Journal Article

Age and metallicity of compact stellar systems in Virgo and Fornax

P. Firth, E. A. Evstigneeva and M. J. Drinkwater

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 394, issue 4, pages 1801-1811
Published in print April 2009 | ISSN: 0035-8711
Published online April 2009 | e-ISSN: 1365-2966 | DOI: https://dx.doi.org/10.1111/j.1365-2966.2009.14479.x
Age and metallicity of compact stellar systems in Virgo and Fornax

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From high signal-to-noise ratio GMOS-N and AAOmega spectra, we have measured line-strength indices in the Lick/IDS system for several luminous and spatially dispersed compact stellar systems (CSSs) located in the Virgo and Fornax galaxy clusters. We estimate their [α/Fe] ratios, ages and metallicities using a simple (single-burst) stellar population model. We confirm that the Virgo core region luminous CSSs () contain ancient stellar populations with subsolar total metallicities, suggesting that they comprise the bright tail of M87's GC distribution. The two Virgo intracluster globular clusters have ages and metallicities consistent with the cluster core CSSs. Two Fornax luminous CSSs also have ancient stellar populations but are at the upper end of the Virgo CSS metallicity range, while the third (UCD3) appears to be relatively young, metal-rich and with a core + halo radial profile. Our results suggest that Fornax may contain an extra population of luminous CSSs formed more recently than the ancient GC-like systems found in both clusters.

Keywords: galaxies: clusters: individual: Virgo cluster; galaxies: clusters: individual: Fornax cluster; galaxies: dwarf; galaxies: individual: M87; galaxies: star clusters; galaxies: stellar content

Journal Article.  7054 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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