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TOPoS: III. An ultra iron-poor multiple CEMP system
E. Caffau, P. Bonifacio, M. Spite +15
One of the primary objectives of the TOPoS survey is to search for the most metal-poor stars. Our search has led to the discovery of one of the most iron-poor objects known, SDSS\,…
TOPoS: II. On the bimodality of carbon abundance in CEMP stars. Implications on the early chemical evolution of galaxies
P. Bonifacio, E. Caffau, M. Spite +18
In the course of the TOPoS (Turn Off Primordial Stars) survey, aimed at discovering the lowest metallicity stars, we have found several carbon-enhanced metal-poor (CEMP) stars. We…
X-Shooter GTO: evidence for a population of extremely metal-poor, alpha-poor stars
E. Caffau, P. Bonifacio, P. Francois +12
The extremely metal-poor stars are the direct descendants of the first generation stars. They carry the chemical signature of the pristine Universe at the time they formed, shortly…
An extremely primitive halo star
E. Caffau, P. Bonifacio, P. François +11
The early Universe had a chemical composition consisting of hydrogen, helium and traces of lithium1, almost all other elements were created in stars and supernovae. The mass fracti…
A primordial star in the heart of the Lion
E. Caffau, P. Bonifacio, P. François +14
Context: The discovery and chemical analysis of extremely metal-poor stars permit a better understanding of the star formation of the first generation of stars and of the Universe…
X-Shooter GTO: Chemical analysis of a sample of EMP candidates
E. Caffau, P. Bonifacio, P. François +11
Context: Extremely metal-poor stars (EMP) are very rare objects that hold in their atmospheres the fossil record of the chemical composition of the early phases of Galactic evoluti…
The metal-poor end of the Spite plateau. 1: Stellar parameters, metallicities and lithium abundances
L. Sbordone, P. Bonifacio, E. Caffau +16
We present VLT-UVES Li abundances for 28 halo dwarf stars between [Fe/H]=-2.5 and -3.5, 10 of which have [Fe/H]<-3. Four different T_eff scales have been used. Direct Infrared Flux…
Non-LTE abundances of Mg and K in extremely metal-poor stars and the evolution of [O/Mg], [Na/Mg], [Al/Mg] and [K/Mg] in the Milky Way
S. M. Andrievsky, Monique Spite, S. A. Korotin +5
LTE abundances of light elements in extremely metal-poor (EMP) stars have been previously derived from high quality spectra. New derivations, free from the NLTE effects, will bette…
Main-Sequence and sub-giant stars in the Globular Cluster NGC6397: The complex evolution of the lithium abundance
J. I. González Hernández, P. Bonifacio, E. Caffau +6
Thanks to the high multiplex and efficiency of Giraffe at the VLT we have been able for the first time to observe the Li I doublet in the Main Sequence (MS) stars of a Globular Clu…
Lithium in the Globular Cluster NGC 6397: Evidence for dependence on evolutionary status
J. I. Gonzalez Hernandez, P. Bonifacio, E. Caffau +6
Most Globular Clusters are believed to host a single stellar populations. They can thus be considered a good place to study the Spite plateau and probe for possible evolutionary mo…
Lithium abundances of Main Sequence and Sub-Giant stars in the Globular Cluster NGC 6397
J. I. González Hernández, P. Bonifacio, E. Caffau +6
We present FLAMES/GIRAFFE spectroscopy obtained at the Very Large Telescope (VLT). Using these observations we have been able for the first time to observe the Li I doublet in the…
First stars XII. Abundances in extremely metal-poor turnoff stars,and comparison with the giants
P. Bonifacio, M. Spite, R. Cayrel +13
CONTEXT:The detailed chemical abundances of extremely metal-poor (EMP) stars are key guides to understanding the early chemical evolution of the Galaxy. Most existing data are, how…
Evolution of the Barium abundance in the early Galaxy from a NLTE analysis of the Ba lines in a homogeneous sample of EMP stars
S. M. Andrievsky, M. Spite, S. A. Korotin +5
Barium is a key element in constraining the evolution of the (not well understood) r-process in the first galactic stars and currently the Ba abundances in these very metal-poor st…