We analyze full-orbit phase curve observations of the transiting hot Jupiters WASP-19b and HAT-P-7b at 3.6 and 4.5Â \mu m obtained using the Spitzer Space Telescope .
For WASP-19b , we measure secondary eclipse depths of 0.485 \% \pm 0.024 \% and 0.584 \% \pm 0.029 \% at 3.6 and 4.5Â \mu m , which are consistent with a single blackbody with effective temperature 2372 \pm 60 Â K. The measured 3.6 and 4.5Â \mu m secondary eclipse depths for HAT-P-7b are 0.156 \% \pm 0.009 \% and 0.190 \% \pm 0.006 \% , which are well described by a single blackbody with effective temperature 2667 \pm 57 Â K. Comparing the phase curves to the predictions of one-dimensional and three-dimensional atmospheric models , we find that WASP-19b ’ s dayside emission is consistent with a model atmosphere with no dayside thermal inversion and moderately efficient day–night circulation .
We also detect an eastward-shifted hotspot , which suggests the presence of a superrotating equatorial jet .
In contrast , HAT-P-7b ’ s dayside emission suggests a dayside thermal inversion and relatively inefficient day–night circulation ; no hotspot shift is detected .
For both planets , these same models do not agree with the measured nightside emission .
The discrepancies in the model-data comparisons for WASP-19b might be explained by high-altitude silicate clouds on the nightside and/or high atmospheric metallicity , while the very low 3.6Â \mu m nightside planetary brightness for HAT-P-7b may be indicative of an enhanced global C/O ratio .
We compute Bond albedos of 0.38 \pm 0.06 and 0 ( < 0.08 at 1 \sigma ) for WASP-19b and HAT-P-7b , respectively .
In the context of other planets with thermal phase curve measurements , we show that WASP-19b and HAT-P-7b fit the general trend of decreasing day–night heat recirculation with increasing irradiation .