The AMBRE Project: [Y/Mg] stellar dating calibration with Gaia

¹ Laboratoire Lagrange (UMR7293), Université de Nice Sophia Antipolis, CNRS, Observatoire de la Côte d’Azur, BP 4229, 06304 Nice Cedex 4, France
e-mail: 2chlaidze@gmail.com
² Sydney Institute for Astronomy (SIfA), School of Physics, A28, The University of Sydney, NSW, 2006 Australia
³ Center of Excellence for Astrophysics in Three Dimensions (ASTRO-3D), Australia
⁴ Leibniz-Institut für Astrophysik Potsdam (AIP), 14482 Potsdam, Germany

Received: 26 June 2018
Accepted: 8 November 2018

Abstract

Chemical abundance dating methods open new paths for temporal evolution studies of the Milky Way stellar populations. In this paper, we use a high spectral resolution database of turn-off stars in the solar neighbourhood to study the age dependence of the [Y/Mg] chemical abundance ratio. Our analysis reveals a clear correlation between [Y/Mg] and age for thin disc stars of different metallicities, in synergy with previous studies of solar-type stars. In addition, no metallicity dependence with stellar age is detected, allowing us to use the [Y/Mg] ratio as a reliable age proxy. Finally, the [Y/Mg]–age relation presents a discontinuity between thin and thick disc stars around 9–10 Gyr. For thick disc stars, the correlation has a different zero point and probably a steeper trend with age, reflecting the different chemical evolution histories of the two disc components.