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.Comment: 10 pages; accepted for publication in MNRA