{
  "id": "1703.03252",
  "version": "v1",
  "published": "2017-03-09T13:02:19.000Z",
  "updated": "2017-03-09T13:02:19.000Z",
  "title": "The ALMA-PILS survey: Detection of CH$_{3}$NCO toward the low-mass protostar IRAS 16293-2422 and laboratory constraints on its formation",
  "authors": [
    "N. F. W. Ligterink",
    "A. Coutens",
    "V. Kofman",
    "H. S. P. Müller",
    "R. T. Garrod",
    "H. Calcutt",
    "S. F. Wampfler",
    "J. K. Jørgensen",
    "H. Linnartz",
    "E. F. van Dishoeck"
  ],
  "comment": "Submitted for MNRAS; shared here on request by the editor. 13 pages, 8 figures",
  "categories": [
    "astro-ph.SR",
    "astro-ph.GA"
  ],
  "abstract": "Methyl isocyanate (CH$_{3}$NCO) belongs to a select group of interstellar molecules considered to be relevant precursors in the formation of larger organic compounds, including those with peptide bonds. The molecule has only been detected in a couple of high-mass protostars and potentially in comets. A formation route on icy grains has been postulated for this molecule but experimental confirmation is lacking. We unambiguously identify CH$_{3}$NCO for the first time in a solar-type protostar through 43 unblended transitions found in the ALMA Protostellar Interferometric Line Survey (PILS) of the low-mass protostellar binary IRAS 16293-2422. The molecule is detected toward both components of the binary with a ratio HNCO/CH$_3$NCO $\\sim$4--12. The isomers CH$_{3}$CNO and CH$_3$OCN are not identified, resulting in upper abundance ratios of CH$_{3}$NCO/CH$_{3}$CNO > 100 and CH$_{3}$NCO/CH$_3$OCN > 10. The resulting abundance ratios compare well with those found for related N-containing species toward high-mass protostars. To constrain its formation, a set of cryogenic UHV experiments is performed. VUV irradiation of CH$_{4}$:HNCO mixtures at 20 K strongly indicate that methyl isocyanate can be formed in the solid-state through CH$_{3}$ and (H)NCO recombinations. Combined with gas-grain models that include this reaction, the solid-state route is found to be a plausible scenario to explain the abundances found in IRAS 16293-2422.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2017-03-09T13:02:19.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "low-mass protostar iras",
      "alma-pils survey",
      "laboratory constraints",
      "alma protostellar interferometric line survey",
      "methyl isocyanate"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 13,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}