Detailed Chemical Abundances of Globular Clusters in Local Group Dwarf Galaxies

Abstract

We present detailed chemical abundances of Fe, Ca and Ba for 17 globular clusters (GCs) in 5 Local Group dwarf galaxies: NGC 205, NGC 6822, WLM, the SMC and LMC. These abundances are part of a larger sample of over 20 individual elements measured in GCs in these galaxies using a new analysis method for high resolution, integrated light spectra. Our analysis also provides age and stellar population constraints. The existence of GCs in dwarf galaxies with a range of ages implies that there were episodes of rapid star formation throughout the history of these galaxies; the abundance ratios of these clusters suggest that the duration of these burst varied considerably from galaxy to galaxy. We find evolution of Fe, Ca, and Ba with age in the LMC, SMC, and NGC 6822 that is consistent with extended, lower-efficiency SF between bursts, with an increasing contribution of low-metallicity AGB ejecta at late times. Our sample of GCs in NGC 205 and WLM are predominantly old and metal-poor with high [Ca/Fe] ratios, implying that the early history of these galaxies was marked by consistently high SF rates.

2 pages, To appear in the proceedings of the conference "A Universe of Dwarf Galaxies" (Lyon, June 14-18, 2010)

References in corpus (3)

• The chemical composition of red giant stars in four intermediate-age clusters of the Large Magellanic Cloud
• Globular Cluster Abundances from High-Resolution Integrated Light Spectra, I: 47 Tuc
• Ages, Metallicities, and [alpha/Fe] ratios of globular clusters in NGC 147, NGC 185, and NGC 205

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• Integrated Light Chemical Tagging Analyses of Seven M31 Outer Halo Globular Clusters from the Pan-Andromeda Archaeological Survey
• The chemical composition of globular clusters in the Local Group
• Spectrum Syntheses of High Resolution Integrated Light Spectra of Galactic Globular Clusters
• Three newly discovered globular clusters in NGC 6822
• Optimal Integrated Abundances for Chemical Tagging of Extragalactic Globular Clusters
• Ca II triplet spectroscopy of RGB stars in NGC 6822: kinematics and metallicities