Constraining the solar neighbourhood age-metallicity relation from white dwarf-main sequence binaries

TL;DR

This study uses white dwarf-main sequence binaries from SDSS and Gaia to analyze the age-metallicity relation in the solar neighborhood, confirming a flat relation with significant scatter, thus supporting previous findings of no strong correlation.

Contribution

It provides the largest sample of white dwarf binaries with metallicity estimates, offering new empirical evidence for the flat age-metallicity relation in the solar neighborhood.

Findings

Age-metallicity relation is flat with ~0.5 dex scatter.

Confirms lack of correlation between age and metallicity.

Supports previous studies using different stellar samples.

Abstract

The age-metallicity relation is a fundamental tool for constraining the chemical evolution of the Galactic disc. In this work we analyse the observational properties of this relation using binary stars that have not interacted consisting of a white dwarf - from which we can derive the total age of the system - and a main sequence star - from which we can derive the metallicity as traced by the [Fe/H] abundances. Our sample consists of 46 widely separated, but unresolved spectroscopic binaries identified within the Sloan Digital Sky Survey, and 189 white dwarf plus main sequence common proper motion pairs identified within the second data release of Gaia. This is currently the largest white dwarf sample for which the metallicity of their progenitors have been determined. We find a flat age-metallicity relation displaying a scatter of [Fe/H] abundances of approximately 0.5 dex around the solar metallicity at all ages. This independently confirms the lack of correlation between age and metallicity in the solar neighbourhood that is found in previous studies focused on analysing single main sequence stars and open clusters.