Integrated spectra of Milky Way globular clusters

Abstract

Integrated spectra of Milky Way globular clusters (GCs) are reproduced by computing synthetic spectra taking into account individual element abundances. Five clusters were selected from their location in the Galactic bulge, for which integrated spectra were available in the WiFeS Atlas of Galactic Globular Cluster Spectra project. Our aim is to further study the oldest GCs located in the Galactic bulge, with a metallicity in the range −1.6 < [Fe/H] < −0.7. We also include the halo cluster NGC 6752 for comparison purposes. We reproduce the full spectra in the range 4500–9000 Å available in these observed spectra, as well as individual lines of Na, Mg, Al, Si, Ca, Ti, Ba, and Eu. We report a list of lines that are suitable for abundance derivation, and by adopting these abundances, we are able to fit the damping parameters that define the wings of strong lines of well-known triplets of Mg i and Ca ii. Finally, the effect of multiple stellar populations through enhanced Na abundances is tested.