S. Van Eck
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View article: Technetium-rich M stars: Prime diagnostics of recent third dredge-up events on the asymptotic giant branch
Technetium-rich M stars: Prime diagnostics of recent third dredge-up events on the asymptotic giant branch Open
Context. Technetium (Tc)-rich M stars have been known for more than 45 years. However, the origin of Tc in these stars, particularly its detection without the concomitant detection of other s -process elements, which are typically produced…
View article: The <i>Gaia</i>-ESO Survey: projected rotational velocities of B stars in the Carina Nebula
The <i>Gaia</i>-ESO Survey: projected rotational velocities of B stars in the Carina Nebula Open
The Carina Nebula is an active star-forming region with several open clusters rich in massive OB stars, thus making it an optimal target for studying stellar properties such as rotation for large samples of these early-type stars. We studi…
View article: From the s-Process to the i-Process: A New Perspective on the Chemical Enrichment of Extrinsic Stars
From the s-Process to the i-Process: A New Perspective on the Chemical Enrichment of Extrinsic Stars Open
Separating stars enriched in the s- and r-processes of nucleosynthesis is usually achieved by analyzing the element ratios of s-process elements (like Ba or La) to r-process elements (like Eu). The situation becomes more complex when analy…
View article: Kilonova ejecta opacity inferred from new large-scale HFR atomic calculations in all elements between Ca (Z = 20) and Lr (Z = 103)
Kilonova ejecta opacity inferred from new large-scale HFR atomic calculations in all elements between Ca (Z = 20) and Lr (Z = 103) Open
In the context of kilonova (KN) modeling, the present work focusses on large-scale atomic data and opacity computations for all heavy elements from Ca to Lr, with a special effort on lanthanides and actinides, for a grid of typical KN ejec…
View article: The <i>Gaia</i>-ESO survey: New spectroscopic binaries in the Milky Way
The <i>Gaia</i>-ESO survey: New spectroscopic binaries in the Milky Way Open
Context . The Gaia -ESO survey (GES) is a large public spectroscopic survey that acquired spectra for more than 100 000 stars across all major components of the Milky Way. In addition to atmospheric parameters and stellar abundances that h…
View article: Appendices: The Gaia-ESO Survey: new spectroscopic binaries in the Milky Way
Appendices: The Gaia-ESO Survey: new spectroscopic binaries in the Milky Way Open
The Gaia-ESO Survey (GES) is a large public spectroscopic survey which acquired spectra for more than 100000 stars across all major components of the Milky Way. In addition to atmospheric parameters and stellar abundances that have been de…
View article: An impressionist view of V Hydrae
An impressionist view of V Hydrae Open
Context. Asymptotic giant branch (AGB) stars enrich the interstellar medium through their mass loss. The mechanism(s) shaping the circumstellar environment of mass-losing stars is not clearly understood so far. Aims. Our purpose is to stud…
View article: A new dimension in the variability of AGB stars: Convection patterns size changes with pulsation
A new dimension in the variability of AGB stars: Convection patterns size changes with pulsation Open
Context. Stellar convection plays an important role in atmospheric dynamics, wind formation, and the mass-loss processes in asymptotic giant branch stars. However, a direct characterization of convective surface structures in terms of size…
View article: A new dimension in the variability of AGB stars: convection patterns size changes with pulsation
A new dimension in the variability of AGB stars: convection patterns size changes with pulsation Open
Stellar convection plays an important role in atmospheric dynamics, wind formation and the mass-loss processes in Asymptotic Giant Branch (AGB) stars. However, a direct characterization of convective surface structures in terms of size, co…
View article: Update of SB9 orbits using HERMES/Mercator radial velocities
Update of SB9 orbits using HERMES/Mercator radial velocities Open
Aims . By combining astrometric orbits (delivered in large numbers by the Gaίa mission) with spectroscopic orbits for systems with two observable spectra (SB2), it is possible to derive the masses of both stellar components. However, to ge…
View article: Abundances of Extreme r-Process Elements in a Sample of CEMP-rs Stars
Abundances of Extreme r-Process Elements in a Sample of CEMP-rs Stars Open
We analyze high-resolution spectra of five carbon-enhanced metal-poor (CEMP) stars acquired using Ultraviolet and Visual Echelle Spectrograph (UVES). Assuming local thermodynamic equilibrium (LTE), we derive the abundances of extreme r-pro…
View article: The Eu Isotopic Ratios in CEMP Stars
The Eu Isotopic Ratios in CEMP Stars Open
Understanding the chemical evolution of galaxies requires accurate abundances of chemical elements in various stellar populations, which are then compared with theoretical predictions to probe their nucleosynthetic origin. However, most of…
View article: An update of SB9 orbits using HERMES/Mercator radial velocities
An update of SB9 orbits using HERMES/Mercator radial velocities Open
The Gaia mission is delivering a large number of astrometric orbits for binary stars. By combining these with spectroscopic orbits for systems with two observable spectra (SB2), it is possible to derive the masses of both components. Howev…
View article: HRMOS White Paper: Science Motivation
HRMOS White Paper: Science Motivation Open
The High-Resolution Multi-Object Spectrograph (HRMOS) is a facility instrument that we plan to propose for the Very Large Telescope (VLT) of the European Southern Observatory (ESO), following the initial presentation at the VLT 2030 worksh…
View article: MELCHIORS: The Mercator Library of High Resolution Stellar Spectroscopy
MELCHIORS: The Mercator Library of High Resolution Stellar Spectroscopy Open
Over the past decades, libraries of stellar spectra have been used in a large variety of science cases, including as sources of reference spectra for a given object or a given spectral type. Despite the existence of large libraries and the…
View article: MELCHIORS
MELCHIORS Open
Aims . Over the past decades, libraries of stellar spectra have been used in a large variety of science cases, including as sources of reference spectra for a given object or a given spectral type. Despite the existence of large libraries …
View article: TITANS metal-poor reference stars
TITANS metal-poor reference stars Open
Context. Representative samples of F-, G-, K-type stars located outside of the solar neighbourhood have started to become available in spectroscopic surveys. The fraction of metal-poor ([Fe/H] ≲ −0.8 dex) giants becomes increasingly releva…
View article: Titans metal-poor reference stars II. Red giants and CEMP stars
Titans metal-poor reference stars II. Red giants and CEMP stars Open
Representative samples of F-, G-, K-type stars located out of the Solar Neighbourhood has started to be available in spectroscopic surveys. The fraction of metal-poor ([Fe/H]~$\lesssim -0.8$~dex) giants becomes increasingly relevant to far…
View article: Does the i-process operate at nearly solar metallicity?
Does the i-process operate at nearly solar metallicity? Open
Context. A sample of 895 s-process-rich candidates has been found among the 454 180 giant stars surveyed by LAMOST at low spectral resolution ( R ~ 1800). In a previous study, taking advantage of the higher resolution ( R ~ 86 000) offered…
View article: The <i>Gaia</i>-ESO Survey: Homogenisation of stellar parameters and elemental abundances
The <i>Gaia</i>-ESO Survey: Homogenisation of stellar parameters and elemental abundances Open
The Gaia -ESO Survey is a public spectroscopic survey that targeted ≳10 5 stars covering all major components of the Milky Way from the end of 2011 to 2018, delivering its final public release in May 2022. Unlike other spectroscopic survey…
View article: The Gaia-ESO Survey: homogenisation of stellar parameters and elemental abundances
The Gaia-ESO Survey: homogenisation of stellar parameters and elemental abundances Open
The Gaia-ESO Survey is a public spectroscopic survey that has targeted $\gtrsim10^5$ stars covering all major components of the Milky Way from the end of 2011 to 2018, delivering its public final release in May 2022. Unlike other spectrosc…
View article: A neutron star candidate in the long-period binary 56 UMa
A neutron star candidate in the long-period binary 56 UMa Open
Context. 56 UMa is a wide binary system that contains a chemically peculiar red giant and a faint companion. Due to its surface chemical abundances, the red giant was classified as a barium (Ba) star. This implies that the companion has to…
View article: Cannibals in the thick disk
Cannibals in the thick disk Open
Context. Determining ages of stars for reconstructing the history of the Milky Way remains one of the most difficult tasks in astrophysics. This involves knowing when it is possible to relate the stellar mass with its age and when it is no…
View article: The <i>Gaia</i>-ESO Survey: Lithium measurements and new curves of growth
The <i>Gaia</i>-ESO Survey: Lithium measurements and new curves of growth Open
Context. The Gaia-ESO Survey (GES) is a large public spectroscopic survey that was carried out using the multi-object FLAMES spectrograph at the Very Large Telescope. The survey provides accurate radial velocities, stellar parameters, and …
View article: The faint companion in 56 UMa unmasked as a neutron star
The faint companion in 56 UMa unmasked as a neutron star Open
Neutron stars are possible end products of massive star evolution (M ≥ 8 Msun). They are exotic astronomical objects observed with masses between 1.2 and 2.35 Msun and typically emitting at radio and X-ray wavelengths, especially when bein…
View article: The Gaia-ESO Public Spectroscopic Survey: Motivation, implementation, GIRAFFE data processing, analysis, and final data products
The Gaia-ESO Public Spectroscopic Survey: Motivation, implementation, GIRAFFE data processing, analysis, and final data products Open
The Gaia-ESO Public Spectroscopic Survey is an ambitious project designed to obtain astrophysical parameters and elemental abundances for 100,000 stars, including large representative samples of the stellar populations in the Galaxy, and a…
View article: The <i>Gaia</i>-ESO Public Spectroscopic Survey: Motivation, implementation, GIRAFFE data processing, analysis, and final data products
The <i>Gaia</i>-ESO Public Spectroscopic Survey: Motivation, implementation, GIRAFFE data processing, analysis, and final data products Open
Context. The Gaia-ESO Public Spectroscopic Survey is an ambitious project designed to obtain astrophysical parameters and elemental abundances for 100 000 stars, including large representative samples of the stellar populations in the Gala…
View article: The <i>Gaia</i>-ESO Public Spectroscopic Survey: Implementation, data products, open cluster survey, science, and legacy
The <i>Gaia</i>-ESO Public Spectroscopic Survey: Implementation, data products, open cluster survey, science, and legacy Open
Context. In the last 15 years different ground-based spectroscopic surveys have been started (and completed) with the general aim of delivering stellar parameters and elemental abundances for large samples of Galactic stars, complementing …
View article: Insights into AGB Nucleosynthesis Thanks to Spectroscopic Abundance Measurements in Intrinsic and Extrinsic Stars
Insights into AGB Nucleosynthesis Thanks to Spectroscopic Abundance Measurements in Intrinsic and Extrinsic Stars Open
The foundations of stellar nucleosynthesis have been established more than 70 years ago. Since then, much progress has been made, both on the theoretical side, with stellar evolution and nucleosynthesis models of increasing complexity, usi…