Hydra Observations of Aluminum Abundances in the Red Giants of the Globular Clusters M80 and NGC 6752 Academic Article uri icon


  • 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.

published proceedings

  • The Astronomical Journal

author list (cited authors)

  • Cavallo, R. M., Suntzeff, N. B., & Pilachowski, C. A.

citation count

  • 27

complete list of authors

  • Cavallo, Robert M||Suntzeff, Nicholas B||Pilachowski, Catherine A

publication date

  • June 2004