Line and Mean Opacities for Ultracool Dwarfs and Extrasolar Planets

Opacities and chemical abundance data are crucial ingredients of ultracool dwarf and extrasolar giant planet atmosphere models. We report here on the detailed sources of molecular opacity data employed by our group for this application. We also present tables of Rosseland and Planck mean opacities which are of use in some studies of the atmospheres, interiors, and evolution of planets and brown dwarfs. For the tables presented here, we have calculated the opacities of atomic and molecular species important in the atmosphere including the effect of pressure induced absorption due to H2 − H2, H2 − He, and H2 −H collisions, and other important sources such as H but neglecting opacity from condensates. Our opacity database includes line opacity from the most important molecular species, and atomic lines due to the strongest transitions of the alkali atoms Na, K, Cs, Rb and Li. We report for each species how we have assembled molecular line data from a combination of public databases, laboratory data that is not yet in the public databases, and our own numerical calculations. We combine these opacities with abundances computed from a chemical equilibrium model using recently revised solar abundances to compute mean opacities. The chemical SETI Institute, Mountain View, CA