在存在九号行星的情况下，遥远的海王星外天体倾角对原星团扰动的约束
Distant TNO Inclinations as a Constraint on Primordial Cluster Perturbations in the Presence of Planet Nine
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中文总结 AI 辅助
研究在九号行星存在时，遥远海王星外天体倾角对原星团扰动的约束。通过比较不同初始构型下测试粒子的长期N体积分，发现观测到的遥远海王星外天体与温和扰动诞生环境相符，若低倾角离散是固有特征，将有力约束原星团扰动程度。
中文摘要 AI 辅助
太阳几乎肯定诞生于一个恒星团，这意味着在太阳系形成初期受到了来自邻近恒星的某种程度的外部作用力。然而，已发表的关于最强相关恒星遭遇的估计跨度很大，从相对温和的扰动到极具破坏性的飞掠。此前，遥远的海王星外天体适度的倾角离散被用来表明强烈的原初遭遇不太可能发生，且外太阳系在诞生时没有受到剧烈搅动。在这项工作中，我们独立研究了这一约束，并探讨在存在九号行星的情况下这一结论是否成立。由于九号行星能在数十亿年的时间尺度上重塑遥远的海王星外天体，目前的倾角分布在多大程度上保留了原星团激发的直接记录，事先并不明确。为解决这个问题，我们比较了长期的N体积分，其中遥远的测试粒子要么从受到强烈星团扰动的构型开始，要么从相对平静的构型开始，然后在已知的巨行星、银河潮汐、过路恒星的影响以及九号行星的作用下演化。我们发现，九号行星并不会将高度激发的原初天体群体转变为类似于观测到的低倾角遥远样本的群体。相反，模拟的和观测到的遥远海王星外天体群体之间的比较表明，即使在存在九号行星的情况下，观测到的遥远海王星外天体与相对温和扰动的诞生环境最为一致。如果这种相对较低的倾角离散被证实是遥远海王星外天体群体的固有特征，而不是观测偏差的产物，那么它对原星团扰动的严重程度构成了一个有力的约束。
英文摘要
The Sun was almost certainly born in a stellar cluster, implying some degree of external forcing from neighboring stars during the Solar System's infancy. Published estimates of the strongest relevant stellar encounter, however, span a broad range, from relatively gentle perturbations to violently disruptive flybys. The modest inclination dispersion of the distant trans-Neptunian population has previously been used to argue that strong primordial encounters were unlikely and that the outer Solar System was not violently stirred at birth. In this work, we independently examine this constraint and ask whether this conclusion holds in the presence of Planet Nine. Because Planet Nine can reshape the distant trans-Neptunian population over gigayear timescales, the extent to which the present-day inclination distribution preserves a direct record of primordial cluster excitation is a priori unclear. To address this question, we compare long-term N-body integrations in which distant test particles begin either in strongly cluster-perturbed configurations or in comparatively quiescent ones, and are then evolved under the influence of the known giant planets, the Galactic tide, the effects of passing stars, and Planet Nine. We find that Planet Nine does not transform a highly excited primordial population into one resembling the observed low-inclination distant sample. Instead, comparisons between the simulated and the observed distant TNO populations indicate that the observed distant TNOs are most consistent with a relatively mildly perturbed birth environment, even in the presence of Planet Nine. If this comparatively low inclination dispersion is confirmed to be an intrinsic feature of the distant TNO population, rather than an artifact of observational bias, it constitutes a robust constraint on the severity of primordial cluster perturbations.
