{
  "id": "1211.6977",
  "version": "v1",
  "published": "2012-11-29T16:48:16.000Z",
  "updated": "2012-11-29T16:48:16.000Z",
  "title": "Parallaxes and Proper Motions of Ultracool Brown Dwarfs of Spectral Types Y and Late T",
  "authors": [
    "Kenneth A. Marsh",
    "Edward L. Wright",
    "J. Davy Kirkpatrick",
    "Christopher R. Gelino",
    "Michael C. Cushing",
    "Roger L. Griffith",
    "Michael F. Skrutskie",
    "Peter R. Eisenhardt"
  ],
  "comment": "31 pages, 5 figures. Accepted for publication in ApJ",
  "categories": [
    "astro-ph.SR"
  ],
  "abstract": "We present astrometric measurements of eleven nearby ultracool brown dwarfs of spectral types Y and late-T, based on imaging observations from a variety of space-based and ground-based telescopes. These measurements have been used to estimate relative parallaxes and proper motions via maximum likelihood fitting of geometric model curves. To compensate for the modest statistical significance (<~ 7) of our parallax measurements we have employed a novel Bayesian procedure for distance estimation which makes use of an a priori distribution of tangential velocities, Vtan, assumed similar to that implied by previous observations of T dwarfs. Our estimated distances are therefore somewhat dependent on that assumption. Nevertheless, the results have yielded distances for five of our eight Y dwarfs and all three T dwarfs. Estimated distances in all cases are >~ 3 pc. In addition, we have obtained significant estimates of Vtan for two of the Y dwarfs; both are <100 km/s, consistent with membership in the thin disk population. Comparison of absolute magnitudes with model predictions as a function of color shows that the Y dwarfs are significantly redder in J-H than predicted by a cloud-free model",
  "revisions": [
    {
      "version": "v1",
      "updated": "2012-11-29T16:48:16.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "proper motions",
      "spectral types",
      "parallaxes",
      "nearby ultracool brown dwarfs",
      "thin disk population"
    ],
    "tags": [
      "journal article"
    ],
    "publication": {
      "doi": "10.1088/0004-637X/762/2/119",
      "journal": "The Astrophysical Journal",
      "year": 2013,
      "month": "Jan",
      "volume": 762,
      "number": 2,
      "pages": 119
    },
    "note": {
      "typesetting": "TeX",
      "pages": 31,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "inspire": 1204752,
      "adsabs": "2013ApJ...762..119M"
    }
  }
}