Observational Analysis of Line Formation Heights in the Flaring Chromosphere Using DKIST

Abstract Solar flares release large amounts of energy, a large fraction of which is deposited in the chromosphere. However, the method of transport of this energy from the coronal energy storage and magnetic reconnection site is not yet agreed upon. Different energy transport models could be constrained through the analysis of chromospheric radiation signatures as a function of distance along the magnetic field. Here, we show an analysis of a compact chromospheric source in a C-class flare observed with the Visible Broadband Imager (VBI) and Visible Spectropolarimeter (ViSP) instruments on the Daniel K. Inouye Solar Telescope (DKIST). We use cross correlation to investigate the spatial offset between flaring sources in Hβand Ca ii K from VBI, and also analyse the change in centroid positions of spatial profiles in Ca ii 8542 Å from ViSP. We find a 0.32” or ∼240 km offset between sources in VBI, and a 0.4” or ∼300 km offset in ViSP. These are interpreted as physical offsets in the formation heights of radiation at the different wavelengths, assuming they form at different locations along the magnetic field. We discuss how these observational results, particularly a slight asymmetry in the Ca ii 8542 Å line, compare with existing transport models. Further flare observations of a similar calibre and comparison with radiation hydrodynamic models should improve constraints on energy transport mechanisms in flares.