Chromospheric Dynamics of an Umbral Flare Kernel—Based on Coordinated SUNRISE III SCIP and Domeless Solar Telescope Observations

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Abstract We report imaging spectroscopic observations of an M1.4 solar flare obtained during a coordinated observation between the infrared spectropolarimeter SCIP onboard the S unrise iii balloon mission and Domeless Solar Telescope (DST) at Hida Observatory, Kyoto University. The flare that occurred on 2024 July 13 in NOAA Active Region 13738 exhibited a compact flare kernel located within a sunspot umbra. SCIP performed rapid slit-scan observations over a field of view of 58″ × 58″ around the umbra with a cadence of 40 s, covering infrared chromospheric and upper-photospheric lines including Ca ii 8498/8542 Å and K i D 1 . At the same time, DST observed a wider surrounding region with a cadence of 25 s in H α , Ca ii 8542 Å, and Na i D 1 /D 2 . Clear flare-related brightenings are detected in all chromospheric lines observed by SCIP and DST, while no significant enhancement is found in photospheric lines. The high spatial resolution of SCIP reveals fine substructures within the kernel on spatial scales of order 1000 km, which appear smeared in ground-based observations. The spectral profiles exhibit temporally and spatially varying Doppler shifts and line broadenings, indicating complex, fine-scale plasma motions in the chromosphere. These results suggest that the observed red asymmetry arises from the temporal succession of multiple fine-scale kernels, as revealed by SCIP, rather than from a single continuous process.

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