{
  "id": "2310.13054",
  "version": "v1",
  "published": "2023-10-19T18:00:03.000Z",
  "updated": "2023-10-19T18:00:03.000Z",
  "title": "CAPOS: The bulge Cluster APOgee Survey IV. Elemental Abundances of the bulge globular cluster NGC 6558",
  "authors": [
    "Danilo González-Díaz",
    "José G. Fernández-Trincado",
    "Sandro Villanova",
    "Doug Geisler",
    "Beatriz Barbuy",
    "Dante Minniti",
    "Timothy C. Beers",
    "Christian Moni Bidin",
    "Francesco Mauro",
    "Cesar Muñoz",
    "Baitian Tang",
    "Mario Soto",
    "Antonela Monachesi",
    "Richard R. Lane",
    "Heinz Frelijj"
  ],
  "comment": "To appear in MNRAS. The paper is 11 pages long, containing 5 figures, 4 tables,",
  "categories": [
    "astro-ph.GA",
    "astro-ph.SR"
  ],
  "abstract": "This study presents the results concerning six red giant stars members of the globular cluster NGC 6558. Our analysis utilized high-resolution near-infrared spectra obtained through the CAPOS initiative (the APOgee Survey of Clusters in the Galactic Bulge), which focuses on surveying clusters within the Galactic Bulge, as a component of the Apache Point Observatory Galactic Evolution Experiment II survey (APOGEE-2). We employ the BACCHUS (Brussels Automatic Code for Characterizing High accUracy Spectra) code to provide line-by-line elemental-abundances for Fe-peak (Fe, Ni), $\\alpha$-(O, Mg, Si, Ca, Ti), light-(C, N), odd-Z (Al), and the $s$-process element (Ce) for the 4 stars with high signal-to-noise ratios. This is the first reliable measure of the CNO abundances for NGC 6558. Our analysis yields a mean metallicity for NGC 6558 of $\\langle$[Fe/H]$\\rangle$ = $-$1.15 $\\pm$ 0.08, with no evidence for a metallicity spread. We find a Solar Ni abundance, $\\langle$[Ni/Fe]$\\rangle$ $\\sim$ $+$0.01, and a moderate enhancement of $\\alpha$-elements, ranging between $+$0.16 to $<+$0.42, and a slight enhancement of the $s$-process element $\\langle$[Ce/Fe]$\\rangle$ $\\sim$ $+$0.19. We also found low levels of $\\langle$[Al/Fe]$\\rangle \\sim $+$0.09$, but with a strong enrichment of nitrogen, [N/Fe]$>+$0.99, along with a low level of carbon, [C/Fe]$<-$0.12. This behaviour of Nitrogen-Carbon is a typical chemical signature for the presence of multiple stellar populations in virtually all GCs; this is the first time that it is reported in NGC 6558. We also observed a remarkable consistency in the behaviour of all the chemical species compared to the other CAPOS bulge GCs of the same metallicity.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2023-10-19T18:00:03.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "bulge globular cluster ngc",
      "bulge cluster apogee survey",
      "elemental abundances",
      "observatory galactic evolution experiment",
      "point observatory galactic evolution"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 11,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}