{
  "id": "1708.05380",
  "version": "v1",
  "published": "2017-08-17T17:54:59.000Z",
  "updated": "2017-08-17T17:54:59.000Z",
  "title": "Catching a star before explosion: the luminous blue variable progenitor of SN 2015bh",
  "authors": [
    "Ioana Boian",
    "Jose Groh"
  ],
  "comment": "12 Pages, 9 figures, submitted to A&A. Comments welcome",
  "categories": [
    "astro-ph.SR",
    "astro-ph.GA",
    "astro-ph.HE"
  ],
  "abstract": "In this paper we analyse the pre-explosion spectrum of SN2015bh by performing radiative transfer simulations using the CMFGEN code. This object has attracted significant attention due to its remarkable similarity to SN2009ip in both its pre- and post-explosion behavior. They seem to belong to a class of events for which the fate as a genuine core-collapse supernova or a non-terminal explosion is still under debate. Our CMFGEN models suggest that the progenitor of SN2015bh had an effective temperature between 8700 and 10000 K, luminosity ~2.7e6 Lsun, contained at least 25% H in mass at the surface, and half-solar Fe abundances. The results also show that the progenitor of SN2015bh generated an extended wind with a mass-loss rate of ~ 6e-4 to 1.5e-3 Msun/yr and a velocity of 1000 km/s. We determined that the wind extended to at least 7e14 cm and lasted for at least 81 days prior to the observations, releasing 2.2e-4 Msun into the circumstellar medium. In analogy to 2009ip, we propose that this is the material that the explosive ejecta will interact at late epochs. We conclude that the progenitor of SN2015bh was most likely a warm luminous blue variable of at least 60 Msun before the explosion. Considering the high wind velocity, we cannot exclude the possibility that the progenitor was a Wolf-Rayet star that inflated just before the 2013 eruption, similar to HD5980 during its 1994 episode. If the star survived, late-time spectroscopy may reveal either a similar LBV or a Wolf-Rayet star, depending on the mass of the H envelope before the explosion. If the star exploded as a genuine SN, 2015bh would be a remarkable case of a successful explosion after black-hole formation in a star with 60 Msun at the pre-SN stage.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2017-08-17T17:54:59.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "luminous blue variable progenitor",
      "sn 2015bh",
      "wolf-rayet star",
      "high wind velocity",
      "genuine core-collapse supernova"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 12,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}