Unprecedented Fine Structure of a Solar Flare Revealed by the 1.6~m New Solar Telescope

TL;DR

This study uses the high-resolution 1.6m New Solar Telescope to observe unprecedented fine structures of a solar flare, revealing details like flare ribbons, coronal rain, and footpoint brightenings at scales below 200 km, advancing understanding of flare energy transport.

Contribution

First high-resolution observation of solar flare fine structures below 500 km, providing detailed measurements of flare features and insights into energy transport mechanisms.

Findings

Flare ribbons and footpoints are 80-200 km wide.

Coronal rain streams along post-flare loops.

Fine-scale brightenings observed at footpoints.

Abstract

Solar flares signify the sudden release of magnetic energy and are sources of so called space weather. The fine structures (below 500 km) of flares are rarely observed and are accessible to only a few instruments world-wide. Here we present observation of a solar flare using exceptionally high resolution images from the 1.6~m New Solar Telescope (NST) equipped with high order adaptive optics at Big Bear Solar Observatory (BBSO). The observation reveals the process of the flare in unprecedented detail, including the flare ribbon propagating across the sunspots, coronal rain (made of condensing plasma) streaming down along the post-flare loops, and the chromosphere's response to the impact of coronal rain, showing fine-scale brightenings at the footpoints of the falling plasma. Taking advantage of the resolving power of the NST, we measure the cross-sectional widths of flare ribbons, post-flare loops and footpoint brighenings, which generally lie in the range of 80-200 km, well below the resolution of most current instruments used for flare studies. Confining the scale of such fine structure provides an essential piece of information in modeling the energy transport mechanism of flares, which is an important issue in solar and plasma physics.