We present chemical abundances for O , Na , Mg , Al , Si , Ca , Ti and Fe in eight red giants and one turnoff star in the metal rich globular cluster 47 Tuc , based on spectroscopy with the MIKE high resolution spectrograph on the Magellan 6.5-m Clay telescope .
A robust line by line differential abundance analysis technique , relative to the K-giant Arcturus , was used to reduce systematic errors from atmospheric and atomic parameters .
Our derived mean LTE [ Fe/H ] of -0.76 \pm 0.01 \pm 0.04 dex ( random and systematic error respectively ) is more metal poor by about 0.1 dex than recent literature results .
The chemical element ratios in this nearby globular cluster most closely resemble those of the Galactic bulge , although there is a non-negligible overlap with the composition of thick-disk stars .
We find that the [ Al/Fe ] and [ Na/Fe ] ratios coincide with the upper boundary of the trends seen in the bulge and thick disk .
There is only a small intrinsic scatter in the majority of the abundance ratios , indicating that 47 Tuc is mostly a rather chemically homogeneous system .