Atmospheric heat redistribution effect on emission spectra of Hot-Jupiters

Abstract

Hot Jupiters are the most studied and easily detectable exoplanets for transit observations. However, the correlation between the atmospheric flow and the emission spectra of such planets is still not understood. Due to huge day–night temperature contrast in hot Jupiter, the thermal redistribution through atmospheric circulation has a significant impact on the vertical temperature–pressure structure and on the emission spectra. In the present work, we aim to study the variation of the temperature–pressure profiles and the emission spectra of such planets due to different amounts of atmospheric heat redistribution. For this purpose, we first derive an analytical relation between the heat redistribution parameter f and the emitted flux from the uppermost atmospheric layers of hot Jupiter. We adopt the three possible values of f under isotropic approximation as 1/4 , 1/2 and 2/3 for full-redistribution, semi-redistribution and no-redistribution cases respectively and calculate the corresponding temperature–pressure profiles and the emission spectra. Next, we model the emission spectra for different values of f by numerically solving the radiative transfer equations using the discrete space theory formalism. We demonstrate that the atmospheric temperature–pressure profiles and the emission spectra both are susceptible to the values of the heat redistribution function. A reduction in the heat redistribution yields a thermal inversion in the temperature–pressure profiles and hence increases the amount of emission flux. Finally, we revisits the hot Jupiter XO-1b temperature–pressure profile degeneracy case and show that a non-inversion temperature–pressure profile best explains this planet’s observed dayside emission spectra.