Observational constraints on the origin of the elements. VII. NLTE analysis of Y II lines in spectra of cool stars and implications for Y as a Galactic chemical clock

Abstract

Yttrium (Y), a key s-process element, is commonly used in nucleosynthesis studies and as a Galactic chemical clock when combined with magnesium (Mg). We study the applicability of the previously assumed LTE line formation assumption in Y abundance studies of main-sequence and red giant stars, and probe the impact of NLTE effects on the [Y/Mg] ratio, a proposed stellar age indicator. We derive stellar parameters, ages, and NLTE abundances of Fe, Mg, and Y for 48 solar analogue stars from high-resolution spectra acquired within the Gaia-ESO survey. For Y, we present a new NLTE atomic model. We determine a solar NLTE abundance of A(Y)${}_{\mathrm{NLTE}}=2.12\pm 0.04$ dex, $0.04$ dex higher than LTE. NLTE effects on Y abundance are modest for optical Y II lines, which are frequently used in Sun-like stars diagnostics. NLTE has a small impact on the [Y/Mg] ratio in such stars. For metal-poor red giants, NLTE effects on Y II lines are substantial, potentially exceeding $+0.5$ dex. For the Gaia/4MOST/WEAVE benchmark star, HD 122563, we find the NLTE abundance ratio of [Y/Fe]${}_{\mathrm{NLTE}}=-0.55\pm 0.04$ dex with consistent abundances obtained from different Y II lines. NLTE has a differential effect on Y abundance diagnostics in late-type stars. They notably affect Y II lines in red giants and very metal-poor stars, which are typical Galactic enrichment tracers of neutron-capture elements. For main-sequence stars, NLTE effects on optical diagnostic Y II lines remain minimal across metallicities. This affirms the [Y/Mg] ratio's reliability as a cosmochronometer for Sun-like stars.

12 pages, 10 figures, accepted by MNRAS

References in corpus (30)

• A grid of MARCS model atmospheres for late-type stars I. Methods and general properties
• Estimating distances from parallaxes. V: Geometric and photogeometric distances to 1.47 billion stars in Gaia Early Data Release 3
• The Dartmouth Stellar Evolution Database
• Galactic chemical evolution: Carbon through Zinc
• The Dawes Review 2: Nucleosynthesis and stellar yields of low and intermediate-mass single stars
• A Search for Stars of Very Low Metal Abundance. VI. Detailed Abundances of 313 Metal-Poor Stars
• High-precision abundances of elements in solar twin stars: Trends with stellar age and elemental condensation temperature
• Near-UV Observations of HD221170: New Insights into the Nature of r-Process-Rich Stars
• Neutron-capture elements in the very metal-poor star HD122563
• Observational constraints on the origin of the elements. IV: The standard composition of the Sun
• The elemental composition of the Sun III. The heavy elements Cu to Th
• The Gaia-ESO Public Spectroscopic Survey: Implementation, data products, open cluster survey, science, and legacy
• Atomic data for the Gaia-ESO Survey
• The Gaia FGK Benchmark Stars - High resolution spectral library
• Abundance to age ratios in the HARPS-GTO sample with Gaia DR2: Chemical clocks for a range of [Fe/H]
• A maximum likelihood method for fitting colour-magnitude diagrams
• Solar oxygen abundance
• The Gaia-ESO survey: the non-universality of the age-chemical-clocks-metallicity relations in the Galactic disc
• On the metallicity dependance of the [Y/Mg] - age relation for solar type stars
• High-precision abundances of elements in Kepler LEGACY stars. Verification of trends with stellar age
• Experimental and theoretical oscillator strengths of Mg I for accurate abundance analysis
• Observational constraints on the origin of the elements II. 3D non-LTE formation of Ba ii lines in the solar atmosphere
• Non-LTE Radiative Transfer with Turbospectrum
• Stellar ages, masses, extinctions and orbital parameters based on spectroscopic parameters of Gaia DR3
• 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
• Fundamental stellar parameters of benchmark stars from CHARA interferometry. I. Metal-poor stars
• The detailed chemical abundance patterns of accreted halo stars from the optical to infrared
• Diversity of Abundance Patterns of Light Neutron-capture Elements in Very-metal-poor Stars
• First detection of oscillations in the Halo giant HD 122563: validation of seismic scaling relations and new fundamental parameters
• Chemical Compositions of Red Giant Stars from Habitable Zone Planet Finder Spectroscopy

Cited by in corpus (23)

• The GALAH survey: Tracing the Milky Way's formation and evolution through RR Lyrae stars
• 3D NLTE modelling of Y and Eu. Centre-to-limb variation and solar abundances
• New Radiative and Collisional Atomic Data for Sr {\sc ii} and Y {\sc ii} with application to Kilonova modelling
• Observational constraints on the origin of the elements. IX. 3D NLTE abundances of metals in the context of Galactic Chemical Evolution Models and 4MOST
• Evidence of Gaia Enceladus experiencing at least two passages around the Milky Way
• Exploring the dependence of chemical traits on metallicity: chemical trends for red giant stars with asteroseismic ages
• NLTE abundances of Eu for a sample of metal-poor stars in the Galactic Halo and Metal-poor Disk with 1D and <3D> models
• 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
• The GALAH survey: Improving chemical abundances using star clusters
• Stellar Population Astrophysics (SPA) with the TNG: NLTE atmospheric parameters and abundances of giant stars in 33 Open Clusters
• Rare Find: Discovery and chemo-dynamical properties of two s-process enhanced RR Lyrae stars
• Abundance analysis of benchmark M dwarfs
• The R-Process Alliance: Exploring the cosmic scatter among ten r-process sites with stellar abundances
• Oxygen Isotope Ratios in Hydrogen-Deficient Carbon Stars: A Correlation with Effective Temperature and Implications for White Dwarf Merger Outcomes
• Chemical composition of planetary hosts: II. Abundances of neutron-capture elements
• Full abundance study of two newly discovered barium giants
• Calibration of the [C/N] and [Y/Mg] chemical clocks with asteroseismic ages from the TESS space mission
• Th/Eu abundance ratio of red giants in the Kepler Field
• Exploring the History of Stellar Mergers with Chemistry: Examining the Origins of Massive $\alpha$-Enriched Stars using Carbon Isotope Ratios
• Quantifying Element Importance for Mass Recovery from Population III Supernova Yield Fits
• 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
• Investigating non-LTE abundances of Neodymium (Nd) in metal-poor FGK stars
• Observational constraints on the origin of the elements. X. Combining NLTE and machine learning for chemical diagnostics of 4 million stars in the 4MIDABLE-HR survey