Making Planet Nine: A Scattered Giant in the Outer Solar System
Abstract
Correlations in the orbits of several minor planets in the outer solar system suggest the presence of a remote, massive Planet Nine. With at least 10 times the mass of the Earth and a perihelion well beyond 100 au, Planet Nine poses a challenge to planet formation theory. Here we expand on a scenario in which the planet formed closer to the Sun and was gravitationally scattered by Jupiter or Saturn onto a very eccentric orbit in an extended gaseous disk. Dynamical friction with the gas then allowed the planet to settle in the outer solar system. We explore this possibility with a set of numerical simulations. Depending on how the gas disk evolves, scattered super-Earths or small gas giants settle on a range of orbits, with perihelion distances as large as 300 au. Massive disks that clear from the inside out on million-year timescales yield orbits that allow a super-Earth or gas giant to shepherd the minor planets as observed. A massive planet can achieve a similar orbit in a persistent, low-mass disk over the lifetime of the solar system.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- July 2016
- DOI:
- arXiv:
- arXiv:1603.08010
- Bibcode:
- 2016ApJ...826...64B
- Keywords:
-
- planetary systems;
- planets and satellites: formation;
- planet─disk interactions;
- planets and satellites: dynamical evolution and stability;
- Kuiper Belt: general;
- Astrophysics - Earth and Planetary Astrophysics;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- 14 pages of text, 2 tables, 5 figures, ApJ, submitted
