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

Abstract

Context. A recent observational census of Kuiper belt objects (KBOs) has unveiled anomalous orbital structures. This has led to the hypothesis that an additional $\sim 5-10m_{\oplus }$ 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 $\delta$ 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 $\delta$ 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 $\delta$ 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 $\delta$ could be as large as $\sim 10^{\circ }$. Using the $1\sigma$ upper limit of $\delta <5^{\circ }$ deduced from real KBO samples as a constraint, we present the most probable parameters of Planet 9.

7 pages, 9 figures, Accepted for publication on Astronomy and Astrophysics

References in corpus (7)

• The Planet Nine Hypothesis
• Solar Obliquity Induced by Planet Nine
• The inclination of the planetary system relative to the solar equator may be explained by the presence of Planet 9
• OSSOS XV: Probing the Distant Solar System with Observed Scattering TNOs
• Solar Obliquity Induced by Planet Nine: Simple Calculation
• The Warped Plane of the Classical Kuiper Belt
• Calibration of the angular momenta of the minor planets in the solar system

Cited by in corpus (4)

• Measuring the Mean Plane of the Distant Kuiper Belt
• Prospects for localising Planet 9 with a future Uranus mission
• Twisted extreme trans-Neptunian orbital parameter space: statistically significant asymmetries confirmed
• A new multiple-arc model of the resonant Kuiper belt objects -- Plutinos