2005/02/02 by Jason W. Ferguson, D. R. Alexander, David R. Alexander +9 · 17 citations
Chemistry · Earth and Planetary Sciences · Physics and Astronomy · #Advanced Chemical Physics Studies #High-pressure geophysics and materials #Spectroscopy and Laser Applications #astro-ph
paper · pdf · doi:10.1086/428642
published as Astrophys.J. 623 (2005) 585-596 · 39 pages with 12 figures. To be published in ApJ, April 2005
arxiv created 2005/02/02 · openalex publication_date 2005/04/10 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/04
Previous computations of low-temperature Rosseland and Planck mean opacities from Alexander & Ferguson are updated and expanded. The new computations include a more complete equation of state (EOS) with more grain species and updated optical constants. Grains are now explicitly included in thermal equilibrium in the EOS 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 Al 2 O 3 and CaTiO 3 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 30,000 to 500 K with gas densities from 10 -4 to 10 -19 g cm -3 . 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 is 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.