Is There an Earth-like Planet in the Distant Kuiper Belt?

TL;DR

This study uses computer simulations to suggest an Earth-like planet in the distant Kuiper Belt could explain observed orbital features of trans-Neptunian objects, predicting testable signatures for future observations.

Contribution

It proposes a specific Earth-mass planet in the Kuiper Belt that accounts for the orbital distribution of TNOs, a novel hypothesis supported by simulation and observational constraints.

Findings

An Earth-like planet can explain detached TNOs and high-inclination objects.

The planet's orbit is distant, inclined, and consistent with stable resonant populations.

Predicted observable signatures include peculiar TNO orbits and the planet itself.

Abstract

The orbits of trans-Neptunian objects (TNOs) can indicate the existence of an undiscovered planet in the outer solar system. Here, we used N-body computer simulations to investigate the effects of a hypothetical Kuiper Belt planet (KBP) on the orbital structure of TNOs in the distant Kuiper Belt beyond ~50 au. We used observations to constrain model results, including the well-characterized Outer Solar System Origins Survey (OSSOS). We determined that an Earth-like planet (m ~ 1.5-3 Earth masses) located on a distant (semimajor axis a ~ 250-500 au, perihelion q ~ 200 au) and inclined (i ~ 30 deg) orbit can explain three fundamental properties of the distant Kuiper Belt: a prominent population of TNOs with orbits beyond Neptune's gravitational influence (i.e., detached objects with q > 40 au), a significant population of high-i objects (i > 45 deg), and the existence of some extreme objects with peculiar orbits (e.g., Sedna). Furthermore, the proposed KBP is compatible with the existence of identified Gyr-stable TNOs in the 2:1, 5:2, 3:1, 4:1, 5:1, and 6:1 Neptunian mean motion resonances. These stable populations are often neglected in other studies. We predict the existence of an Earth-like planet and several TNOs on peculiar orbits in the outer solar system, which can serve as observationally testable signatures of the putative planet's perturbations.