It has recently been shown that stellar clustering plays an important role in shaping the properties of planetary systems. We investigate how the multiplicity distributions and orbital periods of planetary systems depend on the 6D phase space density of stars surrounding planet host systems. We find that stars in high stellar phase space density environments (overdensities) have a factor of 1.6–2.0 excess in the number of single-planet systems compared to stars in low stellar phase space density environments (the field). The multiplicity distribution of planets around field stars is much flatter (i.e., there is a greater fraction of multiplanet systems) than in overdensities. This result is primarily driven by the combined facts that (i) “hot Jupiters” (HJs) are almost exclusively found in overdensities and (ii) HJs are predominantly observed to be single-planet systems. Nevertheless, we find that the difference in multiplicity is even more pronounced when only considering planets in the Kepler sample, which contains few HJs. This suggests that the Kepler dichotomy—an apparent excess of systems with a single transiting planet—plausibly arises from environmental perturbations. In overdensities, the orbital periods of single-planet systems are smaller than orbital periods of multiple-planet systems. As this difference is more pronounced in overdensities, the mechanism responsible for this effect may be enhanced by stellar clustering. Taken together, the pronounced dependence of planetary multiplicity and orbital period distributions on stellar clustering provides a potentially powerful tool to diagnose the impact of environment on the formation and evolution of planetary systems.

最近的研究表明，星团在塑造行星系统的特性方面起着重要作用。我们研究了行星系统的多样性分布和轨道周期如何取决于行星宿主系统周围恒星的 6D 相空间密度。我们发现，与处于低星相空间密度环境（场）中的恒星相比，处于高星相空间密度环境（过密度）中的恒星在单行星系统的数量上多出 1.6-2.0 倍。围绕场星的行星的多样性分布比超密度更平坦（即，多行星系统的比例更大）。这一结果主要是由以下综合事实驱动的：（i）“热木星”（HJ）几乎只在密度过高的地方发现，（ii）HJ 主要被观察到是单行星系统。尽管如此，我们发现当只考虑开普勒样本中的行星时，多样性的差异更加明显，其中包含很少的 HJ。这表明开普勒二分法——一个明显过多的系统与一个过境行星——似乎是由环境扰动引起的。在超密度方面，单行星系统的轨道周期小于多行星系统的轨道周期。由于这种差异在超密度方面更为明显，导致这种效应的机制可能会通过恒星聚集来增强。综合起来，