Milky Way Mapper decoded abundances -- I. Shared disc enrichment patterns

TL;DR

This study models elemental abundances in 70,057 Milky Way disc stars using latent nucleosynthetic patterns, revealing insights into Galactic chemical evolution and enrichment sources.

Contribution

Introduces a data-driven generative model that captures shared nucleosynthetic patterns across stars, linking them to specific enrichment sources and Galactic evolution.

Findings

Model accurately reproduces star abundances with high precision.

Identifies distinct enrichment sources like supernovae and AGB stars.

Reveals how enrichment patterns vary with age, metallicity, and orbital properties.

Abstract

Elemental abundances in the Milky Way disc trace its star-formation and enrichment history, but predicting these abundances from theory is limited by uncertain nucleosynthetic yields and poorly constrained chemical evolution models. Large surveys provide many abundances that enable multi-dimensional insight. However, having so much data available complicates joint visualisation and physical interpretation. Here, we examine the element abundances of 70,057 red giant stars from the Milky Way Mapper survey ([Fe/H] $> -1$), using 16 elements (O,~Mg,~Al,~Si,~S,~K,~Ca,~Ti,~V, ~Cr, Mn,~Fe,~Co,~Ni,~Ce,~Nd). To tackle the challenges of joint-interpretation of these elements, we build a generative data-driven model, expressing each star's abundance vector as a linear combination of a few ($4$) latent nucleosynthetic patterns. These patterns are shared among the population but vary in fraction between stars. The model accurately generates the measured abundances, with $\chi^2 < 3$ (5) for $\sim$ 80\% (95\%) of stars. Model failures, where stars' abundances are not generated by the latent basis reveal accreted material and the role of multiple channels of metal-poor disk enrichment. We associate the recovered patterns, which represent high-precision ($\sigma_P \sim 3$\%) nucleosynthetic channels, with specific enrichment sources; (early and late) core-collapse supernovae, supernovae Type Ia, and asymptotic giant branch stars. We subsequently explore how the dominance of enrichment channels varies across age, metallicity and spatial extent of the disk, and show that enrichment patterns tightly couple to orbital properties. Mean pattern fractions vary smoothly with enrichment, and change rapidly across the valley between the high- and low-$\alpha$ sequences. Our results provide a framework for improving our understanding of Galactic evolution in the Milky Way.