Stringent constraints on single-star evolution theory from masses and radii of well-detached binaries in star clusters

Abstract

Which sample of objects can give strong constraints on single-star evolution theory ? Whilst star cluster members share the same age and the same metallicity, many questions (e.g. field stars contamination, stellar rotation, presence of unresolved binaries) are difficult to clarify properly when using their colour-magnitude diagram to compare with theoretical isochrones. Alternatively, binary stars can be used to put constraints on theoretical predictions. However, while the stellar mass is accurately known for some sample of well-detached binary stars, their metallicities are often poorly known. Then it appears that a better test could be obtained by combining both advantages (well-detached binaries members of a star cluster). This idea is applied in this work to binaries in the Hyades and one binary in the Cepheus OB3 association to test the validity of independent sets of theoretical tracks. A detailed comparison of theoretical vs. observational masses (and radii when possible) is presented.