A Generalized Scattering Model for Semi-Infinite Atmospheres

Abstract

We present our model of aerosol scattering in exoplanet atmospheres. We have developed and implemented a code, using a method similar to Chandrasekhar’s X- and Y- function formalism, that solves the radiative transfer equation in a plane-parallel, semi-infinite, homogeneous atmosphere via an expansion of the single scattering phase function in spherical harmonics. This code can solve the equation of radiative transfer for an arbitrary single-scattering phase function, notably including Mie scattering. We have also implemented and evaluated a δ-function closure to the spherical harmonic expansion which dramatically speeds up computation time. We present reflection spectra and phase curves of 20 different optically thick aerosol atmospheres calculated using our model. We finally discuss the effects of particle size distribution parameters on the observable spectral and phase curve features.