Stellar properties and chemical features of the Gaia Catalogue of Nearby Stars observed by GALAH DR4

TL;DR

This study combines Gaia DR3 and GALAH DR4 data to analyze around 6,000 nearby stars, revealing their physical and chemical properties, ages, and Galactic memberships, to better understand the local stellar population.

Contribution

It presents the first joint analysis of Gaia and GALAH data for nearby stars, providing new insights into their properties and Galactic context.

Findings

Majority are FGK main-sequence stars

Median age approximately 1.6 Gyr

Most stars are disc members, some halo stars

Abstract

The Gaia Catalogue of Nearby Stars (GCNS) comprises approximately 330 000 stars within 100 pc of the Sun, as observed by Gaia data release 3 (Gaia DR3). Meanwhile, the GALAH DR4 survey has spectroscopically characterised nearly one million stars, delivering detailed chemical abundances (up to 30 elements). We present a joint analysis of the $\sim$ 6 000 stars common to both catalogues, offering initial insights into the stellar and chemical properties of the solar neighborhood. Our preliminary results indicate that the majority of these stars are FGK main-sequence objects, with some A-type interlopers (with effective temperatures ranging between 3 000 and 8 000 K), with median ages of $\sim$ 1.6 Gyr (ranging from 0.10 to 14.79 Gyr), and metal-poorer when compared to the Sun: [Fe/H] $\approx$ -0.19 dex. Additionally, most of the stars are disc members, with some local halo (high-velocity) stars identified. Building on this foundation, future work will deeper exploit the full spectroscopic information and orbital parameters from value-added catalogues to refine Galactic component classifications (thin-thick disc versus halo membership), perform detailed chemical profiling, and deliver a comprehensive chemo-dynamical characterisation of the solar neighborhood. This will provide new insights into the formation and evolution of nearby stellar populations.