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T. S. Barman, P. H. Hauschildt (Univ. of Georgia), F. Allard (C.R.A.L. Ecole Normale Superieure)
We have used our general atmosphere code {\tt PHOENIX} (version 10.8) to generate radiative equilibrium models of irradiated planets located near a dM6 and a G2 primary. The external radiation, represented by synthetic spectra from a previous set of {\tt PHOENIX} model atmospheres, was explicitly included in the solution of the radiative transfer equation. We do not use precomputed, ad hoc, temperature-pressure profiles. A cool ({{\rm T}\rm eff} = 500 {\rm K}) and a hot ({{\rm T}\rm eff} = 1000{\rm K}) planet were modeled at various orbital separations from both the dM6 and the G2 primary. In all scenarios, we compared the effects of the irradiation in two extreme cases: one where dust clouds form and remain suspended in the atmosphere and another where dust clouds form but completely settle out of the atmosphere. The atmospheric structure and emergent spectrum strongly depend on the presence or absence of dust clouds.
Several models have also been computed by solving the spherically symmetric radiative transfer equation instead of assuming plane parallel geometry, as is usually done for EGPs. We find that the plane parallel solution may, in some circumstances, significantly underestimate the flux near the planetary limb and should, therefore, be used with caution.