恒星丰度作为岩质系外行星内部的探针：GJ 486b的幔部成分与矿物学
Stellar Abundances as Probes of Rocky Exoplanet Interiors: The Mantle Composition and Mineralogy of GJ 486b
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中文总结 AI 辅助
该研究提出将恒星丰度推断、脱挥发分模型等结合的框架，以GJ 486b为例发现其幔部富铁贫二氧化硅，为关联行星内部与大气表征奠定基础。
中文摘要 AI 辅助
在过去三十年中，已发现数百颗岩质系外行星，其中一些行星展现出指示不同化学组成的大气信号。解释这些大气信号需要基于物理原理理解行星内部，因为内部成分与矿物学控制着次生大气的形成与演化。岩质类地系外行星预计会继承其宿主恒星的难熔成分，这为约束其整体成分与矿物学提供了直接途径。然而，这类行星中的很大一部分围绕M型恒星运行，而由于恒星丰度测量数据有限且存在不确定性，这类恒星的成分仍未得到很好的约束。在此，我们提出一个物理自洽的框架，该框架通过结合恒星丰度推断、用于估算整体及幔部元素丰度的脱挥发分模型、用于推导压力-温度剖面的内部结构计算，以及幔部矿物学的热力学平衡模型，将恒星丰度与岩质系外行星的内部结构和矿物学关联起来。我们首先以地球为基准对该框架进行验证，随后利用从相似M型恒星宿主集合中推导的化学自洽丰度，将其应用于超级地球GJ 486b。我们发现，与地球相比，GJ 486b可能拥有富铁且贫二氧化硅的幔部，同时保留了主要的幔部相变。敏感性分析表明，整体矿物学结构对整体成分和压力-温度剖面的变化具有鲁棒性，温度主要调节关键相变附近的相比例。最后，我们的结果显示，恒星丰度推断结合脱挥发分模型可约束岩质系外行星的内部成分，并为将行星内部与大气表征关联起来奠定基础。
英文摘要
Over the past three decades, hundreds of rocky exoplanets have been discovered. Some of these show atmospheric signatures indicative of diverse chemical compositions. Interpreting these atmospheres requires a physically grounded understanding of planetary interiors, as interior composition and mineralogy govern the formation and evolution of secondary atmospheres. Rocky terrestrial exoplanets are expected to inherit the refractory composition of their host stars, providing a direct pathway to constrain their bulk composition and mineralogy. However, a large fraction of these planets orbit M-type stars, whose compositions remain poorly constrained because of limited and uncertain stellar abundance measurements. Here, we present a physically consistent framework that connects stellar abundances to the interior structure and mineralogy of rocky exoplanets by combining stellar abundance inference, devolatilization modeling to estimate bulk and mantle elemental abundances, interior structure calculations to derive pressure-temperature profiles, and thermodynamic equilibrium modeling of mantle mineralogy. We first benchmark the framework against Earth and then apply it to the super-Earth GJ 486b using chemically consistent abundances derived from ensembles of similar M-dwarf hosts. We find that GJ 486b likely hosts an iron-rich and silica-poor mantle relative to Earth while preserving the major mantle phase transitions. Sensitivity analyses show that the overall mineralogical structure is robust to variations in bulk composition and pressure-temperature profiles, with temperature primarily modulating phase proportions near key transitions. Finally, our results show that stellar-abundance inference combined with devolatilization models constrains the interior composition of rocky exoplanets and provides a foundation for linking planetary interiors to atmospheric characterization.
