{
  "id": "1608.08260",
  "version": "v1",
  "published": "2016-08-29T21:53:39.000Z",
  "updated": "2016-08-29T21:53:39.000Z",
  "title": "New spectroscopic binary companions of giant stars and updated metallicity distribution for binary systems",
  "authors": [
    "P. Bluhm",
    "M. I. Jones",
    "L. Vanzi",
    "M. G. Soto",
    "J. Vos",
    "R. A. Wittenmyer",
    "F. Olivares",
    "H. Drass",
    "R. E. Mennickent",
    "M. Vuckovic",
    "P. Rojo",
    "C. H. F. Melo"
  ],
  "doi": "10.1051/0004-6361/201628459",
  "categories": [
    "astro-ph.SR"
  ],
  "abstract": "We report the discovery of 24 spectroscopic binary companions to giant stars. We fully constrain the orbital solution for 6 of these systems. We cannot unambiguously derive the orbital elements for the remaining stars because the phase coverage is incomplete. Of these stars, 6 present radial velocity trends that are compatible with long-period brown dwarf companions.The orbital solutions of the 24 binary systems indicate that these giant binary systems have a wide range in orbital periods, eccentricities, and companion masses. For the binaries with restricted orbital solutions, we find a range of orbital periods of between $\\sim$ 97-1600 days and eccentricities of between $\\sim$ 0.1-0.4. In addition, we studied the metallicity distribution of single and binary giant stars. We computed the metallicity of a total of 395 evolved stars, 59 of wich are in binary systems. We find a flat distribution for these binary stars and therefore conclude that stellar binary systems, and potentially brown dwarfs, have a different formation mechanism than planets.This result is confirmed by recent works showing that extrasolar planets orbiting giants are more frequent around metal-rich stars. Finally, we investigate the eccentricity as a function of the orbital period. We analyzed a total of 130 spectroscopic binaries, including those presented here and systems from the literature. We find that most of the binary stars with periods $\\lesssim$ 30 days have circular orbits, while at longer orbital periods we observe a wide spread in their eccentricities.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2016-08-29T21:53:39.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "binary systems",
      "spectroscopic binary companions",
      "giant stars",
      "updated metallicity distribution",
      "orbital period"
    ],
    "tags": [
      "journal article"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}