Magnetic reconnection between small-scale loops observed with the New Vacuum Solar Telescope

TL;DR

This paper presents high-resolution observations of magnetic reconnection between small-scale solar loops, revealing a two-step process with slow and rapid phases, consistent with theoretical models.

Contribution

First detailed observational evidence of a two-phase magnetic reconnection process between small-scale loops on the Sun.

Findings

Reconnection involves a slow phase lasting tens of minutes and a rapid phase about three minutes.

Brightenings and material ejections are observed during rapid reconnection.

The observed features align with existing reconnection models.

Abstract

Using the high tempo-spatial resolution H$\alpha$ images observed with the New Vacuum Solar Telescope, we report the solid observational evidence of magnetic reconnection between two sets of small-scale anti-parallel loops with an X-shaped topology. The reconnection process contains two steps: a slow step with the duration of more than several tens of minutes, and a rapid step lasting for only about three minutes. During the slow reconnection, two sets of anti-parallel loops reconnect gradually, and new loops are formed and stacked together. During the rapid reconnection, the anti-parallel loops approach each other quickly, and then the rapid reconnection takes place, resulting in the disappearance of former loops. In the meantime, new loops are formed and separate. The region between the approaching loops is brightened, and the thickness and length of this region are determined to be about 420 km and 1.4 Mm, respectively. During the rapid reconnection process, obvious brightenings at the reconnection site and apparent material ejections outward along reconnected loops are observed. These observed signatures are consistent with predictions by reconnection models. We suggest that the successive slow reconnection changes the conditions around the reconnection site and triggers instabilities, thus leading to the rapid approach of the anti-parallel loops and resulting in the rapid reconnection.