Lammer Helmut, Scherf Manuel, Erkaev Nikolai V, Kubyshkina Daria, Gorbunova Kseniia D, Fossati Luca, Woitke Peter
Space Research Institute, Austrian Academy of Sciences, Graz, Austria.
Institute of Computational Modelling, Siberian Branch of the Russian Academy of Sciences, Krasnoyarsk, Russian Federation.
Nat Astron. 2025;9(7):1022-1030. doi: 10.1038/s41550-025-02550-6. Epub 2025 Jun 12.
The discovery of many low-mass exoplanets, including several planets within the habitable zone of their host stars, has led to the question of which kind of atmosphere surrounds them. Recent exoplanet detections have revealed the existence of a large population of low-mass planets (<3 ) with H-dominated atmospheres that must have been accreted from the protoplanetary disk. As the gas disk usually has an ~10% fraction of helium, we model the possible enrichment of the primordial He fraction in the atmosphere of planets with mass between 0.75 and 3.0 that orbit in the classical habitable zone of Sun-like stars. Depending on the mass accreted by the planet during the gas disk phase and the stellar high-energy flux between ~10 and 120 nm, we find that Earth-like planets with masses between ~0.95 and 1.25 inside the habitable zone of Sun-like stars can end up with He-dominated primordial atmospheres. This finding has important implications for the evolution of Earth-like habitats, as these thick helium-enriched primordial atmospheres can inhibit the habitability of these planets. The upcoming generation of giant telescopes, such as the Extremely Large Telescope, may enable us to observe and explore these atmospheres.
许多低质量系外行星的发现，包括其宿主恒星宜居带内的几颗行星，引发了关于它们周围环绕何种大气层的问题。最近对系外行星的探测揭示了大量低质量行星（<3 ）的存在，这些行星具有以氢为主的大气层，其大气层必定是从原行星盘吸积而来的。由于气体盘通常含有约10%的氦，我们对质量在0.75 至3.0 之间、在类日恒星的经典宜居带内运行的行星大气层中原始氦含量的可能富集情况进行了建模。根据行星在气体盘阶段吸积的质量以及约10至120纳米之间的恒星高能通量，我们发现，在类日恒星宜居带内质量约在0.95 至1.25 之间的类地行星最终可能拥有以氦为主的原始大气层。这一发现对类地宜居环境的演化具有重要意义，因为这些富含氦的浓厚原始大气层可能会抑制这些行星的宜居性。即将问世的新一代巨型望远镜，如极大望远镜，可能使我们能够观测和探索这些大气层。
