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Free keywords:
Quiet sun; Solar ultraviolet emission; Solar corona
Abstract:
We report the smallest coronal jets ever observed in the quiet Sun with recent high-resolution observations from the High Resolution Telescopes (HRIEUV and HRILyα) of the Extreme Ultraviolet Imager on board the Solar Orbiter (SO). In the HRIEUV (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 minutes, 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 HRILyα (H i Lyα at 1216 Å) images and the extreme ultraviolet images taken by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO). Our differential emission-measure (EM) analysis suggests a multithermal nature and an average density of ∼1.4 × 109 cm−3 for these microjets. Their thermal and kinetic energies were estimated to be ∼3.9 × 1024 erg and ∼2.9 × 1023 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.
