M3DIS -- A grid of 3D radiation-hydrodynamics stellar atmosphere models for stellar surveys. II. Carbon-enhanced metal-poor stars

Abstract

Understanding the origin and evolution of carbon-enhanced metal-poor (CEMP) stars is key to tracing the Galaxy's early chemical enrichment. We investigate how realistic 3D radiation-hydrodynamics (RHD) model atmospheres affect carbon abundances in CEMP stars and implications for their classification and Galactic chemical evolution (GCE). We focus on biases from traditional 1D hydrostatic models. We use the M3DIS code to compute 3D RHD model atmospheres for main-sequence and sub-giant stars over a wide range of metallicities and carbon enhancements. Synthetic spectra of the CH G-band are calculated with 3D radiative transfer and compared to spectra from classical 1D MARCS models. We derive abundance corrections and apply them to a large SAGA database sample to quantify effects on the carbon abundance distribution and CEMP classification. Our new 3D CEMP models predict cooler upper atmospheric layers than in 1D models, resulting in stronger CH absorption and lower inferred carbon abundances by up to -0.9 dex at the lowest metallicities. Carbon enhancement in the atmosphere itself increases molecular opacities and leads to radiative re-heating, partly offsetting adiabatic cooling in 3D models and reducing 3D-1D abundance corrections. Applying these corrections lowers the CEMP fraction by up to 20% below [Fe/H]=-3 and alters the relative contribution of CEMP sub-classes. The fraction of CEMP-no stars increases while the number of CEMP-r/s stars decreases, due to the downward revision of absolute carbon abundances. These changes bring the Galactic carbon distribution into better agreement with GCE models assuming a 20% contribution from faint supernovae. Realistic model atmospheres are essential to reliably reconstruct the Galaxy's early chemical enrichment history.

arXiv comment16 pages, 13 figures, accepted by A&A

References in corpus (62)

• A grid of MARCS model atmospheres for late-type stars I. Methods and general properties
• The Nucleosynthetic Signature of Population III
• The Extremely Metal-Poor, Neutron-Capture-Rich Star CS 22892-052: A Comprehensive Abundance Analysis
• Near-Field Cosmology with Metal-Poor Stars
• A stellar relic from the early Milky Way
• Carbon Enhanced Metal-Poor Stars. I. Chemical Compositions of 26 Stars
• A Search for Stars of Very Low Metal Abundance. VI. Detailed Abundances of 313 Metal-Poor Stars
• A High Order Godunov Scheme with Constrained Transport and Adaptive Mesh Refinement for Astrophysical MHD
• The Stellar Abundances for Galactic Archeology (SAGA) Database - Compilation of the Characteristics of Known Extremely Metal-Poor Stars
• Simulations of stellar convection with CO5BOLD
• The early star generations: the dominant effect of rotation on the CNO yields
• The Binary Frequency Among Carbon-Enhanced, s-Process Rich, Metal-Poor Stars
• Carbon-Enhanced Metal-Poor Star Frequencies in the Galaxy: Corrections for the Effect of Evolutionary Status on Carbon Abundances
• Supernova Nucleosynthesis in Population III 13 -- 50 $M_{\odot }$ Stars and Abundance Patterns of Extremely Metal-Poor Stars
• CH in stellar atmospheres: an extensive linelist
• The Stagger-grid: A Grid of 3D Stellar Atmosphere Models - I. Methods and General Properties
• The first chemical enrichment in the universe and the formation of hyper metal-poor stars
• A holistic approach to carbon-enhanced metal-poor stars
• Observational constraints on the origin of the elements. IV: The standard composition of the Sun
• Observational Constraints on First-Star Nucleosynthesis. I. Evidence for Multiple Progenitors of CEMP-no Stars
• 3D Hydrodynamical Simulations of Surface Convection in Red Giant Stars. Impact on spectral line formation and abundance analysis
• The $R$-Process Alliance: First Release from the Southern Search for $r$-Process-Enhanced Stars in the Galactic Halo
• Carbon-enhanced Metal-poor Stars in SDSS/SEGUE. I. Carbon Abundance Estimation and Frequency of CEMP Stars
• The Hamburg/ESO R-process Enhanced Star survey (HERES) III. HE 0338-3945 and the formation of the r+s stars
• Carbon-enhanced metal-poor stars: the most pristine objects?
• Observational constraints on the origin of the elements. I. 3D NLTE formation of Mn lines in late-type stars
• On OH line formation and oxygen abundances in metal-poor stars
• Abundance Analysis of HE2148-1247, A Star With Extremely Enhanced Neutron Capture Elements
• High-Resolution Spectroscopic Study of Extremely Metal-Poor Star Candidates from the SkyMapper Survey
• Descendants of the first stars: the distinct chemical signature of second generation stars
• The role of binaries in the enrichment of the early Galactic halo. II. Carbon-Enhanced Metal-Poor Stars - CEMP-no stars
• The extremely low-metallicity tail of the Sculptor dwarf spheroidal galaxy
• CS 30322-023: an ultra metal-poor TP-AGB star?
• On the origin of HE0107-5240, the most iron deficient star presently known
• Stellar Abundances for Galactic Archaeology Database IV - Compilation of Stars in Dwarf Galaxies
• Solar oxygen abundance
• Advanced LIGO Constraints on Neutron Star Mergers and R-Process Sites
• Why one-dimensional models fail in the diagnosis of average spectra from inhomogeneous stellar atmospheres
• Faint Population III supernovae as the origin of the most iron-poor stars
• On the oxygen abundance of HE0107-5240
• Unveiling systematic biases in 1D LTE excitation-ionisation balance of Fe for FGK stars. A novel approach to determination of stellar parameters
• Galactic Archeology with the AEGIS Survey: The Evolution of Carbon and Iron in the Galactic Halo
• Carbon and Strontium Abundances of Metal-Poor Stars
• Observational Constraints on First-Star Nucleosynthesis. II. Spectroscopy of an Ultra Metal-Poor CEMP-no Star
• The Stagger-grid: A Grid of 3D Stellar Atmosphere Models - II. Horizontal and Temporal Averaging and Spectral Line Formation
• Abundances of carbon-enhanced metal-poor stars as constraints on their formation
• Non-LTE Radiative Transfer with Turbospectrum
• Public Release of A-SLOTH: Ancient Stars and Local Observables by Tracing Halos
• Classification of extremely metal-poor stars: absent region in A(C)-[Fe/H] plane and the role of dust cooling
• The benchmark halo giant HD 122563: CNO abundances revisited with three-dimensional hydrodynamic model stellar atmospheres
• The Most Metal-Poor Stars. V. The CEMP-no Stars in 3D and Non-LTE
• The StaggerGrid Project: a Grid of 3D Model Atmospheres for High-Precision Spectroscopy
• An in-depth spectroscopic examination of molecular bands from 3D hydrodynamical model atmospheres I. Formation of the G-band in metal-poor dwarf stars
• Carbon-Enhanced Metal-Poor Stars. Osmium and Iridium Abundances in the Neutron-Capture-Enhanced Subgiants CS31062-050 and LP625-44
• DISPATCH: A Numerical Simulation Framework for the Exa-scale Era. I. Fundamentals
• An in-depth spectroscopic examination of molecular bands from 3D hydrodynamical model atmospheres. II. Carbon-enhanced metal-poor 3D model atmospheres
• A-SLOTH reveals the nature of the first stars
• NLTE analysis of the methylidyne radical (CH) molecular lines in metal-poor stellar atmospheres
• Stellar evolution of massive stars at very low metallicities
• An extended and refined grid of 3D STAGGER model atmospheres. Processed snapshots for stellar spectroscopy
• TOPoS V: Abundance ratios in a sample of very metal-poor turn-off stars
• Observational constraints on the origin of the elements. IX. 3D NLTE abundances of metals in the context of Galactic Chemical Evolution Models and 4MOST

Cited by in corpus (2)

• Towards model-free stellar chemical abundances. Potential applications in the search for chemically peculiar stars in large spectroscopic surveys
• 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