Ubiquitous Small-scale EUV Upflow-Like Events above Network Regions Observed by the Solar Orbiter/Extreme Ultraviolet Imager

TL;DR

This study uses high-resolution Solar Orbiter observations to analyze 59 small-scale EUV upflow-like events in the quiet Sun, revealing their dynamic features, recurrent behavior, and potential role in coronal heating.

Contribution

It provides detailed characterization of EUV upflow-like events, including their structures, dynamics, and possible connection to chromospheric spicules and network jets, which was not previously documented at this resolution.

Findings

Average velocity of 62 km/s and lifetime of 68.6 seconds.

Some events show blob-like structures and multi-strand evolution.

Events can cause localized plasma heating ahead of their spire.

Abstract

Universal small-scale solar activity in quiet region are suggested to be a potential source of solar wind and the upper solar atmosphere. Here, with the high-resoltion 174 \AA~imaging observations from the Solar Orbiter/Extreme Ultraviolet Imager (EUI), we investigate 59 EUV upflow-like events observed in the quiet Sun. Their average apparent (plane-of-sky) velocity, lifetime, and propagation distance are measured as 62 $\speed$, 68.6 s and 3.94 Mm, respectively. These upflow-like events exhibit dynamic characteristics but lack base brightening, featuring a hot front and subsequent cold plasma ejection. 39\% of the EUV upflow-like events exhibit recurrent characteristics. Unprecedented high-resolution 174 \AA~observations reveal that some EUV upflow-like events exhibit blob-like fine structures and multi-strand evolutionary features, and some upflow-like events can cause localized haze-like plasma heating ahead of their spire region during the ejection process. A subset of the EUV upflow-like events covered by the Solar Dynamics Observatory reveals that they appear at the chromospheric networks. Through emission measure analysis, we found that these upflow-like events eject hot plasma of transient region or coronal temperature (an average of $\sim$10$^{5.5}$K). We suggest that EUV upflow-like events may be EUV counterparts of chromospheric spicules and/or transition region network jets, and play a role in heating localized corona above the network regions.