{
  "id": "1408.6306",
  "version": "v1",
  "published": "2014-08-27T03:53:52.000Z",
  "updated": "2014-08-27T03:53:52.000Z",
  "title": "New molecules in IRC+10216: confirmation of C$_5$S and tentative identification of MgCCH, NCCP, and SiH$_3$CN",
  "authors": [
    "Marcelino Agúndez",
    "José Cernicharo",
    "Michel Guélin"
  ],
  "comment": "Accepted for publication in A&A",
  "categories": [
    "astro-ph.GA"
  ],
  "abstract": "The C-star envelope IRC+10216 harbors a rich variety of molecules, with more than 80 detected to date. During the course of a $\\lambda$ 3 mm survey of IRC+10216 carried out with the IRAM 30-m telescope we have detected various weak lines, with antenna temperatures of a few mK, that we assign to rotational transitions of four new molecules. The observation of three lines of C$_5$S confirms a previous tentative identification of this molecule by Bell et al. (1993) based on a line at 24.0 GHz. We also report the tentative identification of three molecules not yet observed in space: MgCCH, the first metal acetylide detected in space, and NCCP and SiH$_3$CN, the phosphorus and silicon analogs of cyanogen (NCCN) and methyl cyanide (CH$_3$CN). We derive the following column densities: $N$(C$_5$S) = (2-14) $\\times$ 10$^{12}$ cm$^{-2}$ (depending on the rotational temperature adopted), $N$(MgCCH) = 2 $\\times$ 10$^{12}$ cm$^{-2}$, $N$(NCCP) = 7 $\\times$ 10$^{11}$ cm$^{-2}$, and $N$(SiH$_3$CN) = 10$^{12}$ cm$^{-2}$. The S-bearing carbon chain C$_5$S is less abundant than C$_3$S, while MgCCH has an abundance in between that of MgNC and those of MgCN and HMgNC. On the other hand, NCCP and SiH$_3$CN are the least abundant P- and Si-bearing molecules observed to date in IRC+10216. Based on the behavior of similar molecules it is likely that these four species are formed in the outer circumstellar layers of IRC+10216. We discuss possible gas-phase formation routes.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2014-08-27T03:53:52.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "tentative identification",
      "confirmation",
      "gas-phase formation routes",
      "outer circumstellar layers",
      "rotational transitions"
    ],
    "tags": [
      "journal article"
    ],
    "publication": {
      "doi": "10.1051/0004-6361/201424542",
      "journal": "Astronomy and Astrophysics",
      "year": 2014,
      "month": "Oct",
      "volume": 570
    },
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "adsabs": "2014A&A...570A..45A"
    }
  }
}