NLTE model calculations for the solar atmosphere with an iterative treatment of opacity distribution functions

M. Haberreiter, W. Schmutz, Ivan - Hubeny

Research output: Contribution to journalArticle

33 Citations (Scopus)

Abstract

Context. Modeling the variability of the solar spectral irradiance is a key factor in understanding the Sun's influence on the climate of the Earth.Aims. As a first step toward calculating the solar spectral irradiance variations, we reproduce the solar spectrum for the quiet Sun over a broad wavelength range with an emphasis on the UV.Methods. We introduce the radiative transfer code COSI, which calculates solar synthetic spectra under conditions of non-local thermodynamic equilibrium (NLTE). A self-consistent simultaneous solution of the radiative transfer and the statistical equation for the level populations guarantees that the correct physics is considered for wavelength regions where the assumption of local thermodynamic equilibrium (LTE) breaks down. The new concept of iterated opacity distribution functions (NLTE-ODFs) is presented, through which all line opacities are included in the NLTE radiative transfer calculation.Results. We show that it is essential to include the line opacities in the radiative transfer to reproduce the solar spectrum in the UV.Conclusions. Through the implemented scheme of NLTE-ODFs, the COSI code is successful in reproducing the spectral energy distribution of the quiet Sun.

Original languageEnglish (US)
Pages (from-to)833-840
Number of pages8
JournalAstronomy and Astrophysics
Volume492
Issue number3
DOIs
StatePublished - Dec 2008

Fingerprint

solar atmosphere
thermodynamic equilibrium
opacity
radiative transfer
thermodynamics
distribution functions
sun
solar spectra
atmosphere
irradiance
local thermodynamic equilibrium
wavelength
spectral energy distribution
wavelengths
climate
breakdown
physics
calculation
distribution
modeling

Keywords

  • Atomic data
  • Line: profiles
  • Radiative transfer
  • Sun: atmosphere
  • Sun: chromosphere
  • Sun: UV radiation

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

NLTE model calculations for the solar atmosphere with an iterative treatment of opacity distribution functions. / Haberreiter, M.; Schmutz, W.; Hubeny, Ivan -.

In: Astronomy and Astrophysics, Vol. 492, No. 3, 12.2008, p. 833-840.

Research output: Contribution to journalArticle

@article{e9c9bd56581e4ee0ae77e286de33b914,
title = "NLTE model calculations for the solar atmosphere with an iterative treatment of opacity distribution functions",
abstract = "Context. Modeling the variability of the solar spectral irradiance is a key factor in understanding the Sun's influence on the climate of the Earth.Aims. As a first step toward calculating the solar spectral irradiance variations, we reproduce the solar spectrum for the quiet Sun over a broad wavelength range with an emphasis on the UV.Methods. We introduce the radiative transfer code COSI, which calculates solar synthetic spectra under conditions of non-local thermodynamic equilibrium (NLTE). A self-consistent simultaneous solution of the radiative transfer and the statistical equation for the level populations guarantees that the correct physics is considered for wavelength regions where the assumption of local thermodynamic equilibrium (LTE) breaks down. The new concept of iterated opacity distribution functions (NLTE-ODFs) is presented, through which all line opacities are included in the NLTE radiative transfer calculation.Results. We show that it is essential to include the line opacities in the radiative transfer to reproduce the solar spectrum in the UV.Conclusions. Through the implemented scheme of NLTE-ODFs, the COSI code is successful in reproducing the spectral energy distribution of the quiet Sun.",
keywords = "Atomic data, Line: profiles, Radiative transfer, Sun: atmosphere, Sun: chromosphere, Sun: UV radiation",
author = "M. Haberreiter and W. Schmutz and Hubeny, {Ivan -}",
year = "2008",
month = "12",
doi = "10.1051/0004-6361:200809503",
language = "English (US)",
volume = "492",
pages = "833--840",
journal = "Astronomy and Astrophysics",
issn = "0004-6361",
publisher = "EDP Sciences",
number = "3",

}

TY - JOUR

T1 - NLTE model calculations for the solar atmosphere with an iterative treatment of opacity distribution functions

AU - Haberreiter, M.

AU - Schmutz, W.

AU - Hubeny, Ivan -

PY - 2008/12

Y1 - 2008/12

N2 - Context. Modeling the variability of the solar spectral irradiance is a key factor in understanding the Sun's influence on the climate of the Earth.Aims. As a first step toward calculating the solar spectral irradiance variations, we reproduce the solar spectrum for the quiet Sun over a broad wavelength range with an emphasis on the UV.Methods. We introduce the radiative transfer code COSI, which calculates solar synthetic spectra under conditions of non-local thermodynamic equilibrium (NLTE). A self-consistent simultaneous solution of the radiative transfer and the statistical equation for the level populations guarantees that the correct physics is considered for wavelength regions where the assumption of local thermodynamic equilibrium (LTE) breaks down. The new concept of iterated opacity distribution functions (NLTE-ODFs) is presented, through which all line opacities are included in the NLTE radiative transfer calculation.Results. We show that it is essential to include the line opacities in the radiative transfer to reproduce the solar spectrum in the UV.Conclusions. Through the implemented scheme of NLTE-ODFs, the COSI code is successful in reproducing the spectral energy distribution of the quiet Sun.

AB - Context. Modeling the variability of the solar spectral irradiance is a key factor in understanding the Sun's influence on the climate of the Earth.Aims. As a first step toward calculating the solar spectral irradiance variations, we reproduce the solar spectrum for the quiet Sun over a broad wavelength range with an emphasis on the UV.Methods. We introduce the radiative transfer code COSI, which calculates solar synthetic spectra under conditions of non-local thermodynamic equilibrium (NLTE). A self-consistent simultaneous solution of the radiative transfer and the statistical equation for the level populations guarantees that the correct physics is considered for wavelength regions where the assumption of local thermodynamic equilibrium (LTE) breaks down. The new concept of iterated opacity distribution functions (NLTE-ODFs) is presented, through which all line opacities are included in the NLTE radiative transfer calculation.Results. We show that it is essential to include the line opacities in the radiative transfer to reproduce the solar spectrum in the UV.Conclusions. Through the implemented scheme of NLTE-ODFs, the COSI code is successful in reproducing the spectral energy distribution of the quiet Sun.

KW - Atomic data

KW - Line: profiles

KW - Radiative transfer

KW - Sun: atmosphere

KW - Sun: chromosphere

KW - Sun: UV radiation

UR - http://www.scopus.com/inward/record.url?scp=57649230077&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=57649230077&partnerID=8YFLogxK

U2 - 10.1051/0004-6361:200809503

DO - 10.1051/0004-6361:200809503

M3 - Article

AN - SCOPUS:57649230077

VL - 492

SP - 833

EP - 840

JO - Astronomy and Astrophysics

JF - Astronomy and Astrophysics

SN - 0004-6361

IS - 3

ER -