重新审视 Eta-Earth I：估算类地球宜居栖息地最大数量的公式
Eta-Earth Revisited I: A Formula for Estimating the Maximum Number of Earth-like Habitats
AI总结：
本文提出类地球宜居栖息地 $η_{\ m EH}$ 定义，并推导可估算银河系中高级类动物生命宜居岩石行星最大出现率的概率公式。
摘要：
在这篇假说性论文中，我们讨论了需氧生物能够生长和存活的行星环境的基本要求，包括基于物理极限对毫米至米级生物动物生命的大气限制，以及 O$_2$、N$_2$ 和 CO$_2$ 的毒性水平。通过假设类似动物的外星生物遵循相似的限制，我们将类地球宜居栖息地（$η_{\ m EH}$）定义为位于复杂生命宜居带内的岩石系外行星，这些行星拥有以 N$_2$-O$_2$ 为主、含少量 CO$_2$ 的大气，原则上高级类动物生命可在其上演化和存在。随后，我们推导了一个新公式，可用于估算银河系中此类类地球宜居栖息地的最大出现率。该公式包含现实的概率论证，可通过未来空间和地面望远镜的大气表征进行微调和约束。作为示例，我们简要讨论了纳入新公式的两个具体要求；尽管目前尚无法量化，但由于未来对系外行星及其大气的观测，这些要求将在未来数十年内具备科学上的可量化性。
英文摘要：
In this hypothesis article, we discuss the basic requirements of planetary environments where aerobe organisms can grow and survive, including atmospheric limitations of millimeter-to-meter-sized biological animal life based on physical limits, and O$_2$, N$_2$, and CO$_2$ toxicity levels. By assuming that animal-like extraterrestrial organisms adhere to similar limits, we define Earth-like Habitats ($η_{\rm EH}$) as rocky exoplanets in the Habitable Zone of Complex Life that host N$_2$-O$_2$-dominated atmospheres with minor amounts of CO$_2$, at which advanced animal-like life can in principle evolve and exist. We then derive a new formula that can be used to estimate the maximum occurrence rate of such Earth-like Habitats in the Galaxy. This contains realistic probabilistic arguments that can be fine-tuned and constrained by atmospheric characterization with future space and ground-based telescopes. As an example, we briefly discuss two specific requirements feeding into our new formula that, although not quantifiable at present, will become scientifically quantifiable in the upcoming decades due to future observations of exoplanets and their atmospheres.
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。
