An extended upper atmosphere around the extrasolar planet HD209458b
An extended upper atmosphere around the extrasolar planet HD209458b
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DOI：
10.1038/nature01448
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发表时间：
2003-03
期刊：
影响因子：
64.8
通讯作者：
A. Vidal-Madjar;A. D. Étangs;J. Désert;G. Ballester;R. Ferlet;G. Hébrard;M. Mayor
中科院分区：
文献类型：
--
作者：
A. Vidal-Madjar;A. D. Étangs;J. Désert;G. Ballester;R. Ferlet;G. Hébrard;M. Mayor
HD209458系统中的行星是第一颗被观测到重复穿越恒星盘的行星。再加上径向速度测量，这导致了行星半径和质量的确定，确认它是一个气体巨星。但是，尽管对大气特征进行了无数次的搜索，通过中性钠吸收的检测，只观察到了HD209458b的稠密低层大气。本文报道了在HD 209458 b三次凌日过程中探测到恒星莱曼α线上氢原子的吸收。观察到15 ± 4%（1σ）的吸收。与模型的比较表明，这种吸收应该发生在罗氏极限之外，因此可以从逃逸氢原子的角度来理解。
The planet in the system HD209458 is the first one for which repeated transits across the stellar disk have been observed,. Together with radial velocity measurements, this has led to a determination of the planet's radius and mass, confirming it to be a gas giant. But despite numerous searches for an atmospheric signature,,, only the dense lower atmosphere of HD209458b has been observed, through the detection of neutral sodium absorption. Here we report the detection of atomic hydrogen absorption in the stellar Lyman α line during three transits of HD209458b. An absorption of 15 ± 4% (1σ) is observed. Comparison with models shows that this absorption should take place beyond the Roche limit and therefore can be understood in terms of escaping hydrogen atoms.