基于因果发现的热木星膨胀成因研究
Causes of Hot Jupiter Inflation from Causal Discovery
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中文总结 AI 辅助
本研究通过因果发现分析328颗短周期巨行星数据，发现热木星半径与轨道周期、恒星温度直接相关，提示Gold-Soter热潮汐等过程是其膨胀的重要成因，为热木星膨胀机制研究提供了新方法。
中文摘要 AI 辅助
热木星的半径往往大于标准冷却-收缩模型的预测值，但目前仍不清楚是哪个过程提供或保留了额外的内部热量。我们利用因果发现（一种统计框架，用于确定在控制其他观测属性后，哪些观测属性仍与行星半径直接相关）分析了328颗拥有行星质量$M_p$、半径$R_p$、轨道周期$P_{\rm orb}$及宿主恒星有效温度$T_{\rm eff}$测量值的短周期巨行星。作为验证，同一流程能在超级地球对照样本中恢复预期的质量-半径关联。对于热木星，最优因果图显示$R_p$直接与$P_{\rm orb}$、$T_{\rm eff}$相关，而与$M_p$无关。由于入射通量随$T_{\rm eff}$升高而增加、随$P_{\rm orb}$缩短而增大，这种配对关联可自然解释为辐射调控膨胀的群体水平特征。将该图与解析半径超额标度关系对比后发现，Gold-Soter热潮汐的作用相对重要，动能/机械加热与欧姆耗散可能也有贡献。纯周期控制的引力潮汐因缺乏对恒星温度的主导依赖，不被认可为唯一解释。要区分热潮汐、动能/机械加热、欧姆耗散及混合场景，需测量控制入射通量、年龄、成分、恒星属性及选择效应后的半径超额。更广泛而言，本研究表明因果发现可将系外行星群体数据转化为热木星膨胀的物理解释性测试，它通过检验哪些观测量保留对$R_p$的直接条件依赖，且不施加特定半径关系，补充了参数化贝叶斯群体模型，不过样本量有限限制了推断图的适用范围。
英文摘要
Hot Jupiters often have radii larger than predicted by standard cooling--contraction models, but it remains unclear which process supplies or preserves the extra internal heat. We analyze 328 short-period giant planets with measured $M_p$, $R_p$, $P_{\rm orb}$, and host-star $T_{\rm eff}$ using causal discovery, a statistical framework that asks which observed properties remain directly connected to planet radius after the others are accounted for. As a check, the same pipeline recovers the expected mass--radius connection for a super-Earth control sample. For hot Jupiters, the preferred graph links $R_p$ directly to $P_{\rm orb}$ and $T_{\rm eff}$, but not to $M_p$. Since incident flux increases with $T_{\rm eff}$ and decreases with $P_{\rm orb}$ at fixed stellar properties, this paired dependence is naturally interpreted as a population-level signature of irradiation-regulated inflation. Comparing the graph with analytic radius-excess scalings suggests a comparatively important role for Gold--Soter thermal tides, with kinetic/mechanical heating and ohmic dissipation potentially contributing alongside them. Purely period-controlled gravitational tides are disfavored as the sole explanation because they lack a leading dependence on stellar temperature. Distinguishing thermal tides, kinetic/mechanical heating, ohmic dissipation, and mixed scenarios will require radius-excess measurements that control for incident flux, age, composition, stellar properties, and selection effects. More broadly, this work shows how causal discovery can turn population-level exoplanet data into physically interpretable tests of hot-Jupiter inflation. Causal discovery complements parametric Bayesian population models by testing which observables retain direct conditional dependence on $R_p$ without imposing a specific radius relation, although the modest sample size limits the scope of the inferred graph.
