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Документ Are the s-Cepheids crossing the instability strip for the first time?(Astroprint, 2012) Andrievsky, Serhii M.; Harbuzov H. O.; Doikov, D. N.; Андрієвський, Сергій Михайлович; Андриевский, Сергей МихайловичUsing the literature data on secular period changes reported for the small-amplitude Cepheids (s-Cepheids) it is shown that these stars are not crossing the instability strip for the first time. After correction of the observed pulsational chracteristics of s-Cepheids, in the diagram ”log(dP/P)100 - log P” they become indistinguishable from usual classic Cepheids, which are supposed to have already crossed the instability strip more than (or at least) once.Документ Ionisation loss and shock excitation of 44/20 Са I and 44/20 Са II atoms in cold remnants of type II supernovae(Одеський національний університет імені І. І. Мечникова, 2017) Doikov, D. N.; Andrievsky, Serhii M.; Андрієвський, Сергій Михайлович; Андриевский, Сергей МихайловичThe light emission (“glow”) of cold dusty plasma of the remnant of SN1987A was confirmed by the Hubble Space Telescope observations on 7th January, 1995. In particular, Ca I and Ca II lines were recorded and identified in the spectrum of the supernova’s envelope. The period of complete hydrogen recombination in the remnant is 800 days. Thus, it is only radioactive decay that could be a primary source of the plasma light emission at the moment of observation. This paper describes the conditions of shock excitation and recombination of 44/20 Ca resulted from the decay of radioactive 44/20 Ti travelling in the remnant’s cold dust. The overionisation in the remnant resulted from the motion of the 44/20 Ca recoil nucleus, as well as its impact on the spectrum formation, was studied. It has been shown that the calcium lines are formed by the 44/20 Ca II ion in the inner layers of the remnant. We have reached the conclusion that the Ca I/Ca II lines strength ratio corresponds to the isotopic abundance ratio [44/20 Ca] /[44/20 Ca ] in type II supernova remnants.