Cannibals in the thick disk

Determining ages of stars for reconstructing the history Milky Way remains one most difficult tasks in astrophysics. This involves knowing when it is possible to relate stellar mass with its age and not. The young $\alpha-$rich (YAR) present such a case which we are still not sure about their because they relatively massive, implying ages, but abundances $\alpha-$enhanced, implies old ages. We report results from new observations long-term radial-velocity-monitoring campaign complemented high-resolution spectroscopy, as well astrometry seismology sample 41 red giants third version APOKASC, includes YAR stars. aim better characterize terms binarity, mass, abundance trends, kinematic properties.The radial velocities HERMES, APOGEE, Gaia were combined determine binary fraction among In combination estimate, evolutionary status, chemical composition, properties, allowed us constrain nature these objects. found that $\mathrm{M} < 1 \mathrm{M}_\odot$ all single, whereas > could be either single or binary. agreement theoretical predictions population synthesis models. Studying [C/N], [C/Fe], [N/Fe], trends became clear many do follow APOKASC stars, favoring scenario them product transfer. Abr.