{
  "id": "1204.2027",
  "version": "v1",
  "published": "2012-04-10T02:12:18.000Z",
  "updated": "2012-04-10T02:12:18.000Z",
  "title": "The young stellar cluster [DBS2003] 157 associated with the H II region GAL 331.31-00.34",
  "authors": [
    "Marcio C. Pinheiro",
    "Zulema Abraham",
    "Marcus V. F. Copetti",
    "Roberto Ortiz",
    "Diego A. Falceta-Gonçalves",
    "Alexandre Roman-Lopes"
  ],
  "comment": "The paper contains 11 figures and 5 tables. Accepted for publication in MNRAS",
  "categories": [
    "astro-ph.GA"
  ],
  "abstract": "We report a study of the stellar content of the Near-infrared cluster [DBS2003]\\,157 embedded in the extended H\\,{\\sc ii} region GAL\\,331.31-00.34, which is associated with the IRAS source 16085-5138. $JHK$ photometry was carried out in order to identify potential ionizing candidates, and the follow-up NIR spectroscopy allowed the spectral classification of some sources, including two O-type stars. A combination of NIR photometry and spectroscopy data was used to obtain the distance of these two stars, with the method of spectroscopic parallax: IRS\\,298 (O6\\,{\\sc V}, $3.35 \\pm 0.61$\\,kpc) and IRS\\,339 (O9\\,{\\sc V}, $3.24 \\pm 0.56$\\,kpc). Adopting the average distance of $3.29 \\pm 0.58$\\,kpc and comparing the Lyman continuum luminosity of these stars with that required to account for the radio continuum flux of the H\\,{\\sc ii} region, we conclude that these two stars are the ionizing sources of GAL\\,331.31-00.34. Young stellar objects (YSOs) were searched by using our NIR photometry and MIR data from the GLIMPSE survey. The analysis of NIR and MIR colour-colour diagrams resulted in 47 YSO candidates. The GLIMPSE counterpart of IRAS\\,16085-5138, which presents IRAS colour indices compatible with an ultra-compact H\\,{\\sc ii} region, has been identified. The analysis of its spectral energy distribution between 2 and $100\\,\\mu$m revealed that this source shows a spectral index $\\alpha = 3.6$ between 2 and $25\\,\\mu$m, which is typical of a YSO immersed in a protostellar envelope. Lower limits to the bolometric luminosity and the mass of the embedded protostar have been estimated as $L=7.7\\times10^3L_{\\sun}$ and $M = 10\\,M_{\\sun}$, respectively, which corresponds to a B0--B1\\,{\\sc V} ZAMS star.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2012-04-10T02:12:18.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "young stellar cluster",
      "region gal",
      "nir photometry",
      "lyman continuum luminosity",
      "follow-up nir spectroscopy"
    ],
    "tags": [
      "journal article"
    ],
    "publication": {
      "doi": "10.1111/j.1365-2966.2012.21049.x",
      "journal": "Monthly Notices of the Royal Astronomical Society",
      "year": 2012,
      "month": "Jul",
      "volume": 423,
      "number": 3,
      "pages": 2425
    },
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "inspire": 1107865,
      "adsabs": "2012MNRAS.423.2425P"
    }
  }
}