The Chemical Composition of Blue Horizontal Branch Stars in M4 and NGC 6397

High-resolution (lambda/Delta lambda is approximately equal to 18,000) spectra of two horizontal branch stars in M4 and one in NGC 6397 provide a metallicity in good agreement with the values obtained previously by others from analyses of cluster red giants. For one HB star in M4, the C, N, O abundances derived from near-infrared C I, N I, O I lines are consistent with those obtained for red giants by Brown et al. (1990). The result suggests that the He-core flash cannot always result in products of He-burning being mixed into the envelope.