The first accurate parallax distance to a black hole

J. C.A. Miller-Jones, P. G. Jonker, V. Dhawan, W. Brisken, M. P. Rupen, G. Nelemans, E. Gallo

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Using astrometric VLBI observations, we have determined the parallax of the black hole X-ray binary V404 Cyg to be 0.418 ± 0.024mas, corresponding to a distance of 2.39 ± 0.14kpc, significantly lower than the previously accepted value. This model-independent estimate is the most accurate distance to a Galactic stellar-mass black hole measured to date. With this new distance, we confirm that the source was not super-Eddington during its 1989 outburst. The fitted distance and proper motion imply that the black hole in this system likely formed in a supernova, with the peculiar velocity being consistent with a recoil (Blaauw) kick. The size of the quiescent jets inferred to exist in this system is <1.4AU at 22GHz. Astrometric observations of a larger sample of such systems would provide useful insights into the formation and properties of accreting stellar-mass black holes.

Original languageEnglish (US)
Pages (from-to)L230-L234
JournalAstrophysical Journal
Issue number2 PART 2
StatePublished - 2009


  • Astrometry
  • Radio continuum: stars
  • Stars: distances
  • Stars: individual (V404 Cyg)
  • Stars: kinematics
  • X-rays: binaries


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