Unveiling Unprecedented Fine Structure in Coronal Flare Loops with the DKIST

TL;DR

This study uses the DKIST to observe solar flare loops at unprecedented resolution, revealing fine structures and loop widths around 21-48 km, advancing understanding of coronal magnetic fields.

Contribution

First high-resolution H-alpha observations of a solar flare with DKIST, resolving coronal loop fine structures at scales near 21 km.

Findings

Mean loop width near 48 km

Minimum loop width ~21 km

Potential to resolve fundamental coronal loop scales

Abstract

We present the highest-resolution H$\alpha$ observations of a solar flare to date, collected during the decay phase of an X1.3-class flare on 8 August 2024 at 20:12 UT. Observations with the Visible Broadband Imager at the National Science Foundation's (NSF) Daniel K. Inouye Solar Telescope reveal dark coronal loop strands at unprecedented spatial resolution in the flare arcade above highly structured chromospheric flare ribbons. After surveying the 20 best-seeing images, we calculate a mean loop width near the top of the arcade of 48.2 km, with a minimum loop width of ~21 km and distribution mode of ~43 km. The distributions of loop widths observed by the DKIST in our study are often symmetric about the mean loop width. This is initial evidence that the DKIST may be capable of resolving the fundamental scale of coronal loops, although further investigation is required to confirm this result. We demonstrate that the resolving power of the DKIST represents a significant step towards advancing modern flare models and our understanding of fine structure in the coronal magnetic field.