Chemically characterising nearby evolved Open Clusters
Résumé
Open Clusters (OCs) are excellent tracers of the formation and evolution of the Galaxy, as well as an ideal laboratory to test theories of stellar evolution. In particular, nearby OCs spanning a wide age range are commonly used as benchmark objects for galactic and stellar studies owing to the highest precision that is achievable. We have designed a project to perform an in-depth study of 45 nearby (closer than 500 pc) and old (age>300Myr) OCs. After Gaia DR2, very accurate memberships, distances, motions and ages are available for these OCs, allowing us to revise their physical properties. In particular, we are determining their chemical composition in a homogeneous way using a strictly line-by-line differential method with high-resolution, high signal-to-noise spectra, either retrieved from public archives or from our own observations. We present the first results of this project where we mesure the internal dispersions of abundances within the studied OCs and compare their chemical signatures.