Chemodynamically Tagged Groups of CEMP Stars in the Halo of the Milky Way. I. Untangling the Origins of CEMP-s and CEMP-no Stars

J Zepeda, TC Beers, VM Placco, D Shank… - The Astrophysical …, 2023 - iopscience.iop.org
We construct a sample of 644 carbon-enhanced metal-poor (CEMP) stars with abundance
analyses based on moderate-to high-resolution spectroscopic studies. Dynamical …

Probing the Galactic halo with RR Lyrae stars–V. Chemistry, kinematics, and dynamically tagged groups

J Cabrera Garcia, TC Beers, Y Huang… - Monthly Notices of …, 2024 - academic.oup.com
We employ a sample of 135 873 RR Lyrae stars (RRLs) with precise photometric-metallicity
and distance estimates from the newly calibrated P–ϕ31–R 21–[Fe/H] and Gaia G band P–R …

Europium enrichment and hierarchical formation of the Galactic halo

L Cavallo, G Cescutti, F Matteucci - Astronomy & Astrophysics, 2023 - aanda.org
Context. The origin of the large star-to-star variation of the [Eu/Fe] ratios observed in the
extremely metal-poor (at [Fe/H]≤− 3) stars of the Galactic halo is still a matter of debate …

Discovery of an Extremely r-process-enhanced Thin-disk Star with [Eu/H]=+ 0.78

XJ Xie, J Shi, HL Yan, TY Chen, CA Prieto… - The Astrophysical …, 2024 - iopscience.iop.org
Highly r-process-enhanced (RPE) stars are rare and usually metal poor ([Fe/H]<− 1.0), and
they mainly populate the Milky Way halo and dwarf galaxies. This study presents the …

Detection of the Actinide Th in an r-process-enhanced Star with Accretion Origin

Q Xing, G Zhao, W Aoki, H Li, J Zhao… - The Astrophysical …, 2024 - iopscience.iop.org
The thorium and six second-peak r-process element (56≤ Z≤ 72) abundances are
determined for the α-poor star LAMOST J1124+ 4535 based on a high-resolution spectrum …

Four-hundred Very Metal-poor Stars Studied with LAMOST and Subaru. III. Dynamically Tagged Groups and Chemodynamical Properties

R Zhang, T Matsuno, H Li, W Aoki, XX Xue… - The Astrophysical …, 2024 - iopscience.iop.org
Very metal-poor (VMP) stars record the signatures of early accreted galaxies, making them
essential tools for unraveling the early stages of Galaxy formation. Understanding the origin …

The -process Alliance: Enrichment of -process Elements in a Simulated Milky Way-like Galaxy

Y Hirai, TC Beers, YS Lee, S Wanajo… - arXiv preprint arXiv …, 2024 - arxiv.org
We study the formation of stars with varying amounts of heavy elements synthesized by the
rapid neutron-capture process ($ r $-process) based on our detailed cosmological zoom-in …

The R-Process Alliance: 2MASS J22132050-5137385, the Star with the Highest-known r-process Enhancement at [Eu/Fe]=+ 2.45

IU Roederer, TC Beers, K Hattori, VM Placco… - arXiv preprint arXiv …, 2024 - arxiv.org
We present stellar parameters and chemical abundances of 47 elements detected in the
bright (V= 11.63) very metal-poor ([Fe/H]=-2.20+-0.12) star 2MASS J22132050-5137385 …

An integrated perspective of robustness in regression through the lens of the bias-variance trade-off

A Okuno - arXiv preprint arXiv:2407.10418, 2024 - arxiv.org
This paper presents an integrated perspective on robustness in regression. Specifically, we
examine the relationship between traditional outlier-resistant robust estimation and robust …

Detection of the actinide Th in an r-process-enhanced star with accretion origin

X Qianfan, Z Gang, A Wako, L Haining… - arXiv preprint arXiv …, 2024 - arxiv.org
The thorium and six second-peak r-process element (56< Z< 72) abundances are
determined for the alpha-poor star LAMOST J1124+ 4535 based on a high-resolution …