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

By B. Letarte, V. Hill, E. Tolstoy, P. Jablonka, M. Shetrone, K. Venn, M. Spite, M. Irwin, G. Battaglia, A. Helmi and 6 more. 2010

166 citations recorded by the source corpus.

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.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/70edd8cf8305bed4d28616c4e8c8e6aaa850147c

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In Astronomy and Astrophysics

1. M. Walker
2. A. Helmi
3. James S. Bullock
4. J. Simon
5. E. Kirby
6. M. Geha
7. M. Irwin
8. J. Cohen

In Instrumentation

1. M. Walker
2. A. Helmi
3. J. Simon
4. James S. Bullock
5. M. Geha
6. E. Olszewski
7. M. Irwin
8. M. Mateo

Citations in the corpus

• The star formation and chemical evolution history of the Fornax dwarf spheroidal galaxy (2012, methodology): “2c shows that the [Mg/Fe] derived for the highest signal-to-noise ratio (S/N) measurements from Kirby et al. (2010) are consistent with those determined from the HR spectroscopy of Letarte et al. (2010).”
• The Dynamical and Chemical Evolution of Dwarf Spheroidal Galaxies with GEAR (2009, methodology): “The abundance ratios were taken from Tolstoy et al. (2009), Letarte et al. (2010), Shetrone et al. (2003), and Koch et al. (2008).”
• MULTI-ELEMENT ABUNDANCE MEASUREMENTS FROM MEDIUM-RESOLUTION SPECTRA. II. CATALOG OF STARS IN MILKY WAY DWARF SATELLITE GALAXIES (2010, background): “Twenty stars, listed in Table 7, have previously published HRS abundance measurements (Shetrone et al. 2003; Letarte et al. 2010), and all 20 were observed.”