Infrared Light Curves and the Detectability of Close-In Extrasolar Giant Planets

Abstract

We compute theoretical infrared light curves for several known extrasolar planets. We have constructed a set of routines to calculate the orbital parameters for a given planet and integrate over the planetary disk to determine the total flux density of the planet as it orbits the parent star. We have further developed a spectral synthesis routine to calculate theoretical spectra of extrasolar giant planets from 3–24 $\mu$ m. The code requires a temperature-pressure profile as input, calculated by solving the radiative transfer equation; it then calculates continuous opacities and line opacities for water, carbon monoxide, and methane, and finally integrates over the layers of the atmosphere to determine the emergent flux. By integrating the theoretical spectrum over the bandpass of a particular instrument and including realistic instrument noise, we produce a set of multi-wavelength, infrared light curves. Using these light curves, we predict whether a particular known planet can be observed and characterized using the Spitzer Space Telescope, as well as other proposed space-based instruments, such as the Fourier-Kelvin Stellar Interferometer (FKSI) and the James Webb Space Telescope (JWST).