On the Hipparcos parallaxes of O stars

  title={On the Hipparcos parallaxes of O stars},
  author={Stefan Schroeder and Lex Kaper and Henny J.G.L.M. Lamers and A. G. A. Brown and Astronomical InstituteAnton Pannekoek'' and University of Amsterdam and Astronomical Institute and Utrecht University and Leiden Observatory},
  journal={Astronomy and Astrophysics},
We compare the absolute visual magnitude of the majority of bright O stars in the sky as predicted from their spectral type with the absolute magnitude calculated from their apparent magnitude and the Hipparcos parallax. We find that many stars appear to be much fainter than expected, up to five magnitudes. We find no evidence for a correlation between magnitude differences and the stellar rotational velocity as suggested for OB stars by Lamers et al. (1997, AA Howarth & Prinja 1989, ApJS, 69… 

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