GALAH Survey: Chemically Tagging the Thick Disk

TL;DR

The GALAH survey aims to chemically tag the Milky Way's thick disk by measuring detailed elemental abundances and kinematics for a million stars, enabling insights into stellar migration and galaxy evolution.

Contribution

This work introduces a large-scale survey that combines high-resolution spectroscopy with Gaia data to chemically tag the thick disk, providing new insights into stellar migration over cosmic time.

Findings

Successful measurement of up to 30 elemental abundances for stars.

Potential to directly observe stellar migration patterns.

Enhanced understanding of the thick disk's formation history.

Abstract

The GALAH survey targets one million stars in the southern hemisphere down to a limiting magnitude of V = 14 at the Anglo- Australian Telescope. The project aims to measure up to 30 elemental abundances and radial velocities (~1 km/s accuracy) for each star at a resolution of R = 28000. These elements fall into 8 independent groups (e.g. alpha, Fe peak, r-process). For all stars, Gaia will provide distances to 1% and transverse velocities to 1 km/s or better, giving us a 14D set of parameters for each star, i.e. 6D phase space and 8D abundance space. There are many scientic applications but here we focus on the prospect of chemically tagging the thick disk and making a direct measurement of how stellar migration evolves with cosmic time.