2017/08/01 by D. Kuridze, V. Henriques, M. Mathioudakis +5 · 1 citation
Physics and Astronomy · #astro-ph.SR
paper · pdf · doi:10.3847/1538-4357/aa83b9
published as The Astrophysical Journal, Volume 846, Issue 1, article id. 9, 9 pp. (2017) · 9 pages, 6 figures, accepted in ApJ
arxiv created 2017/08/01 · arxiv updated 2018/01/18
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, \mathrmlog~τ500~≈ -2.5~and~ -3.5 is ∼5-6.5~kK, close to the flare peak, reducing gradually to ∼5~kK. The temperature in the middle and upper chromosphere, between \mathrmlog~τ500 ≈ - 3.5~and~- 5.5, is estimated to be ∼6.5 - 20~kK, decreasing to pre-flare 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 Ca ii 8542 Å formation height.