A NLTE line blanketed model of a solar type star

Abstract

We present LTE and NLTE atmospheric models of a star with solar parameters, and study the effect of treating many thousands of Iron group lines out of LTE on the computed atmospheric structure, overall absolute flux distribution, and the moderately high resolution spectrum in the visible and near UV bands. Our NLTE modeling includes the first two or three ionization stages of 20 chemical elements, up to and including much of the Fe-group, and includes about 20000 Fe I and II lines. We investigate separately the effects of treating the light metals and the Fe-group elements in NLTE. Our main conclusions are that 1) NLTE line blanketed models with direct multi-level NLTE for many actual transitions gives qualitatively similar results as the more approximate treatment of Anderson (1989) for both the Fe statistical equilibrium and the atmospheric temperature structure, 2) models with many Fe lines in NLTE have a temperature structure that agrees more closely with LTE semi-empirical models based on center-to-limb variation and a wide variety of spectra lines, whereas LTE models agree more with semi-empirical models based only on an LTE calculation of the Fe I excitation equilibrium, 3) the NLTE effects of Fe-group elements on the model structure and flux distribution are much more important than the NLTE effects of all the light metals combined, and serve to substantially increases the violet and near UV flux level as a result of NLTE Fe over-ionization. These results suggest that there may still be important UV opacity missing from the models.

Accepted for publication in The Astrophysical Journal

References in corpus (4)

• Stellar Iron Abundances: non-LTE Effects
• Resonance Averaged Photoionization Cross Sections for Astrophysical Models
• Atmospheric models of red giants with massive scale NLTE
• Massive Multi-species, Multi-level NLTE Model Atmospheres for Novae in Outburst

Cited by in corpus (31)

• The chemical composition of the Sun
• NLTE line formation of Fe in late-type stars II: 1D spectroscopic stellar parameters
• HAZMAT I: The Evolution of Far-UV and Near-UV Emission from Early M Stars
• Radiative transfer with scattering for domain-decomposed 3D MHD simulations of cool stellar atmospheres
• Ionization balance of Ti in the photospheres of the Sun and four late-type stars
• Non-LTE line formation for heavy elements in four very metal-poor stars
• The broadening of Fe II lines by neutral hydrogen collisions
• Mg line formation in late-type stellar atmospheres: I. The model atom
• The GALAH Survey: Non-LTE departure coefficients for large spectroscopic surveys
• How realistic are solar model atmospheres?
• On the Limb Darkening, Spectral Energy Distribution, and Temperature Structure of Procyon
• NLTE model calculations for the solar atmosphere with an iterative treatment of opacity distribution functions
• HAZMAT III: The UV Evolution of Mid- to Late-M Stars with GALEX
• NLTE Strontium and Barium in metal poor red giant stars
• The role of the Fraunhofer lines in solar brightness variability
• Three-dimensional interferometric, spectrometric, and planetary views of Procyon
• Non-LTE modeling of the near UV band of late-type stars
• HAZMAT. V. The Ultraviolet and X-ray Evolution of K Stars
• SAtlas: Spherical Versions of the Atlas Stellar Atmosphere Program
• HAZMAT II: Ultraviolet Variability of Low-Mass Stars in the GALEX Archive
• Predicting Lyman-alpha and Mg II Fluxes from K and M Dwarfs Using GALEX Ultraviolet Photometry
• HAZMAT. IX. An Analysis of the UV and X-Ray Evolution of Low-Mass Stars in the Era of Gaia
• NLTE modelling of integrated light spectra. Abundances of barium, magnesium, and manganese in a metal-poor globular cluster
• Eclipses observed by LYRA - a sensitive tool to test the models for the solar irradiance
• Modeling the near-UV band of GK stars, Paper II: NLTE models
• Analysis of stellar spectra with 3D and NLTE models
• Non-Equilibrium Spectrum Formation Affecting Solar Irradiance
• NLTE 1.5D Modeling of Red Giant Stars
• Revisiting the statistical equilibrium of H${}^{-}$ in stellar atmospheres
• Formation of chromospheric Fe I lines in the near ultraviolet in 1D atmospheres
• Role of input atomic data in spectroscopic analyses of the Sun and metal-poor stars