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A chemical study of the old open cluster M67

Clio Bertelli Motta

The chemical composition of a star is not constant throughout its life.
It changes due to different evolutionary processes such as atomic
diffusion between the main sequence and the sub-giant brach, the first
dredge-up along the sub-giant branch, and extra-mixing taking place
after the luminosity bump on the red giant branch. All these effects are
hard to measure observationally, since a fairly large sample of stars
belonging to the same stellar population and in different evolutionary
stages is required. Being built up of a single stellar population, open
clusters are therefore perfect laboratories for the study of stellar
evolution. We present the well known old open cluster M67 as a
test-bench for different evolutionary effects using high-resolution
spectroscopic data from APOGEE and Gaia-ESO. We compare the
observational results to predictions from theoretical models and discuss
them with respect to broader implications such as the [C/N]-age
relation, recently proposed for the age-dating of field stars.