带有遥远巨行星伴星的凌星行星系统仍保持中等共面性
Transiting Planetary Systems with Distant Giant Companions Remain Moderately Coplanar
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中文总结 AI 辅助
该研究结合RV与Hipparcos--Gaia数据，用分层贝叶斯框架推断19个含凌星内行星和外巨行星的系统轨道结构，发现其ΔI呈σ=15.8°的瑞利分布，共面性高于各向同性预期，还探讨了内行星质量对ΔI的影响，指出未来Gaia DR4数据可深化相关研究。
中文摘要 AI 辅助
内行星与遥远巨行星伴星之间的相互倾角是探测行星系统形成与动力学演化的重要探针，但该量的直接测量仍十分稀少。我们将径向速度（RV）观测数据与依巴谷-盖亚（Hipparcos--Gaia）天体测量数据结合，对19个至少拥有一颗凌星内行星和一颗外巨行星伴星的行星系统的轨道结构进行约束。采用分层贝叶斯框架，我们推断内、外行星轨道间最小相互倾角ΔI的总体分布，发现ΔI分布可由瑞利模型很好地描述，其尺度参数为σ = 15.8°（不确定性范围为+2.8°至-2.6°），该分布相比各向同性分布具有显著优势（Δlog Z=5.45）。此结果表明，带有遥远巨行星伴星的凌星系统相比各向同性群体预期值，共面性显著更高，与原始共面性的部分保留一致。按凌星内行星质量（0.3 M_Jup）划分后，巨行星-内行星系统的ΔI可能小于小型内行星系统，其概率P(σ_巨行星<σ_小型)=0.952；不过，当前数据并未显著支持允许两个子样本具有不同σ值的模型，而非两者共享同一σ值的模型。未来盖亚DR4天体测量数据将能对带有遥远巨行星伴星的系统三维结构开展更可靠的总体研究。
英文摘要
The mutual inclination between inner planets and distant giant companions provides an important probe of planetary system formation and dynamical evolution, yet direct measurements of this quantity remain scarce. We combine radial velocity (RV) observations with Hipparcos--Gaia astrometry to constrain the orbital architecture of 19 planetary systems hosting at least one transiting inner planet and one outer giant companion. Using a hierarchical Bayesian framework, we infer the population-level distribution of the minimum mutual inclination, $ΔI$, between the inner and outer planetary orbits. We find that the $ΔI$ distribution is well described by a Rayleigh model with a scale parameter of $σ= 15.8^{+2.8}_{-2.6}°$, which is strongly preferred over an isotropic distribution ($Δ\log Z=5.45$). This result suggests that transiting systems hosting distant giant companions remain substantially more coplanar than expected for an isotropic population, consistent with the partial preservation of primordial coplanarity. A division by the mass ($0.3\,M_{\rm Jup}$) of the inner transiting planet suggests that giant-inner-planet systems may have lower $ΔI$ than small-inner-planet systems, with $P(σ_{\rm giant}<σ_{\rm small})=0.952$; however, the current data do not significantly favor a model allowing different $σ$ values for the two subsamples over one in which they share a common $σ$. Future Gaia DR4 astrometry will enable more robust population-level studies of the three-dimensional architectures of systems with distant giant companions.
发表机构
- State Key Laboratory of Dark Matter Physics, Tsung-Dao Lee Institute & School of Physics and Astronomy, Shanghai Jiao Tong University（暗物质物理国家重点实验室，李政道理论与计算科学中心及物理与天文学院，上海交通大学）
- CAS Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences（中国科学院光学天文重点实验室，国家天文台，中国科学院）
- Institute for Astronomy, University of Hawai‘i（夏威夷大学天体物理研究所）
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