# Dynamical age of the Tucana-Horologium young stellar association

## TL;DR

This study uses Gaia astrometry and spectroscopy to determine the dynamical age of the Tucana-Horologium stellar association, aligning it with previous age estimates and enhancing understanding of young stellar groups.

## Contribution

It provides a new dynamical age estimate for Tucana-Horologium using orbit traceback analysis, aligning it with isochrone and lithium depletion ages.

## Key findings

- Dynamical age of 38.5 Myr with uncertainties.
- Consistent with isochrone fitting ages (30-50 Myr).
- Reconciles dynamical and lithium depletion ages.

## Abstract

The Tucana-Horologium association is one of the closest young stellar groups to the Sun and despite the close proximity its age is still debated in the literature. We take advantage of the state-of-the-art astrometry delivered by the third data release of the Gaia space mission combined with precise radial velocity measurements obtained from high-resolution spectroscopy to investigate the dynamical age of the association. We perform an extensive traceback analysis using a combination of different samples of cluster members, metrics to evaluate the minimum size of the association in the past and models for the galactic potential to integrate the stellar orbits back in time. The dynamical age of $38.5^{+1.6}_{-8.0}$ Myr that we derive in this paper is consistent with the various age estimates obtained from isochrone fitting in the literature (30-50 Myr) and reconciles, for the first time, the dynamical age of the Tucana-Horologium association with the age obtained from lithium depletion ($\sim40$ Myr). Our results are independent from stellar models and represent one more step towards constructing a self-consistent age scale for the young stellar groups of the Solar neighbourhood based on the 3D space motion of the stars.