Spectroscopy of the lambda 7699 K I line among globular cluster giants

Echelle spectra have been obtained of giants in the globular clusters NGC 6752, M4, and 47 Tucanae to determine whether the Na I and Al I line enhancements found among the CN-rich stars are accompanied by enhancements of the 7699-A K I line. Correlated behavior would be expected if the sodium and aluminum lines are strengthened as a result of upper atmospheric cooling in the CN-rich giants. The K I line is found, however, to be of equal strength in the spectra of the CN-rich and CN-poor stars. This result strengthens the hypothesis that Na and Al line variations are due to real abundance differences among the cluster stars.