A. M. Amarsi
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View article: The solar sulphur abundance in view of large-scale atomic structure calculations and 3D non-LTE models
The solar sulphur abundance in view of large-scale atomic structure calculations and 3D non-LTE models Open
The solar chemical composition is a fundamental yardstick in astrophysics and the topic of heated debate in recent literature. We re-evaluated the abundance of sulphur in the photosphere by studying seven S I lines in the solar disc-centre…
View article: Abundance Analysis of Chemically Depleted Post-AGB/Post-RGB Binaries with Faint Discs
Abundance Analysis of Chemically Depleted Post-AGB/Post-RGB Binaries with Faint Discs Open
Post-AGB and post-RGB binaries with stable circumbinary discs provide key insights into late stellar and disc evolution, revealing how binary interactions shape disc structure and stellar surface composition. A defining trait of such syste…
View article: The solar sulphur abundance in view of large-scale atomic structure calculations and 3D non-LTE models
The solar sulphur abundance in view of large-scale atomic structure calculations and 3D non-LTE models Open
The solar chemical composition is a fundamental yardstick in astrophysics and the topic of heated debate in recent literature. We re-evaluate the abundance of sulphur in the photosphere by studying seven S I lines in the solar disc-centre …
View article: Grid/NLTE
Grid/NLTE Open
Non-LTE departure coefficients for late-type stars. For this version, see primarily The solar sulphur abundance in view of large-scale atomic structure calculations and 3D non-LTE models (Amarsi, Li, Grevesse, and Jurewicz, A&A, submitted)…
View article: How homogeneous was the chemical enrichment of the Milky Way 13 gigayears ago?
How homogeneous was the chemical enrichment of the Milky Way 13 gigayears ago? Open
We reanalyze the chemical composition of the metal-poorest tail of the Galactic halo using highly accurate atmospheric parameters Giribaldi et al. (2021, 2023) and cutting-edge 3D NLTE models Amarsi et al (2018). Most [Mg/Fe] versus [Fe/H]…
View article: Homogeneous Stellar Atmospheric Parameters and 22 Elemental Abundances for FGK Stars Derived from LAMOST Low-resolution Spectra with DD-PAYNE
Homogeneous Stellar Atmospheric Parameters and 22 Elemental Abundances for FGK Stars Derived from LAMOST Low-resolution Spectra with DD-PAYNE Open
A deep understanding of our Galaxy calls for detailed decomposition of its stellar populations via their chemical fingerprints. This requires precise stellar abundances of many elements for a large number of stars. Here, we present an upda…
View article: The PLATO mission
The PLATO mission Open
View article: Influence of the magnetic activity cycle on mean density and acoustic radius inversions
Influence of the magnetic activity cycle on mean density and acoustic radius inversions Open
Context. Asteroseismic modelling is set to play a crucial role in upcoming space-based missions such as PLATO, CubeSpec, and Roman. Despite the significant progress made in this field, asteroseismology has uncovered notable discrepancies b…
View article: The most metal-poor tail of the Galactic halo: Hypothesis for its origin from precise spectral analysis
The most metal-poor tail of the Galactic halo: Hypothesis for its origin from precise spectral analysis Open
Context . The origin of the Galactic halo is one of the fundamental topics linking the study of galaxy formation and evolution to cosmology. Aims . Our goal is to derive precise and accurate stellar parameters, Mg abundances, and ages for …
View article: 3D non-LTE Ca II line formation in metal-poor FGK stars
3D non-LTE Ca II line formation in metal-poor FGK stars Open
Context. The Ca II near-ultraviolet resonance doublet (H&K) and the near-infrared triplet (CaT) are among the strongest features in stellar spectra of FGK-type stars. These spectral lines remain prominent down to extremely low metallicitie…
View article: Revisiting inelastic Cu + H collisions and the non-LTE Galactic evolution of copper
Revisiting inelastic Cu + H collisions and the non-LTE Galactic evolution of copper Open
The Galactic evolution of copper remains poorly understood, partly due to the strong departures from local thermodynamic equilibrium (LTE) affecting Cu I lines. A key source of uncertainty in non-LTE modelling is the treatment of inelastic…
View article: Tracing chemical depletion in evolved binaries hosting second-generation transition discs
Tracing chemical depletion in evolved binaries hosting second-generation transition discs Open
The mechanisms responsible for chemical depletion across diverse astrophysical environments are not yet fully understood. In this paper, we investigate chemical depletion in post-AGB/post-RGB binary stars hosting second-generation transiti…
View article: Chemical Abundances in the Nuclear Star Cluster of the Milky Way: Alpha-element Trends and Their Similarities with the Inner Bulge
Chemical Abundances in the Nuclear Star Cluster of the Milky Way: Alpha-element Trends and Their Similarities with the Inner Bulge Open
Chemical characterization of the Galactic center is essential for understanding its formation and structural evolution. Trends of alpha ( α ) elements, such as magnesium, silicon, and calcium, serve as powerful diagnostic tools, offering i…
View article: Constraints on the properties of macroscopic transport in the Sun from combined lithium and beryllium depletion
Constraints on the properties of macroscopic transport in the Sun from combined lithium and beryllium depletion Open
Context. The Sun is a privileged laboratory of stellar evolution, thanks to the quality and complementary nature of available constraints. Using these observations, we are able to draw a detailed picture of its internal structure and dynam…
View article: Constraints on the properties of macroscopic transport in the Sun from combined lithium and beryllium depletion
Constraints on the properties of macroscopic transport in the Sun from combined lithium and beryllium depletion Open
Context. The Sun is a privileged laboratory of stellar evolution, thanks to the quality and complementary nature of available constraints. Using these observations, we are able to draw a detailed picture of its internal structure and dynam…
View article: The GALAH survey: Data release 4
The GALAH survey: Data release 4 Open
The stars of the Milky Way carry the chemical history of our Galaxy in their atmospheres as they journey through its vast expanse. Like barcodes, we can extract the chemical fingerprints of stars from high-resolution spectroscopy. The four…
View article: s-process enriched post-AGB star J003643.94–723722.1 in the SMC with an extreme C/O ratio and the first precise detection of lead
s-process enriched post-AGB star J003643.94–723722.1 in the SMC with an extreme C/O ratio and the first precise detection of lead Open
Post-asymptotic giant branch (post-AGB) stars are exquisite tracers of s -process nucleosynthesis, preserving the surface chemical signatures of their AGB evolution. The increasing chemical diversity observed among them challenges current …
View article: Chemical Abundances in the Nuclear Star Cluster of the Milky Way: alpha-Element Trends and Their Similarities with the Inner Bulge
Chemical Abundances in the Nuclear Star Cluster of the Milky Way: alpha-Element Trends and Their Similarities with the Inner Bulge Open
A chemical characterization of the Galactic Center is essential for understanding its formation and structural evolution. Trends of alpha-elements, such as Mg, Si, and Ca, serve as powerful diagnostic tools, offering insights into star-for…
View article: The age of the Methuselah star in light of stellar evolution models with tailored abundances
The age of the Methuselah star in light of stellar evolution models with tailored abundances Open
Context. HD140283, or the Methuselah star, is a well-known reference object in stellar evolution. Its peculiar chemical composition, proximity and absence of reddening makes it an interesting case-study of Pop II stars. Thanks to recent ob…
View article: The age of the Methuselah star in the light of stellar evolution models with tailored abundances
The age of the Methuselah star in the light of stellar evolution models with tailored abundances Open
Context. HD140283, or the Methuselah star, is a well-known reference object in stellar evolution. Its peculiar chemical composition, proximity and absence of reddening makes it an interesting case-study of Pop II stars. Thanks to recent ob…
View article: Differences in elemental abundances between <scp>CI</scp> chondrites and the solar photosphere
Differences in elemental abundances between <span>CI</span> chondrites and the solar photosphere Open
CI chondrites have been a proxy for the solar system since the mid‐20th century. The photospheric and CI chondrite abundances ( P and CI , respectively) show a strong correlation. CI as a proxy is also justified by the (i) smoothness of th…
View article: The solar beryllium abundance revisited with 3D non-LTE models
The solar beryllium abundance revisited with 3D non-LTE models Open
The present-day abundance of beryllium in the solar atmosphere provides clues about mixing mechanisms within stellar interiors. However, abundance determinations based on the Be II 313.107 nm line are prone to systematic errors due to impe…
View article: The solar beryllium abundance revisited with 3D non-LTE models
The solar beryllium abundance revisited with 3D non-LTE models Open
The present-day abundance of beryllium in the solar atmosphere provides clues about mixing mechanisms within stellar interiors. However, abundance determinations based on the Be II 313.107 nm line are prone to systematic errors due to impe…
View article: Spectroscopic characterisation of gravitationally lensed stars at high redshifts
Spectroscopic characterisation of gravitationally lensed stars at high redshifts Open
Deep imaging of galaxy cluster fields have in recent years revealed tens of candidates for gravitationally lensed stars at redshifts z ≈ 1 − 6, and future searches are expected to reveal highly magnified stars from even earlier epochs. Mul…
View article: Revisiting the statistical equilibrium of H<sup>−</sup> in stellar atmospheres
Revisiting the statistical equilibrium of H<sup>−</sup> in stellar atmospheres Open
The negative hydrogen ion H − is, almost without exception, treated in local thermodynamic equilibrium (LTE) in the modelling of F, G, and K stars, where it is the dominant opacity source in the visual spectral region. This assumption rest…
View article: Imprint of the magnetic activity cycle on solar asteroseismic characterisation based on 26 years of GOLF and BiSON data
Imprint of the magnetic activity cycle on solar asteroseismic characterisation based on 26 years of GOLF and BiSON data Open
Context. Asteroseismic modelling will play a key role in future space-based missions, such as PLATO, CubeSpec, and Roman . Despite remarkable achievements, asteroseismology has revealed significant discrepancies between observations and th…
View article: An extended and refined grid of 3D STAGGER model atmospheres
An extended and refined grid of 3D STAGGER model atmospheres Open
Context . Traditional one-dimensional hydrostatic model atmospheres introduce systematic modelling errors into spectroscopic analyses of FGK-type stars. Aims . We present an updated version of the STAGGER-grid of three-dimensional model at…
View article: 3D non-local thermodynamic equilibrium magnesium abundances reveal a distinct halo population
3D non-local thermodynamic equilibrium magnesium abundances reveal a distinct halo population Open
Magnesium is one of the most important elements in stellar physics as an electron donor; in Galactic archaeology, magnesium serves to distinguish different stellar populations. However, previous studies of Mg I and Mg II lines in metal-poo…
View article: Three-Dimensional Nonlocal Thermodynamic Equilibrium Abundance Analyses of Late-Type Stars
Three-Dimensional Nonlocal Thermodynamic Equilibrium Abundance Analyses of Late-Type Stars Open
The chemical compositions of stars encode the history of the universe and are thus fundamental for advancing our knowledge of astrophysics and cosmology. However, measurements of elemental abundance ratios, and our interpretations of them,…
View article: The PLATO Mission
The PLATO Mission Open
PLATO (PLAnetary Transits and Oscillations of stars) is ESA's M3 mission designed to detect and characterise extrasolar planets and perform asteroseismic monitoring of a large number of stars. PLATO will detect small planets (down to <2 R_…