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arXiv 1502.03605astro-ph.EP
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我们能从质量和半径测量中约束岩石系外行星的内部结构吗?

Can we constrain interior structure of rocky exoplanets from mass and radius measurements?

Caroline Dorn, Amir Khan, Kevin Heng, Yann Alibert, James A. D. Connolly, Willy Benz, Paul Tackley

摘要:

我们提出了一种基于贝叶斯分析的反演方法来约束类地系外行星的内部结构,以地幔的化学成分和核心大小的形式。具体来说,我们确定哪些部分的内部结构的类地系外行星可以确定的质量,半径和恒星元素丰度的观测。我们执行一个完整的概率逆分析,正式占观测和模型的不确定性,并获得内部结构模型的置信区域。这使我们能够描述模型变异性如何依赖于数据和相关的不确定性。我们测试我们的方法对类地太阳系行星,发现我们的模型预测是一致的独立估计。此外,我们将我们的方法应用于合成系外行星,质量高达10个地球,半径高达1.7个地球,以及系外行星开普勒-36b。重要的是,这里提出的反演策略为理解描述系外行星内部所需的精度水平提供了一个框架。我们的主要结论是:(1)质量和半径的观测足以限制核心的大小;(2)恒星元素丰度(Fe,Si,Mg)是减少内部结构模型简并并限制地幔成分的关键约束;(3)根据质量和半径观测确定内部结构的固有简并不仅取决于测量精度,还取决于系外行星的实际大小和密度。我们认为,恒星元素丰度的精确观测是中央,以限制行星的整体组成,并减少模型简并。[...]

英文摘要:

We present an inversion method based on Bayesian analysis to constrain the interior structure of terrestrial exoplanets, in the form of chemical composition of the mantle and core size. Specifically, we identify what parts of the interior structure of terrestrial exoplanets can be determined from observations of mass, radius, and stellar elemental abundances. We perform a full probabilistic inverse analysis to formally account for observational and model uncertainties and obtain confidence regions of interior structure models. This enables us to characterize how model variability depends on data and associated uncertainties. We test our method on terrestrial solar system planets and find that our model predictions are consistent with independent estimates. Furthermore, we apply our method to synthetic exoplanets up to 10 Earth masses and up to 1.7 Earth radii as well as to exoplanet Kepler-36b. Importantly, the inversion strategy proposed here provides a framework for understanding the level of precision required to characterize the interior of exoplanets. Our main conclusions are: (1) observations of mass and radius are sufficient to constrain core size; (2) stellar elemental abundances (Fe, Si, Mg) are key constraints to reduce degeneracy in interior structure models and to constrain mantle composition; (3) the inherent degeneracy in determining interior structure from mass and radius observations does not only depend on measurement accuracies but also on the actual size and density of the exoplanet. We argue that precise observations of stellar elemental abundances are central in order to place constraints on planetary bulk composition and to reduce model degeneracy. [...]

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。

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