The age of the Galaxy's thick disk

TL;DR

This paper reviews methods for dating stellar disks in the solar neighborhood, presents preliminary spectroscopic age estimates, and concludes that the thick disk is generally older than the thin disk, with some caution about potential biases.

Contribution

It provides new spectroscopic age and abundance data for stars in the thin and thick disks, offering insights into their relative ages and formation history.

Findings

Thick disk stars are generally older than thin disk stars.

Spectroscopic analysis yields age estimates for individual stars.

Potential biases due to temperature selection may affect age distribution conclusions.

Abstract

We discuss the age of the stellar disks in the solar neighbourhood. After reviewing the various methods for age dating we discuss current estimates of the age of both the thin and the thick disk. We present preliminary results for kinematically-selected stars that belong to the thin as well as the thick disk. All of these dwarf and sub-giant stars have been studied spectroscopically and we have derived both elemental abundances as well as ages for them. A general conclusion is that in the solar neighbourhood, on average, the thick disk is older than the thin disk. However, we caution that the exclusion of stars with effective temperatures around 6500 K might result in a biased view on the full age distribution for the stars in the thick disk.