Hydra Observations of Aluminum Abundances in the Red Giants of the Globular Clusters M80 and NGC 6752
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Aluminum and other metal abundances were determined in 21 red giants in the globular clusters NGC 6752 and M80 as part of a larger study to determine whether the aluminum distribution on the red giant branch is related to the second-parameter effect that causes clusters of similar metallicity to display different horizontal-branch morphologies. The observations were obtained of the Al I lines near 6700 with the Cerro Tololo Inter-American Observatory Blanco 4 m telescope and Hydra multiobject spectrograph. The spectra have a resolving power of 18,000 or 9400, with typical signal-to-noise ratios of 100-200. Mean [Fe/H] values obtained from the spectra are -1.58 for NGC 6752 and -1.73 for M80; this represents the first spectroscopic iron abundance determination for M80. Both NGC 6752 and M80 display a spread in aluminum abundance, with mean [Al/Fe] ratios of +0.51 and +0.37, respectively. No trend in the variation of the mean Al abundance with position on the giant branch is discernible in either cluster with our small sample.