{
  "id": "2407.11572",
  "version": "v1",
  "published": "2024-07-16T10:23:29.000Z",
  "updated": "2024-07-16T10:23:29.000Z",
  "title": "Discovery of an Extremely r-process-enhanced Thin-disk Star with [Eu/H] = +0.78",
  "authors": [
    "Xiao-Jin Xie",
    "Jianrong Shi",
    "Hong-Liang Yan",
    "Tian-Yi Chen",
    "Carlos Allende Prieto",
    "Timothy C. Beers",
    "Shuai Liu",
    "Chun-Qian Li",
    "Ming-Yi Ding",
    "Yao-Jia Tang",
    "Ruizhi Zhang",
    "Renjing Xie"
  ],
  "comment": "5 figures, 3 tables",
  "categories": [
    "astro-ph.SR",
    "astro-ph.GA"
  ],
  "abstract": "Highly r-process-enhanced stars are rare and usually metal-poor ([Fe/H] < - 1.0), and mainly populate the Milky Way halo and dwarf galaxies. This study presents the discovery of a relatively bright (V = 12.72), highly r-process-enhanced (r-II) star ([Eu/Fe] = +1.32, [Ba/Eu] = - 0.95), LAMOST J020623.21 + 494127.9. This star was selected from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) medium-resolution (R ~ 7500) spectroscopic survey; follow-up high-resolution (R ~ 25,000) observations were conducted with the High Optical Resolution Spectrograph (HORuS) installed on the Gran Telescopio Canarias (GTC). The stellar parameters (${T_{\\rm eff}}$ = 4130 K, $\\rm log\\,g $ = 1.52, $ \\rm[Fe/H] $ = $ - $0.54, $\\xi$ = 1.80 $ \\rm{km\\,{s^{-1}}} $) have been inferred taking into account non-local thermodynamic equilibrium (NLTE) effects. The abundances of [Ce/Fe], [Pr/Fe], and [Nd/Fe] are +0.19, +0.65 and +0.64, respectively, relatively low compared to the Solar r-process pattern normalized to Eu. This star has a high metallicity ([Fe/H] = - 0.54) compared to most other highly r-process-enhanced stars, and has the highest measured abundance ratio of Eu to H ([Eu/H] = +0.78). It is classified as a thin-disk star based on its kinematics, and does not appear to belong to any known stream or dwarf galaxy.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2024-07-16T10:23:29.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "extremely r-process-enhanced thin-disk star",
      "area multi-object fiber spectroscopic telescope",
      "large sky area multi-object fiber",
      "sky area multi-object fiber spectroscopic"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}