THE ASTRONOMICAL JOURNAL    VOLUME 107, NUMBER 3, PAGE 1556          APRIL 1994

     THE LATE B-TYPE STARS: REFINED MK CLASSIFICATION, CONFRONTATION WITH
               STROMGREN PHOTOMETRY, AND THE EFFECTS OF ROTATION

                                R. F. GARRISON

   David Dunlap Observatory, University of Toronto, Box 360, Richmond Hill,
                            Ontario, Canada L4C 4Y6
              Electronic mail: garrison@centaur.astro.utoronto.ca

                                  R. O. GRAY

   David Dunlap Observatory, University of Toronto, Box 360, Richmond Hill,
       Ontario, Canada L4C 4Y6, and Department of Physics and Astronomy,
           Appalachian State University, Boone, North Carolina 28608
                  Electronic mail: grayro@conrad.appstate.edu

                                   ABSTRACT

    In the fourth and final of a series of papers on the late B to the
    early F type stars, we refine the MK spectral classification system for
    the late B type stars and consider the effect of rotation on both
    spectral classification and Stromgren photometry of these stars.  We
    extend the work of Morgan by establishing self-consistent sequences of
    narrow and broadlined standards.  We reclassify a number of Bp stars,
    compare these classifications with Stromgren photometry and consider
    the question of whether all Bp stars are main-sequence objects.