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C. Goukenleuque (NRC/GSFC)
A radiative equilibrium atmospheric model for HD 209458 b is presented. Opacity from alkalii metals (K, Na) in the visible have been included, using vertical abundance profiles of alkalii atoms calculated by Tim Brown (preprint, 2001) and accounting for photoionization by the parent star's radiation. Absorption from the neutral Potassium and Sodium atoms strongly reduces the planetary reflected flux in the 0.4-0.8 \mum wavelength range. Although these atoms (whose modelling of the line profiles may overestimate the absorption in the wings and underestimate the absorption in the line cores) are remarkably depleted in the upper atmosphere (above the 1-mbar level) through photoionization, they tend to increase the effective temperature of the planet by more than 100 K. In addition, convective adjustment and correction for water vapor abundance have been applied to a model for a Jupiter-like planet at 1 AU orbiting a solar-type star.
This work was made possible thanks to the National Research Council Research Associate Program.