标题： 行星围绕红矮星运行支持产氧光合作用和复杂生命的潜力 显示英文标题

标题： The Potential of Planets Orbiting Red Dwarf Stars to Support Oxygenic Photosynthesis and Complex Life

摘要： 我们回顾了关于太阳系外行星的最新发现及其支持类似地球生命的可能性。 专注于围绕红矮星（RD）运行的行星，这种恒星类型最为常见，我们表明，将RDs作为潜在的宿主恒星考虑在内，可以将找到生物行星的概率提高多达一千倍，并将我们最近的生物邻居的距离估计减少多达10倍。 我们认为，在讨论系外行星适居性时，需要考虑到双星和多星系统。 早期的考虑认为，RD行星上的条件对生命是不利的，因为其适居区（液态水可能存在区域）会如此接近，以至于行星会被潮汐锁定在其恒星上。 这被认为会导致气候不稳定，并使生命形式暴露在电离辐射的耀斑中。 最近的计算表明，这些负面因素比最初设想的要轻微得多。 有人提出，相对较冷的RDs的辐射光子能量较低，不足以支持产氧光合作用（OP）和其他相关耗能反应。 许多作者建议，RD行星上的OP可能会进化出利用红外光子的能力。 然而，我们通过类比OP的进化以及地球陆地植被的环境生理学和分布情况，认为利用红外辐射的进化压力会很小。 这是因为RD行星上的植被可以享受连续的中等强度光照，其中包含显著的光合作用400-700 nm辐射成分。 我们得出结论，RD行星上可能存在OP的条件，因此复杂生命的进化可能是可能的。 此外，RDs数量巨大且寿命很长，使得在RD周围发现具有光合作用和生命的行星比在太阳型恒星周围更有可能。 显示英文摘要

摘要： We review the latest findings on extra-solar planets and their potential to support Earth-like life. Focusing on planets orbiting Red Dwarf (RD) stars, the most abundant stellar type, we show that including RDs as potential host stars could increase the probability of finding biotic planets by a factor of up to a thousand, and reduce the estimate of the distance to our nearest biotic neighbor by up to 10. We argue that binary and multiple star systems need to be taken into account when discussing exoplanet habitability. Early considerations indicated that conditions on RD planets would be inimical to life, as their Habitable Zones (where liquid water could exist) would be so close as to make planets tidally locked to their star. This was thought to cause an erratic climate and expose life forms to flares of ionizing radiation. Recent calculations show that these negative factors are less severe than originally thought. It has been argued that the lesser photon energy of the radiation of the relatively cool RDs would not suffice for Oxygenic Photosynthesis (OP) and other related energy expending reactions. Numerous authors suggest that OP on RD planets may evolve to utilize photons in the infrared. We however argue, by analogy to the evolution of OP and the environmental physiology and distribution of land-based vegetation on Earth, that the evolutionary pressure to utilize infrared radiation would be small. This is because vegetation on RD planets could enjoy continuous illumination of moderate intensity, containing a significant component of photosynthetic 400-700 nm radiation. We conclude that conditions for OP could exist on RD planets and consequently the evolution of complex life might be possible. Furthermore, the huge number and the long lifetime of RDs make it more likely to find planets with photosynthesis and life around RDs than around solar type stars.