Buildup, Explosion, and Untwisting of a Solar Active Region Jet Observed with Solar Orbiter, IRIS, and SDO

TL;DR

The study addresses whether active-region coronal jets share the minifilament eruption and flux-cancelation mechanism established for quieter solar environments. It leverages a coordinated, high-resolution dataset from Solar Orbiter EUI, IRIS, and SDO to capture a single AR jet from pre-eruption buildup through untwisting of the jet spire, while analyzing magnetic flux cancelation and energy release. The results show a minifilament residing in a left-handed twisted flux rope formed by ongoing flux cancelation at a neutral line; its eruption drives an outward jet spire that untwists counterclockwise, with supporting Doppler and imaging evidence, and a substantial magnetic, thermal, and kinetic energy budget consistent with local coronal heating. Collectively, the findings support a unified jet-generation paradigm across solar environments and demonstrate the value of high-cadence, high-resolution observations in confirming the minifilament eruption scenario for active-region jets.

Abstract

We present detailed analysis of an active region coronal jet accompanying a minifilament eruption that is fully captured and well-resolved in high spatial resolution 174A coronal images from Solar Orbiters Extreme Ultraviolet Imager (EUI). The active region jet is simultaneously observed by the Interface Region Imaging Spectrograph (IRIS) and the Solar Dynamics Observatory (SDO). An erupting minifilament is rooted at the edge of an active region where mixed-polarity magnetic flux is present. Minority-polarity positive flux merges and cancels with the active regions dominant negative flux at an average rate of 1019 Mx/hr, building a minifilament-holding flux rope and triggering its eruption. The eruption shows a slow rise followed by a fast rise, akin to large-scale filament eruptions. EUI images and Mg II k spectra, displaying simultaneously blueshifts and redshifts at the opposite edges of the spire, indicate counterclockwise untwisting of the jet spire. This jet is the clearest, most comprehensively observed active-region jet with this instrument set, displaying striking similarities with quiet Sun and coronal hole jets. Its magnetic, thermal, and kinetic energies suggest a significant contribution to local coronal heating. We conclude that magnetic flux cancelation builds a minifilament-carrying twisted flux rope and also eventually triggers the flux ropes eruption that makes the coronal jet, in line with our recent results on the buildup and explosion of solar coronal jets in quiet Sun and coronal holes. That is, this active region jet clearly works the same way as the vast majority of quiet Sun and coronal hole jets.

Figures (11)

• Figure 1: Active region (AR) jet observed on 29-March-2023 (NOAA 13262). Panel (a) shows an HRI$_{EUV}$ 174 Å image of the AR coronal jet. Panels (b and c), respectively, show an SDO/AIA 171 Å image and an IRIS 1400 Å SJI of the same jet. Panel (d) shows an SDO/HMI magnetogram of the AR jet-base region. The white box shows the field of view (FOV) in Figures \ref{['fig2']}, \ref{['fig4']}, \ref{['fig5']}. HMI contours, of levels $\pm$50, 100 G, at 14:15:29 UT are overlaid in panel (b), where red and cyan contours outline positive and negative magnetic flux, respectively.
• Figure 2: Evolution of active region magnetic field and AIA 94 Å intensity. Panels (a--d) show the evolution of the jet-base region for two days. Panel (e) shows the time-distance map from along the red-dashed line shown in (c). Panel (f) shows the the total absolute magnetic flux (black), positive flux (red), and negative flux (blue) curves from flux that is measured inside the yellow box region of panel (c). The dashed-green line in (f) is the least square fit to the black curve. Panel (g) displays an AIA 94 Å image with the main jet in the yellow box. Panel (h) shows an intensity plot of the 94 Å intensity integrated over the yellow box in panel (g). The orange vertical line marks the jet onset time. The HMI contours, of levels $\pm$500, $\pm$400, $\pm$300, $\pm$200 G, at 29-Mar-2023 14:17:44 UT are overlaid in panel (g), where red and cyan contours outline positive and negative magnetic flux, respectively. The animation (Movie) runs from 28-Mar-2023 23:59 UT to 30-Mar-2023 04:56 UT. The animation is unannotated and the FOV is same as shown in Panels (a--d) and (g).
• Figure 3: Active region jet in HRI$_{EUV}$ 174 Å images during the eruption onset. The cyan arrows point to the erupting minifilament. The red arrows point to the jet bright point (JBP). The white dashed line in (c) shows the slice for the time-distance image in Figure \ref{['fig3']}. The animation (Movie1) runs from 13:40 to 14:29 UT. The animation is unannotated and the FOV is same as in this figure.
• Figure 4: HRI$_{EUV}$ 174 Å time-distance map from the white-dashed line of Figure \ref{['fig2']}c. The plot shows the (un)twisting of the jet spire with time. The white lines trace some of the left-to-right (untwisting) motion transverse to the spire of bright strands of the spire.
• Figure 5: Active region jet in AIA 171 Å images and simultaneous magnetogram. Panels (a--e) show the evolution of the erupting minifilament and jet spire. The cyan and red arrows, respectively, point to the erupting minifilament and jet base bright point. Panels (f--j) are line of sight HMI magnetograms of the jet-base region. The yellow rectangular box in (g) shows the region that is used to make the time-distance map in Figure \ref{['fig4a']}. The distance between major ticks is 20 pixels. The HMI contours, of levels $\pm$500, $\pm$400, $\pm$300 G, at 14:17:44 UT are overlaid in panel (g), where red and cyan contours outline positive and negative magnetic flux, respectively. The animation (Movie2) runs from 12:15 to 14:40 UT. The animation is unannotated and the FOV is same as this figure.