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M.D. Shetrone (McDonald Observatory)
NGC 288 and NGC 362 have been the center of controversy for many years. Some investigators have claimed significant age differences between the two clusters while others claim no age difference. Spectroscopic results have also proven disparate. Metallicity claims have varied from [Fe/H] = -1.0 to [Fe/H] = -1.4. Dickens et al. (1991, Nature 351, 212) claim to find oxygen depleted stars in NGC 362 but not in NGC 288. In addition, they find both clusters are [Fe/H] = -1.0. However, analysis of a new larger sample of stars from both NGC 288 and NGC 362 reveals a metallicity of [Fe/H] = -1.3 (on the Lick-Texas scale), and evidence for deep mixing, oxygen depletion, and sodium and aluminum enhancements, in both clusters. An overview of the implications for the second parameter debate is presented.
The author(s) of this abstract have provided an email address for comments about the abstract: shetrone@astro.as.utexas.edu