The outer solar system exhibits an anomalous pattern of orbital clustering, characterized by an approximate alignment of the apsidal lines and angular momentum vectors of distant, long-term stable Kuiper Belt objects. One explanation for this dynamical confinement is the existence of a yet-undetected planetary-mass object, “Planet Nine (P9).” Previous work has shown that trans-Neptunian objects, that originate within the scattered disk population of the Kuiper Belt, can be corralled into orbital alignment by Planet Nine’s gravity over ∼Gyr timescales, and characteristic P9 parameters have been derived by matching the properties of a synthetic Kuiper Belt generated within numerical simulations to the available observational data. In this work, we show that an additional dynamical process is in play within the framework of the Planet Nine hypothesis, and demonstrate that P9-induced dynamical evolution facilitates orbital variations within the otherwise dynamically frozen inner Oort cloud. As a result of this evolution, inner Oort cloud bodies can acquire orbits characteristic of the distant scattered disk, implying that if Planet Nine exists, the observed census of long-period trans-Neptunian objects is comprised of a mixture of Oort cloud and Kuiper Belt objects. Our simulations further show that although inward-injected inner Oort cloud objects exhibit P9-driven orbital confinement, the degree of clustering is weaker than that of objects originating within the Kuiper Belt. Cumulatively, our results suggest that a more eccentric Planet Nine is likely necessary to explain the data than previously thought.

外太阳系表现出异常的轨道聚集模式，其特征是远距离、长期稳定的柯伊伯带天体的近点线和角动量矢量近似对齐。这种动态限制的一种解释是存在一个尚未被探测到的行星质量物体，“第九行星（P9）”。先前的工作表明，起源于柯伊伯带分散盘群的跨海王星天体，可以通过行星九的引力在∼Gyr 时间尺度上将其纳入轨道对齐，并且特征 P9 参数已通过匹配在可用观测数据的数值模拟中生成的合成柯伊伯带。在这项工作中，我们表明在行星九假说的框架内有一个额外的动力过程在起作用，并证明 P9 诱导的动力学演化促进了原本动态冻结的奥尔特内云内的轨道变化。由于这种演变，内部奥尔特云体可以获得遥远的分散盘的轨道特征，这意味着如果第九行星存在，则观测到的长周期跨海王星天体的普查由奥尔特云和柯伊伯带的混合物组成对象。我们的模拟进一步表明，尽管向内注入的内奥尔特云天体表现出 P9 驱动的轨道限制，但其聚集程度弱于源自柯伊伯带内的天体。累积起来，我们的结果表明，可能需要比以前认为的更古怪的第九行星来解释数据。