Evidence for the accretion origin of halo stars with an extreme r-process enhancement

  title={Evidence for the accretion origin of halo stars with an extreme r-process enhancement},
  author={Qianfan Xing and Gang Zhao and Wako Aoki and Satoshi Honda and Haining Li and Miho N. Ishigaki and Tadafumi Matsuno},
  journal={Nature Astronomy},
Small stellar systems such as dwarf galaxies are suggested to be the main building blocks of our Galaxy according to numerical simulations1 in Λ cold dark matter models and observational support for this hypothesis comes from the existence of stellar streams such as the Sagittarius tidal stream2. However, it is unclear how many and what kind of stars in our Galaxy originate from satellite dwarf galaxies, something that could be constrained by analysing chemical abundances of metal-poor stars… 

Extreme r-process Enhanced Stars at High Metallicity in Fornax

We present and discuss three extremely r-process enhanced stars located in the massive dwarf spheroidal galaxy Fornax. These stars are very unique with an extreme Eu enrichment (1.25 ≤ [Eu/Fe]≤1.45)

Progress on the structure and evolution of the Milky Way based on LAMOST survey

The Milky Way is, at least for now, the only galaxy that we can obtain the full 3 dimensional spatial and kinematical information of individual stars. This makes it the most important galaxy sample

Chemical abundances of field halo stars - Implications for the building blocks of the Milky Way

  • M. Ishigaki
  • Physics
    Proceedings of the International Astronomical Union
  • 2019
Abstract I would like to review recent efforts of detailed chemical abundance measurements for field Milky Way halo stars. Thanks to the advent of wide-field spectroscopic surveys up to a several kpc

Evidence for Corotation Origin of Super-metal-rich Stars in LAMOST-Gaia: Multiple Ridges with a Similar Slope in the ϕ versus L z Plane

Super-metal-rich (SMR) stars in the solar neighborhood are thought to be born in the inner disk and come to their present location by radial migration, which is most intense at the corotation

The R-Process Alliance: First Magellan/MIKE Release from the Southern Search for R-process-enhanced Stars

Extensive progress has recently been made in our understanding of heavy-element production via the r-process in the universe, specifically with the first observed neutron star binary merger (NSBM)

Four-hundred Very Metal-poor Stars Studied with LAMOST and Subaru. I. Survey Design, Follow-up Program, and Binary Frequency

The chemical abundances of very metal-poor stars provide important constraints on the nucleosynthesis of the first generation of stars and early chemical evolution of the Galaxy. We have obtained

Abundance Analysis of New r-process-enhanced Stars from the HESP–GOMPA Survey

We present a study on the detailed chemical abundances of five new relatively bright r-process-enhanced stars that were initially observed as part of the SDSS/MARVELS pre-survey. These stars were

The R-Process Alliance: Chemodynamically Tagged Groups of Halo r-process-enhanced Stars Reveal a Shared Chemical-evolution History

We derive dynamical parameters for a large sample of 446 r-process-enhanced (RPE) metal-poor stars in the halo and disk systems of the Milky Way, based on data releases from the R-Process Alliance,

Four-hundred Very Metal-poor Stars Studied with LAMOST and Subaru. II. Elemental Abundances

We present homogeneous abundance analysis of over 20 elements for 385 very metal-poor (VMP) stars based on the LAMOST survey and follow-up observations with the Subaru Telescope. It is the largest



Tracing Galaxy Formation with Stellar Halos. I. Methods

If the favored hierarchical cosmological model is correct, then the Milky Way system should have accreted ~100-200 luminous satellite galaxies in the past ~12 Gyr. We model this process using a

Stellar Archaeology — Exploring the Universe with Metal-Poor Stars

The abundance patterns of the most metal-poor stars in the Galactic halo and small dwarf galaxies provide us with a wealth of information about the early Universe. In particular, these old survivors

Early chemo-dynamical evolution of dwarf galaxies deduced from enrichment of r-process elements

The abundance of elements synthesized by the rapid neutron-capture process (r-process elements) of extremely metal-poor (EMP) stars in the Local Group galaxies gives us clues to clarify the early

Star-Formation Histories, Abundances, and Kinematics of Dwarf Galaxies in the Local Group

Within the Local Universe galaxies can be studied in great detail star by star, and here we review the results of quantitative studies in nearby dwarf galaxies. The color-magnitude diagram synthesis

R-process enrichment from a single event in an ancient dwarf galaxy

It is reported that seven of the nine brightest stars in Reticulum II, observed with high-resolution spectroscopy, show strong enhancements in heavy neutron-capture elements, with abundances that follow the universal r-process pattern beyond barium.

An r-process Enhanced Star in the Dwarf Galaxy Tucana III

Chemically peculiar stars in dwarf galaxies provide a window for exploring the birth environment of stars with varying chemical enrichment. We present a chemical abundance analysis of the brightest

Stellar Abundances for Galactic Archaeology Database IV - Compilation of Stars in Dwarf Galaxies

We have constructed the database of stars in the local group using the extended version of the SAGA (Stellar Abundances for Galactic Archaeology) database that contains stars in 24 dwarf spheroidal

Chemical Substructure in the Milky Way Halo: A New Population of Old Stars

We report the results of a coherent study of a new class of halo stars defined on the basis of the chemical compositions of three metal-poor objects ([Fe/H] ≃ -2) that exhibit unusually low


As we know, the majority of metal-poor Galactic halo stars appear to have chemical abundances that were enhanced by α-elements (e.g., O, Mg, Si, Ca, and Ti) during the early stage of the Galaxy.


▪ Abstract The metallicity of stars in the Galaxy ranges from [Fe/H] = −4 to +0.5 dex, and the solar iron abundance is e(Fe) = 7.51 ± 0.01 dex. The average values of [Fe/H] in the solar neighborhood,