Spectroscopic inversions of the Ca ii 8542 Å line in a C-class solar flare

Abstract

We study the C8.4 class solar flare SOL2016-05-14T11:34 UT using high-resolution spectral imaging in the Ca ii 8542 Å line obtained with the CRISP imaging spectropolarimeter on the Swedish 1-m Solar Telescope. Spectroscopic inversions of the Ca ii 8542 Å line using the non-LTE code NICOLE are used to investigate the evolution of the temperature and velocity structure in the flare chromosphere. A comparison of the temperature stratification in flaring and non-flaring areas reveals strong footpoint heating during the flare peak in the lower atmosphere. The temperature of the flaring footpoints between continuum optical depth at 500~nm, $\log {\tau }_{500}\approx -2.5\mathrm{and}-3.5$ is $\sim 5-6.5\mathrm{kK}$, close to the flare peak, reducing gradually to $\sim 5\mathrm{kK}$. The temperature in the middle and upper chromosphere, between $\log {\tau }_{500}\approx -3.5\mathrm{and}-5.5$, is estimated to be $\sim 6.5-20\mathrm{kK}$, decreasing to pre-flare temperatures, $\sim 5-10\mathrm{kK}$, after approximately 15 minutes. However, the temperature stratification of the non-flaring areas is unchanged. The inverted velocity fields show that the flaring chromosphere is dominated by weak downflowing condensations at the Ca ii 8542 Å formation height.

9 pages, 6 figures, accepted in ApJ

References in corpus (10)

• CRISP Spectropolarimetric Imaging of Penumbral Fine Structure
• CRISPRED: A data pipeline for the CRISP imaging spectropolarimeter
• An Open Source, Massively Parallel Code for Non-LTE Synthesis and Inversion of Spectral Lines and Zeeman-induced Stokes Profiles
• Advanced Forward Modeling and Inversion of Stokes Profiles Resulting from the Joint Action of the Hanle and Zeeman Effects
• The solar chromosphere at high resolution with IBIS. I. New insights from the Ca II 854.2 nm line
• 3D Temperature Mapping of Solar Photospheric Fine Structure Using Ca II H Filtergrams
• Radiative diagnostics in the solar photosphere and chromosphere
• Spectropolarimetric observations of the Ca II 8498 A and 8542 A lines in the quiet Sun
• Fast inversion of solar Ca II spectra
• Observations and simulations of the Na I D1 line profiles in an M-class solar flare

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• RADYNVERSION: Learning to Invert a Solar Flare Atmosphere with Invertible Neural Networks
• The New 2018 Version of the Meudon Spectroheliograph
• Spectral diagnostics of cool flare loops observed by SST: I. Inversion of the Ca II 8542 Å and H$\beta$ lines
• Synthesizing Sun-as-a-star flare spectra from high-resolution solar observations
• Spectral Characteristics and Formation Height of Off-Limb Flare Ribbons
• Chromospheric velocities in an M3.2 flare using He I 1083.0 nm and Ca II 854.2 nm
• Semi-empirical models of spicule from inversion of Ca II 8542 Å line
• Understanding the thermal and magnetic properties of a X-class flare in the low solar atmosphere
• Dark off-limb gap: manifestation of temperature minimum and dynamic nature of the chromosphere