Fundamental parameters of red giants in 47 Tucanae

Abstract

In these proceedings we present initial results of a spectroscopic analysis of a small sample of evolved K-giants in the globular cluster 47 Tucanae. We derive the effective temperature, surface gravity and microturbulence of all targets using standard methods. Further we derive LTE abundances of [Fe/H] and [O/Fe] as well as the abundance of sodium, using NLTE corrections. We find a mean metallicity for the cluster of [Fe/H]$=-0.75\pm0.10$, in excellent agreement with several other studies. Also, we confirm the sodium-oxygen anticorrelation previously reported by a number of other authors. Finally, we see indications of the sodium enriched stars also being enriched in heavy magnesium isotopes.

4 pages, 4 figures, proceedings of "Reading the book of globular clusters with the lens of stellar evolution", Rome, Nov. 26-28, 2012, in Memorie della Societa' Astronomica Italiana Supplementi