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View article: Distinct barium isotope ratios in CEMP-s and CEMP-rs stars
Distinct barium isotope ratios in CEMP-s and CEMP-rs stars Open
We present a spectroscopic analysis of ten carbon enhanced metal-poor (CEMP) stars of type CEMP-s and CEMP-rs and determine their NLTE abundances of Ba and Eu, as well as the fractions of the odd Ba isotopes (F_odd). The Ba abundances infe…
View article: The Pristine survey
The Pristine survey Open
The discovery of the most metal-poor stream, C-19, provides us with a fossil record of a stellar structure born very soon after the big bang. In this work, we search for new C-19 members throughout the sky by combining two complementary st…
View article: The Pristine survey: XXVII. The extremely metal-poor stream C-19 stretches over more than 100 degrees
The Pristine survey: XXVII. The extremely metal-poor stream C-19 stretches over more than 100 degrees Open
The discovery of the most metal-poor stream, C-19, provides us with a fossil record of a stellar structure born very soon after the Big Bang. In this work, we search for new C-19 members over the whole sky by combining two complementary st…
View article: Slowly Rotating Peculiar Star BD00°1659 as a Benchmark for Stratification Studies in Ap/Bp Stars
Slowly Rotating Peculiar Star BD00°1659 as a Benchmark for Stratification Studies in Ap/Bp Stars Open
We present the results of a self-consistent analysis of the magnetic silicon star BD+00°1659, based on its high-resolution spectra taken from the ESPaDOnS archive (R = 68,000). This narrow-lined star shows the typical high Si abundance and…
View article: HR-GO I: Comprehensive NLTE abundance analysis of the Cetus stream
HR-GO I: Comprehensive NLTE abundance analysis of the Cetus stream Open
Dwarf galaxy streams encode vast amounts of information essential to understanding early galaxy formation and nucleosynthesis channels. Due to the variation in the timescales of star formation history in their progenitors, stellar streams …
View article: The Pristine survey – XXII. A serendipitous discovery of an extremely Li-rich very metal-poor giant and a new method of 6Li/7Li isotope measurement
The Pristine survey – XXII. A serendipitous discovery of an extremely Li-rich very metal-poor giant and a new method of 6Li/7Li isotope measurement Open
We report the serendipitous discovery of a very metal-poor (VMP) Li-rich giant star (Teff = 4690 ± 80 K, log g = 1.34 ± 0.13, [Fe/H] = −2.43 ± 0.07). We analyse the Li i 6103 and 6707 Å lines accounting for departures from local thermodyna…
View article: The Pristine survey -- XXII. A serendipitous discovery of an extremely Li-rich very metal-poor giant and a new method of $^6$Li/$^7$Li isotope measurement
The Pristine survey -- XXII. A serendipitous discovery of an extremely Li-rich very metal-poor giant and a new method of $^6$Li/$^7$Li isotope measurement Open
We report the serendipitous discovery of a very metal-poor (VMP) Li-rich giant star ($T_{\rm eff}$ = 4690$\pm$80 K, log g = 1.34$\pm$0.13, [Fe/H] = $-2.43\pm$0.07). We analyse the Li I 6103 and 6707 Å lines accounting for departures from l…
View article: Non-LTE abundance analysis of A-B stars with low rotational velocities. II. Do A-B stars with normal abundances exist?
Non-LTE abundance analysis of A-B stars with low rotational velocities. II. Do A-B stars with normal abundances exist? Open
We present chemical composition and fundamental parameters (the effective temperature, surface gravity and radius) for four sharp-lined A-type stars $γ$ Gem (HD 41705), o Peg (HD 214994), $θ$ Vir (HD 114330) and $ν$ Cap (HD 193432). Our an…
View article: 1D non-LTE corrections for chemical abundance analyses of very metal-poor stars
1D non-LTE corrections for chemical abundance analyses of very metal-poor stars Open
Detailed chemical abundances of very metal-poor (VMP; [Fe/H] < −2) stars are important for better understanding the first stars, early star formation, and chemical enrichment of galaxies. Big on-going and coming high-resolution spectros…
View article: 1D non-LTE corrections for chemical abundance analyses of very metal-poor stars
1D non-LTE corrections for chemical abundance analyses of very metal-poor stars Open
Detailed chemical abundances of very metal-poor (VMP, [Fe/H] < -2) stars are important for better understanding the First Stars, early star formation and chemical enrichment of galaxies. Big on-going and coming high-resolution spectroscopi…
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: Non-LTE abundances of zinc in different spectral type stars and the Galactic [Zn/Fe] trend based on quantum-mechanical data on inelastic processes in zinc-hydrogen collisions
Non-LTE abundances of zinc in different spectral type stars and the Galactic [Zn/Fe] trend based on quantum-mechanical data on inelastic processes in zinc-hydrogen collisions Open
We present a new model atom of Zn i-Zn ii based on the most up-to-date photoionization cross-sections, electron-impact excitation rates, and rate coefficients for the Zn i + H i and Zn ii + H− collisions. The latter were calculated using t…
View article: Detailed abundances of the wide pairs of stars with and without planets: the binary systems 16 Cyg and HD 219542
Detailed abundances of the wide pairs of stars with and without planets: the binary systems 16 Cyg and HD 219542 Open
We present results of the comparative analysis of the two wide binary systems – 16 Cyg, with a giant gas planet orbiting around 16 Cyg B, and HD 219542 without planet detected. Atmospheric parameters of the binary components and the Sun we…
View article: Non-LTE Analysis of the Si II Lines in $$\boldsymbol{\iota}$$ Her with Various Atomic Data Sets
Non-LTE Analysis of the Si II Lines in $$\boldsymbol{\iota}$$ Her with Various Atomic Data Sets Open
This study shows that the statistical equilibrium of Si II in the atmosphere of a B3 IV type star iota Her is extremely sensitive to a variation in photoionization cross-sections for the Si II levels. The difference in abundances derived f…
View article: Fundamental parameters of the Ap-stars GO And, 84 UMa, and $\kappa$ Psc.
Fundamental parameters of the Ap-stars GO And, 84 UMa, and $\kappa$ Psc. Open
The aim of this work is to determine fundamental parameters of three Ap stars, GO And (HD 4778), $\kappa$ Psc (HD 220825), and 84 UMa (HD 120198), using spectroscopic techniques. By analysing these stars, we complete the sample of Ap stars…
View article: Fundamental parameters of the Ap-stars GO And, 84 UMa, and <i>κ</i> Psc
Fundamental parameters of the Ap-stars GO And, 84 UMa, and <i>κ</i> Psc Open
Aims. The aim of this work is to determine fundamental parameters of three Ap stars, GO And (HD 4778), κ Psc (HD 220825), and 84 UMa (HD 120198), using spectroscopic techniques. By analysing these stars, we complete the sample of Ap stars …
View article: The formation of the Milky Way halo and its dwarf satellites: A NLTE–1D abundance analysis. V. The Sextans galaxy
The formation of the Milky Way halo and its dwarf satellites: A NLTE–1D abundance analysis. V. The Sextans galaxy Open
We present a homogeneous set of accurate atmospheric parameters for a sample of eleven very metal-poor (−3.32 ≤ [Fe/H] ≤−2.61) stars in the Sextans dwarf spheroidal galaxy (dSph) and the non-local thermodynamic equilibrium (NLTE) abundance…
View article: The Pristine survey – XIV. Chemical analysis of two ultra-metal-poor stars
The Pristine survey – XIV. Chemical analysis of two ultra-metal-poor stars Open
Elemental abundances of the most metal-poor stars reflect the conditions in the early Galaxy and the properties of the first stars. We present a spectroscopic follow-up of two ultra-metal-poor stars ([Fe/H] < −4.0) identified by the sur…
View article: The formation of the Milky Way halo and its dwarf satellites; a NLTE-1D abundance analysis
The formation of the Milky Way halo and its dwarf satellites; a NLTE-1D abundance analysis Open
LASTRO
View article: The formation of the milky way halo and its dwarf satellites: a NLTE-1D abundance analysis. IV. Segue 1, Triangulum <scp>ii</scp>, and Coma Berenices UFDs
The formation of the milky way halo and its dwarf satellites: a NLTE-1D abundance analysis. IV. Segue 1, Triangulum <span>ii</span>, and Coma Berenices UFDs Open
We present atmospheric parameters and abundances for chemical elements from carbon to barium in metal-poor stars in Segue 1 (seven stars), Coma Berenices (three stars), and Triangulum ii (one star) ultrafaint dwarf galaxies (UFDs). The eff…
View article: Chemical diversity among A–B stars with low rotational velocities: non-LTE abundance analysis
Chemical diversity among A–B stars with low rotational velocities: non-LTE abundance analysis Open
We present accurate element abundance patterns based on the non-local thermodynamic equilibrium (non-LTE, NLTE) line formation for 14 chemical elements from He to Nd for a sample of nine A9 to B3-type stars with well-determined atmospheric…
View article: Mono-enriched stars and Galactic chemical evolution
Mono-enriched stars and Galactic chemical evolution Open
A long sought after goal using chemical abundance patterns derived from metal-poor stars is to understand the chemical evolution of the Galaxy and to pin down the nature of the first stars (Pop III). Metal-poor, old, unevolved stars are ex…
View article: Impact of the convective mixing-length parameter <i>α</i> on stellar metallicity
Impact of the convective mixing-length parameter <i>α</i> on stellar metallicity Open
Context. Mixing-length theory is used to treat stellar convection. As a simulation in one-dimensional stellar atmospheres models, the mixing-length parameter α is calibrated from the Sun and then applied to other stars. However, there is n…
View article: Mono-enriched stars and Galactic chemical evolution : Possible biases in observations and theory
Mono-enriched stars and Galactic chemical evolution : Possible biases in observations and theory Open
A long sought after goal using chemical abundance patterns derived from metal-poor stars is to understand the chemical evolution of the Galaxy and to pin down the nature of the first stars (Pop III). Metal-poor, old, unevolved stars are ex…
View article: Ultra metal-poor stars: improved atmospheric parameters and NLTE abundances of magnesium and calcium
Ultra metal-poor stars: improved atmospheric parameters and NLTE abundances of magnesium and calcium Open
The most metal-poor stars are the oldest objects, they provide a unique opportunity to study the earliest epoch of the Galaxy formation and individual nucleosynthesis events. These stars should be investigated with a scrupulous care, takin…
View article: Chemical composition of metal-poor stars in Coma Berenices ultra-faint dwarf galaxy as a proxy to individual chemical enrichment events
Chemical composition of metal-poor stars in Coma Berenices ultra-faint dwarf galaxy as a proxy to individual chemical enrichment events Open
We present NLTE abundances and atmospheric parameters for three metal-poor stars ([Fe/H]
View article: Chemical Composition of Metal-Poor Stars in Coma Berenices Ultra-Faint Dwarf as a Proxy to Individual Chemical Enrichment Events
Chemical Composition of Metal-Poor Stars in Coma Berenices Ultra-Faint Dwarf as a Proxy to Individual Chemical Enrichment Events Open
View article: Early chemical enrichment of the Milky Way dwarf satellites from high-resolution and NLTE analysis of VMP stars
Early chemical enrichment of the Milky Way dwarf satellites from high-resolution and NLTE analysis of VMP stars Open
We present the NLTE abundances of 10 chemical species in 65 very metal-poor stars in eight dSphs and the Milky Way halo. The classical dSphs Sculptor, Ursa Minor, Sextans, and Fornax reveal a similar plateau at [α/Fe] = 0.3 for each of Mg,…
View article: A-type Stellar Abundances: A Corollary to Herschel Observations of Debris Disks
A-type Stellar Abundances: A Corollary to Herschel Observations of Debris Disks Open
In order to assess the relationship between metallicity and exoplanetary systems, we compare the abundances of AF-type main-sequence stars with debris disk properties assessed using Herschel observations of an unbiased survey of nearby sta…
View article: A NLTE line formation for neutral and singly ionized calcium in model atmospheres of B-F stars
A NLTE line formation for neutral and singly ionized calcium in model atmospheres of B-F stars Open
We present non-local thermodynamic equilibrium (NLTE) line formation\ncalculations for Ca I and Ca II in B-F stars. The sign and the magnitude of\nNLTE abundance corrections depend on line and stellar parameters. We determine\ncalcium abun…