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A high-resolution VLT/FLAMES study of individual stars in the centre of the Fornax dwarf spheroidal galaxy

Letarte, B. and Hill, V. and Tolstoy, E. and Jablonka, P. and Shetrone, M. and Venn, K. A. and Spite, M. and Irwin, M. J. and Battaglia, G. and Helmi, A. and Primas, F. and François, P. and Kaufer, A. and Szeifert, T. and Arimoto, N. and Sadakane, K. (2010) A high-resolution VLT/FLAMES study of individual stars in the centre of the Fornax dwarf spheroidal galaxy. Astronomy and Astrophysics (523). Art. No. A17. ISSN 0004-6361.

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For the first time we show the detailed, late-stage, chemical evolution history of a small nearby dwarf spheroidal galaxy in the Local Group. We present the results of a high-resolution (R ~ 20 000, λ = 5340–5620; 6120–6701) FLAMES/GIRAFFE abundance study at ESO/VLT of 81 photometrically selected, red giant branch stars in the central 25 of the Fornax dwarf spheroidal galaxy. We also carried out a detailed comparison of the effects of recent developments in abundance analysis (e.g., spherical models vs. plane-parallel) and the automation that is required to efficiently deal with such large data sets. We present abundances of α-elements (Mg, Si, Ca, and Ti), iron-peak elements (Fe, Ni, and Cr), and heavy elements (Y, Ba, La, Nd, and Eu). Our sample was randomly selected and is clearly dominated by the younger and more metal-rich component of Fornax, which represents the major fraction of stars in the central region. This means that the majority of our stars are 1−4 Gyr old, and thus represent the end phase of chemical evolution in this system. Our sample of stars has unusually low [α/Fe], [Ni/Fe], and [Na/Fe] compared to the Milky Way stellar populations at the same [Fe/H]. The particularly important role of stellar winds from low-metallicity AGB stars in the creation of s-process elements is clearly seen from the high [Ba/Y]. Furthermore, we present evidence of an s-process origin of Eu.

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Letarte, B.0000-0001-5462-4140
Additional Information:© 2010 ESO. Received 6 October 2009, Accepted 6 July 2010, Published online 11 November 2010. Based on FLAMES observations collected at the European Southern Observatory, proposal number 171.B-0588. Tables A1–A5 are only available in electronic form at This work was made possible by a grant from NWO (614.031.018). B.L. and E.T. thank Paris Observatory for hospitality and the Programme National Galaxies financial support. We thank Marco Gullieuszik and Enrico Held for sending us in advance of publication their IR photometry for stars in our sample. M.S. thanks the National Science Foundation for support under AST-0306884. E.T. gratefully acknowledges support from an NWO-VICI grant.
Funding AgencyGrant Number
Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO)614.031.018
Programme National Galaxies et Cosmologie (PNCG)UNSPECIFIED
Subject Keywords:stars: abundances – galaxies: dwarf – galaxies: evolution – galaxies: formation – galaxies: stellar content – galaxies: individual: Fornax dwarf galaxy
Issue or Number:523
Record Number:CaltechAUTHORS:20110118-155825612
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Official Citation:A high-resolution VLT/FLAMES study of individual stars in the centre of the Fornax dwarf spheroidal galaxy B. Letarte, V. Hill, E. Tolstoy, P. Jablonka, M. Shetrone, K. A. Venn, M. Spite, M. J. Irwin, G. Battaglia, A. Helmi, F. Primas, P. François, A. Kaufer, T. Szeifert, N. Arimoto and K. Sadakane A&A 523 A17 (2010) DOI: 10.1051/0004-6361/200913413
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:21800
Deposited By: Benjamin Perez
Deposited On:19 Jan 2011 16:14
Last Modified:03 Oct 2019 02:29

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