GEMINI PLANET IMAGER SPECTROSCOPY OF THE HR 8799 PLANETS c AND d

Abstract

During the first-light run of the Gemini Planet Imager (GPI) we obtained\nK-band spectra of exoplanets HR 8799 c and d. Analysis of the spectra indicates\nthat planet d may be warmer than planet c. Comparisons to recent patchy cloud\nmodels and previously obtained observations over multiple wavelengths confirm\nthat thick clouds combined with horizontal variation in the cloud cover\ngenerally reproduce the planets' spectral energy distributions. When combined\nwith the 3 to 4 um photometric data points, the observations provide strong\nconstraints on the atmospheric methane content for both planets. The data also\nprovide further evidence that future modeling efforts must include cloud\nopacity, possibly including cloud holes, disequilibrium chemistry, and\nsuper-solar metallicity.\n