Reconnection nanojets associated with a prominence eruption observed with Solar Orbiter/EUI-HRI

TL;DR

This study uses high-resolution EUV imaging from Solar Orbiter to analyze reconnection nanojets during a prominence eruption, revealing their properties, energies, and potential role in solar activity.

Contribution

First detailed analysis of nanojets during a prominence eruption using Solar Orbiter's high-resolution EUV data, showing their increased activity and energetic properties.

Findings

Approximately 120 nanojets detected, 40 analyzed in detail

Nanojets had lengths of 200-5000 km, speeds of 150-600 km/s

Nanojets are more energetic and numerous than previously observed

Abstract

Magnetic reconnection is a proposed mechanism for nanojets associated with coronal heating. We investigate the characteristics of reconnection-driven nanojets just before and during a prominence eruption using the High Resolution Imager (HRI) of the Extreme Ultraviolet imager (EUI) aboard Solar Orbiter during its perihelion on September 30, 2024. Extreme UV (EUV) images at unprecedented high spatial and temporal resolution from \hrieuv were analysed. The dimensions and propagation speeds of nanojets were estimated and used to estimate the kinetic energies. Nanojet activity was compared with GOES X-ray flux to assess its relation to flare evolution. The high spatial and temporal resolution in the EUV was found to be essential to fully capture the properties and numbers of reconnection nanojets. Approximately 120 nanojets were detected during the eruption, with 40 analysed in detail. Nanojets exhibited lengths of $200 - 5000$~km, widths of $200 - 500$~km and durations of $2-12$~s. Instant velocities ranged from 150 km~s$^{-1}- 600~$km~s$^{-1}$ with kinetic energies reaching $1.56\times10^{27}$~erg. These nanojets are faster, longer, more energetic and more numerous compared to previous studies. We also find clear signatures of acceleration and deceleration, reflecting magnetic tension release and reach of new equilibria. Reconnection events during the eruption were found to be more frequent and energetically intense. Pre-flare nanojet clustering indicates small-scale reconnection may precede large eruptive activity. These results suggest that nanojets also occur in fully ionised coronal plasma, playing a role in both quiescent and eruptive solar activity.