The age-metallicity structure of the Milky Way disc with APOGEE

TL;DR

This study uses APOGEE data to create a detailed 3D map of the Milky Way disc's stellar density, revealing insights into its formation, evolution, and structural properties based on age and chemical composition.

Contribution

First detailed 3D map of the Galactic disc's stellar density as a function of age, metallicity, and alpha-element abundance, providing new constraints on disc formation models.

Findings

Disc structure varies with stellar age and composition.

Radial migration influences disc flaring and density profiles.

Inside-out formation is supported by the data.

Abstract

The best way to trace back the history of star formation and mass assembly of the Milky Way disc is by combining chemical compositions, ages and phase-space information for a large number of disc stars. With the advent of large surveys of the stellar populations of the Galaxy, such data have become available and can be used to pose constraints on sophisticated models of galaxy formation. We use SDSS-III/APOGEE data to derive the first detailed 3D map of stellar density in the Galactic disc as a function of age, [Fe/H] and $\mathrm{[\alpha/Fe]}$. We discuss the implications of our results for the formation and evolution of the disc, presenting new constraints on the disc structural parameters, stellar radial migration and its connection with disc flaring. We also discuss how our results constrain the inside out formation of the disc, and determine the surface-mass density contributions at the solar radius for mono-age, mono-[Fe/H] populations.