ИСТИНА

New evidence is obtained that hydrogen emission lines as well as metallic ones originate below molecular line absorbing layers in spectra of Mira stars. The time scale tc is calculated as function of T0 for the final stage of gas cooling behind a shock wave propagating through the star atmosphere, when gas temperature tends to its preshock value T0. We have computed tc for T0=(2800…3000)К, which is typical values for the layers absorbing in the molecular lines, and have compared it with the pulsation period P of S Car, T Col, RR Sco, R Aql, R Car, o Cet, RR Sgr, S Sco, W Vel, R Leo. It occurs that the gas has no sufficient time to be cooled to its preshock state. So, T0 should be greater than temperature of molecular layer. This result is agrees with the spectra of Mira-like stars known in the literature. The emission lines show a complex structure, having an asymmetric, or a multicomponent profile, what is due to molecular line absorption. This work was partly supported by the Russian Foundation for Basic Research (projects 13-02-00136 and 15-03-03302).