A New Spectral Classification System for the Earliest O Stars: Definition of Type O2

  title={A New Spectral Classification System for the Earliest O Stars: Definition of Type O2},
  author={Nolan R. Walborn and Ian D. Howarth and Daniel J. Lennon and Philip Massey and M. S. Oey and Anthony F. J. Moffat and Gwenael Skalkowski and Nidia I. Morrell and Laurent Drissen and Joel Wm. Parker},
  journal={The Astronomical Journal},
High-quality, blue-violet spectroscopic data are collected for 24 stars that have been classified as type O3 and that display the hallmark N IV and N V lines. A new member of the class is presented; it is the second known in the Cyg OB2 association, and only the second in the northern hemisphere. New digital data are also presented for several of the other stars. Although the data are inhomogeneous, the uniform plots by subcategory reveal some interesting new relationships. Several issues… 

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