Bibcode
Letarte, B.; Hill, V.; Tolstoy, E.; Jablonka, P.; Shetrone, M.; Venn, K. A.; Spite, M.; Irwin, M. J.; Battaglia, G.; Helmi, A.; Primas, F.; François, P.; Kaufer, A.; Szeifert, T.; Arimoto, N.; Sadakane, K.
Bibliographical reference
Astronomy and Astrophysics, Volume 523, id.A17, 40 pp.
Advertised on:
11
2010
Journal
Citations
192
Refereed citations
173
Description
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.
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