Publications (22)
Molecular bands in extremely metal-poor stars. Granulation effects
Piercarlo Bonifacio, Elisabetta Caffau, Hans-Günter Ludwig +4
The bands of diatomic molecules are important abundance indicators, especially in metal-poor stars, where they are still measurable in metallicity regimes where the atomic lines of…
Carbon-enhanced metal-poor stars: the most pristine objects?
Monique Spite, E. Caffau, Piercarlo Bonifacio +4
Carbon-enhanced metal poor stars (CEMP) form a significant proportion of the metal-poor stars, their origin is not well understood. Three very metal-poor C-rich turnoff stars were…
Precise boron abundance in a sample of metal-poor stars from far-ultraviolet lines
Monique Spite, Beatriz Barbuy, Kefeng Tan
The light elements beryllium (Be; ) and boron (B; ) are mainly produced by spallation reactions between cosmic rays and carbon (C; ), nitrogen (N; ), and oxygen…
Li isotopes in metal-poor halo dwarfs, a more and more complicated story
Monique Spite, François Spite
The nuclei of the lithium isotopes are fragile, easily destroyed, so that, at variance with most of the other elements, they cannot be formed in stars through steady hydrostatic nu…
The evolution of the Milky Way from its earliest phases : constraints on stellar nucleosynthesis
Patrick Francois, Francesca Matteucci, Roger Cayrel +3
We computed the evolution of the abundances of O, Mg, Si, Ca, K, Ti, Sc, Ni, Mn, Co, Fe and Zn in the Milky Way. We made use of the most widely adopted nucleosynthesis calculations…
High resolution study of the abundance pattern of the heavy elements in very metal-poor field stars
Monique Spite, François Spite
The abundances of heavy elements in EMP stars are not well explained by the simple view of an initial basic "rapid" process. In a careful and homogeneous analysis of the "First sta…
Lithium abundance in a turnoff halo star on an extreme orbit
Monique Spite, François Spite, Elisabetta Caffau +1
The lithium abundance in turnoff stars of the old population of our Galaxy is remarkably constant in the metallicity interval -2.8\textless{}[Fe/H] \textless{}-2.0, defining a plat…
Extremely metal-poor stars in SDSS fields
Piercarlo Bonifacio, Elisabetta Caffau, Patrick François +12
Some insight on the first generation of stars can be obtained from the chemical composition of their direct descendants, extremely metal-poor stars (EMP), with metallicity less tha…
A CEMP-no star in the ultra-faint dwarf galaxy Pisces II
Monique Spite, François Spite, Patrick François +3
A probable carbon enhanced metal-poor (CEMP) star, Pisces II 10694, was discovered recently in the ultra-faint (UFD) galaxy Pisces II. This galaxy is supposed to be very old, suspe…
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…
Abundance patterns of the light neutron-capture elements in very and extremely metal-poor stars
François Spite, Monique Spite, Beatriz Barbuy +3
We measured new abundances of so-called light neutron-capture of first peak elements using local thermodynamic equilibrium (LTE) 1D analysis; this analysis resulted in a sample of…
Line shift, line asymmetry, and the 6Li/7Li isotopic ratio determination
Roger Cayrel, Matthias Steffen, Hum Chand +6
Context: Line asymmetries are generated by convective Doppler shifts in stellar atmospheres, especially in metal-poor stars, where convective motions penetrate to higher atmospheri…
Young stars discovered in dwarf spheroidal galaxies confirm their recent infall into the Milky way
Francois Hammer, Piercarlo Bonifacio, Elisabetta Caffau +10
Recent observations from the ESA Gaia satellite and with the ESO VLT, have identified the presence of a population of young, 0.5 to 2 Gyr old, stars in the halo and in dwarf sphero…
VLT/FLAMES high-resolution chemical abundances in Sculptor: a textbook dwarf spheroidal galaxy
Vanessa Hill, Ãsa Skúladóttir, Eline Tolstoy +12
We present detailed chemical abundances for 99 red-giant branch stars in the centre of the Sculptor dwarf spheroidal galaxy, obtained from high-resolution VLT/FLAMES spectroscopy.…
Lithium-6 : Evolution from Big Bang to Present
Elisabeth Vangioni-Flam, Michel Casse, Roger Cayrel +3
The primordial abundances of Deuterium, he4, and li7 are crucial to determination of the baryon density of the Universe in the framework of standard Big Bang nucleosynthesis (BBN).…
First Stars XIV. Sulfur abundances in extremely metal-poor (EMP) stars
Monique Spite, E. Caffau, S. M. Andrievsky +15
Sulfur is important: the site of its formation is uncertain, and at very low metallicity the trend of [S/Fe] against [Fe/H] is controversial. Below [Fe/H]=-2.0, [S/Fe] remains cons…
Chemical abundances of 20 barium stars from the OHP spectra
Guochao Yang, Jingkun Zhao, Yanchun Liang +7
Based on the high resolution and high signal-to-noise spectra, we derived the chemical abundances of 20 elements for 20 barium (Ba-) stars. For the first time, the detailed abundan…
NLTE determination of the calcium abundance and 3D corrections in extremely metal-poor stars
Monique Spite, S. M. Andrievsky, F. Spite +6
(Abridged) Extremely metal-poor stars contain the fossil records of the chemical composition of the early Galaxy. The NLTE profiles of the calcium lines were computed in a sample o…
Abundances of CNO in candidate young metal-poor stars
Piercarlo Bonifacio, Elisabetta Caffau, Luca Sbordone +6
In this contribution we investigate the CNO abundances in five apparently young evolved stars, with the aim of discriminating between truly young stars and stars that were rejuvena…
The Gaia RVS Benchmark Stars. III . Confirmed and New High Radial Velocity Stars From Gaia DR3
Elisabetta Caffau, David Katz, Piercarlo Bonifacio +12
High-velocity stars are interesting targets to unveil the formation of the Milky Way. In fact they can be recently accreted from an infalling dwarf galaxies or they can be the resu…
Abundances in a sample of turnoff and subgiant stars in NGC 6121 (M4)
Monique Spite, Francois Spite, Andrew J. Gallagher +4
{The aim of this work is to investigate the relations between the abundances of different elements in the globular cluster M4, selected for its uniform deficiency of iron, to explo…
Sulphur abundances in halo stars from Multiplet 3 at 1045 nm
Elisabetta Caffau, Luca Sbordone, Hans-Günter Ludwig +2
Sulphur is a volatile alpha-element which is not locked into dust grains in the interstellar medium (ISM). Hence, its abundance does not need to be corrected for dust depletion whe…