A Theoretical Interpretation of the Measurements of the Secondary Eclipses of TrES-1 and HD 209458b

We calculate the planet-star flux-density ratios as a function of wavelengthfrom 0.5 microns to 25 microns for the transiting extrasolar giant planetsTrES-1 and HD209458b and compare them with the recent Spitzer/IRAC-MIPSsecondary eclipse data in the 4.5, 8.0, and 24 micron bands. With only threedata points and generic calibration issues, detailed conclusions are difficult,but inferences regarding atmospheric composition, temperature, and globalcirculation can be made. Our models reproduce the observations reasonably well,but not perfectly, and we speculate on the theoretical consequences ofvariations around our baseline models. One preliminary conclusion is that wemay be seeing in the data indications that the day side of a close-inextrasolar giant planet is brighter in the mid-infrared than its night side,unlike Jupiter and Saturn. This correspondence will be further tested when thedata anticipated in other Spitzer bands are acquired, and we make predictionsfor what those data may show.Comment: 15 pages, including 3 color figures, submitted to the Astrophysical Journa