VARIABILITY OF Hα LINE IN SUPERGIANT STARS OF SPECTRAL TYPE B, A AND F

Abstract

The variability in the profiles of the Hα line profiles in selected B, A and F spectral class supergiant stars was comparatively analyzed based on the spectra obtained at the 2-meter telescope at the Shamakhy Astrophysical Observatory. This study investigates the variability in the values of the parameters characterizing the profiles of the H_α line and the changes in profile shapes in the spectra of the supergiant stars HD 190603 (B1.5 Ia), HD 208501 (B8 Ib), HD 187982 (A2 Ia), HD 207260 (A2 Iae), HD 195593 (F5 Ib), HD 163506 (F2 Ibe) and HD7927 (F0 Ia). For each star, the reasons for these changes were investigated,
leading to general conclusions.

From the study of the selected supergiant stars of spectral type B, A and F, it can be concluded that from the supergiant stars of spectral type B to the supergiant stars of spectral type A and F, i.e., as the effective temperature decreases, the variability in the atmosphere of the star is observed less. In particular, stellar wind is stronger in B spectral type supergiant stars. Some
of the ejected matter disperses into the interstellar medium, some returns and falls on the surface of the star, and some collects around the star, and turns into a disk or inhomogeneous cover. In F spectral type supergiant stars, since the temperature is relatively low, the magnitude of the variability in the star atmosphere is small. Therefore, in the studied F-type stars, the profile of the H_a line is often observed as a full absorption profile.