Moving structures in ultraviolet bright points: observations from Solar Orbiter/EUI

TL;DR

This study observes and analyzes moving structures in ultraviolet bright points in the quiet Sun and active regions, revealing bi-directional flows and quasi-periodic motions likely driven by magnetic reconnection processes.

Contribution

First detailed observation of bi-directional and converging moving structures in UV bright points using Solar Orbiter/EUI data, linking them to magnetic reconnection phenomena.

Findings

Bi-directional motions start from bright cores and propagate outward.

Converging motions originate from double ends and merge, indicating inflows or chromospheric evaporation.

Quasi-periodic motions observed in some bright points.

Abstract

Moving structures have been detected in coronal bright points and in a solar flare in active regions, which were bi-directional, symmetrical, simultaneous, and quasi-periodic (Ning & Guo 2014; Ning 2016; Li et al. 2016a). They could be regarded as observational evidence of plasma outflows via magnetic reconnection. In this article, we explored pairs of moving structures in fifteen ultraviolet bright points (UBPs), which were observed in the quiet Sun or inside a small active region on 19 November 2020, and measured by the High Resolution (HRI) Telescopes of the Extreme Ultraviolet Imager (EUI) on board the Solar Orbiter (SolO) in two passbands, HRIEUV 174 {\AA} and HRILy{\alpha} 1216 {\AA}. Moving structures observed in ten UBPs as starting from their bright cores and propagating toward two ends, are interpreted as diverging motions of bi-directional moving structures. These moving structures are also characterized by simultaneity and symmetry and in the case of seven UBPs they exhibit quasi-periodicity. They could be generated by outflows after magnetic reconnections. Moving structures seen in another five UBPs as originating from double ends and moving closer, and merging together, are manifested as converging motions, which might be caused by inflows through the magnetic reconnection, or might be interpreted as upflows driven by the chromospheric evaporation.