elusive. Here, we show simultaneous detection of a 4-min decayless kink oscillation from two non-parallel lines-of-sights, separated by about 104\textdegree, provided by unique combination of the High Resolution Imager on Solar Orbiter and the Atmospheric Imaging Assembly on Solar Dynamics Observatory. The observations reveal a horizontal or weakly oblique linear polarisation of the oscillation. This conclusion is based on the comparison of observational results with forward modelling of the observational manifestation of various kinds of polarisation of kink oscillations. The revealed polarisation favours the sustainability of these oscillations by quasi-steady flows which may hence supply the energy for coronal heating.