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Title: Ceci N'est Pas a globular cluster: the metallicity distribution of the stellar system Terzan 5

We present new determinations of the iron abundance for 220 stars belonging to the stellar system Terzan 5 in the Galactic bulge. The spectra have been acquired with FLAMES at the Very Large Telescope of the European Southern Observatory and DEIMOS at the Keck II Telescope. This is by far the largest spectroscopic sample of stars ever observed in this stellar system. From this data set, a subsample of targets with spectra unaffected by TiO bands was extracted and statistically decontaminated from field stars. Once combined with 34 additional stars previously published by our group, a total sample of 135 member stars covering the entire radial extent of the system has been used to determine the metallicity distribution function of Terzan 5. The iron distribution clearly shows three peaks: a super-solar component at [Fe/H] ≅ 0.25 dex, accounting for ∼29% of the sample, a dominant sub-solar population at [Fe/H] ≅ –0.30 dex, corresponding to ∼62% of the total, and a minor (6%) metal-poor component at [Fe/H] ≅ –0.8 dex. Such a broad, multi-modal metallicity distribution demonstrates that Terzan 5 is not a genuine globular cluster but the remnant of a much more complex stellar system.
Authors:
; ; ; ; ;  [1] ; ;  [2] ; ;  [3] ;  [4] ;  [5]
  1. Dipartimento di Fisica e Astronomia, Università degli Studi di Bologna, v.le Berti Pichat 6/2, I-40127 Bologna (Italy)
  2. INAF-Osservatorio Astronomico di Bologna, via Ranzani 1, I-40127 Bologna (Italy)
  3. Department of Physics and Astronomy, Math-Sciences 8979, UCLA, Los Angeles, CA 90095-1562 (United States)
  4. European Southern Observatory, Karl-Schwarzschild-Strasse 2, D-85748 Garching bei München (Germany)
  5. Observatoire Astronomique, Université de Strasbourg, CNRS, 11, rue de l'Université. F-67000 Strasbourg (France)
Publication Date:
OSTI Identifier:
22370332
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 795; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCOUNTING; COVERINGS; DISTRIBUTION; DISTRIBUTION FUNCTIONS; ELEMENT ABUNDANCE; IRON; METALLICITY; SPECTRA; STARS; TELESCOPES; TITANIUM OXIDES