{
  "id": "1107.0441",
  "version": "v2",
  "published": "2011-07-03T09:32:24.000Z",
  "updated": "2017-07-29T11:11:27.000Z",
  "title": "The OH Masers Towards IRAS 19092+0841",
  "authors": [
    "K. A. Edris",
    "G. A. Fuller",
    "S. Etoka",
    "R. J. Cohen"
  ],
  "comment": "6 pages, 2 figures and 3 tables",
  "categories": [
    "astro-ph.GA"
  ],
  "abstract": "Context. Maser emission is a strong tool for studying high mass star forming regions and their evolutionary stages. OH masers in particular can trace the circumstellar material around protostars and determine their magnetic field strengths at milliarcsecond resolution. Aims. Imaging OH maser mission towards high mass protostellar objects to determine their evolutionary stages and to locate the detected maser emission in the process of high mass star formation. Methods. In 2007, we surveyed OH maser towards 217 high mass protostellar objects to study its presence. In this paper, we present a follow up MERLIN observations of a ground state OH maser emission towards one of these objects, IRAS 19092+0841. Results. Emission from the two OH main spectral lines, 1665 and 1667 MHz, were detected close to the central object. The positions and velocities of the OH maser features have been determined. The masers are distributed over a region of ~ 500 corresponding to 22400 AU (or ~ 0.1 pc) at a distance of 4.48 kpc. The polarization properties of the OH maser features were determined as well. We identify three Zeeman pairs from which we inferred a magnetic field strength of ~ 4:4mG pointing towards the observer. Conclusions. The relatively small velocity spread and the relatively wide spacial distribution of the OH maser features support the suggestion that this object could be in an early evolutionary state before the presence of disk and/or jet/outfows.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2011-07-03T09:32:24.000Z",
      "abstract": "We present high angular resolution spectral line observations of ground state OH maser emission towards the young high mass proto-stellar object IRAS 19092+0841. The two OH main spectral lines, 1665 and 1667 MHz were observed using MERLIN. The two OH lines have been detected close to the central object. The interferometric data have been reduced and a map for both observed frequencies have been produced. The positions and velocities of the OH maser components have been determined. The polarization properties of the OH maser components were determined as well. The main components OH maser components are spread over a region of ~ 5\" corresponding to 22400 AU (or ~ 0.1 pc) at a distance 4.48 kpc. The spread of the relatively small velocity range of the OH masers over a relatively wide distribution and their association of the 44 GHz class I methanol masers indicate that the OH masers emission is probably associated with the external shell of a collapsing core. With the absence of any sign of a disk, outflow or an UCHII region, this would be the first OH masers associated with a star forming region in such an early evolutionary stage. High angular resolution observations of other tracers are needed to reveal the nature of this source. The association between OH masers and the two classes of methanol masers could be a crude evolutionary indicator, such that an association OH masers-class I methanol masers would indicate an earlier evolutionary state than the association OH masers-class II methanol masers. Surveys of class I and class II methanol masers towards OH masers sources are needed to confirm this suggestion.",
      "comment": "7 pages, 3 figures and 3 tables",
      "journal": null,
      "doi": null
    },
    {
      "version": "v2",
      "updated": "2017-07-29T11:11:27.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "methanol masers",
      "components oh maser components",
      "angular resolution spectral line",
      "mass proto-stellar object iras",
      "high mass proto-stellar object"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 6,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "inspire": 916884,
      "adsabs": "2011arXiv1107.0441E"
    }
  }
}