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[31.12] Sulfur and Phosphorus Chemistry in Substellar Objects

C. Visscher, B. Fegley, Jr. (Planetary Chemistry Laboratory, Department of Earth and Planetary Sciences, McDonnell Center for the Space Sciences, Washington University in St. Louis)

We use thermochemical equilibrium and kinetic calculations to model sulfur and phosphorus chemistry in giant planets, brown dwarfs, and extrasolar giant planets (EGPs). The chemical speciation of sulfur and phosphorus is computed in a grid from T = 800 to 2500 K and P_T = 10⁴ to10^-6 bar at various metallicities and therefore in principle the equilibrium composition may be determined for any atmospheric profile. Some of our results are presented in the accompanying figure, which illustrates the abundances of S- and P-bearing gases at equilibrium along the nominal P-T profile of the T dwarf Gliese 229B (T_eff = 960 K; Marley et al. 1996, Science). This modeling is used to identify potentially observable gases and to provide constraints for atmospheric composition, structure, and opacity. Support by NASA NAG5-11958.

The author(s) of this abstract have provided an email address for comments about the abstract: visscher@wustl.edu

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Bulletin of the American Astronomical Society, 37 #3
© 2004. The American Astronomical Soceity.