Hi-C & AIA observations of transverse MHD waves in active regions

TL;DR

This study uses high-resolution Hi-C and SDO observations to analyze low-frequency transverse MHD waves in active region coronal loops, revealing their small amplitudes and low energy, which are consistent over time.

Contribution

It provides detailed measurements of coronal loop widths and wave properties using unprecedented spatial resolution, highlighting the low-energy nature of these transverse waves.

Findings

Coronal loops have widths of 150-310 km.

Transverse waves have displacement amplitudes <50 km.

Wave velocity amplitudes are typically <3 km/s.

Abstract

The recent launch of the High resolution Coronal imager (Hi-C) provided a unique opportunity to study the EUV corona with unprecedented spatial resolution. We utilize these observations to investigate the properties of low frequency (50-200 s) active region transverse waves, whose omnipresence had been suggested previously. The five-fold improvement in spatial resolution over SDO/AIA reveals coronal loops with widths 150-310 km and that these loops support transverse waves with displacement amplitudes <50 km. However, the results suggest that wave activity in the coronal loops is of low energy, with typical velocity amplitudes <3 km/s. An extended time-series of SDO data suggest low-energy wave behaviour is typical of the coronal structures both before and after the Hi-C observations.