aat Acta Astrophys. Tau. Acta Astrophysica Taurica 2712-925X Kiselev Nikolai Nikolaevich, Mosсow, settlement Moskovskii, Tat'yanin Park Str., 12, Moscow, Russia. RU 103 Research articles Analysis of events during the M 2.5 flare on June 7, 2011 Kupryakov Yurii Maliutin Victor Bychkov Konstantin Belova Oksana Gorshkov Aleksei Sternberg Astronomical Institute, Moscow State University, Universitetsky pr. 13, Moscow 119234, Russia; Astronomical Institute of the Czech Academy of Sciences, Fričova 298, 25165 Ondřejov, Czech Republic Sternberg Astronomical Institute, Moscow State University, Universitetsky pr. 13, Moscow 119234, Russia Sternberg Astronomical Institute, Moscow State University, Universitetsky pr. 13, Moscow 119234, Russia Sternberg Astronomical Institute, Moscow State University, Universitetsky pr. 13, Moscow 119234, Russia Sternberg Astronomical Institute, Moscow State University, Universitetsky pr. 13, Moscow 119234, Russia 22 03 2025 6 1 1 4 12 03 2025 Copyright (c) 2026 Kupryakov Y., Maliutin V., Bychkov K., Belova O., Gorshkov A. 2026 Yurii Kupryakov, Victor Maliutin, Konstantin Bychkov, Oksana Belova, Aleksei Gorshkov The metadata for this submission is licensed under a Creative Commons Attribution 4.0 International License. Copyright and publishing rights for texts published in Acta Astrophysica Taurica is retained by the authors, with first publication rights granted to the journal.Texts are free to use with proper attribution and link to the licensing (Creative Commons Attribution 4.0 International).

The object under study is the fragments of the falling matter during the M 2.5 flare in the NOAA AR 11226 on June 7, 2011. Observations were carried out with the horizontal solar installation HSFA-2 and the multichannel flare spectrograph MFS (Ondrejov Observatory). The traces of fragments were found in the CaII H, Hα, and Hβ lines. After reducing the line spectra, absorption fluxes were calculated for four moments of time, and a system of equations was solved for the populations of discrete levels and the ionization state of the hydrogen atom and CaII ion. The source of radiation was considered in the approximation of a homogeneous layer of heated gas. The gas parameters were selected in such a way that the observed and theoretical fluxes coincide with an accuracy of better than 5%. Calculations have shown that the temperature range T varies from 7 to 12 thousand K, the column concentration N is 1–5 10 19 cm -2 , and the turbulent speed varies from 6 to 21 km/s.

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