A New View of the Dwarf Spheroidal Satellites of the Milky Way from VLT FLAMES: Where Are the Very Metal-poor Stars? - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue The Astrophysical journal letters Année : 2006

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

Résumé

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.

Dates et versions

hal-03796911 , version 1 (04-10-2022)

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Citer

Amina Helmi, Michael J. Irwin, Eline Tolstoy, Giuseppina Battaglia, Vanessa Hill, et al.. A New View of the Dwarf Spheroidal Satellites of the Milky Way from VLT FLAMES: Where Are the Very Metal-poor Stars?. The Astrophysical journal letters, 2006, 651, pp.L121-L124. ⟨10.1086/509784⟩. ⟨hal-03796911⟩
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