{
  "id": "1807.03734",
  "version": "v1",
  "published": "2018-07-10T16:15:33.000Z",
  "updated": "2018-07-10T16:15:33.000Z",
  "title": "The R-Process Alliance: Chemical Abundances for a Trio of R-Process-Enhanced Stars -- One Strong, One Moderate, One Mild",
  "authors": [
    "Madelyn Cain",
    "Anna Frebel",
    "Maude Gull",
    "Alexander P. Ji",
    "Vinicius M. Placco",
    "Timothy C. Beers",
    "Jorge Melendez",
    "Rana Ezzeddine",
    "Andrew R. Casey",
    "Terese T. Hansen",
    "Ian U. Roederer",
    "Charli Sakari"
  ],
  "comment": "30 pages, includes a long table, 5 figures",
  "categories": [
    "astro-ph.SR",
    "astro-ph.GA"
  ],
  "abstract": "We present detailed chemical abundances of three new bright (V ~ 11), extremely metal-poor ([Fe/H] ~ -3.0), r-process-enhanced halo red giants based on high-resolution, high-S/N Magellan/MIKE spectra. We measured abundances for 20-25 neutron-capture elements in each of our stars. J1432-4125 is among the most r-process rich r-II stars, with [Eu/Fe]= +1.44+-0.11. J2005-3057 is an r-I star with [Eu/Fe] = +0.94+-0.07. J0858-0809 has [Eu/Fe] = +0.23+-0.05 and exhibits a carbon abundance corrected for evolutionary status of [C/Fe]_corr = +0.76, thus adding to the small number of known carbon-enhanced r-process stars. All three stars show remarkable agreement with the scaled solar r-process pattern for elements above Ba, consistent with enrichment of the birth gas cloud by a neutron star merger. The abundances for Sr, Y, and Zr, however, deviate from the scaled solar pattern. This indicates that more than one distinct r-process site might be responsible for the observed neutron-capture element abundance pattern. Thorium was detected in J1432-4125 and J2005-3057. Age estimates for J1432-4125 and J2005-3057 were adopted from one of two sets of initial production ratios each by assuming the stars are old. This yielded individual ages of 12+-6 Gyr and 10+-6 Gyr, respectively.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2018-07-10T16:15:33.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "chemical abundances",
      "r-process alliance",
      "r-process-enhanced stars",
      "r-process rich r-ii stars",
      "distinct r-process site"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 30,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}