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 \m, for TrES-1, and 24 \m, for HD209458b. We find that standard solar metallicity models fit the observations for HD209458b. For TrES-1, which has an Tₑff ~300 K cooler, we find that models with a metallicity 3-5 times enhanced over solar abundances can match the 1\ error bar at 4. 5 \m and 2\ at 8. 0\m. Models with solar abundances that included energy deposition into the stratosphere give fluxes that fall within the 2\ 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.