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arXiv 2004.06914astro-ph.EP
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在行星9存在的情况下，柯伊伯带在50 AU以外的平均面

Mean plane of the Kuiper belt beyond 50 AU in the presence of Planet 9

Jian Li, Zhihong Jeff Xia

备注：
7 pages, 9 figures, Accepted for publication on Astronomy and Astrophysics
发表信息：
A&A 637, A87 (2020)
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摘要：

上下文最近对柯伊伯带天体（KBO）的观测普查揭示了异常的轨道结构。这导致了一种假设，即存在另一颗$\sim5-10~m_{\oplus}$行星。这颗行星被称为行星9，占据了数百个天文单位的偏心和倾斜轨道。然而，正在考虑的KBO在$a>250$ AU处具有最大的已知半长轴;因此它们非常难以检测。目标。在提出的行星9的背景下，我们的目标是测量在$a>50$ AU的柯伊伯带的平均平面。在比较预期和观测到的平均平面时，这颗未被发现的行星的质量和轨道会受到一些限制。方法.我们采用并发展了Volk & Malhotra（2017）的理论方法，以确定柯伊伯带的预期平均平面与由八颗已知行星确定的不变平面之间的相对角度$δ$。构造了数值模拟来验证我们的理论方法。然后，类似于Volk & Malhotra（2017），我们推导了实际观测KBO与$100<a<200$ AU的角度$δ$，并估计了测量不确定度。最后，为了进行比较，为可能的行星9参数的不同组合创建了理论上预期的$δ$地图。结果柯伊伯带的预期平均面几乎与$a=90$ AU内部的上述不变面重合。但是由于行星9的存在，这两个平面在$a>100$ AU处明显地相互偏离，因为相对角度$δ$可能和$\sim10^{\circ}$一样大。使用$1σ$上限的$δ<5^{\circ}$推导出真实的KBO样本作为约束，我们提出了最可能的行星9的参数。

英文摘要：

Context. A recent observational census of Kuiper belt objects (KBOs) has unveiled anomalous orbital structures. This has led to the hypothesis that an additional $\sim5-10~m_{\oplus}$ planet exists. This planet, known as Planet 9, occupies an eccentric and inclined orbit at hundreds of astronomical units. However, the KBOs under consideration have the largest known semimajor axes at $a>250$ AU; thus they are very difficult to detect.// Aims. In the context of the proposed Planet 9, we aim to measure the mean plane of the Kuiper belt at $a>50$ AU. In a comparison of the expected and observed mean planes, some constraints would be put on the mass and orbit of this undiscovered planet. Methods. We adopted and developed the theoretical approach of Volk & Malhotra (2017) to the relative angle $δ$ between the expected mean plane of the Kuiper belt and the invariable plane determined by the eight known planets. Numerical simulations were constructed to validate our theoretical approach. Then similar to Volk & Malhotra (2017), we derived the angle $δ$ for the real observed KBOs with $100<a<200$ AU, and the measurement uncertainties were also estimated. Finally, for comparison, maps of the theoretically expected $δ$ were created for different combinations of possible Planet 9 parameters. Results. The expected mean plane of the Kuiper belt nearly coincides with the said invariable plane interior to $a=90$ AU. But these two planes deviate noticeably from each other at $a>100$ AU owing to the presence of Planet 9 because the relative angle $δ$ could be as large as $\sim10^{\circ}$. Using the $1σ$ upper limit of $δ<5^{\circ}$ deduced from real KBO samples as a constraint, we present the most probable parameters of Planet 9.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

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