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arXiv 1005.3589astro-ph.EP
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大气、生命和气候的共同进化

Co-evolution of atmospheres, life, and climate

John Lee Grenfell, Heike Rauer, Franck Selsis, Lisa Kaltenegger, Charles Beichman, William Danchi, Carlos Eiroa, Malcolm Fridlund, Thomas Henning, Tom Herbst, H… 展开作者

John Lee Grenfell, Heike Rauer, Franck Selsis, Lisa Kaltenegger, Charles Beichman, William Danchi, Carlos Eiroa, Malcolm Fridlund, Thomas Henning, Tom Herbst, Helmut Lammer, Alain Léger, René Liseau, Jonathan Lunine, Francesco Paresce, Alan Penny, Andreas Quirrenbach, Huub Röttgering, Jean Schneider, Daphne Stam, Giovanna Tinetti, Glenn J. White

摘要:

在地球诞生之后,我们的主星太阳的亮度比今天低了20%到25%。如果没有类似温室的条件来温暖大气层,我们早期的星球将是一个冰球,生命可能永远不会进化。但生命确实进化了,这表明温室气体必须存在于早期地球上,以使地球变暖。来自地质记录的证据表明温室气体CO2的丰度。甲烷可能也存在,在这方面,产甲烷细菌,属于一个不同的厌氧原核生物群,将二氧化碳和氢气发酵成甲烷,可能有助于改变早期的大气。分子氧并不存在,正如对那个时代岩石的研究所表明的那样,它含有碳酸铁而不是氧化铁。多细胞生物起源于菌落中的细胞,这些细胞变得越来越专业化。光合作用的发展使得太阳的能量可以被生命形式直接获取。生成的氧气在大气中积累,在高层大气中形成臭氧层。在臭氧层吸收有害紫外线辐射的帮助下,生命在地球表面定居。我们自己的星球就是一个很好的例子,说明生命形式如何在行星的生命周期中改变大气层。我们表明,这些事实必须考虑到当我们发现和表征大气的类地系外行星。如果生命是在一颗行星上起源和进化的,那么应该可以预期,生命和大气之间发生了强烈的共同进化,其结果是行星的气候。

英文摘要:

After Earth's origin, our host star, the Sun, was shining 20 to 25 percent less brightly than today. Without greenhouse-like conditions to warm the atmosphere, our early planet would have been an ice ball and life may never have evolved. But life did evolve, which indicates that greenhouse gases must have been present on early Earth to warm the planet. Evidence from the geologic record indicates an abundance of the greenhouse gas CO2. CH4 was probably present as well, and in this regard methanogenic bacteria, which belong to a diverse group of anaerobic procaryotes that ferment CO 2 plus H2 to CH4, may have contributed to modification of the early atmosphere. Molecular oxygen was not present, as is indicated by the study of rocks from that era, which contain iron carbonate rather than iron oxide. Multicellular organisms originated as cells within colonies that became increasingly specialized. The development of photosynthesis allowed the Sun's energy to be harvested directly by life forms. The resultant oxygen accumulated in the atmosphere and formed the ozone layer in the upper atmosphere. Aided by the absorption of harmful UV radiation in the ozone layer, life colonized Earth's surface. Our own planet is a very good example of how life forms modified the atmosphere over the planets' life time. We show that these facts have to be taken into account when we discover and characterize atmospheres of Earth-like exoplanets. If life has originated and evolved on a planet, then it should be expected that a strong co-evolution occurred between life and the atmosphere, the result of which is the planets' climate.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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