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A New View of the Dwarf Spheroidal Satellites of the Milky Way from VLT FLAMES: Where Are the Very Metal-poor Stars?

A New View of the Dwarf Spheroidal Satellites of the Milky Way from VLT FLAMES: Where Are the Very Metal-poor Stars?

Authors :
Andreas Kaufer
Tom Abel
Giuseppina Battaglia
Matthew Shetrone
P. Francois
Kim Venn
Thomas Szeifert
Eline Tolstoy
Amina Helmi
Mike Irwin
Vanessa Hill
Nobuo Arimoto
Francesca Primas
Pascale Jablonka
Kozo Sadakane
B. Letarte
Source :
The Astrophysical Journal. 651:L121-L124
Publication Year :
2006
Publisher :
American Astronomical Society, 2006.

Abstract

As part of the Dwarf galaxies Abundances and Radial-velocities Team (DART) program, we have measured the metallicities of a large sample of stars in four nearby dwarf spheroidal galaxies (dSph's): Sculptor, Sextans, Fornax, and Carina. The low mean metal abundances and the presence of very old stellar populations in these galaxies have supported the view that they are fossils from the early universe. However, contrary to naive expectations, we find a significant lack of stars with metallicities below [Fe/H] ~ -3 dex in all four systems. This suggests that the gas that made up the stars in these systems had been uniformly enriched prior to their formation. Furthermore, the metal-poor tail of the dSph metallicity distribution is significantly different from that of the Galactic halo. These findings show that the progenitors of nearby dSph's appear to have been fundamentally different from the building blocks of the Milky Way, even at the earliest epochs.<br />4 pages, 3 figures

Details

ISSN :
15384357 and 0004637X
Volume :
651
Database :
OpenAIRE
Journal :
The Astrophysical Journal
Accession number :
edsair.doi.dedup.....a3ca89fc9b334f79baf22c1d9b193f28
Full Text :
https://doi.org/10.1086/509784