Blue Horizontal--Branch Stars: The "Jump" in Stromgren u, Low Gravities, and Radiative Levitation of Metals

F. Grundahl, M. Catelan, W. B. Landsman +3

We study the ``jump'' in the blue horizontal--branch (BHB) distribution first detected by Grundahl et al. (1998) in the Galactic globular cluster (GC) M13. On the basis of Stromgre…