Nikku Madhusudhan, Adam Burrows
New observational facilities are becoming increasingly capable of observing
reflected light from transiting and directly imaged extrasolar planets. In this
study, we provide an analytic framework to interpret observed phase curves,
geometric albedos, and polarization of giant planet atmospheres. We compute the
observables for non-conservative Rayleigh scattering in homogeneous
semi-infinite atmospheres using both scalar and vector formalisms. In addition,
we compute phase curves and albedos for Lambertian, isotropic, and anisotropic
scattering phase functions. We provide analytic expressions for geometric
albedos and spherical albedos as a function of the scattering albedo for
Rayleigh scattering in semi-infinite atmospheres. Given an observed geometric
albedo our prescriptions can be used to estimate the underlying scattering
albedo of the atmosphere, which in turn is indicative of the scattering and
absorptive properties of the atmosphere. We also study the dependence of
polarization in Rayleigh scattering atmospheres on the orbital parameters of
the planet-star system, particularly on the orbital inclination. We show how
the orbital inclination of non-transiting exoplanets can be constrained from
their observed polarization parameters. We consolidate the formalism, solution
techniques, and results from analytic models available in the literature, often
scattered in various sources, and present a systematic procedure to compute
albedos, phase curves, and polarization of reflected light.
View original:
http://arxiv.org/abs/1112.4476
No comments:
Post a Comment