Coronal microjets in quiet-Sun regions observed with the Extreme Ultraviolet Imager onboard Solar Orbiter

Abstract

We report the smallest coronal jets ever observed in the quiet Sun with recent highresolution observations from the High Resolution Telescopes (HRI EUV and HRI Lyα ) of the Extreme Ultraviolet Imager (EUI) onboard Solar Orbiter. In the HRI EUV (174 Å) images, these microjets usually appear as nearly collimated structures with brightenings at their footpoints. Their average lifetime, projected speed, width, and maximum length are 4.6 min, 62 km s −1 , 1.0 Mm, and 7.7 Mm, respectively. Inverted-Y shaped structures and moving blobs can be identified in some events. A subset of these events also reveal signatures in the HRI Lyα (H i Lyα at 1216 Å) images and the extreme ultraviolet images taken by the Atmospheric Imaging Assembly onboard the Solar Dynamics Observatory. Our differential emission measure analysis suggests a multi-thermal nature and an average density of ∼1.4×10 9 cm −3 for these microjets. Their thermal and kinetic energies were estimated to be ∼3.9×10 24 erg and ∼2.9×10 23 erg, respectively, which are of the same order of the released energy predicted by the nanoflare theory. Most events appear to be located at the edges of network lanes and magnetic flux concentrations, suggesting that these coronal microjets are likely generated by magnetic reconnection between small-scale magnetic loops and the adjacent network field.