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 Sunlike stars. In this paper, synthetic spectra from atmospheric models are compared to these observations. The daynight 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.