Stragglers of the thick disc

Young alpha-rich (YAR) stars have been detected in the past as outliers to local age − [ α /Fe] relation. These objects are enhanced -elements, but they apparently younger than typical thick disc stars. Here, we study global kinematics and chemical properties of YAR giant APOGEE DR17 survey show that similar those standard stellar population. This leads us conclude rejuvenated objects, most likely explanation is evolved blue stragglers. confirmed by their position Hertzsprung–Russel diagram (HRD). Extending our selection dwarfs allowed obtain first general straggler distribution an HRD field We also compared elemental abundances sample with found shifted oxygen, magnesium, sodium, slow neutron-capture element cerium. Although no sign binarity for enhancement cerium may be a signature mass transfer from asymptotic branch companion. The massive suggest star not only plausible formation pathway other scenarios, such collision or coalescence, should considered.