4MOST Consortium Survey 2: The Milky Way Halo High-Resolution Survey

TL;DR

This survey aims to analyze the Milky Way's formation and chemical evolution by studying over 1.5 million stars, focusing on elemental abundances, kinematics, and substructures to test galaxy formation models.

Contribution

It provides the largest high-resolution spectroscopic dataset of Milky Way stars, including a significant sample of extremely metal-poor stars, enabling unprecedented insights into early galaxy evolution.

Findings

Detailed elemental abundances for up to 20 elements in over 1.5 million stars.

Identification of kinematic substructures linked to star formation history.

Enhanced understanding of the early chemical enrichment of the Milky Way.

Abstract

We will study the formation history of the Milky Way, and the earliest phases of its chemical enrichment, with a sample of more than 1.5 million stars at high galactic latitude. Elemental abundances of up to 20 elements with a precision of better than 0.2 dex will be derived for these stars. The sample will include members of kinematically coherent substructures, which we will associate with their possible birthplaces by means of their abundance signatures and kinematics, allowing us to test models of galaxy formation. Our target catalogue is also expected to contain 30,000 stars at a metallicity of less than one hundredth that of the Sun. This sample will therefore be almost a factor of 100 larger than currently existing samples of metal-poor stars for which precise elemental abundances are available (determined from high-resolution spectroscopy), enabling us to study the early chemical evolution of the Milky Way in unprecedented detail.