Highly-Irradiated Eccentric Hot Jupiter WASP-14b may be Emitting Observable Internal Heat

3.6 and 4.5 μm Phase Curves of the Highly-Irradiated Eccentric Hot Jupiter WASP-14b

Authors:

Wong et al

Abstract:

We present full-orbit phase curve observations of the eccentric (e~0.08) transiting hot Jupiter WASP-14b obtained in the 3.6 and 4.5 μm bands using the Spitzer Space Telescope. We use two different methods for removing the intrapixel sensitivity effect and compare their efficacy in decoupling the instrumental noise. Our measured secondary eclipse depths of 0.1857%±0.0104% and 0.2241%±0.0087% at 3.6 and 4.5 μm, respectively, are both consistent with a blackbody temperature of 2379±55 K. We place a 2σ upper limit on the nightside flux at 3.6 μm and find it to be 10%±1% of the dayside flux, corresponding to a 1322±212 K difference in brightness temperature. At 4.5 μm, the minimum planet flux is 30%±3% of the maximum flux, corresponding to a 1016±99 K difference in brightness temperature. We compare our measured phase curves to the predictions of one-dimensional radiative transfer and three-dimensional general circulation models. We find that WASP-14b's measured dayside emission is consistent with a model atmosphere with equilibrium chemistry and a moderate temperature inversion. These same models provide a poor match to the planet's nightside emission, which is lower than predicted at 3.6 μm and higher at 4.5 μm. We propose that this discrepancy might be explained by an enhanced global C/O ratio. In addition, we find that the phase curves of WASP-14b (7.3 MJup) are consistent with a much lower albedo than those of other Jovian mass planets with thermal phase curve measurements, suggesting that it may be emitting detectable heat from the deep atmosphere or interior processes.