Spectroscopic Inversions of the Ca ii 8542 Å Line in a C-class Solar Flare

David Kuridze, V. Henriques, M. Mathioudakis, J. Koza, T. V. Zaqarashvili, J. Rybák, A. Hanslmeier, F. P. Keenan

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16 Citations (Scopus)

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 flaring 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 $\mathrm{log}\,{\tau }_{500}\,\approx -2.5\,\mathrm{and}\,-3.5$, where τ 500 is the continuum optical depth at 500 nm, is $\sim 5\mbox{--}6.5\,\mathrm{kK}$ close to the flare peak, reducing gradually to $\sim 5\,\mathrm{kK}$. The temperature in the middle and upper chromosphere, between $\mathrm{log}\,{\tau }_{500}\approx -3.5$ and −5.5, is estimated to be ~6.5–20 kK, decreasing to preflare temperatures, ~5–10 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 formation height of Ca ii 8542 Å.
Original languageEnglish
Article number9
JournalAstrophysical Journal
Volume846
Issue number1
DOIs
Publication statusPublished - 28 Aug 2017

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