Related papers: A second-generation star in a relic dwarf galaxy

Growing evidence supports an unusual elemental feature appearing in nearby dwarf galaxies, especially dwarf spheroidals (dSphs), indicating a key process of galaxy evolution that is different from that of the Galaxy. In addition to the…

The S2 stream is a kinematically cold stream that is plunging downwards through the Galactic disc. It may be part of a hotter and more diffuse structure called the Helmi stream. We present a multi-instrument chemical analysis of the stars…

Deep observations are revealing a growing number of young galaxies in the first billion year of cosmic time. Compared to typical galaxies at later times, they show more extreme emission-line properties, higher star formation rates, lower…

We estimate the potential contribution of M < 10^9 Msun dwarf galaxies to the reionization and early metal-enrichment of the Milky Way environment, or circum-Galactic Medium. Our approach is to use the observed properties of ancient stars…

We report a possible discovery of a relic star cluster in the Sextans dwarf spheroidal galaxy. Using the \textit{hk} index ($\equiv$($Ca-b$)$-$($b-y$)) as a photometric metallicity indicator, we discriminate the metal-poor and metal-rich…

We present the discovery of a new dwarf galaxy, Hydra II, found serendipitously within the data from the ongoing Survey of the MAgellanic Stellar History (SMASH) conducted with the Dark Energy Camera on the Blanco 4m Telescope. The new…

We present Magellan/MIKE and Keck/HIRES high-resolution spectra of six red giant stars in the dwarf galaxy Segue 1. Including one additional Segue 1 star observed by Norris et al. (2010), high-resolution spectra have now been obtained for…

Little is known about the origin of the fastest stars in the Galaxy. Our understanding of the Milky Way and surrounding dwarf galaxies chemical evolution history allows us to use the chemical composition of a star to investigate its origin,…

We examine the spatial distribution of the oldest and most metal poor stellar populations of Milky Way-sized galaxies using the APOSTLE cosmological hydrodynamical simulations of the Local Group. In agreement with earlier work, we find…

We report on an analysis of the chemical composition of five carbon-rich, very metal-poor stars based on high-resolution spectra. One star, CS22948-027, exhibits very large overabundances of carbon, nitrogen, and the neutron-capture…

Based on high-resolution spectra obtained during gravitational microlensing events we present a detailed elemental abundance analysis of 32 dwarf and subgiant stars in the Galactic bulge. [ABRIDGED], we now have 58 microlensed bulge dwarfs…

We present a Magellan/MIKE high-resolution (R ~ 35,000) spectrum of the ancient star SD 1313-0019 which has an iron abundance of [Fe/H] = -5.0, paired with a carbon enhancement of [C/Fe] ~ 3.0. The star was initially identified by Allende…

The first stars formed out of pristine gas, causing them to be so massive that none are expected to have survived until today. If their direct descendants were sufficiently low-mass stars, such stars could exist today and would be…

We study the stellar mass-iron metallicity relation of dwarf galaxies in the new high-resolution MEGATRON cosmological radiation-hydrodynamics simulations. These simulations model galaxy formation up to $z\approx8$ in a region that will…

The chemical composition of stars with extremely low metal contents (taking ``metals'' to mean all elements other than hydrogen and helium) provides us with information on the masses of the stars that produced the first metals. Such a…

We present an analysis of the chemical abundances and kinematics of six low-mass dwarf stars, previously claimed to be candidate hypervelocity stars (HVSs). We obtained moderate-resolution ($R\sim$ 6000) spectra of these stars to estimate…

A long sought after goal using chemical abundance patterns derived from metal-poor stars is to understand the Galactic chemical evolution (GCE) and to pin down the nature of the first stars (Pop III). Here, we use a sample of 14 metal-poor…

This chapter presents an overview of the recent progress on spectroscopic observations of metal-poor stars with r-process element signatures found in the Milky Way's stellar halo and satellite dwarf galaxies. Major empirical lessons related…

We present chemical abundance analyses of sodium, iron-peak and neutron-capture elements for 97 kinematically selected thick disk, inner halo and outer halo stars with metallicities -3.3<[Fe/H]<-0.5. The main aim of this study is to examine…

A few rare halo giants in the range [Fe/H] $\simeq -2.9\pm0.3$ exhibit {\it r}-process element abundances that vary as a group by factors up to [$r$/Fe] $\sim80$, relative to those of the iron peak and below. Yet, the astrophysical…