Study of nonstationarity of the atmosphere of κ Cas. I. Variability of profiles of photospheric and He I wind lines

Abstract

Temporal variations of radial velocities and line profiles in the spectrum of the supergiant κ Cas were investigated. Variability of radial velocities and profiles of photospheric lines Si III, OII, He I, H₁₀–Hδ and wind lines He I λ 5875, 6678 Å ismainly caused by non-radial pulsations. For photospheric lines quasisinusoidal variabilities of the radial velocity were found. Temporal variability of radial velocity of the wind lines He I λ 5875, 6678 A˚ differ from each other and from the photospheric lines. Gamma velocities and amplitudes of radial velocity variability were determined. The amplitude of variability and the velocity of expansion increase from lower to upper layers of the atmosphere. Emission components are superimposed on the line profiles at positions about −135 ± 10.0, −20 ± 20 and 135 ± 10.0 kms⁻¹ respectively. They are more obvious in the wind line profiles, although, there are signs of emissions also in the photospheric lines. Such a character of variability of all the lines in the κ Cas spectrum confirms its Be nature.