Solar flares in the Solar Orbiter era: Short-exposure EUI/FSI observations of STIX flares

Abstract

Aims: This paper aims to demonstrate the importance of short-exposure extreme ultraviolet (EUV) observations of solar flares in the study of particle acceleration, heating and energy partition in flares. This work highlights the observations now available from the Extreme Ultraviolet Imager (EUI) instrument suite on board Solar Orbiter while operating in short-exposure mode. Methods: A selection of noteworthy flares observed simultaneously by the Spectrometer Telescope for Imaging X-rays (STIX) and the Full Sun Imager of EUI (EUI/FSI) are detailed. New insights are highlighted and potential avenues of investigation are demonstrated, including forward-modelling the atmospheric response to a non-thermal beam of electrons using the RADYN 1D hydrodynamic code, in order to compare the predicted and observed EUV emission. Results: The examples given in this work demonstrate that short-exposure EUI/FSI observations are providing important diagnostics during flares. A dataset of more than 9000 flares observed by STIX (from November 2022 until December 2023) with at least one short-exposure EUI/FSI 174 Å image is currently available. The observations reveal that the brightest parts of short-exposure observations consist of substructure in flaring ribbons that spatially overlap with the hard X-ray emission observed by STIX in the majority of cases. We show that these observations provide an opportunity to further constrain the electron energy flux required for flare modelling, among other potential applications.

9 pages, 5 figures, accepted by A&A. Version 2 includes formatting corrections from the editor

References in corpus (10)

• The Solar Orbiter mission -- Science overview
• Microwave Spectral Imaging of an Erupting Magnetic Flux Rope: Implications for the Standard Solar Flare Model in Three Dimensions
• The development of lower-atmosphere turbulence early in a solar flare
• The data center for the Spectrometer and Telescope for Imaging X-rays (STIX) onboard Solar Orbiter
• The F-CHROMA grid of 1D RADYN flare models
• First Perihelion of EUI on the Solar Orbiter mission
• Forward-fitting STIX visibilities
• Localising pulsations in the hard X-ray and microwave emission of an X-class flare
• Solar flare hard X-rays from the anchor points of an eruptive filament
• Characterising fast-time variations in the hard X-ray time profiles of solar flares using Solar Orbiter's STIX

Cited by in corpus (3)

• Solar flare ribbons structured by uncombed chromospheric loops
• Spectral component imaging of solar X-ray flares
• Small-Scale and Transient EUV Kernels in Solar Flare Ribbons