Hi-C 2.1 Observations of Small-Scale Miniature-Filament-Eruption-Like Cool Ejections in Active Region Plage

Abstract

We examine 172 Ang ultra-high-resolution images of a solar plage region from the Hi-C 2.1 ("Hi-C") rocket flight of 2018 May 29. Over its five-minute flight, Hi-C resolves a plethora of small-scale dynamic features that appear near noise level in concurrent Solar Dynamics Observatory (SDO) Atmospheric Imaging Assembly (AIA) 171 Ang images. For ten selected events, comparisons with AIA images at other wavelengths and with the Interface Region Imaging Spectrograph (IRIS) images indicate that these features are cool (compared to the corona) ejections. Combining Hi-C 172 Ang, AIA 171 Ang, IRIS 1400 Ang, and H$\alpha$, we see that these ten cool ejections are similar to the H$\alpha$ "dynamic fibrils" and Ca ii "anemone jets" found in earlier studies. The front of some of our cool ejections are likely heated, showing emission in IRIS 1400 Ang. On average, these cool ejections have approximate widths: $3^{\prime \prime }.2\pm 2^{\prime \prime }.1$, (projected) maximum heights and velocities: $4^{\prime \prime }.3\pm 2^{\prime \prime }.5$ and $23\pm 6$ km/s, and lifetimes: $6.5\pm 2.4$ min. We consider whether these Hi-C features might result from eruptions of sub-minifilaments (smaller than the minifilaments that erupt to produce coronal jets). Comparisons with SDO's Helioseismic and Magnetic Imager (HMI) magnetograms do not show magnetic mixed-polarity neutral lines at these events' bases, as would be expected for true scaled-down versions of solar filaments/minifilaments. But the features' bases are all close to single-polarity strong-flux-edge locations, suggesting possible local opposite-polarity flux unresolved by HMI. Or, it may be that our Hi-C ejections instead operate via the shock-wave mechanism that is suggested to drive dynamic fibrils and the so-called type I spicules.

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Cited by in corpus (8)

• Observation and Modeling of Solar Jets
• Possible Production of Solar Spicules by Microfilament Eruptions
• Solar Spicules, Filigrees and Solar Wind Switchbacks
• Hi-C 2.1 Observations of Reconnection Nanojets
• Solar Chromospheric Network as a Source for Solar Wind Switchbacks
• Inconspicuous Solar Polar Coronal X-ray Jets as the Source of Conspicuous Hinode/EUV Imaging Spectrometer (EIS) Doppler Outflows
• The properties of small magnetic flux ropes inside the solar wind come from coronal holes, active regions, and quiet Sun
• High-resolution spectroscopy of an erupting minifilament and its impact on the nearby chromosphere