High-mass eclipsing binaries: A testbed for models of interior structure and evolution

Abstract

Aims. The surface chemical compositions of stars are affected by physical processes that bring the products of thermonuclear burning to the surface. Despite their potential in helping us understand the structure and evolution of stars, elemental abundances are available for only a few high-mass binary stars. We aim to enlarge this sample by determining the physical properties and photospheric abundances for four eclipsing binary systems that contain high-mass stars: V1034 Sco, GL Car, V573 Car, and V346 Cen. The components have masses of 8–17 M⊙, have effective temperatures from 22 500 to 32 200 K, and are all on the main sequence. Methods. We present new high-resolution and high signal-to-noise spectroscopy from the High Accuracy Radial velocity Planet Searcher (HARPS), which we analysed using spectral disentangling and non-local thermodynamic equilibrium spectral synthesis. We modelled existing light curves and new photometry from the Transiting Exoplanet Survey Satellite (TESS). Results. We measure the stellar masses to a 0.6–2.0% precision, radii to a 0.8–1.7% precision, effective temperatures to a 1.1–1.6% precision, and abundances of C, N, O, Mg, and Si. The abundances are similar to those found in our previous studies of high-mass eclipsing binaries; our sample now comprises 25 high-mass stars in 13 binary systems. We also find tidally excited pulsations in V346 Cen. Conclusions. These results reinforce our previous conclusions: interior chemical element transport is not as efficient in binary star components as in their single-star counterparts in the same mass regime and evolutionary stage, possibly due to the effects of tidal forces. Our ultimate goal is to provide a larger sample of OB-type stars in binaries to enable a thorough comparison to stellar evolutionary models, as well as to single high-mass stars.