s- and r-process element abundances in the CMD of 47 Tucanae using the Robert Stobie Spectrograph on SALT

TL;DR

This study investigates s- and r-process element abundances in 47 Tucanae using SALT spectroscopy, finding no significant abundance variations at the spectral resolution used, and assessing the observational capabilities for future detailed analysis.

Contribution

It demonstrates the spectral resolution needed to detect abundance variations and provides initial abundance limits for key elements in 47 Tucanae.

Findings

Resolving power of 10,000 is sufficient to observe abundance variations.

Spectral resolution of R ~ 5000 is inadequate for precise abundances.

No significant abundance variations found within measurement limits.

Abstract

A recent study by Wylie et al 2006 has revealed that s-process element abundances are enhanced relative to iron in both red giant branch and asymptotic giant branch stars of 47 Tucanae. A more detailed investigation into s-process element abundances throughout the colour-magnitude diagram of 47 Tucanae is vital in order to determine whether the observed enhancements are intrinsic to the cluster. This paper explores this possibility through observational and theoretical means. The visibility of s- and r-process element lines in synthetic spectra of giant and dwarf stars throughout the colour magnitude diagram of 47 Tucanae has been explored. It was determined that a resolving power of 10 000 was sufficient to observe s-process element abundance variations in globular cluster giant branch stars. These synthetic results were compared with the spectra of eleven 47 Tucanae giant branch stars observed during the performance verification of the Robert Stobie Spectrograph on the Southern African Large Telescope. Three s-process elements, Zr, Ba, Nd, and one r-process element, Eu, were investigated. No abundance variations were found such that [X/Fe] = 0.0 +/- 0.5 dex. It was concluded that this resolving power, R ~ 5000, was not sufficient to obtain exact abundances but upper limits on the s-process element abundances could be determined.