@misc{OskinovaFeldmeierKretschmar2012,
  author    = {Oskinova, Lida and Feldmeier, Achim and Kretschmar, Peter},
  title     = {Clumped stellar winds in supergiant high-mass X-ray binaries},
  series = {Postprint der universit{\"a}t Potsdam : Mathematisch Naturwissenschaftliche Reihe},
  journal   = {Postprint der universit{\"a}t Potsdam : Mathematisch Naturwissenschaftliche Reihe},
  number    = {573},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-41391},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-413916},
  pages     = {287 -- 288},
  year      = {2012},
  abstract  = {The clumping of massive star winds is an established paradigm, which is confirmed by multiple lines of evidence and is supported by stellar wind theory. We use the results from time-dependent hydrodynamical models of the instability in the line-driven wind of a massive supergiant star to derive the time-dependent accretion rate on to a compact object in the Bondi-Hoyle-Lyttleton approximation. The strong density and velocity fluctuations in the wind result in strong variability of the synthetic X-ray light curves. Photoionization of inhomogeneous winds is different from the photoinization of smooth winds. The degree of ionization is affected by the wind clumping. The wind clumping must also be taken into account when comparing the observed and model spectra of the photoionized stellar wind.},
  language  = {en}
}
@article{OskinovaFeldmeierKretschmar2012,
  author    = {Oskinova, Lida and Feldmeier, Achim and Kretschmar, Peter},
  title     = {Clumped stellar winds in supergiant high-mass X-ray binaries: X-ray variability and photoionization},
  series = {Monthly notices of the Royal Astronomical Society},
  volume    = {421},
  journal   = {Monthly notices of the Royal Astronomical Society},
  number    = {4},
  publisher = {Wiley-Blackwell},
  address   = {Malden},
  issn      = {0035-8711},
  doi       = {10.1111/j.1365-2966.2012.20507.x},
  pages     = {2820 -- 2831},
  year      = {2012},
  abstract  = {The clumping of massive star winds is an established paradigm, which is confirmed by multiple lines of evidence and is supported by stellar wind theory. The purpose of this paper is to bridge the gap between detailed models of inhomogeneous stellar winds in single stars and the phenomenological description of donor winds in supergiant high-mass X-ray binaries (HMXBs). We use the results from time-dependent hydrodynamical models of the instability in the line-driven wind of a massive supergiant star to derive the time-dependent accretion rate on to a compact object in the BondiHoyleLyttleton approximation. The strong density and velocity fluctuations in the wind result in strong variability of the synthetic X-ray light curves. The model predicts a large-scale X-ray variability, up to eight orders of magnitude, on relatively short time-scales. The apparent lack of evidence for such strong variability in the observed HMXBs indicates that the details of the accretion process act to reduce the variability resulting from the stellar wind velocity and density jumps.},
  language  = {en}
}