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Published online by Cambridge University Press: 08 August 2017
We have developed a method for determining elemental Fe-group abundances in planetary nebulae using an infrared emission line of Zn, the least refractory Fe-group species. Many planetary nebulae, particularly those of the Milky Way’s thick disk and bulge, display subsolar [Fe/H] (as inferred from Zn) although their abundances of α elements such as O, S, and Ar are nearly solar. We discuss the implications for determining enhancements of species synthesized by the progenitor star during the AGB (e.g., s-process products), and for galactic chemical evolution in view of the metallicity dependence of AGB nucleosynthetic yields.