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View article: Unveiling the nature of HE 0107-5240
Unveiling the nature of HE 0107-5240 Open
The vast majority of the most iron-poor stars in the Galaxy exhibit a strong carbon enhancement, with C/H ratios only about two orders of magnitude below solar. This unusual chemical composition likely reflects the properties of the gas cl…
View article: Precise boron abundance in a sample of metal-poor stars from far-ultraviolet lines
Precise boron abundance in a sample of metal-poor stars from far-ultraviolet lines Open
Context . The light elements beryllium (Be; Z = 4) and boron (B; Z = 5) are mainly produced by spallation reactions between cosmic rays and carbon (C; Z = 6), nitrogen (N; Z = 7), and oxygen (O; Z = 8) nuclei. Only traces of Be or B would …
View article: The Gaia RVS Benchmark Stars. III . Confirmed and New High Radial Velocity Stars From Gaia DR3
The Gaia RVS Benchmark Stars. III . Confirmed and New High Radial Velocity Stars From Gaia DR3 Open
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 result of a turbulent merging of galaxies. Gaia is providing th…
View article: SDSS J102915.14+172927.9: Revisiting the chemical pattern
SDSS J102915.14+172927.9: Revisiting the chemical pattern Open
Context . The small- to intermediate-mass (M < 0.8 M ⊙ ), most metal-poor stars that formed in the infancy of the Universe are still shining today in the sky. They are very rare, but their discovery and investigation brings new knowledge o…
View article: MINCE
MINCE Open
Context . Most of the studies on the determination of the chemical composition of metal-poor stars have been focused on the search of the most pristine stars, searching for the imprints of the ejecta of the first supernovae. Apart from the…
View article: MINCE II. Neutron capture elements
MINCE II. Neutron capture elements Open
The MINCE (Measuring at Intermediate metallicity Neutron-Capture Elements) project aims to gather the abundances of neutron-capture elements but also of light elements and iron peak elements in a large sample of giant stars in this metalli…
View article: High speed stars
High speed stars Open
Context. The Gaia satellite has provided the community with three releases containing astrometrical and photometric data as well as by products, such as stellar parameters and variability indicators. Aims. By selecting in the Gaia database…
View article: High-speed stars
High-speed stars Open
Context. The data from the Gaia satellite led us to revise our conception of the Galaxy structure and history. Hitherto unknown components have been discovered and a deep re-thinking of what the Galactic halo is in progress. Aims. We selec…
View article: Neutron-capture elements in a sample of field metal-poor N-rich dwarfs
Neutron-capture elements in a sample of field metal-poor N-rich dwarfs Open
Context. The aim of this work is to measure the abundances of n-capture elements in a sample of six metal-poor N-rich dwarfs that were formed in globular clusters, and subsequently became unbound from the cluster. These N-rich stars, HD 25…
View article: The <i>Gaia</i> RVS benchmark stars
The <i>Gaia</i> RVS benchmark stars Open
Context. The Gaia satellite has already provided the astronomical community with three data releases, and the Radial Velocity Spectrometer (RVS) on board Gaia has provided the radial velocity for 33 million stars. Aims. When deriving the r…
View article: Reanalysis of neutron-capture elements in the benchmark r-rich star CS 31082−001
Reanalysis of neutron-capture elements in the benchmark r-rich star CS 31082−001 Open
We revisit the abundances of neutron-capture elements in the metal-poor ([Fe/H] = −2.9) r-process-rich halo star CS 31082−001. Partly motivated by the development of the new near-ultraviolet Cassegrain U-band Efficient Spectrograph for the…
View article: The Pristine survey – XIX. Cu and Zn abundances in metal-poor giants
The Pristine survey – XIX. Cu and Zn abundances in metal-poor giants Open
Metal-poor stars formed from a gas enriched by the ejecta of the explosion of one/few generations of first massive stars. With the Pristine photometry combined with the Gaia data, we selected a sample of bright giants metal-poor candidates…
View article: MINCE
MINCE Open
Context. In recent years, Galactic archaeology has become a particularly vibrant field of astronomy, with its main focus set on the oldest stars of our Galaxy. In most cases, these stars have been identified as the most metal-poor. However…
View article: Detailed analysis of a sample of field metal-poor N-rich dwarfs
Detailed analysis of a sample of field metal-poor N-rich dwarfs Open
Aims. The aim of this work is to compare the detailed chemical composition of the field N-rich dwarf stars to the second-generation stars of globular clusters (GCs) in order to investigate the hypothesis that they originated in GCs. Method…
View article: Discovery of a thin lithium plateau among metal-poor red giant branch stars
Discovery of a thin lithium plateau among metal-poor red giant branch stars Open
The surface lithium abundance, A (Li), of warm metal-poor dwarf stars exhibits a narrow plateau down to [Fe/H] ~ −2.8 dex, while at lower metallicities the average value drops by 0.3 dex with a significant star-by-star scatter (called ‘lit…
View article: Detailed investigation of two high‐speed evolved Galactic stars
Detailed investigation of two high‐speed evolved Galactic stars Open
The study of metal poor stars provides clarification and knowledge about the primordial Universe. Specially, halo stars provide explanations of the nature of the first generations of stars and the nucleosynthesis in the metal‐poor regime. …
View article: TOPoS
TOPoS Open
Context. The goal of the Turn-Off Primordial Stars survey (TOPoS) project is to find and analyse turn-off (TO) stars of extremely low metallicity. To select the targets for spectroscopic follow-up at high spectral resolution, we relied on …
View article: The <i>Gaia</i> RVS benchmark stars
The <i>Gaia</i> RVS benchmark stars Open
Context. The Radial Velocity Spectrometer (RVS) on board the Gaia satellite is not provided with a wavelength calibration lamp. It uses its observations of stars with known radial velocity to derive the dispersion relation. To derive an ac…
View article: High-speed stars: Galactic hitchhikers
High-speed stars: Galactic hitchhikers Open
Context. The search for stars born in the very early stages of the Milky Way star formation history is of paramount importance in the study of the early Universe since their chemistry carries irreplaceable information on the conditions in …
View article: Reviving old controversies: is the early Galaxy flat or round?
Reviving old controversies: is the early Galaxy flat or round? Open
We analysed a set of very metal-poor stars, for which accurate chemical abundances have been obtained as part of the ESO Large Program “First stars” in the light of the Gaia DR2 data. The kinematics and orbital properties of the stars in t…
View article: Reviving old controversies: is the early Galaxy flat or round? Investigations into the early phases of the Milky Way formation through stellar kinematics and chemical abundances
Reviving old controversies: is the early Galaxy flat or round? Investigations into the early phases of the Milky Way formation through stellar kinematics and chemical abundances Open
We analyse a set of very metal-poor stars for which accurate chemical abundances have been obtained as part of the ESO Large Program "First stars" in the light of the Gaia DR2 data. The kinematics and orbital properties of the stars in the…
View article: The CEMP star SDSS J0222–0313: the first evidence of proton ingestion in very low-metallicity AGB stars?
The CEMP star SDSS J0222–0313: the first evidence of proton ingestion in very low-metallicity AGB stars? Open
Context. Carbon-enhanced metal-poor (CEMP) stars are common objects in the metal-poor regime. The lower the metallicity we look at, the larger the fraction of CEMP stars with respect to metal-poor stars with no enhancement in carbon. The c…
View article: The galactic very metal-poor stars : from La Silla to Paranal
The galactic very metal-poor stars : from La Silla to Paranal Open
The search for the most galactic metal-poor stars began soon after the publication of the fundamental paper of Burbidge et al. (1957): the elements are synthesised little by little in the stars, and thus the most metal-poor galactic stars …
View article: Probing the existence of very massive first stars
Probing the existence of very massive first stars Open
We present a novel approach aimed at identifying the key chemical elements to\nsearch for the (missing) descendants of very massive first stars exploding as\nPair Instability Supernovae (PISN). Our simple and general method consists in a\n…
View article: Extremely metal-poor stars: the need for UV spectra
Extremely metal-poor stars: the need for UV spectra Open
Our current understanding of the chemical evolution of the Universe is that a first generation of stars was formed out of primordial material, completely devoid of metals (Pop III stars). This first population of stars comprised massive st…
View article: Be and O in the ultra metal-poor dwarf 2MASS J18082002-5104378: the Be–O correlation
Be and O in the ultra metal-poor dwarf 2MASS J18082002-5104378: the Be–O correlation Open
Context. Measurable amounts of Be could have been synthesised primordially if the Universe were non-homogeneous or in the presence of late decaying relic particles. Aims. We investigate the Be abundance in the extremely metal-poor star 2MA…
View article: TOPoS V: Abundance ratios in a sample of very metal-poor turn-off stars
TOPoS V: Abundance ratios in a sample of very metal-poor turn-off stars Open
Extremely metal-poor stars are keys to understand the early evolution of our Galaxy. The ESO large programme TOPoS has been tailored to analyse a new set of metal-poor turn-off stars, whereas most of the previously known extremely metal-po…
View article: TOPoS
TOPoS Open
Context. Extremely metal-poor stars are keys to understand the early evolution of our Galaxy. The ESO large programme TOPoS has been tailored to analyse a new set of metal-poor turn-off stars, whereas most of the previously known extremely…
View article: A CEMP-no star in the ultra-faint dwarf galaxy Pisces II
A CEMP-no star in the ultra-faint dwarf galaxy Pisces II Open
Aims. 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, suspected to include dark matter, and likely formed the b…
View article: Gaia confirms that SDSS J102915+172927 is a dwarf star
Gaia confirms that SDSS J102915+172927 is a dwarf star Open
The Gaia Data Release 2 provides a parallax of 0.734+/-0.073 mas for SDSS J102915+172927, currently the most metal-poor known object. This parallax implies that it is dwarf star, ruling out the scenario that it is a subgiant. The subgiant …