Fine Structures of Tiny Quiet Sun Jets Observed by Solar Orbiter and Big Bear Solar Observatory

Abstract

We present the first joint high-resolution observations of small-scale EUV jets using Solar Orbiter(SolO)'s Extreme Ultraviolet Imager and High Resolution Imager (HRI) and H$\alpha$ imaging from the Visible Imaging Spectrometer (VIS) installed on the 1.6~m Goode Solar Telescope (GST) at the Big Bear Solar Observatory (BBSO). These jets occurred on 2022-10-29 around 19:10 UT in a quiet Sun region and their main axis aligns with the overarching magnetic structure traced by a cluster of spicules. However, they develop a helical morphology, while the H$\alpha$ spicules maintain straight, linear trajectories elsewhere. Alongside the spicules, thin, elongated red- and blue-shifted H$\alpha$ features appear to envelope the EUV jets, which we tentatively call sheath flows. The EUI jet moving upward at speed of ~110 km/s is joined by strong H$\alpha$ red-shift ~20 km/s to form the bidirectional outflows lasting ~2 min. Using AI-assisted differential emission measure (DEM) analysis of SolO's Full Sun Imager (FSI) we derived total energy of the EUV jet as ~$1.9 \times 10^{26}$ erg with 87% in thermal energy and 13% in kinetic energy. The parameters and morphology of this small-scale EUV jet are interpreted based on a thin flux tube model that predicts Alfvenic waves driven by impulsive interchange reconnection localized as narrowly as ~1.6 Mm with magnetic flux of ~$5.4\times 10^{17}$ Mx, belonging to the smallest magnetic features in the quiet Sun. This detection of intricate corona--chromospheric coupling highlights the power of high-resolution imaging in unraveling the mechanisms behind small-scale solar ejections across atmospheric layers.