标题： 行星HD 209458b白昼半球光谱中的水、甲烷和二氧化碳 显示英文标题

标题： Water, Methane, and Carbon Dioxide Present in the Dayside Spectrum of the Exoplanet HD 209458b

摘要： 利用哈勃空间望远镜上的NICMOS仪器，我们测量了HD 209458b行星白昼面在1.5至2.5微米波段的光谱。 发射光谱主要由甲烷（CH4）和水蒸气（H2O）的存在所引起的特征主导，同时有来自二氧化碳（CO2）较小的贡献。 将这个近红外光谱与现有的中红外测量结果相结合，表明存在温度反转，并证实了之前光度测量的解释。 我们找到了一组可能的分子丰度和详细的温度剖面的解。 通过观测解决丰度和温度之间的歧义需要要么（1）改进白昼辐射光谱的波长覆盖范围或光谱分辨率，要么（2）一个传输光谱，其中丰度测定对温度结构的敏感性较低。 显示英文摘要

摘要： Using the NICMOS instrument on the Hubble Space Telescope, we have measured the dayside spectrum of HD 209458b between 1.5--2.5 microns. The emergent spectrum is dominated by features due to the presence of methane (CH4) and water vapor (H2O), with smaller contributions from carbon dioxide (CO2). Combining this near-infrared spectrum with existing mid-infrared measurements shows the existence of a temperature inversion and confirms the interpretation of previous photometry measurements. We find a family of plausible solutions for the molecular abundance and detailed temperature profile. Observationally resolving the ambiguity between abundance and temperature requires either (1) improved wavelength coverage or spectral resolution of the dayside emission spectrum, or (2) a transmission spectrum where abundance determinations are less sensitive to the temperature structure.