The detection of habitable exoplanets is an exciting scientific and technical challenge. Owing to the current and most likely long-lasting impossibility of performing in situ exploration of exoplanets, their study and hypotheses regarding their capability to host life will be based on the restricted low-resolution spatial and spectral information of their atmospheres. On the other hand, with the advent of the upcoming exoplanet survey missions and technological improvements, there is a need for preliminary discrimination that can prioritize potential candidates within the fast-growing list of exoplanets. Here we estimate, for the first time and using the kinetic theory of gases, a list of the possible atmospheric species that can be retained in the atmospheres of the known exoplanets. We conclude that, based on our current knowledge of the detected exoplanets, 45 of them are good candidates for habitability studies. These exoplanets could have Earth-like atmospheres and should be able to maintain stable liquid water. Our results suggest that the current definition of a habitable zone around a star should be revisited and that the capacity of the planet to host an Earth-like atmosphere to support the stability of liquid water should be added.

中文翻译：

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基于气体热逃逸的系外行星大气成分及其对宜居性的影响

探测宜居系外行星是一项令人兴奋的科学和技术挑战。由于目前和最有可能长期不可能对系外行星进行原位探索，他们关于其承载生命能力的研究和假设将基于其大气的受限低分辨率空间和光谱信息。另一方面，随着即将到来的系外行星调查任务和技术改进的到来，需要进行初步区分，以便在快速增长的系外行星列表中优先考虑潜在的候选者。在这里，我们首次使用气体动力学理论估计了可以保留在已知系外行星大气中的可能大气物种列表。我们得出的结论是，根据我们目前对探测到的系外行星的了解，其中 45 颗是宜居性研究的良好候选者。这些系外行星可能有类似地球的大气层，应该能够保持稳定的液态水。我们的结果表明，应该重新审视当前对恒星周围宜居带的定义，并且应该增加这颗行星承载类地大气以支持液态水稳定性的能力。