Detecting Life-bearing Extrasolar Planets with Space Telescopes
Detecting Life-bearing Extrasolar Planets with Space Telescopes
复制标题
用太空望远镜探测有生命的太阳系外行星
DOI：
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发表时间：
2007
期刊：
影响因子：
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通讯作者：
S. Beckwith
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文献类型：
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作者：
S. Beckwith
在太阳系外行星（系外行星）上寻找生命的一种有希望的方法是在系外行星大气的化学不平衡中检测其特征。寻找甲烷、氧气、二氧化碳或水所需的中等分辨率的光谱将需要大的收集区域和大的直径来捕获和隔离来自恒星周围可居住区行星的光。带有日冕仪以隔离来自行星的光线的单台望远镜的直径必须达到8米或更大，才能产生具有找到至少一颗生命行星的合理可能性的样本量;使用较小望远镜的干涉仪可以克服一些限制，但仍需要同样大的收集面积。甚至需要更大的望远镜来探测凌日行星的大气特征。在所有情况下，样本量增加望远镜直径的三倍。使用日冕仪或干涉仪的直接观测对质量与太阳相似的恒星周围的行星最敏感，而凌日观测则有利于接近核燃烧极限的低质量恒星。如果能够克服建造超大型太空望远镜的技术困难，它们将能够以足够的分辨率和灵敏度观测数百至数千颗恒星附近的行星，以寻找生命的迹象。
One of the promising methods to search for life on extrasolar planets (exoplanets) is to detect its signature in the chemical disequilibrium of exoplanet atmospheres. Spectra at the modest resolutions needed to search for methane, oxygen, carbon dioxide, or water will demand large collecting areas and large diameters to capture and isolate the light from planets in the habitable zones around the stars. Single telescopes with coronagraphs to isolate the light from the planet will have to be 8 m or more in diameter to generate sample sizes with a reasonable probability of finding at least one life-bearing planet; interferometers using smaller telescopes can overcome some of the limitations but will still need similarly large collecting areas. Even larger telescopes will be needed to detect atmospheric signatures in transiting planets. In all cases, the sample sizes increase at the third power of telescope diameter. Direct observation using coronagraphs or interferometers are most sensitive to planets around stars with masses similar to that of the Sun, whereas transit observations favor low-mass stars near the nuclear burning limit. If the technical difficulties of constructing very large space telescopes can be overcome, they will be able to observe planets near hundreds to thousands of stars with adequate resolution and sensitivity to look for the signatures of life.