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The globular cluster system of the Sagittarius dwarf spheroidal galaxy: the age of Terzan 8 |
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| Authors: | Montegriffo Bellazzini Ferraro Martins Sarajedini & Fusi Pecci |
| Institution: | Osservatorio Astronomico di Bologna, Via Zamboni 33, 40125 Bologna, Italy,;University of Alaska, Department of Physics and Astronomy, Anchorage, Alaska, USA,;National Optical Astronomy Observatories, Kitt Peak National Observatory, Tucson, Arizona, USA,;San Francisco State University, Department of Physics and Astronomy, 1600 Holloway Avenue, San Francisco, California 94132, USA,;Stazione Astronomica di Cagliari, Cagliari, Italy |
| Abstract: | We present deep V - and I -band CCD photometry of the globular cluster Terzan 8, recently found to be a member of the globular cluster system of the Sagittarius dwarf spheroidal galaxy. We accurately estimate the metallicity of Terzan 8, and provide the first direct determination of the colour excess toward this cluster. Our robust age estimate confirms that this cluster is indeed coeval with typical Galactic globulars of comparable metal content, and thus it is probably significantly older than at least two other Sagittarius clusters, Terzan 7 and Arp 2. The implications of this result on the star formation history of the Sagittarius galaxy are briefly discussed. |
| Keywords: | globular clusters: individual: Terzan 8 Galaxy: halo galaxies: individual: Sagittarius dwarf spheroidal Local Group galaxies: star clusters |