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