Photometric Light Curves and Polarization of Close‐in Extrasolar Giant Planets

The close-in extrasolar giant planets [CEGPs], $\ltorder$ 0.05 AU from theirparent stars, may have a large component of optically reflected light. Wepresent theoretical optical photometric light curves and polarization curvesfor the CEGP systems, from reflected planetary light. Different particle sizesof three condensates are considered. In the most reflective case, thevariability is $\approx 100$ micromagnitudes, which will be easily detectableby the upcoming satellite missions MOST, COROT, and MONS, and possibly from theground in the near future. The least reflective case is caused by small, highlyabsorbing grains such as solid Fe, with variation of much less than onemicromagnitude. Polarization for all cases is lower than current detectabilitylimits. We also discuss the temperature-pressure profiles and resultingemergent spectra of the CEGP atmospheres. We discuss the observational resultsof Tau Boo b by Cameron et al. (1999) and Charbonneau et al. (1999) in contextof our model results. The predictions - the shape and magnitude of the lightcurves and polarization curves - are highly dependent on the size and type ofcondensates present in the planetary atmosphere.Comment: 33 pages, accepted by Ap