Chemical properties of the central part of the Galactic nuclear stellar disc. Abundances in four classical Cepheids revisited

Abstract

ABSTRACT This paper is a revised abundance analysis of four yellow supergiant stars Cepheids which are located in the Galactic nucleus. The results are based on the spectra secured with the help of Subaru telescope, which are of the better quality comparing to previously analysed spectra taken with the Infrared Telescope Facility. A significantly improved method of the effective temperature determination of program stars, which is based on the calibrating relations between the temperature and line depth ratios, was applied. The present results confirmed our previous finding about the solar metallicity level at the Galaxy centre. It is very likely that the four stars of our program were born from an interstellar medium having homogeneous chemical properties, since all the stars are located close to each other, have close pulsation periods, and hence the age. However, one of the stars has a somewhat increased abundance of all studied elements compared to the abundance in the other three stars. A possible reason of this fact is discussed.