Analysis of Thermal Emissions of Exoplanets with Axially Symmetric Temperature Gradients

Abstract

Abstract Here a new method of modeling the thermal emissions of exoplanets is described, in which the temperature gradient of an exoplanet is approximated by splitting it into N zones. First, we seek to determine how much this method differs from a simple dayside–nightside model used by previous researchers and found that the difference between the N-zone and the dayside–nightside models is greatest during the primary transit of the exoplanet, and for large temperature gradients. Next, we determine under what conditions EXONEST, a Bayesian inference software package, is able to correctly determine the model used to generate synthetic light-curve data. EXONEST is best able to determine the model used to generate synthetic data when the mass of the exoplanet is known, the added noise to the data is low, and the thermal emissions are large compared to the ellipsoidal variations. Finally, EXONEST was used to analyze photometric data for exoplanets Kepler-41b and Kepler-412b, and the dayside brightness temperatures were estimated to be 2574 ± 59 and 2496 ± 64 K, and those of the nightside were estimated to be 860 ± 316 and 874 ± 333 K for Kepler-41b and Kepler-412b, respectively. Finally, we found that the hottest zone for both planets was the zone nearest the terminator on the dayside of the exoplanet. This surprising result suggests that the model is better applied to exoplanets with little to no heat recirculation.