October 24-28, 2016

Abstract

Effects of sharp transmission boundaries on the effective radius of a transiting exoplanet.

Yan Betremieux (JPL/Caltech)

Mark R. Swain (JPL/Caltech)

Most exoplanet transmission spectroscopy radiative transfer codes either use or are validated against the formalism presented by Lecavelier des Etangs et al. (2008), who showed that the effective radius of an exoplanet with a clear isothermal atmosphere occurs where the slant optical depth through the atmosphere is about 0.56. Although this formalism is extremely useful to understand what shapes transmission spectra, it does not include the effects of sharp transmission boundaries. However, with recent advances on the effects of refraction in exoplanet transmission spectra, it turns out that all exoplanets have a sharp transmission boundary in the form of either a surface, optically thick clouds, or a refractive boundary. We have derived a first-order analytical solution, against which radiative transfer codes can be tested, for the effective radius of an exoplanets accounting for sharp transmission boundaries and discuss their effects on exoplanetary transmission spectra.

Mode of presentation: poster