Oscillatory Magnetic Reconnection at a Coronal Bright Point

Abstract Coronal bright points (CBPs) are typical small-scale coronal brightenings that consist of a bundle of miniature coronal loops. Using the ultrahigh-resolution coronal images from the Extreme Ultraviolet Imager on board Solar Orbiter, we report the first observational evidence of oscillatory magnetic reconnection at a CBP. The reconnection is characterized by two bursty phases defined by a reconnection reversal. In the first phase, a current sheet (C1) was found to form in front of an expanding loop of the bright point. Interestingly, C1 shortened to a null point during 10 minutes after reaching its maximum length (∼2.4 Mm). Less than 3 minutes later, a new current sheet (C2) was clearly seen to grow out from the null point, but along an orthogonal direction relative to C1. C2 reached a maximum length of ∼4 Mm in 10 minutes and then became short and invisible in the next few minutes as the reconnection declined. The magnetic reconnection is evidenced by the brightening, plasma flow, and temperature increase at the ends of both C1 and C2. No significant magnetic cancellation or emergence but gradual convergence occurred during the few hours before the reconnection underneath the CBP. The transition from C1 to C2 suggests the occurrence of coronal oscillatory reconnection, whereby the inflow and outflow regions in the first phase become the outflow and inflow regions in the second phase, respectively. It is further found that the oscillatory reconnection could slightly modulate the change in brightness of the CBP. We propose that oscillatory reconnection has the potential to continuously heat solar small-scale structures without destroying their overall magnetic configurations.