The R-Process Alliance: Chemodynamically Tagged Groups. II. An Extended Sample of Halo r-process-enhanced Stars

Orbital characteristics based on Gaia Early Data Release 3 astrometric parameters are analyzed for ∼1700 r -process-enhanced (RPE; [Eu/Fe] > +0.3) metal-poor stars ([Fe/H] ≤ −0.8) compiled from the R -Process Alliance, the GALactic Archaeology with HERMES (GALAH) DR3 survey, and additional litera...

Full description

Saved in:
Bibliographic Details
Published in:The Astrophysical journal 2023-01, Vol.943 (1), p.23
Main Authors: Shank, Derek, Beers, Timothy C., Placco, Vinicius M., Gudin, Dmitrii, Catapano, Thomas, Holmbeck, Erika M., Ezzeddine, Rana, Roederer, Ian U., Sakari, Charli M., Frebel, Anna, Hansen, Terese T.
Format: Article
Language:English
Subjects:
Algorithms
Archaeology
Astrophysics
Dwarf galaxies
Enceladus
Galactic archaeology
Galaxy dynamics
Globular clusters
Iron
Machine learning
Metallicity
Milky Way
Milky Way dynamics
Milky Way evolution
Milky Way formation
Milky Way stellar halo
R-process
Stars
Unsupervised learning
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Orbital characteristics based on Gaia Early Data Release 3 astrometric parameters are analyzed for ∼1700 r -process-enhanced (RPE; [Eu/Fe] > +0.3) metal-poor stars ([Fe/H] ≤ −0.8) compiled from the R -Process Alliance, the GALactic Archaeology with HERMES (GALAH) DR3 survey, and additional literature sources. We find dynamical clusters of these stars based on their orbital energies and cylindrical actions using the HDBSCAN unsupervised learning algorithm. We identify 36 chemodynamically tagged groups (CDTGs) containing between five and 22 members; 17 CDTGs have at least 10 member stars. Previously known Milky Way (MW) substructures such as Gaia-Sausage-Enceladus, the splashed disk, the metal-weak thick disk, the Helmi stream, LMS-1 (Wukong), and Thamnos are reidentified. Associations with MW globular clusters are determined for seven CDTGs; no recognized MW dwarf galaxy satellites were associated with any of our CDTGs. Previously identified dynamical groups are also associated with our CDTGs, adding structural determination information and possible new identifications. Carbon-enhanced metal-poor RPE (CEMP- r ) stars are identified among the targets; we assign these to morphological groups in a Yoon–Beers A (C) c versus [Fe/H] diagram. Our results confirm previous dynamical analyses that showed RPE stars in CDTGs share common chemical histories, influenced by their birth environments.
ISSN:0004-637X
1538-4357
1538-4357
DOI:10.3847/1538-4357/aca322