Comparative Planetary Atmospheres: Models of TrES-1 and HD 209458b

We present new self-consistent atmosphere models for transiting planets TrES-1 and HD209458b. The planets were recently observed with the Spitzer Space Telescope in bands centered on 4.5 and 8.0 \μm, for TrES-1, and 24 \μm, for HD209458b. We find that standard solar metallicity models fit the observations for HD209458b. For TrES-1, which has an T_eff ~300 K cooler, we find that models with a metallicity 3-5 times enhanced over solar abundances can match the 1\σ error bar at 4.5 \μm and 2\σ at 8.0\μm. Models with solar abundances that included energy deposition into the stratosphere give fluxes that fall within the 2\σ error bars in both bands. The best-fit models for both planets assume that reradiation of absorbed stellar flux occurs over the entire planet. For all models of both planets we predict planet/star flux ratios in other Spitzer bandpasses.