Oxygen, α-element and iron abundance distributions in the inner part of the Galactic thin disc - II

Abstract

We have derived the abundances of 36 chemical elements in one Cepheid star, ASAS 181024- 2049.6, located RG = 2.53 kpc from the Galactic Centre. This star falls within a region of the inner thin disc poorly sampled in Cepheids. Our spectral analysis shows that iron, magnesium, silicon, calcium and titanium local thermodynamic equilibrium abundances in that star support the presence of a plateau-like abundance distribution in the thin disc within 5 kpc of theGalactic Centre, as previously suggested by Martin et al. If confirmed, the flattening of the abundance gradient within that region could be the result of a decrease in the star formation rate due to dynamic effects, possibly from the central Galactic bar.