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Probing Chromospheric Dynamics with DKIST Observations of a C-class Solar Flare

Presentation #304.05 in the session From Filaments to Flares.

Published onSep 18, 2023
Probing Chromospheric Dynamics with DKIST Observations of a C-class Solar Flare

Recent advances in our understanding of solar and stellar flares have revealed several unexplained phenomena in flare dynamics. For example, in red dwarf flares, the hydrogen Balmer lines peak in intensity earlier and are much broader when compared to Ca II lines. Solar flare data appear to follow a similar pattern, but have, until now, been of insufficient resolution to provide an explanation. There also remain unexplained differences between the simulated and observed evolution and intensity of the red-shifted component of chromospheric lines. To address these remaining questions, we obtained observations of the GOES class C6.7 solar flare SOL2022-08-19T20:31 from the Daniel K. Inouye Solar Telescope (DKIST) Visible Spectro-polarimeter (ViSP) and Visible Broadband Imager (VBI). In this work, we analyze spectral line evolution in the Ca II H 396.8 nm, H-epsilon 397.0 nm, and Fe I 630.0 nm lines from ViSP observations. We describe the data calibration and processing unique to fulfilling our science goals. We compare the equivalent widths, effective widths, and broadening of the Ca II H and H-epsilon lines at all flaring locations along the ViSP slit in order to constrain the relative amounts of turbulent, velocity, and pressure broadening. We investigate the presence of a double-component structure in the Fe I line and compare to past findings of redshifted components in iron lines to better understand the details of chromospheric condensation. We discuss how these data will facilitate interpretation of spatially unresolved observations of the same wavelength regions in stellar flares. In the future, results from this study will inform the next generation of 1D radiative-hydrodynamic flare models calculated with the RH and RADYN codes by placing constraints on the details of electron and proton pressure broadening profiles.

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