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Article Dans Une Revue The Astrophysical Journal Année : 2022

Dynamically Tagged Groups of Metal-poor Stars from the Best and Brightest Survey

Derek Shank
  • Fonction : Auteur
Timothy Beers
Vinicius Placco
Guilherme Limberg
  • Fonction : Auteur
Emma Jaques
  • Fonction : Auteur
Zhen Yuan
Kevin Schlaufman
  • Fonction : Auteur
Andrew Casey
  • Fonction : Auteur
Yang Huang
Young Sun Lee
  • Fonction : Auteur
Kohei Hattori
  • Fonction : Auteur
Rafael Santucci
  • Fonction : Auteur

Résumé

Abstract Orbital characteristics based on Gaia Early Data Release 3 astrometric parameters are analyzed for ∼4000 metal-poor stars ([Fe/H] ≤ −0.8) compiled from the Best and Brightest survey. Selected as metal-poor candidates based on broadband near- and far-IR photometry, 43% of these stars had medium-resolution (1200 ≲ R ≲ 2000) validation spectra obtained over a 7 yr campaign from 2014 to 2020 with a variety of telescopes. The remaining stars were chosen based on photometric metallicity determinations from the Huang et al. recalibration of the Sky Mapper Southern Survey. Dynamical clusters of these stars are obtained from the orbital energy and cylindrical actions using the HDBSCAN unsupervised learning algorithm. We identify 52 dynamically tagged groups (DTGs) with between five and 21 members; 18 DTGs have at least 10 member stars. Milky Way (MW) substructures such as Gaia-Sausage-Enceladus, the Metal-Weak Thick-Disk, Thamnos, the Splashed Disk, and the Helmi Stream are identified. Associations with MW globular clusters are determined for eight DTGs; no recognized MW dwarf galaxies were associated with any of our DTGs. Previously identified dynamical groups are also associated with our DTGs, with emphasis placed on their structural determination and possible new identifications. Chemically peculiar stars are identified as members of several DTGs, with six DTGs that are associated with r -process-enhanced stars. We demonstrate that the mean carbon and α -element abundances of our DTGs are correlated with their mean metallicity in an understandable manner. Similarly, we find that the mean metallicity, carbon, and α -element abundances are separable into different regions of the mean rotational-velocity space.
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hal-03585650 , version 1 (24-02-2022)

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Derek Shank, Timothy Beers, Vinicius Placco, Guilherme Limberg, Emma Jaques, et al.. Dynamically Tagged Groups of Metal-poor Stars from the Best and Brightest Survey. The Astrophysical Journal, 2022, 926 (1), pp.26. ⟨10.3847/1538-4357/ac409a⟩. ⟨hal-03585650⟩
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