发表机构
The Ohio State University; ETH Zurich（俄亥俄州立大学; 苏黎世联邦理工学院）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过混合模型分析小系外行星密度分布，发现FGK恒星周围行星的岩石核心质量分数比M矮星周围高约16%，且挥发分含量高度集中，表明行星组成强烈依赖恒星环境。
AI 中文摘要
我们通过使用一个将内部结构模型与可观测物理量联系起来的混合框架，对密度的人口级分布进行建模，从而研究小系外行星的岩石与挥发分组成。我们分析了跨越不同恒星环境的三个互补样本：Luque & Pallé M矮星样本、DACE M矮星样本和DACE FGK样本。我们考虑了对数正态参数化，该参数化捕捉了特征核心质量分数（CMF）和内在离散度，以描述单一岩石行星种群。单一岩石种群的推断表明，FGK恒星周围的小行星的CMF比M恒星周围的小行星高约16%（7-11σ，取决于样本选择）。我们还考虑了幂律参数化，该参数化探测了CMF=0.32处成分边界附近的聚类。幂律参数化提供了一种替代解释：FGK恒星周围89.9%至97.0%的行星是岩石行星，而M恒星周围多达61.6%（范围从4.1%到61.6%）的行星是岩石行星。此外，我们发现挥发分质量分数高度集中。例如，为了使用岩石、富水和富气行星的混合来描述DACE M矮星样本，我们发现超过99.5%的气态行星的大气质量分数（AMF）≲0.01%，超过55.4%（82.7%）的气态行星的水质量分数（WMF）≲0.1%（≲1%）。这些结果表明，虽然含挥发分行星很常见，但它们的组成和普遍性强烈依赖于恒星环境，并且它们的挥发分储量受到形成和演化过程的严格约束。
英文摘要
We investigate the rocky and volatile composition of small exoplanets by modeling the population-level distribution of densities using a mixture framework that links interior structure models to observable quantities. We analyze three complementary samples spanning different stellar environments: the Luque \& Pallé M-dwarf sample, the DACE M-dwarf sample, and the DACE FGK sample. We consider a log-normal parameterization, which captures a characteristic core mass fraction (CMF) and the intrinsic dispersion to describe a single rocky population. The single rocky population inference suggests a higher CMF for small planets around FGK stars than those around M stars by $\sim$16\% (7-11 $σ$ depending on sample selection). We also consider a power-law parameterization, which probes clustering near compositional boundaries at CMF=0.32. The power-law parameterization provides an alternative interpretation: 89.9\% to 97.0\% of the planets around FGK stars are rocky whereas up to 61.6\% (ranging from 4.1\% to 61.6\%) of planets around M stars are rocky. In addition, we find that volatile mass fractions are highly concentrated. For example, to describe the DACE M-dwarf sample using a mixture of rocky, water-rich, and gas-rich planets, we find that more than 99.5\% gaseous planets have an atmospheric mass fraction (AMF) $\lesssim 0.01\%$, and more than 55.4\% (82.7\%) gaseous planets have a water mass fraction (WMF) $\lesssim 0.1\%$ ($\lesssim 1\%$). These results suggest that while volatile-bearing planets are common, their composition and prevalence depend strongly on stellar environment, and their volatile inventories are tightly constrained by formation and evolutionary processes.
CommentsAccepted by APJ
