| Abstract : | Polarimetric studies of the extra-solar planets are gaining momentum as these studies complement the existing photometric and spectroscopic techniques and help us learn more about the atmospheres of the exoplanets. Atmospheric scattering causes the light reflected or emitted from the planets to be linearly polarized at each local point over the disk. Partial illumination of the planetary disks or oblate shape of the young fast-rotating planets can cause the observable disk-integrated linear polarization of the planets to be non-zero. Atmospheric clouds play a significant role in determining the total polarization observable from the planets in both cases. Polarimetric observations provide a unique opportunity to study the properties of the exoplanets in great detail such as orbital or axial inclination, atmospheric clouds, atmospheric species such as Na, K, H2O, etc. Also, these techniques do not pose any constraint on the orbital alignment of the planets under study unlike the techniques like transit or radial velocity. In this talk, I will present the three-dimensional numerical radiative transfer models we have developed to calculate the Stokes vectors across the planetary disks. We compute the pertinent atmospheric models for both the reflecting planets and the self-luminous directly imaged planets (DIPs) using our atmospheric code. Using our models, we have simulated polarization phase curves for the hot-Jupiters such as HD189733b and polarization spectra for the DIPs such as Beta Pic b, ROXs42Bb, etc. These models will be extremely useful in interpreting the high-quality polarimetric observations from the existing and upcoming next-generation polarimetric missions/instruments such as PlanetPOL, HIPPI, HabEx, TMT-MODHIS, TMT-PSI, among others. |
