The GALAH Survey: Non-LTE departure coefficients for large spectroscopic surveys

Abstract

Massive sets of stellar spectroscopic observations are rapidly becoming available and these can be used to determine the chemical composition and evolution of the Galaxy with unprecedented precision. One of the major challenges in this endeavour involves constructing realistic models of stellar spectra with which to reliably determine stellar abundances. At present, large stellar surveys commonly use simplified models that assume that the stellar atmospheres are approximately in local thermodynamic equilibrium (LTE). To test and ultimately relax this assumption, we have performed non-LTE calculations for $13$ different elements (H, Li, C, N, O, Na, Mg, Al, Si, K, Ca, Mn, and Ba), using recent model atoms that have physically-motivated descriptions for the inelastic collisions with neutral hydrogen, across a grid of $3756$ 1D MARCS model atmospheres that spans $3000\le T_{\mathrm{eff}}/\mathrm{K}\le 8000$, $-0.5\le \log g/\mathrm{cm}{\mathrm{s}}^{-2}\le 5.5$, and $-5\le [Fe/H]\le 1$. We present the grids of departure coefficients that have been implemented into the GALAH DR3 analysis pipeline in order to complement the extant non-LTE grid for iron. We also present a detailed line-by-line re-analysis of $50126$ stars from GALAH DR3. We found that relaxing LTE can change the abundances by between $-0.7\mathrm{dex}$ and $+0.2\mathrm{dex}$ for different lines and stars. Taking departures from LTE into account can reduce the dispersion in the $[A/Fe]$ versus $[Fe/H]$ plane by up to $0.1\mathrm{dex}$, and it can remove spurious differences between the dwarfs and giants by up to $0.2\mathrm{dex}$. The resulting abundance slopes can thus be qualitatively different in non-LTE, possibly with important implications for the chemical evolution of our Galaxy.

arXiv comment19 pages, 25 figures, 2 tables, arXiv abstract abridged; accepted for publication in A&A

References in corpus (100)

• The chemical composition of the Sun
• Gaia Data Release 2. Summary of the contents and survey properties
• A grid of MARCS model atmospheres for late-type stars I. Methods and general properties
• The Sixteenth Data Release of the Sloan Digital Sky Surveys: First Release from the APOGEE-2 Southern Survey and Full Release of eBOSS Spectra
• Exploring the Milky Way stellar disk. A detailed elemental abundance study of 714 F and G dwarf stars in the Solar neighbourhood
• Galactic chemical evolution: Carbon through Zinc
• The GALAH Survey: Scientific Motivation
• ASPCAP: The Apogee Stellar Parameter and Chemical Abundances Pipeline
• The Dawes Review 2: Nucleosynthesis and stellar yields of low and intermediate-mass single stars
• Chemical Cartography with APOGEE: Metallicity Distribution Functions and the Chemical Structure of the Milky Way Disk
• Two distinct halo populations in the solar neighborhood. Evidence from stellar abundance ratios and kinematics
• The Primordial Lithium Problem
• Spectroscopy Made Easy: Evolution
• The Cannon: A data-driven approach to stellar label determination
• Non-LTE calculations for neutral Na in late-type stars using improved atomic data
• The GALAH Survey: Second Data Release
• NLTE line formation of Fe in late-type stars II: 1D spectroscopic stellar parameters
• High-precision abundances of elements in solar twin stars: Trends with stellar age and elemental condensation temperature
• The 12C(a,g)16O reaction and its implications for stellar helium burning
• First stars XII. Abundances in extremely metal-poor turnoff stars,and comparison with the giants
• The Payne: self-consistent ab initio fitting of stellar spectra
• Chemical abundances of 1111 FGK stars from the HARPS GTO planet search program II: Cu, Zn, Sr, Y, Zr, Ba, Ce, Nd and Eu
• The Status of Multi-Dimensional Core-Collapse Supernova Models
• Abundance Estimates for 16 Elements in 6 Million Stars from LAMOST DR5 Low-Resolution Spectra
• The intermediate neutron-capture process and carbon-enhanced metal-poor stars
• 3D Hydrodynamical Simulations of Surface Convection in Red Giant Stars. Impact on spectral line formation and abundance analysis
• Non-LTE line formation of Fe in late-type stars - III. 3D non-LTE analysis of metal-poor stars
• Two distinct halo populations in the solar neighborhood. II. Evidence from stellar abundances of Mn, Cu, Zn, Y, and Ba
• The Chemical Homogeneity of Sun-like Stars in the Solar Neighborhood
• Production and evolution of Li, Be and B isotopes in the Galaxy
• Verifying asteroseismically determined parameters of Kepler stars using hipparcos parallaxes: self-consistent stellar properties and distances
• 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
• The Sixth Data Release of the Radial Velocity Experiment (RAVE) -- II: Stellar Atmospheric Parameters, Chemical Abundances and Distances
• Carbon, oxygen, and iron abundances in disk and halo stars. Implications of 3D non-LTE spectral line formation
• Partition functions and equilibrium constants for diatomic molecules and atoms of astrophysical interest
• Disentangling the Galactic Halo with APOGEE: I. Chemical and Kinematical Investigation of Distinct Metal-Poor Populations
• Li abundances in F stars: planets, rotation and galactic evolution
• NLTE determination of the aluminium abundance in a homogeneous sample of extremely metal-poor stars
• Observational constraints on the origin of the elements. I. 3D NLTE formation of Mn lines in late-type stars
• The lithium isotopic ratio in very metal-poor stars
• Non-LTE aluminium abundances in late-type stars
• Solar abundance of manganese: a case for the existence of near Chandrasekhar-mass Type Ia supernova progenitors
• Inelastic H+Li and H^-+Li^+ collisions and non-LTE Li I line formation in stellar atmospheres
• New Type Ia supernova Yields and the Manganese and Nickel Problems in the Milky Way and Dwarf Spheroidal Galaxies
• Non-LTE oxygen line formation in 3D hydrodynamic model stellar atmospheres
• Non-local thermodynamic equilibrium stellar spectroscopy with 1D and <3D> models - I. Methods and application to magnesium abundances in standard stars
• Accurate abundance analysis of late-type stars: advances in atomic physics
• On inelastic hydrogen atom collisions in stellar atmospheres
• High-precision stellar abundances of the elements - methods and applications
• Mg line formation in late-type stellar atmospheres: I. The model atom
• The evolution of CNO isotopes: the impact of massive stellar rotators
• Abundances of neutron-capture elements in stars of the galactic disk substructures
• NLTE analysis of Sr lines in spectra of late-type stars with new R-matrix atomic data
• Oxygen abundances in low- and high-alpha field halo stars and the discovery of two field stars born in globular clusters
• Center-to-Limb Variation of Solar Line Profiles as a Test of NLTE Line Formation Calculations
• Stellar parametrization from Gaia RVS spectra
• The photospheric solar oxygen project: IV. 3D-NLTE investigation of the 777 nm triplet lines
• The solar silicon abundance based on 3D non-LTE calculations
• High-precision abundances of Sc, Mn, Cu, and Ba in solar twins. Trends of element ratios with stellar age
• Excitation and charge transfer in low-energy hydrogen atom collisions with neutral atoms: Theory, comparisons, and application to Ca
• Spatial variations in the Milky Way disc metallicity-age relation
• Non-LTE line formation of Fe in late-type stars IV: Modelling of the solar centre-to-limb variation in 3D
• Effective temperature determinations of late-type stars based on 3D non-LTE Balmer line formation
• The GALAH survey: The data reduction pipeline
• Inelastic Na+H collision data for non-LTE applications in stellar atmospheres
• The Gaia-ESO Survey: Sodium and aluminium abundances in giants and dwarfs - Implications for stellar and Galactic chemical evolution
• Inelastic O+H collisions and the OI 777nm solar centre-to-limb variation
• Grid of theoretical NLTE equivalent widths of four Ba II lines and barium abundance in cool stars
• Inelastic Mg+H collision data for non-LTE applications in stellar atmospheres
• Planet signatures and effect of the chemical evolution of the Galactic thin-disk stars
• Evidence for Sub-Chandrasekhar Type Ia Supernovae from Stellar Abundances in Dwarf Galaxies
• Non-LTE analysis of K I in late-type stars
• Observational constraints on the origin of the elements II. 3D non-LTE formation of Ba ii lines in the solar atmosphere
• Learning about the intermediate neutron-capture process from lead abundances
• NLTE for APOGEE: Simultaneous Multi-Element NLTE Radiative Transfer
• A NLTE line blanketed model of a solar type star
• Mg line formation in late-type stellar atmospheres: II. Calculations in a grid of 1D models
• IRIS: A Generic Three-Dimensional Radiative Transfer Code
• Exploring the production and depletion of lithium in the Milky Way stellar disk
• Accurate effective temperatures of the metal-poor benchmark stars HD 140283, HD 122563 and HD 103095 from CHARA interferometry
• Manganese Indicates a Transition from Sub- to Near-Chandrasekhar Type Ia Supernovae in Dwarf Galaxies
• 3D non-LTE line formation of neutral carbon in the Sun
• Observational constraints on the origin of the elements. III. Evidence for the dominant role of sub-Chandrasekhar SN Ia in the chemical evolution of Mn and Fe in the Galaxy
• Fundamental stellar parameters of benchmark stars from CHARA interferometry. I. Metal-poor stars
• The Impact of Nuclear Reaction Rate Uncertainties On The Evolution of Core-Collapse Supernova Progenitors
• Mn abundances in the stars of the Galactic disc with metallicities -1.0 < [Fe/H] < 0.3
• The GALAH Survey: A new constraint on cosmological lithium and Galactic lithium evolution from warm dwarf stars
• The NLTE Barium Abundance in Dwarf Stars in the Metallicity Range of -1 < [Fe/H] < +0.3
• Non-local thermodynamic equilibrium stellar spectroscopy with 1D and 3D models - II. Chemical properties of the Galactic metal-poor disc and the halo
• Influence of departures from LTE on calcium, titanium, and iron abundance determinations in cool giants of different metallicities
• On the variation of carbon abundance in galaxies and its implications
• Ca line formation in late-type stellar atmospheres: I. The model atom
• Explaining the decrease in ISM lithium at super-solar metallicities in the solar vicinity
• High-resolution Spectroscopic Study of Dwarf Stars in the Northern Sky: Lithium, Carbon, and Oxygen Abundances
• The 3D non-LTE solar nitrogen abundance from atomic lines
• Rayleigh Scattering Cross Section Redward of Ly$\alpha$ by Atomic Hydrogen
• Neutron-capture elements in dwarf galaxies II: Challenges for the s- and i-processes at low metallicity
• Abundances of alpha-Process Elements in Thin-Disk, Thick-Disk, and Halo Stars of the Galaxy: Non-LTE Analysis
• Barium abundance in red giants of NGC 6752. Non-local thermodynamic equilibrium and three-dimensional effects
• The GALAH survey: a catalogue of carbon-enhanced stars and CEMP candidates

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• Non-LTE Radiative Transfer with Turbospectrum
• Abundance-age relations with red clump stars in open clusters
• Characterizing epochs of star formation across the Milky Way disc using age-metallicity distributions of GALAH stars
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• PySME -- Spectroscopy Made Easier
• The K2 Galactic Archaeology Program Data Release 3: Age-abundance patterns in C1-C8 and C10-C18
• Non-LTE abundance corrections for late-type stars from 2000Å to 3μm: I. Na, Mg, and Al
• Evidence that the Hot Jupiter WASP-77 A b Formed Beyond Its Parent Protoplanetary Disk's H2O Ice Line
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• Evidence for sub-Chandrasekhar Type Ia supernovae from the last major merger
• Korg: a modern 1D LTE spectral synthesis package
• The AMBRE Project: Origin and evolution of sulfur in the Milky Way
• Chemical Evolution of R-process Elements in Stars (CERES). I. Stellar parameters and chemical abundances from Na to Zr
• Residual Abundances in GALAH DR3: Implications for Nucleosynthesis and Identification of Unique Stellar Populations
• Comparative high-resolution spectroscopy of M dwarfs -- exploring non-LTE effects
• The homogeneous characterisation of Ariel host stars
• The Lithium Abundances from the Large Sky Area Multi-object Fiber Spectroscopic Telescope Medium-resolution Survey. I. The Method
• 1D non-LTE corrections for chemical abundance analyses of very metal-poor stars
• M giants with IGRINS I. Stellar parameters and $\alpha$-abundance trends of the solar neighborhood population
• The Gaia-ESO Survey: Chemical evolution of Mg and Al in the Milky Way with Machine-Learning
• VLTI/GRAVITY Observations and Characterization of the Brown Dwarf Companion HD 72946 B
• Trading oxygen for iron I: the [O/Fe] -- specific star formation rate relation of galaxies
• Detailed $\alpha$ abundance trends in the inner Galactic bulge
• Revisiting inelastic Cu+H collisions and the non-LTE Galactic evolution of copper
• The Chemical Composition of Extreme-Velocity Stars
• A distinct halo population revealed from 3D non-LTE magnesium abundances
• Homogeneous Stellar Atmospheric Parameters and 22 Elemental Abundances for FGK Stars Derived From LAMOST Low-resolution Spectra with DD-Payne
• Solar center-to-limb variation in Rossiter-McLaughlin and exoplanet transmission spectroscopy
• Using heritability of stellar chemistry to reveal the history of the Milky Way
• Chemical evolution of the Galactic bulge as traced by microlensed dwarf and subgiant stars. VIII. Carbon and oxygen
• Line-depth ratios as indicators of effective temperature and surface gravity
• Chemical Compositions of Red Giant Stars from Habitable Zone Planet Finder Spectroscopy
• Exploring the dependence of chemical traits on metallicity: chemical trends for red giant stars with asteroseismic ages
• Atomic diffusion and mixing in old stars VII. Abundances of Mg, Ti, and Fe in M30
• Probing Na in giant exoplanets with ESPRESSO and 3D NLTE stellar spectra
• LOTUS: A (non-)LTE Optimization Tool for Uniform derivation of Stellar atmospheric parameters
• The peculiar composition of the Sun is not related to giant planets
• Potential Impact of the Sagittarius Dwarf Galaxy on the Formation of Young O-rich Stars
• Determination of Sodium Abundance Ratio from Low-Resolution Stellar Spectra and Its Applications
• The GALAH survey: Improving chemical abundances using star clusters
• Gaia Barium Dwarfs and Their Ostensibly Ordinary Counterparts
• A high-resolution spectroscopic search for multiple populations in the 2 Gyr old cluster NGC 1846
• 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
• The solar sulphur abundance in view of large-scale atomic structure calculations and 3D non-LTE models
• Revisiting the statistical equilibrium of H${}^{-}$ in stellar atmospheres
• 3D non-LTE Ca II line formation in metal-poor FGK stars. I. Abundance corrections, radial velocity corrections, and synthetic spectra
• The metal-poorest tail of the Galactic halo: hypothesis on its origin from precise spectral analysis
• Chemical analysis of the Milky Way's Nuclear Star Cluster: Evidence for a metallicity gradient
• Gaia FGK Benchmark Stars: Selecting Infrared Lines for Abundance Determination
• Quantifying Element Importance for Mass Recovery from Population III Supernova Yield Fits
• The GALAH Survey: A New Sample of Extremely Metal-Poor Stars Using A Machine Learning Classification Algorithm
• Neutron-capture elements record the ordered chemical evolution of the disc over time
• The solar carbon, nitrogen, and oxygen abundances from a 3D LTE analysis of molecular lines
• Supergiant GCIRS 22 in the Milky Way Nuclear Star Cluster: Revised alpha abundances
• APOGEE chemical abundances of stars in the MW satellites Fornax, Sextans, Draco and Carina
• Cepheid Metallicity in the Leavitt Law (C--MetaLL) survey: VIII. High-Resolution IGRINS Spectroscopy of 23 Classical Cepheids: Validating NIR Abundances
• Two sequences in the age-metallicity relation as seen from [C/N] abundances in APOGEE
• A method to derive self-consistent NLTE astrophysical parameters for 4 million high-resolution 4MOST stellar spectra in half a day with invertible neural networks