Detailed models are compared to recent infrared observations of the nearbyextrasolar planet, HD 189733b. It is demonstrated that atmospheric water ispresent and that the planet's day side has a non-isothermal structure down togas pressures of ~ 0.1 bars. Furthermore, model spectra with different amountsof CO are compared to the observations and an atmosphere absent of CO isexcluded at roughly 2-sigma. Constraining the CO concentration beyond that isunfortunately not possible with the current Spitzer photometry. However,radically enhanced (or depleted) metal abundances are unlikely and the basiccomposition of this planet is probably similar to that of its host star. Whencombined with Spitzer observations, a recent ground-based upper limit for theK-band day side flux allows one to estimate the day-to-night energyredistribution efficiency to be ~ 43%.
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