Low Temperature Opacities
نویسندگان
چکیده
Previous computations of low temperature Rosseland and Planck mean opacities from Alexander & Ferguson (1994b) are updated and expanded. The new computations include a more complete equation of state with more grain species and updated optical constants. Grains are now explicitly included in thermal equilibrium in the equation of state calculation, which allows for a much wider range of grain compositions to be accurately included than was previously the case. The inclusion of high temperature condensates such as Al2O3 and CaTiO3 significantly affects the total opacity over a narrow range of temperatures before the appearance of the first silicate grains. The new opacity tables are tabulated for temperatures ranging from 30000 K to 500 K with gas densities from 10 g cm to 10 g cm. Comparisons with previous Rosseland mean opacity calculations are discussed. At high temperatures, the agreement with OPAL and Opacity Project is quite good. Comparisons at lower temperatures are more divergent as a result of differences in molecular and grain physics included in different calculations. The computation of Planck mean opacities performed with the opacity sampling method are shown to require a very large number of opacity sampling wavelength points; previously published results obtained with fewer wavelength points are shown to be significantly in error. Methods for requesting or obtaining the new tables are provided. Subject headings: atomic data — equation of state — methods: numerical — molecular data Department of Physics, Wichita State University, Wichita, KS 67260-0032; [email protected]; [email protected]; [email protected] CRAL-ENS, 46 Allee d’Italie, Lyon, 69364 France, Cedex 07; [email protected] Now at Gemini Observatory, 670 North A’ohoku Place, Hilo, HI 96720-2700; [email protected] Hamburger Sternwarte, Gojenbergsweg 112, 21029 Hamburg, Germany; [email protected] Now at Astrophysical Institute and University Observatory, Friedrich-Schiller-University Jena, Schillergaesschen 3, D-07745 Jena, Germany; [email protected]
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