Abstract

The observed chemical diversity of Milky Way stars carries implications for Galactic chemical evolution, the expected diversity of exoplanetary systems in the Milky Way, and the inferred chemical distributions of unresolved stars in extragalactic systems, among other topics.  Recent works have found that the chemical diversity of Milky Way stars is low.  For example, the APOGEE chemical “doppelganger rate,” or the rate at which random pairs of field stars appear as chemically similar as stars born together, is high, and the chemical distributions of APOGEE stars are well-described using models with just two dimensions.  However, limited attention has been paid to the heavy elements (Z > 30) in this context.  In this talk, I will present our recent work using GALAH DR3 to assess the role of the neutron-capture elements in enhancing the chemical diversity of Milky Way stars.  We find that the neutron-capture elements significantly reduce the doppelganger rate.  Our results also suggest that the slow neutron-capture process elements may carry greater distinguishing power than the rapid neutron-capture process elements.  This talk will highlight the importance of considering the neutron-capture elements when chemically characterizing stars in the Milky Way and validate ongoing work to improve their measurements in spectroscopic surveys.