The Assembly of the Halo System of the Milky Way as Revealed by SDSS/SEGUE -- The CEMP Star Connection

TL;DR

This paper uses SDSS/SEGUE spectroscopic data to analyze the Milky Way's halo, revealing its dual structure and the relationship between halo components and the prevalence of CEMP stars at low metallicity.

Contribution

It identifies the inner and outer halo components of the Milky Way and links their properties to the distribution of CEMP stars, advancing understanding of galactic formation.

Findings

The Milky Way halo has at least two distinct components.

The fraction of CEMP stars increases with decreasing metallicity.

Different characteristics of inner and outer halo components are demonstrated.

Abstract

In recent years, massive new spectroscopic data sets, such as the over half million stellar spectra obtained during the course of SDSS (in particular its sub-survey SEGUE), have provided the quantitative detail required to formulate a coherent story of the assembly and evolution of the Milky Way. The disk and halo systems of our Galaxy have been shown to be both more complex, and more interesting, than previously thought. Here we concentrate on the halo system of the Milky Way. New data from SDSS/SEGUE has revealed that the halo system comprises at least two components, the inner halo and the outer halo, with demonstrably different characteristics (metallicity distributions, density distributions, kinematics, etc.). In addition to suggesting new ways to examine these data, the inner/outer halo dichotomy has enabled an understanding of at least one long-standing observational result, the increase of the fraction of carbon-enhanced metal-poor (CEMP) stars with decreasing metallicity.