The age-metallicity relation in the solar neighbourhood from a pilot sample of white dwarf-main sequence binaries

TL;DR

This study uses white dwarf-main sequence binaries to investigate the age-metallicity relation in the solar neighborhood, providing new observational evidence that challenges previous assumptions about their correlation.

Contribution

It introduces a novel method using WDMS binaries to accurately determine stellar ages and metallicities, offering new insights into the Galactic disc's chemical evolution.

Findings

No correlation between age and metallicity at 0-7 Gyrs.

White dwarf ages can be accurately determined from their cooling times.

Main sequence companions provide reliable metallicity measurements.

Abstract

The age-metallicity relation (AMR) is a fundamental observational constraint for understanding how the Galactic disc formed and evolved chemically in time. However, there is not yet an agreement on the observational properties of the AMR for the solar neighbourhood, primarily due to the difficulty in obtaining accurate stellar ages for individual field stars. We have started an observational campaign for providing the much needed observational input by using wide white dwarf-main sequence (WDMS) binaries. White dwarfs are natural clocks and can be used to derive accurate ages. Metallicities can be obtained from the main sequence companions. Since the progenitors of white dwarfs and the main sequence stars were born at the same time, WDMS binaries provide a unique opportunity to observationally constrain in a robust way the properties of the AMR. In this work we present the AMR derived from analysing a pilot sample of 23 WDMS binaries and provide clear observational evidence for the lack of correlation between age and metallicity at young and intermediate ages (0-7 Gyrs).