Three-minute Sunspot Oscillations Driven by Magnetic Reconnection in a Light Bridge

TL;DR

This study observes three-minute chromospheric oscillations in a sunspot triggered by magnetic reconnection events in a light bridge, revealing a link between small-scale magnetic activity and sunspot oscillations.

Contribution

It demonstrates that magnetic reconnection in light bridges can impulsively excite oscillations in nearby sunspot umbrae, a novel insight into sunspot dynamics.

Findings

Transient brightening associated with magnetic reconnection observed.

Oscillation period increased from 2.3 to 3.0 minutes over time.

Oscillation amplitude doubled after brightening.

Abstract

We report a different type of three-minute chromospheric oscillations above a sunspot in association with a small-scale impulsive event in a light bridge. During our observations, we found a transient brightening in the light bridge. The brightening was composed of elementary bursts that may be a manifestation of fast repetitive magnetic reconnections in the light bridge. Interestingly, the oscillations in the nearby sunspot umbra were impulsively excited when the intensity of the brightening reached its peak. The initial period of the oscillations was about 2.3 minutes and then gradually increased to 3.0 minutes with time. In addition, we found that the amplitude of the excited oscillations was twice the amplitude of oscillations before the brightening. Based on our results, we propose that magnetic reconnection occurring in a light bridge can excite of oscillations in the nearby sunspot umbra.