Quasiperiodic Super-Alfvenic Slippage Along Flare Ribbons Observed by the Interface Region Imaging Spectrograph

TL;DR

This study reports the first direct observation of quasiperiodic super-Alfvénic slipping motion along flare ribbons during a solar flare, revealing periodic magnetic reconnection with high temporal resolution data.

Contribution

It provides the first observational evidence of periodic super-Alfvénic slipping reconnection in solar flares using high-resolution IRIS data.

Findings

Super-Alfvénic slippage speeds up to 1688 km/s observed.

Quasiperiodic slipping with a period of 8.4 to 11.9 seconds detected.

First evidence of periodicity in slipping-running magnetic reconnection.

Abstract

The apparent slipping motion of flare loops is regarded as a key feature of the 3D magnetic reconnection in the solar flares. The slippage with a super-Alfv\'enic speed could be defined as slipping-running reconnection while the slippage with a sub-Alfv\'enic speed is called slipping reconnection. Due to the limitation of the observational instrument temporal resolution, the apparent slippage of the flare loop footpoints along the flare ribbons with super-Alfv\'enic speed is quite rare to our knowledge. In this paper, we report a unique event that exhibits not only the sub-Alfv\'enic slippage, but also the quasiperiodic super-Alfv\'enic slippage of ribbon substructures during a C3.4-class flare (SOL2023-01-18-T15:23), using the high temporal resolution observations of the Interface Region Imaging Spectrograph ($\sim$2 s). The super-Alfv\'enic slippage with a speed of up to $\sim$ 1688 km s$^{-1}$ is directly observed in this study. The calculated period of the apparent super-Alfv\'enic slippage in both ribbons is between 8.4 and 11.9 seconds. This work provides the first observational evidence of the periodicity for the slipping-running magnetic reconnection.