{
  "id": "1007.1420",
  "version": "v1",
  "published": "2010-07-08T17:10:07.000Z",
  "updated": "2010-07-08T17:10:07.000Z",
  "title": "Strong CH+ J=1-0 emission and absorption in DR21",
  "authors": [
    "E. Falgarone",
    "V. Ossenkopf",
    "M. Gerin",
    "P. Lesaffre",
    "B. Godard",
    "J. Pearson",
    "S. Cabrit",
    "Ch. Joblin",
    "A. O. ~Benz",
    "F. Boulanger",
    "A. Fuente",
    "R. Güsten",
    "A. Harris",
    "T. Klein",
    "C. Kramer",
    "S. Lord",
    "P. Martin",
    "J. Martin-Pintado",
    "D. Neufeld",
    "T. G. ~Phillips",
    "M. Röllig",
    "R. Simon",
    "J. Stutzki",
    "F. van der Tak",
    "D. Teyssier",
    "H. Yorke",
    "N. Erickson",
    "M. Fich",
    "W. Jellema",
    "A. Marston",
    "C. Risacher",
    "M. Salez",
    "F. Schmülling"
  ],
  "comment": "Accepted for publication in A&A",
  "categories": [
    "astro-ph.GA"
  ],
  "abstract": "We report the first detection of the ground-state rotational transition of the methylidyne cation CH+ towards the massive star-forming region DR21 with the HIFI instrument onboard the Herschel satellite. The line profile exhibits a broad emission line, in addition to two deep and broad absorption features associated with the DR21 molecular ridge and foreground gas. These observations allow us to determine a CH+ J=1-0 line frequency of 835137 +/- 3 MHz, in good agreement with a recent experimental determination. We estimate the CH+ column density to be a few 1e13 cm^-2 in the gas seen in emission, and > 1e14 cm^-2 in the components responsible for the absorption, which is indicative of a high line of sight average abundance [CH+]/[H] > 1.2x10^-8. We show that the CH+ column densities agree well with the predictions of state-of-the-art C-shock models in dense UV-illuminated gas for the emission line, and with those of turbulent dissipation models in diffuse gas for the absorption lines.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2010-07-08T17:10:07.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "column density",
      "hifi instrument onboard",
      "column densities agree",
      "broad emission line",
      "state-of-the-art c-shock models"
    ],
    "tags": [
      "journal article"
    ],
    "publication": {
      "doi": "10.1051/0004-6361/201014671",
      "journal": "Astronomy and Astrophysics",
      "year": 2010,
      "month": "Jul",
      "volume": 518
    },
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "inspire": 860763,
      "adsabs": "2010A&A...518L.118F"
    }
  }
}