Determining the speed of gas flow in the shells of red giants on the resonant broadening of hydrogen lines

The article describes the method for determining the absolute spatial speed of the gas and its concentration in the shells of the red giants on the basis of the analysis of the profile of the $H_a$ - line of hydrogen, taking into account of the resonance broadening of spectral lines. Line of hydrogen can be represented as a superposition of thermal profiles, the central frequency of which randomly varies in some limits by interatomic interactions. The absolute spatial velocity of the gas and its concentration for shells of 20 red giants is defined. The absolute spatial velocity of the gas are in the range from $7500$ to $14500$ m/s. Concentrations are in the range of $(6,8-8,5)$ $10^{23}$ м$^{-3}$.