Influence of inelastic collisions with hydrogen atoms on the non-LTE modelling of Ca I and Ca II lines in late-type stars

Abstract

We perform the non-local thermodynamic equilibrium (NLTE) calculations for Ca I-II with the updated model atom that includes new quantum-mechanical rate coefficients for Ca I + H I collisions from two recent studies, that is, by Barklem and by Mitrushchenkov, Guitou, Belyaev, Yakovleva, Spielfiedel, and Feautrier, and investigate the accuracy of calcium abundance determinations using the Sun, Procyon, and five metal-poor (MP) stars with well-determined stellar parameters. We show that both collisional recipes lead to very similar NLTE results. When using the subordinate lines of Ca I and the high-excitation lines of Ca II, NLTE provides the smaller line-to-line scatter compared with the LTE case for each star. For Procyon, NLTE removes a steep trend with line strength among strong Ca I lines seen in LTE and leads to consistent [Ca/H] abundances from the two ionisation stages. In the MP stars, the NLTE abundance from Ca II 8498 A agrees well with that from the Ca I subordinate lines. NLTE largely removes abundance discrepancies between the high-excitation lines of Ca I and Ca II 8498 A obtained for our four [Fe/H] < -2 stars under the LTE assumption. We investigate the formation of the Ca I resonance line in the [Fe/H] < -2 stars. Consistent NLTE abundances from the Ca I resonance line and the Ca II lines are found for two hyper metal-poor stars HE0107-5240 and HE1327-2326. We provide the NLTE abundance corrections for 28 lines of Ca I in a grid of model atmospheres suitable for abundance analysis of FGK-type dwarfs and subgiants.

arXiv comment12 pages, 3 tables, 10 figures; accepted for publication in A&A

References in corpus (36)

• A grid of MARCS model atmospheres for late-type stars I. Methods and general properties
• First stars V - Abundance patterns from C to Zn and supernova yields in the early Galaxy
• GAIA: Composition, Formation and Evolution of the Galaxy
• The Radial Velocity Experiment (RAVE): first data release
• Nucleosynthetic signatures of the first stars
• A stellar relic from the early Milky Way
• A single low-energy, iron-poor supernova as the source of metals in the star SMSS J 031300.36-670839.3
• An extremely primitive halo star
• The kinematic status and mass content of the Sculptor dwarf spheroidal galaxy
• Gaia FGK Benchmark Stars: Effective temperatures and surface gravities
• A non-LTE study of neutral and singly-ionized iron line spectra in 1D models of the Sun and selected late-type stars
• Hubble Space Telescope Astrometry of the Procyon System
• Stellar Diameters and Temperatures III. Main Sequence A, F, G, & K Stars: Additional high-precision measurements and empirical relations
• HE 0557-4840 - Ultra-Metal-Poor and Carbon-Rich
• The elemental composition of the Sun I. The intermediate mass elements Na to Ca
• The NIR Ca II triplet at low metallicity - Searching for extremely low-metallicity stars in classical dwarf galaxies
• HE0107-5240, A Chemically Ancient Star.I. A Detailed Abundance Analysis
• HE1327-2326, an unevolved star with [Fe/H]<-5.0. I. A Comprehensive Abundance Analysis
• Normal and Outlying Populations of the Milky Way Stellar Halo at [Fe/H] < -2
• A non-LTE study of neutral and singly-ionized calcium in late-type stars
• TOPoS: II. On the bimodality of carbon abundance in CEMP stars. Implications on the early chemical evolution of galaxies
• Systematic non-LTE study of the $-2.6\le$ [Fe/H] $\le 0.2$ F and G dwarfs in the solar neighbourhood. II. Abundance patterns from Li to Eu
• Isotope-selective photo-ionization for calcium ion trapping
• Kinetic equilibrium of iron in the atmospheres of cool stars III. The ionization equilibrium of selected reference stars
• A primordial star in the heart of the Lion
• Systematic NLTE study of the -2.6 < [Fe/H] < 0.2 F and G dwarfs in the solar neighbourhood. I. Stellar atmosphere parameters
• SD 1313-0019 -- Another second-generation star with [Fe/H] = -5.0, observed with the Magellan Telescope
• Excitation and charge transfer in low-energy hydrogen atom collisions with neutral atoms: Theory, comparisons, and application to Ca
• A grid of NLTE corrections for magnesium and calcium in late-type giant and supergiant stars: application to Gaia
• NLTE determination of the calcium abundance and 3D corrections in extremely metal-poor stars
• Accuracy of atmospheric parameters of FGK dwarfs determined by spectrum fitting
• Atomic data from the Iron Project. LXIV. Radiative transition rates and collision strengths for Ca II
• Non-LTE Abundances and Consequences for the Evolution of the alpha elements in the Galaxy
• Three-dimensional interferometric, spectrometric, and planetary views of Procyon
• Influence of departures from LTE on calcium, titanium, and iron abundance determinations in cool giants of different metallicities
• HE 1327-2326, an unevolved star with [Fe/H] < -5.0 III. Does Its Atmosphere Reflect Its Natal Composition?

Cited by in corpus (32)

• The chemical make-up of the Sun: A 2020 vision
• Observational constraints on the origin of the elements. IV: The standard composition of the Sun
• High-precision stellar abundances of the elements - methods and applications
• High-precision abundances of elements in Kepler LEGACY stars. Verification of trends with stellar age
• Non-LTE Radiative Transfer with Turbospectrum
• Pristine IX: CFHT ESPaDOnS Spectroscopic Analysis of 115 Bright Metal-Poor Candidate Stars
• The Gaia-ESO survey: 3D NLTE abundances in the open cluster NGC 2420 suggest atomic diffusion and turbulent mixing at the origin of chemical abundance variations
• 3D non-LTE iron abundances in FG-type dwarfs
• A blue depression in the optical spectra of M dwarfs
• Detailed chemical compositions of the wide binary HD 80606/80607: revised stellar properties and constraints on planet formation
• Ca line formation in late-type stellar atmospheres: I. The model atom
• Copper abundance from Cu I and Cu II lines in metal-poor star spectra: NLTE vs LTE
• Mono-enriched stars and Galactic chemical evolution -- Possible biases in observations and theory
• The chemical composition of $\alpha$ Cen AB revisited
• NLTE analysis of copper lines in different stellar populations
• The Pristine survey -- XVII. The C-19 stream is dynamically hot and more extended than previously thought
• Comparative high-resolution spectroscopy of M dwarfs -- exploring non-LTE effects
• The Pristine survey XIV: chemical analysis of two ultra-metal-poor stars
• 1D non-LTE corrections for chemical abundance analyses of very metal-poor stars
• Abundances of alpha-Process Elements in Thin-Disk, Thick-Disk, and Halo Stars of the Galaxy: Non-LTE Analysis
• NLTE modelling of integrated light spectra. Abundances of barium, magnesium, and manganese in a metal-poor globular cluster
• The Pristine Inner Galaxy Survey (PIGS) VII: a discovery of the first inner Galaxy CEMP-r/s star
• G112-43/44: A metal-poor binary star with a unique chemical composition and kinematics like the Helmi streams
• Detailed abundances of the wide pairs of stars with and without planets: the binary systems 16 Cyg and HD 219542
• Probing 3D and NLTE models using APOGEE observations of globular cluster stars
• Accurate Metallicities for Very Metal-Poor Stars from the Ca~II Infrared Triplet
• Discovery of a pair of very metal-poor stars enriched in neutron-capture elements: The proto-disk r-II star BPS CS 29529-0089 and the Gaia-Sausage-Enceladus r-I star TYC 9219-2422-1
• Revisiting the iron abundance in the hyper iron-poor star HE 1327-2326 with UV COS/$HST$ data
• 3D non-LTE Ca II line formation in metal-poor FGK stars. I. Abundance corrections, radial velocity corrections, and synthetic spectra
• The chemical DNA of the Magellanic Clouds V. R-process dominates neutron capture elements production in the oldest SMC stars
• The SAPP pipeline for the determination of stellar abundances and atmospheric parameters of stars in the core program of the PLATO mission
• The R-Process Alliance: A Nearly Complete R-Process Abundance Template Derived from Ultraviolet Spectroscopy of the R-Process-Enhanced Metal-Poor Star HD 222925