A Hipparcos Census of the Nearby OB Associations

  title={A Hipparcos Census of the Nearby OB Associations},
  author={P. Tim de Zeeuw and Ronnie Hoogerwerf and Jos de Bruijne and A. G. A. Brown and Adriaan Blaauw},
  journal={The Astronomical Journal},
  pages={354 - 399}
A comprehensive census of the stellar content of the OB associations within 1 kpc from the Sun is presented, based on Hipparcos positions, proper motions, and parallaxes. It is a key part of a long-term project to study the formation, structure, and evolution of nearby young stellar groups and related star-forming regions. OB associations are unbound "moving groups," which can be detected kinematically because of their small internal velocity dispersion. The nearby associations have a large… 

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