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Abstract

In this work we investigate how stellar evolutionary processes change the surface chemical composition of stars. As a test-bench, we use the old open cluster M67, for whose stars high-resolution spectroscopic data are available in many different evolutionary stages, from the main sequence to the red clump. In particular, we use data retrieved from the archives of large spectroscopic surveys such as APOGEE and Gaia-ESO. First we investigate the effects of the so-called first dredge-up on the surface [C/N] abundance of M67 stars. We then analyse variations in the surface abundances of several elements from the main-sequence to the red-giant phase of M67 stars and discuss how these can be explained by atomic diffusion effects. We also present the results of these investigations in the broader context of Galactic archaeology studies. Furthermore, we investigate the chemical composition of three blue straggler stars and two evolved blue straggler stars in M67 in order to find hints for their formation scenario and discuss the results from the point of view of stellar evolution. Finally, we present an experiment based on TGAS data for the study of the dynamical evolution of OB associations.