Letter to the Editor

Helical flows along coronal loops following the launch of a coronal mass ejection

¹ Astronomy & Astrophysics Section, School of Cosmic Physics, Dublin Institute for Advanced Studies, DIAS Dunsink Observatory, Dublin D15 XR2R, Ireland
² Centre for Astrophysics and Relativity, School of Physical Sciences, Dublin City University, Glasnevin Campus, Dublin D09 V209, Ireland
³ Mullard Space Science Laboratory, University College London, Holmbury St Mary, Dorking, Surrey RH5 6NT, UK
⁴ Konkoly Observatory, Research Centre for Astronomy and Earth Sciences, Hungarian Academy of Sciences, Konkoly Thege út 15-17, H-1121 Budapest, Hungary

^⋆ Corresponding author; mohamed.nedal@dias.ie

Received: 19 December 2024
Accepted: 22 February 2025

Abstract

Context. Solar flares and coronal mass ejections (CMEs) are manifestations of energy release in the solar atmosphere. They can be accompanied by dynamic mass motions and waves in the surrounding atmosphere.

Aims. We present observations of plasma moving in a helical trajectory along a set of coronal loops formed following the eruption of a CME on 2024 May 14. This helical motion was observed in extreme ultraviolet images from the Solar Dynamics Observatory (SDO) and provides new insights into plasma properties in a set of post-eruption coronal loops.

Methods. We utilized images from the SDO Atmospheric Imaging Assembly (AIA) instrument to track the helical motion of plasma and to characterize its speed, acceleration, and physical properties. Additionally, we explored the evolution of the plasma density and temperature along the helical structure using the differential emission measure technique.

Results. The helical structure was visible to AIA for approximately 22 minutes; it had a diameter of ∼22 Mm and a total trajectory of nearly 184 Mm. According to our analysis of the AIA observations, the speed of the plasma flow along this helical coronal loop ranged from 77 to 384 km s⁻¹, temperatures from 3.46 to 10.2 MK, densities from 4.3 × 10⁶ to 1.55 × 10⁷ cm⁻³, and the magnetic field strength from 0.05 to 0.3 G.

Conclusions. Following the launch of the CME, we find clear evidence for impulsive heating and expansion of the plasma, which travelled along a helical trajectory along a set of post-eruption loops. These observations provide an insight into impulsive plasma flows along coronal loops and the topology of coronal loops.