Chemical abundances in the globular clusters NGC 288, NGC 362, NGC 6397 and M 55.

Blue spectra at a resolution of 0.5 Å of red giants in the globular clusters NGC 288, 362, 6397 and 6809(M55) have been obtained with the Anglo-Australian Telescope. Abundances of C, N, Fe and other heavy elements have been determined by fitting synthetic spectra, calculated from model atmospheres, to the observational data. NGC 288 and 362 have very similar C+N+O and heavy-element abundances, indicating that another parameter is needed to account for their different horizontal-branch morphologies.