THE TRANSIT TRANSMISSION SPECTRUM OF A COLD GAS GIANT PLANET
THE TRANSIT TRANSMISSION SPECTRUM OF A COLD GAS GIANT PLANET
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冷气态巨行星的凌日传输光谱
DOI：
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发表时间：
2015
期刊：
影响因子：
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通讯作者：
M. Veyette
中科院分区：
文献类型：
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作者：
P. Dalba;P. Muirhead;J. Fortney;M. Hedman;P. Nicholson;M. Veyette
我们利用卡西尼号飞船上的可见光和红外测绘光谱仪观测到的太阳掩星来提取土星的 1-5 μm 透射光谱，就好像它是一颗凌日系外行星一样。我们检测到甲烷、乙烷、乙炔、脂肪族碳氢化合物以及可能的一氧化碳的吸收，尽管存在氨云，峰峰值特征仍高达百万分之 90。我们还发现，与云或薄雾相反，大气折射决定了凌日期间可以探测到的最低高度。自洽的系外行星大气模型与土星的透射光谱表现出良好的一致性，但未能重现 3.4 μm 附近的大吸收特征，这可能是由气态乙烷和未知脂肪烃的 C-H 拉伸模式引起的。这一大特征位于斯皮策太空望远镜带通之一，如果建模不当，可能会改变透射光谱的解释。土星透射光谱中的大信号表明，当前和未来的天文台应该可以实现冷、长周期气态系外行星的透射光谱。受这些结果的启发，我们简要考虑了利用机会目标方法进行调查来搜索和表征类似于木星和土星的冷系外行星的可行性。
We use solar occultations observed by the Visual and Infrared Mapping Spectrometer on board the Cassini Spacecraft to extract the 1–5 μm transmission spectrum of Saturn, as if it were a transiting exoplanet. We detect absorption from methane, ethane, acetylene, aliphatic hydrocarbons, and possibly carbon monoxide, with peak-to-peak features of up to 90 parts-per-million despite the presence of ammonia clouds. We also find that atmospheric refraction, as opposed to clouds or haze, determines the minimum altitude that could be probed during mid-transit. Self-consistent exoplanet atmosphere models show good agreement with Saturn’s transmission spectrum but fail to reproduce a large absorption feature near 3.4 μm, likely caused by gaseous ethane and a C–H stretching mode of an unknown aliphatic hydrocarbon. This large feature is located in one of the Spitzer Space Telescope bandpasses and could alter interpretations of transmission spectra if not properly modeled. The large signal in Saturn’s transmission spectrum suggests that transmission spectroscopy of cold, long-period gaseous exoplanets should be possible with current and future observatories. Motivated by these results, we briefly consider the feasibility of using a survey to search for and characterize cold exoplanets that are analogous to Jupiter and Saturn utilizing a target-of-opportunity approach.
来自卡西尼-惠更斯号的土星
DOI：
10.1007/978-1-4020-9217-6_12
发表时间：
2009
期刊：
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影响因子：
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作者：
Kurth W
通讯作者：
Kurth W