A solar flare disturbing a light wall above a sunspot light bridge

TL;DR

This study observes a light wall above a sunspot light bridge that was disturbed by a solar flare, revealing how magnetic reconnection affects the wall's oscillation amplitude and orientation.

Contribution

It provides new insights into the magnetic coupling between light walls and flare loops, demonstrating how solar flares influence light wall oscillations.

Findings

Oscillation amplitude increased from 0.5 Mm to 1.6 Mm before the flare.

Oscillation amplitude decreased to 0.6 Mm after the flare.

Light wall's orientation changed due to magnetic reconnection.

Abstract

With the high-resolution data from the Interface Region Imaging Spectrograph, we detect a light wall above a sunspot light bridge in the NOAA active region (AR) 12403. In the 1330 A slit-jaw images, the light wall is brighter than the ambient areas while the wall top and base are much brighter than the wall body, and it keeps oscillating above the light bridge. A C8.0 flare caused by a filament activation occurred in this AR with the peak at 02:52 UT on 2015 August 28, and the flare's one ribbon overlapped the light bridge which was the observational base of the light wall. Consequently, the oscillation of the light wall was evidently disturbed. The mean projective oscillation amplitude of the light wall increased from 0.5 Mm to 1.6 Mm before the flare, and decreased to 0.6 Mm after the flare. We suggest that the light wall shares a group of magnetic field lines with the flare loops, which undergo a magnetic reconnection process, and they constitute a coupled system. When the magnetic field lines are pushed upwards at the pre-flare stage, the light wall turns to the vertical direction, resulting in the increase of the light wall's projective oscillation amplitude. After the magnetic reconnection takes place, a group of new field lines with smaller scales are formed underneath the reconnection site and the light wall inclines. Thus, the projective amplitude decreases remarkably at the post-flare stage.