DKIST Captures Unexpected Ca II H & Hε in Solar Flare
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- DKIST captured the fading remnants of a C‑class solar flare on August 19, 2022, using its Visible Spectropolarimeter (ViSP) and Visible Broadband Imager to obtain high‑cadence, high‑resolution spectra.
- Cole Tamburri led the science team that observed unusually strong calcium II H and hydrogen‑epsilon spectral lines during the flare’s decay phase, with line shapes and brightness exceeding model expectations.
- Solar Physics published the findings in a 2026 paper titled “Spectroscopic Analysis and RHD Modeling of the First Ca II H and Hε Flare Spectra from DKIST/ViSP.”
- RADYN simulations reproduced the hydrogen‑epsilon line shape but failed to match the calcium II H line shape, highlighting deficiencies in current radiative‑hydrodynamic flare models.
- NSO researchers noted that ground‑based flare spectroscopy is rare because of telescope‑time and instrumentation limits, making DKIST’s high‑resolution data especially valuable for model testing.
- C6.7‑class flare showed stronger‑than‑expected calcium II H and hydrogen‑epsilon emissions during its decline, contradicting the expectation that such lines weaken as the flare cools.
Why it matters: Solar physicists gain concrete data that reveal shortcomings in RADYN‑based flare heating simulations, prompting model revisions that could improve predictions of solar atmospheric behavior and space‑weather impacts, which matter for satellite operations and communication systems. Accurate models also aid scientific understanding of magnetic field dynamics and energy transport in the chromosphere, informing future research and instrumentation development.
