Signatures of dynamic fibrils at the coronal base: Observations from Solar Orbiter/EUI

Abstract

The solar chromosphere hosts a wide variety of transients, including dynamic fibrils (DFs) that are characterised as elongated, jet-like features seen in active regions, often through H$\alpha$ diagnostics. So far, these features have been difficult to identify in coronal images primarily due to their small size and the lower spatial resolution of the current EUV imagers. Here we present the first unambiguous signatures of DFs in coronal EUV data using high-resolution images from the Extreme Ultraviolet Imager (EUI) on board Solar Orbiter. Using the data acquired with the 174~Å High Resolution Imager (HRI${}_{EUV}$) of EUI, we find many bright dot-like features (of size 0.3-0.5 Mm) that move up and down (often repeatedly) in the core of an active region. In a space-time map, these features produce parabolic tracks akin to the chromospheric observations of DFs. Properties such as their speeds (14 km~s${}^{-1}$), lifetime (332~s), deceleration (82 m~s${}^{-2}$) and lengths (1293~km) are also reminiscent of the chromospheric DFs. The EUI data strongly suggest that these EUV bright dots are basically the hot tips (of the cooler chromospheric DFs) that could not be identified unambiguously before because of a lack of spatial resolution.

Accepted for publication in A&A Letters. Event movie can be downloaded from https://drive.google.com/file/d/1o_4jHA5JbyQtrpUBtB3ItE_s3HjF6ncc/view?usp=sharing

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• Evolution of dynamic fibrils from the cooler chromosphere to the hotter corona
• Beyond small-scale transients: a closer look at the diffuse quiet solar corona
• Extreme-ultraviolet (EUV) observables of simulated plasmoid-mediated reconnection in the solar corona
• Anomalous cross-field motions of solar coronal loops
• Bright Dots and Coronal Plume Formation in Sunspot Penumbra
• Long-lived coronal loops in solar active regions
• Active region upflows in various coronal structures and their coupling to the lower atmosphere
• High-resolution observations of small-scale activity in coronal hole plumes
• Fine Structures of Tiny Quiet Sun Jets Observed by Solar Orbiter and Big Bear Solar Observatory