Low Temperature Opacities

Low Temperature Opacities

2 Feb 2005 | Jason W. Ferguson¹, David R. Alexander¹, France Allard², Travis Barman¹, Julia G. Bodnarik¹³, Peter H. Hauschildt⁴, Amanda Heffner-Wong¹, Akemi Tamanai¹⁵
This paper presents updated and expanded low-temperature opacity tables for use in astrophysical modeling. The new tables include a more complete equation of state with additional grain species and updated optical constants, allowing for a wider range of grain compositions to be accurately included. The inclusion of high-temperature condensates such as Al₂O₃ and CaTiO₃ significantly affects the total opacity over a narrow temperature range before the appearance of silicate grains. The new opacity tables are tabulated for temperatures from 30000 K to 500 K and gas densities from 10⁻⁴ g cm⁻³ to 10⁻¹⁹ g cm⁻³. Comparisons with previous Rosseland mean opacity calculations show good agreement at high temperatures but more divergence at lower temperatures due to differences in molecular and grain physics. The computation of Planck mean opacities requires a large number of wavelength points, and previous results with fewer points are shown to be significantly in error. The new tables are available for download and can be customized as needed. The paper discusses the equation of state, sources of opacity data, and the computation of Planck mean opacities. It also presents comparisons of the new tables with previous opacity databases and highlights the importance of accurate opacity calculations for astrophysical modeling. The results show that the new tables provide better agreement with OPAL and OP at high temperatures and include a more complete set of molecular and grain opacities. The paper also discusses the effects of metallicity and hydrogen fraction on opacity and the importance of accurate opacity data for astrophysical modeling.This paper presents updated and expanded low-temperature opacity tables for use in astrophysical modeling. The new tables include a more complete equation of state with additional grain species and updated optical constants, allowing for a wider range of grain compositions to be accurately included. The inclusion of high-temperature condensates such as Al₂O₃ and CaTiO₃ significantly affects the total opacity over a narrow temperature range before the appearance of silicate grains. The new opacity tables are tabulated for temperatures from 30000 K to 500 K and gas densities from 10⁻⁴ g cm⁻³ to 10⁻¹⁹ g cm⁻³. Comparisons with previous Rosseland mean opacity calculations show good agreement at high temperatures but more divergence at lower temperatures due to differences in molecular and grain physics. The computation of Planck mean opacities requires a large number of wavelength points, and previous results with fewer points are shown to be significantly in error. The new tables are available for download and can be customized as needed. The paper discusses the equation of state, sources of opacity data, and the computation of Planck mean opacities. It also presents comparisons of the new tables with previous opacity databases and highlights the importance of accurate opacity calculations for astrophysical modeling. The results show that the new tables provide better agreement with OPAL and OP at high temperatures and include a more complete set of molecular and grain opacities. The paper also discusses the effects of metallicity and hydrogen fraction on opacity and the importance of accurate opacity data for astrophysical modeling.
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