Photochemical model for planet WASP-12b

A recent thermochemical equilibrium analysis based on Spitzer and ground-based infrared observations suggests that the presence of CH_4_ in its atmosphere and the lack of H_2_O features can only be explained if the carbon-to-oxygen ratio in the planet's atmosphere is much greater than the solar ratio ([C]/[O]=0.54).

Here, we use a one-dimensional photochemical model to study the effect of disequilibrium chemistry on the observed abundances of H_2_O, CO, CO_2_, and CH_4_ in the WASP-12b atmosphere. We consider two cases: one with solar [C]/[O] and another with [C]/[O]=1.08. The solar case predicts that H_2_ O and CO are more abundant than CO_2_ and CH_4_, as expected, whereas the high [C]/[O] model shows that CO, C_2_H_2_, and HCN are more abundant.