A New View of the Dwarf Spheroidal Satellites of the Milky Way from VLT FLAMES: Where Are the Very Metal-poor Stars?
- 26 October 2006
- journal article
- Published by American Astronomical Society in The Astrophysical Journal
- Vol. 651 (2), L121-L124
- https://doi.org/10.1086/509784
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.Comment: 4 pages, 3 figureKeywords
This publication has 27 references indexed in Scilit:
- Chemical Abundance Distributions of Galactic Halos and Their Satellite Systems in a ΛCDM UniverseThe Astrophysical Journal, 2006
- The distribution and kinematics of early high-σ peaks in present-day haloes: implications for rare objects and old stellar populationsMonthly Notices of the Royal Astronomical Society, 2005
- The Discovery and Analysis of Very Metal-Poor Stars in the GalaxyAnnual Review of Astronomy and Astrophysics, 2005
- The Hamburg/ESO R-process enhanced star survey (HERES)Astronomy & Astrophysics, 2005
- Nucleosynthetic signatures of the first starsNature, 2005
- The First StarsAnnual Review of Astronomy and Astrophysics, 2004
- The effects of age on red giant metallicities derived from the near-infrared Ca II tripletMonthly Notices of the Royal Astronomical Society, 2004
- A stellar relic from the early Milky WayNature, 2002
- Heavy-element enrichment in low-density regions of the intergalactic mediumNature, 1998
- Metallicities for old stellar systems from CA II triplet strengths in member giantsThe Astronomical Journal, 1991