Chemical evolution of high-mass stars in close binaries. I. The eclipsing binary V453 Cygni

TL;DR

This study performs a detailed chemical abundance analysis of the high-mass eclipsing binary V453 Cygni, revealing solar-like elemental abundances and providing precise stellar parameters through spectral disentangling and non-LTE modeling.

Contribution

It introduces a high-precision abundance analysis of both components of V453 Cygni using spectral disentangling and non-LTE line profile fitting, improving understanding of chemical evolution in high-mass binary stars.

Findings

Both stars have elemental abundances similar to Galactic OB stars.

The primary star shows a normal helium abundance with no CNO-processed material.

Effective temperatures are precisely measured at 27900 K and 26200 K.

Abstract

The eclipsing and double-lined spectroscopic binary system V453 Cygni consists of two early B-type stars, one of which is nearing the terminal age main sequence and one which is roughly halfway through its main sequence lifetime. Accurate measurements of the masses and radii of the two stars are available, which makes a detailed abundance analysis both more interesting and more precise than for isolated stars. We have reconstructed the spectra of the individual components of V453 Cyg from the observed composite spectra using the technique of spectral disentangling. From these disentangled spectra we have obtained improved effective temperature measurements of 27900 +/- 400 K and 26200 +/- 500 K, for the primary and secondary stars respectively, by fitting non-LTE theoretical line profiles to the hydrogen Balmer lines. Armed with these high-precision effective temperatures and the accurately known surface gravities of the stars we have obtained the abundances of helium and metallic elements. A detailed abundance analysis of the primary star shows a normal (solar) helium abundance if the microturbulence velocity derived from metallic lines is used. The elemental abundances show no indication that CNO-processed material is present in the photosphere of this high-mass terminal age main sequence star. The elemental abundances of the secondary star were derived by differential study against a template spectrum of a star with similar characteristics. Both the primary and secondary components display elemental abundances which are in the ranges observed in the Galactic OB stars.