FINDING EXTRATERRESTRIAL LIFE USING GROUND-BASED HIGH-DISPERSION SPECTROSCOPY
FINDING EXTRATERRESTRIAL LIFE USING GROUND-BASED HIGH-DISPERSION SPECTROSCOPY
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DOI：
10.1088/0004-637x/764/2/182
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发表时间：
2013-02
期刊：
影响因子：
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通讯作者：
I. Snellen;R. Kok;R. Poole;M. Brogi;J. Birkby
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文献类型：
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作者：
I. Snellen;R. Kok;R. Poole;M. Brogi;J. Birkby
对系外行星的观测预示着有一天会揭开外星生命存在的面纱。处于强烈化学不平衡状态的大气化合物将指向大规模的生物活动，就像地球大气中的氧气和甲烷一样。类地行星探测器和达尔文探测器任务的取消意味着，在未来25年内不太可能发射专门用于搜寻系外行星大气中生物标志物气体的太空望远镜。在这里，我们表明，地面望远镜提供了一个强有力的替代寻找生物标志物在系外行星大气通过过境观测。最近对热彗星的研究结果表明，利用行星的多普勒频移，高色散光谱学在分离地外信号和大地信号方面具有巨大的潜力。从一颗围绕着一颗小红矮星星星运行的地球孪生子发出的氧气传输信号，只比最近在热木星牧夫座τ B中探测到的一氧化碳传输信号小三倍，尽管这样的一颗星星的数量级会更暗。我们表明，如果类地行星很常见，计划中的超大型望远镜可以在几十次凌日内探测到氧气。最终，配备高色散光谱仪的大型专用通量收集望远镜阵列可以提供对太阳附近的生命行星进行统计研究所需的大收集区域。
Exoplanet observations promise one day to unveil the presence of extraterrestrial life. Atmospheric compounds in strong chemical disequilibrium would point to large-scale biological activity just as oxygen and methane do in the Earth's atmosphere. The cancellation of both the Terrestrial Planet Finder and Darwin missions means that it is unlikely that a dedicated space telescope to search for biomarker gases in exoplanet atmospheres will be launched within the next 25 years. Here we show that ground-based telescopes provide a strong alternative for finding biomarkers in exoplanet atmospheres through transit observations. Recent results on hot Jupiters show the enormous potential of high-dispersion spectroscopy to separate the extraterrestrial and telluric signals, making use of the Doppler shift of the planet. The transmission signal of oxygen from an Earth-twin orbiting a small red dwarf star is only a factor of three smaller than that of carbon monoxide recently detected in the hot Jupiter τ Boötis b, albeit such a star will be orders of magnitude fainter. We show that if Earth-like planets are common, the planned extremely large telescopes can detect oxygen within a few dozen transits. Ultimately, large arrays of dedicated flux-collector telescopes equipped with high-dispersion spectrographs can provide the large collecting area needed to perform a statistical study of life-bearing planets in the solar neighborhood.