A kinematic calibration of the O-rich Mira variable period-age relation from Gaia

TL;DR

This paper calibrates the period-age relation of Mira variables using Gaia DR3 data, enabling better understanding of stellar evolution and star formation in the Local Group.

Contribution

It provides a new empirical period-age relation for O-rich Mira variables based on Gaia data and dynamical models, improving previous calibrations.

Findings

The derived period-age relation is $ au oughly(6.9 ext{ Gyr})$ with a hyperbolic tangent dependence on period.

Results agree with previous studies and Local Group cluster data.

Calibration enhances the use of Mira variables as probes of galaxy evolution.

Abstract

Empirical and theoretical studies have demonstrated that the periods of Mira variable stars are related to their ages. This, together with their brightness in the infrared, makes them powerful probes of the formation and evolution of highly-extincted or distant parts of the Local Group. Here we utilise the Gaia DR3 catalogue of long-period variable candidates to calibrate the period-age relation of the Mira variables. Dynamical models are fitted to the O-rich Mira variable population across the extended solar neighbourhood and then the resulting solar neighbourhood period-kinematic relations are compared to external calibrations of the age-kinematic relations to derive a Mira variable period-age relation of $\tau\approx(6.9\pm0.3)\,\mathrm{Gyr}(1+\tanh((330\,\mathrm{d}-P)/(400\pm90)\mathrm{d})$. Our results compare well with previous calibrations using smaller datasets as well as the period-age properties of Local Group cluster members. This calibration opens the possibility of accurately characterising the star formation and the impact of different evolutionary processes throughout the Local Group.