[Y/Mg] chemical clock from asteroseismic ages

Building on our previous study, which demonstrated the necessity of accounting for departures from the local thermodynamic equilibrium while determining elemental abundances, and the importance of asteroseismic ages, we aim to characterise the spatial variations of the empirical [Y/Mg]-age relation across the Galactic disc with a significantly larger sample of stars. We observed high-resolution stellar spectra and determined Mg and Y abundances via spectral synthesis of multiple spectral features, rigorously accounting for non-local thermodynamic equilibrium (NLTE) effects.

To anchor the time scale, we determined asteroseismic ages for stars showing solar-type pulsations, while employing cross-checked isochrone-based methods for the remaining stars. We determined the main atmospheric parameters and abundances of Mg and Y for a sample of 528 Galactic field stars, as well as asteroseismic ages for 307 stars and cross-checked isochronal ages for 221 stars. We identified two new triple-lined and nine double-lined spectroscopic stellar systems.