Complexity in small-scale dwarf spheroidal galaxies

TL;DR

This paper reviews the complex kinematic and chemical properties of dwarf spheroidal galaxies, highlighting recent findings on their inhomogeneous enrichment and potential contributions to the Galactic halo.

Contribution

It synthesizes current spectroscopic data to explore the chemical diversity and evolutionary histories of both luminous and ultra-faint dwarf spheroidal galaxies.

Findings

Ultra-faint dSphs are highly dark matter dominated and metal poor.

Some dSphs show highly inhomogeneous chemical enrichment.

Faintest dSph candidates may have contributed to the Galactic halo.

Abstract

Our knowledge about the dynamics, the chemical abundances and the evolutionary histories of the more luminous dwarf spheroidal (dSph) galaxies is constantly growing. However, very little is known about the enrichment of the ultra-faint systems recently discovered in large numbers in large sky surveys. Current low-resolution spectroscopy and photometric data indicate that these galaxies are highly dark matter dominated and predominantly metal poor. On the other hand, recent high-resolution abundance analyses indicate that some dwarf galaxies experienced highly inhomogenous chemical enrichment, where star formation proceeds locally on small scales. In this article, I will review the kinematic and chemical abundance information of the Milky Way satellite dSphs that is presently available from low- and high resolution spectroscopy. Moreover, some of the most peculiar element and inhomogeneous enrichment patterns will be discussed and related to the question of to what extent the faintest dSph candidates could have contributed to the Galactic halo, compared to more luminous systems.