Nonstationarity of the Atmosphere of κ Cas. III. Atmosphere Kinematics

Abstract

Abstract—The variability of radial velocities, equivalent widths and central line depths in the spectrum of the κ Cas supergiant was studied using CCD coude-echelle spectra with high spectral resolution and signal-to-noise ratio. The radial velocity variability of all the studied lines is due to non-radial pulsations. The variability parameters (period P, amplitude A and average value γ) of radial velocity, equivalent width and central depth of the lines were determined. These parameters differ for different lines. Based on the calculation of the formation depth of the lines log τλ, the stratification of these parameters in the atmosphere of the star was studied. For the radial velocity, the period, amplitude, and rate of expansion (γ-velocity) increase from the lower to the upper layers of the atmosphere. The amplitudes of variability of the equivalent widths and central depths of the lines also increase with the height in the atmosphere.