Chemical abundances of globular clusters in NGC 5128 (Centaurus A)

Svea Hernandez*, Søren Larsen, Scott Trager, Lex Kaper, Paul Groot

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

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Abstract

We perform a detailed abundance analysis on integrated-light spectra of 20 globular clusters (GCs) in the early-type galaxy NGC 5128 (Centaurus A). The GCs were observed with X-Shooter on the Very Large Telescope (VLT). The cluster sample spans a metallicity range of -1.92 <[Fe/H] <-0.13 dex. Using theoretical isochrones, we compute synthetic integratedlight spectra and iterate the individual abundances until the best fit to the observations is obtained. We measured abundances of Mg, Ca, and Ti, and find a slightly higher enhancement in NGC 5128 GCs with metallicities [Fe/H] <-0.75 dex, of the order of similar to 0.1 dex, than in the average values observed in the Milky Way (MW) for GCs of the same metallicity. If this alpha-enhancement in the metal-poor GCs in NGC 5128 is genuine, it could hint at a chemical enrichment history different than that experienced by the MW. We also measure Na abundances in 9 out of 20 GCs. We find evidence for intracluster abundance variations in six of these clusters where we see enhanced [Na/Fe] > + 0.25 dex. We obtain the first abundance measurements of Cr, Mn, and Ni for a sample of the GC population in NGC 5128 and find consistency with the overall trends observed in theMW, with a slight enhancement (<0.1 dex) in the Fe-peak abundances measured in the NGC 5128.

Original languageEnglish
Pages (from-to)5189-5215
Number of pages27
JournalMonthly Notices of the Royal Astronomical Society
Volume476
Issue number4
DOIs
Publication statusPublished - 1-Jun-2018

Keywords

  • galaxies: abundances
  • galaxies: star clusters: general

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