The [Y/Mg] chemical clock and the stellar ages of solar-type stars in the solar neighbourhood

Abstract

Stellar ages are an important parameter for studying the chemical evolution of the Galaxy. To improve age estimates, various complementary methods to the conventional isochrone-fitting method have been implemented in the last decade. The [Y/Mg] ratio has been proposed as a chemical clock for solar-metallicity stars, due to its strong dependence on stellar age. In this work, we study the behaviour of the abundance ratio [Y/Mg] in metal-poor stars, along with other solar-type disk stars, as a function of stellar age determined through isochrones. The analysis is based on the line-by-line differential technique, applied to a sample covering a wide metallicity range ($-$0.70 $\le$ [Fe/H] $<$ +0.34), using high-resolution (R = 115,000) and high S/N spectra (= 270 - 1000) taken with the HARPS spectrograph at the ESO La Silla Observatory. We find that the stellar sample follows a metallicity-dependent [Y/Mg]-Age relation.

arXiv commentPublished in the proceedings of the International Astronomical Union