{
  "id": "1105.4757",
  "version": "v1",
  "published": "2011-05-24T13:10:12.000Z",
  "updated": "2011-05-24T13:10:12.000Z",
  "title": "Spectral Classification of O2-3.5If*/WN5-7 stars",
  "authors": [
    "Paul Crowther",
    "Nolan Walborn"
  ],
  "comment": "16 pages, 8 figures, accepted for MNRAS",
  "categories": [
    "astro-ph.SR"
  ],
  "abstract": "An updated classification scheme for transition O2-3.5If*/WN5-7 stars is presented, following recent revisions to the spectral classifications for O and WN stars. We propose that O2-3.5If*, O2-3.5If*/WN5-7 and WN5-7 stars may be discriminated using the morphology of Hbeta to trace increasing wind density as follows: purely in absorption for O2-3.5If* stars in addition to the usual diagnostics from Walborn et al.; P Cygni for O2-3.5If*/WN5-7 stars; purely in emission for WN stars in addition to the usual diagnostics from Smith et al. We also discuss approximate criteria to discriminate between these subtypes from near-IR spectroscopy. The physical and wind properties of such stars are qualitatively discussed together with their evolutionary significance. We suggest that the majority of O2-3.5If*/WN5-7 stars are young, very massive hydrogen-burning stars, genuinely intermediate between O2-3.5If* and WN5-7 subtypes, although a minority are apparently core helium-burning stars evolving blueward towards the classical WN sequence. Finally, we reassess classifications for stars exhibiting lower ionization spectral features plus Hbeta emission.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2011-05-24T13:10:12.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "spectral classification",
      "exhibiting lower ionization spectral",
      "ionization spectral features plus hbeta",
      "spectral features plus hbeta emission",
      "lower ionization spectral features plus"
    ],
    "tags": [
      "journal article"
    ],
    "publication": {
      "doi": "10.1111/j.1365-2966.2011.19129.x",
      "journal": "Monthly Notices of the Royal Astronomical Society",
      "year": 2011,
      "month": "Sep",
      "volume": 416,
      "number": 2,
      "pages": 1311
    },
    "note": {
      "typesetting": "TeX",
      "pages": 16,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "inspire": 901130,
      "adsabs": "2011MNRAS.416.1311C"
    }
  }
}