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arXiv · 1002.2144

SAO-6m Telescope Spectroscopic Observations of Globular Clusters in Nearby Galaxies

Margarita E. Sharina·Rupali Chandar·Thomas H. Puzia·Paul Goudfrooij·Emmanuel Davoust
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Abstract

We present the results of medium-resolution spectroscopy of 28 globular clusters (GCs) in six nearby galaxies of different luminosities and morphological types, situated in: M33 (15 objects), M31 (3), IC10 (4), UGCA86 (4), HolmbergIX (1), and DDO71 (1) obtained at the Special Astrophysical Observatory 6-meter telescope. Measurements of Lick absorption-line indices and comparison with SSP models enabled us to obtain their spectroscopic ages, metallicities and alpha-element to Fe abundance ratios. We found that all old and intermediate-age GCs in our sample have low metallicities [Z/H] < -0.8 dex. Metal-rich clusters are young and are preferentially found in galaxies more massive than ~10^9 M_sun. The least massive dwarfs of our sample, DDO71 and HolmbergIX, host one massive intermediate-age and one massive young metal-poor GC, respectively. [a/Fe] abundance ratios tend to be enhanced but closer to solar values for dwarf galaxies compared to GCs in more massive galaxies. We analyse the age-metallicity relation for GCs in our galaxy sample and others from the literature, and find, that 1) there is a general trend for GCs in low surface brightness dwarf galaxies to be more metal-poor at a given age than GCs in more massive galaxies; 2) the GC metallicity spread is wider for more massive galaxies; 3) intermediate-age GCs in early-type dwarf galaxies are more metal-rich at any given age than those in irregular galaxies of similar luminosity.

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Margarita E. Sharina, Rupali Chandar, Thomas H. Puzia, Paul Goudfrooij, Emmanuel Davoust. 2010-02-10. SAO-6m Telescope Spectroscopic Observations of Globular Clusters in Nearby Galaxies. https://doi.org/10.1111/j.1365-2966.2010.16510.x

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