This article has an erratum: [https://doi.org/10.1051/0004-6361/200913413e]
Volume 523, November-December 2010
|Number of page(s)||40|
|Section||Galactic structure, stellar clusters and populations|
|Published online||11 November 2010|
A high-resolution VLT/FLAMES study of individual stars in the centre of the Fornax dwarf spheroidal galaxy⋆,⋆⋆
Kapteyn Astronomical Institute, University of Groningen,
PO Box 800,
2 California Institute of Technology, 1200E. California Blvd, MC105-24, Pasadena, CA 91125, USA
3 South African Astronomical Observatory, PO Box 9, Observatory 7935, South Africa
4 GEPI, Observatoire de Paris, CNRS, Université Paris Diderot, 92125 Meudon Cedex, France
5 Université de Nice Sophia-Antipolis, CNRS, Observatoire de Côte d’Azur, Laboratoire Cassiopée, 06304 Nice Cedex 4, France
6 Observatoire de Genève, University of Geneva, 1290 Sauverny, Switzerland
7 McDonald Observatory, University of Texas, Fort Davis, TX 79734, USA
8 Dept. of Physics & Astronomy, University of Victoria, 3800 Finerty Road, Victoria, BC V8P 1A1, Canada
9 Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK
10 European Southern Observatory, Karl-Schwarzschild-str. 2, 85748 Garching bei München, Germany
11 European Southern Observatory, Alonso de Cordova 3107, Santiago, Chile
12 National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
13 Astronomical Institute, Osaka Kyoiku University, Asahigaoka, Kashiwara, Osaka 582-8582, Japan
Accepted: 6 July 2010
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 ~ 20000, 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-processorigin of Eu.
Key words: stars: abundances / galaxies: dwarf / galaxies: evolution / galaxies: formation / galaxies: stellar content / galaxies: individual: Fornax dwarf galaxy
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 http://www.aanda.org
© ESO, 2010
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.