Phase-dependent Properties of Extrasolar Planet Atmospheres

Recently the Spitzer Space Telescope observed the transiting extrasolar planets, TrES-1 and HD 209458b. These observations have provided the first estimates of the day-side thermal flux from two extrasolar planets orbiting Sun-like stars. In this paper, synthetic spectra from atmospheric models are compared to these observations. The day-night temperature difference is explored and phase-dependent flux densities are predicted for both planets. For HD 209458b and TrES-1, models with significant day-to-night energy redistribution are required to reproduce the observations. However, the observational error bars are large, and a range of models remains viable.