Integrated Spectra of Milky Way Globular Cluster

TL;DR

This study models the integrated spectra of Milky Way globular clusters by synthesizing spectra with detailed element abundances, enabling improved understanding of their stellar populations and chemical compositions.

Contribution

It introduces a method to reproduce observed spectra of globular clusters considering individual element abundances and tests the impact of multiple stellar populations on spectral features.

Findings

Successfully reproduces spectra of selected clusters in 4500-9000 Å range

Identifies spectral lines suitable for abundance analysis

Demonstrates effects of Na enhancement on spectral features

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 GC located in the Galactic bulge, with 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 $\mathring{A}$ 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.