{
  "id": "1712.04446",
  "version": "v1",
  "published": "2017-12-12T15:50:38.000Z",
  "updated": "2017-12-12T15:50:38.000Z",
  "title": "Nitrogen oxide in protostellar envelopes and shocks: the ASAI survey",
  "authors": [
    "C. Codella",
    "S. Viti",
    "B. Lefloch",
    "J. Holdship",
    "R. Bachiller",
    "E. Bianchi",
    "C. Ceccarelli",
    "C. Favre",
    "I. Jiménez-Serra",
    "L. Podio",
    "M. Tafalla"
  ],
  "comment": "MNRAS, in press",
  "categories": [
    "astro-ph.GA",
    "astro-ph.SR"
  ],
  "abstract": "The high-sensitivity of the IRAM 30-m ASAI unbiased spectral survey in the mm-window allows us to detect NO emission towards both the Class I object SVS13-A and the protostellar outflow shock L1157-B1. We detect the hyperfine components of the $^2\\Pi_{\\rm 1/2}$ $J$ = 3/2 $\\to$ 1/2 (at 151 GHz) and the $^2\\Pi_{\\rm 1/2}$ $J$ = 5/2 $\\to$ 3/2 (250 GHz) spectral pattern. The two objects show different NO profiles: (i) SVS13-A emits through narrow (1.5 km s$^{-1}$) lines at the systemic velocity, while (ii) L1157-B1 shows broad ($\\sim$ 5 km s$^{-1}$) blue-shifted emission. For SVS13-A the analysis leads to $T_{\\rm ex}$ $\\geq$ 4 K, $N(\\rm NO)$ $\\leq$ 3 $\\times$ 10$^{15}$ cm$^{-2}$, and indicates the association of NO with the protostellar envelope. In L1157-B1, NO is tracing the extended outflow cavity: $T_{\\rm ex}$ $\\simeq$ 4--5 K, and $N(\\rm NO)$ = 5.5$\\pm$1.5 $\\times$ 10$^{15}$ cm$^{-2}$. Using C$^{18}$O, $^{13}$C$^{18}$O, C$^{17}$O, and $^{13}$C$^{17}$O ASAI observations we derive an NO fractional abundance less than $\\sim$ 10$^{-7}$ for the SVS13-A envelope, in agreement with previous measurements towards extended PDRs and prestellar objects. Conversely, a definite $X(NO)$ enhancement is measured towards L1157-B1, $\\sim$ 6 $\\times$ 10$^{-6}$, showing that the NO production increases in shocks. The public code UCLCHEM was used to interpret the NO observations, confirming that the abundance observed in SVS13-A can be attained in an envelope with a gas density of 10$^5$ cm$^{-3}$ and a kinetic temperature of 40 K. The NO abundance in L1157-B1 is reproduced with pre-shock densities of 10$^5$ cm$^{-3}$ subjected to a $\\sim$ 45 km s$^{-1}$ shock.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2017-12-12T15:50:38.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "protostellar envelope",
      "asai survey",
      "nitrogen oxide",
      "protostellar outflow shock l1157-b1",
      "public code uclchem"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}