{
  "id": "2002.05168",
  "version": "v1",
  "published": "2020-02-12T19:00:01.000Z",
  "updated": "2020-02-12T19:00:01.000Z",
  "title": "Mass loss and the Eddington parameter: a new mass-loss recipe for hot and massive stars",
  "authors": [
    "Joachim M. Bestenlehner"
  ],
  "comment": "Accepted for publication in MNRAS, 9 pages, 5 figures",
  "categories": [
    "astro-ph.SR"
  ],
  "abstract": "Mass loss through stellar winds plays a dominant role in the evolution of massive stars. In particular the mass-loss rates of very massive stars (VMSs, $> 100\\,M_{\\odot}$) are highly uncertain. Such stars display Wolf-Rayet spectral morphologies (WNh) whilst on the main-sequence. Metal-poor VMSs are progenitors of gamma-ray bursts and pair instability supernovae. In this study we extended the widely used stellar wind theory by Castor, Abbott & Klein from the optically thin (O star) to the optically thick main-sequence (WNh) wind regime. In particular we modify the mass-loss rate formula in a way that we are able to explain the empirical mass-loss dependence on the Eddington parameter ($\\Gamma_{\\rm e}$). The new mass-loss recipe is suitable for incorporation into current stellar evolution models for massive and very massive stars. It makes verifiable predictions, namely how the mass-loss rate scales with metallicity and at which Eddington parameter the transition from optically thin O star to optically thick WNh star winds occurs. In the case of the star cluster R136 in the Large Magellanic Cloud we find in the optically thin wind regime $\\dot{M} \\propto \\Gamma_{\\rm e}^{3}$ while in the optically thick wind regime $\\dot{M} \\propto 1/ (1 - \\Gamma_{\\rm e})^{3.5}$. The transition from optically thin to optically thick winds occurs at $\\Gamma_{\\rm e, trans} \\approx 0.47$. The transition mass-loss rate is $\\log \\dot{M}~(M_{\\odot} \\mathrm{yr}^{-1}) \\approx -4.76 \\pm 0.18$, which is in line with the prediction by Vink & Gr\\\"afener assuming a volume filling factor of $f_{\\rm V} = 0.23_{-0.15}^{+0.40}$.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2020-02-12T19:00:01.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "massive stars",
      "eddington parameter",
      "mass-loss recipe",
      "mass loss",
      "mass-loss rate"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 9,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}