{
  "id": "1009.2682",
  "version": "v1",
  "published": "2010-09-14T14:46:11.000Z",
  "updated": "2010-09-14T14:46:11.000Z",
  "title": "Extended emission of D2H+ in a prestellar core",
  "authors": [
    "B. Parise",
    "A. Belloche",
    "F. Du",
    "R. Güsten",
    "K. M. Menten"
  ],
  "comment": "8 pages, 10 figures, accepted for publication in Astronomy and Astrophysics",
  "categories": [
    "astro-ph.GA",
    "astro-ph.SR"
  ],
  "abstract": "Context: In the last years, the H2D+ and D2H+ molecules have gained great attention as probes of cold and depleted dense molecular cloud cores. These ions are at the basis of molecular deuterium fractionation, a common characteristic observed in star forming regions. H2D+ is now routinely observed, but the search for its isotopologue D2H+ is still difficult because of the high frequency of its ground para transition (692 GHz). Aims: We have observed molecular transitions of H2D+ and D2H+ in a cold prestellar core to characterize the roots of deuterium chemistry. Methods: Thanks to the sensitive multi-pixel CHAMP+ receiver on the APEX telescope where the required excellent weather conditions are met, we not only successfully detect D2H+ in the H-MM1 prestellar core located in the L1688 cloud, but also obtain information on the spatial extent of its emission. We also detect H2D+ at 372 GHz in the same source. We analyse these detections using a non-LTE radiative transfer code and a state-of-the-art spin-dependent chemical model. Results: This observation is the first secure detection of D2H+ in space. The emission is moreover extended over several pixels of the CHAMP+ array, i.e. on a scale of at least 40'', corresponding to ~ 4800 AU. We derive column densities on the order of 1e12-1e13 cm-2 for both molecules in the LTE approximation depending on the assumed temperature, and up to two orders of magnitude higher based on a non-LTE analysis. Conclusions: Our modeling suggests that the level of CO depletion must be extremely high (>10, and even >100 if the temperature of the core is around 10 K) at the core center, in contradiction with CO depletion levels directly measured in other cores. Observation of the H2D+ spatial distribution and direct measurement of the CO depletion in H-MM1 will be essential to confirm if present chemical models investigating the basis of deuterium [...].",
  "revisions": [
    {
      "version": "v1",
      "updated": "2010-09-14T14:46:11.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "extended emission",
      "depleted dense molecular cloud cores",
      "molecular deuterium fractionation",
      "first secure detection",
      "ground para transition"
    ],
    "tags": [
      "journal article"
    ],
    "publication": {
      "doi": "10.1051/0004-6361/201015475",
      "journal": "Astronomy and Astrophysics",
      "year": 2011,
      "month": "Feb",
      "volume": 526
    },
    "note": {
      "typesetting": "TeX",
      "pages": 8,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "inspire": 867379,
      "adsabs": "2011A&A...526A..31P"
    }
  }
}