The orbital structure in the distant Kuiper Belt: Evidence for an Earth-mass planet?
Session 7.01 Dynamics
Wednesday 06-26 | 10:10 - 10:30
Takashi Ito (伊藤孝士)[NAOJ, Chiba Tech]

The orbits of distant trans-Neptunian objects (TNOs) can indicate the existence of an undiscovered planet in the outer solar system. We used N-body computer simulations to investigate the effects of a hypothetical Kuiper Belt planet (KBP) on the orbital structure in the distant Kuiper Belt beyond 50 au. We used observations to constrain model results, including the well-characterized Outer Solar System Origins Survey. We found that an Earth-like planet (m ~ 1.5–3 Earth masses) 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 large population of TNOs in orbits outside Neptune's gravitational influence (i.e., detached objects with q > 40 au)
  • A significant population of high-i TNOs (i > 45 deg)
  • The existence of some extreme TNOs with peculiar orbits (e.g., Sedna)
  • This Earth-like KBP is also compatible with identified Gyr-stable TNOs in the 2:1, 5:2, 3:1, 4:1, 5:1, and 6:1 Neptunian mean motion resonances, often neglected in other studies. We predict the existence of the KBP and several TNOs on peculiar orbits in the outer solar system, offering observationally testable signatures of the planet's influence.

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