Surprising Metallicity of a Newly Discovered M79 Post-AGB Star

Abstract

A detailed chemical composition analysis based on a high-resolution (R=35,000) CCD spectrum is presented for a newly discovered post-AGB star in the globular cluster M79 for the first time. The elemental abundance results of M79 Post-AGB star are found to be [C/Fe]=-0.7, [O/Fe]=+1.4, [alpha- process/Fe]=0.5, and [s-process/Fe]=-0.1. The surprising result is that the iron abundance of the star is apparently about 0.6 dex less than that of the cluster's red giants as reported by published studies including a recent high-resolution spectroscopic analysis by Carretta and colleagues.

arXiv commentTo appear in Proceedings of the Bash Symposium 2009 "New Horizons in Astronomy", 18-20 Oct. 2009; eds. L. Stanford, L. Hao, Y. Mao, J. Green; ASP conference series