Molecular signatures in the near-infrared dayside spectrum of HD 189733b

Abstract

We have measured the dayside spectrum of HD 189733b between 1.5 and 2.5 μm using the NICMOS instrument on the Hubble Space Telescope. The emergent spectrum contains significant modulation, which we attribute to the presence of molecular bands seen in absorption. We find that water (H2O), carbon monoxide (CO), and carbon dioxide (CO2) are needed to explain the observations, and we are able to estimate the mixing ratios for these molecules. We also find temperature decreases with altitude in the-0.01 < P