Dynamical effects on the classical Kuiper belt during the excited-Neptune model

• Published in: Icarus (New York, N.Y. 1962) N.Y. 1962), 2019-12, Vol.334, p.89-98
• Main Authors: Ribeiro de Sousa, Rafael, Gomes, Rodney, Morbidelli, Alessandro, Vieira Neto, Ernesto
• Format: Article
• Language: English
• Subjects: Astrophysics; Earth and Planetary Astrophysics; Kuiper belt; Sciences of the Universe; Self-gravity; Solar system formation
• ISSN: 0019-1035; 1090-2643
• DOI: 10.1016/j.icarus.2018.08.008

•Simulations with an excited Neptune overexcite the KB cold population.•A self graviting planetesimal disk helps objects to return to an unexcited mode.•The self-gravity is effective just for a cold population with Pluto-sized objects.•Without self gravity, we need very specific secular configurations for Neptune. The link between the dynamical evolution of the giant planets and the Kuiper Belt orbital structure can provide clues and insight about the dynamical history of the Solar System. The classical region of the Kuiper Belt has two populations (the cold and hot populations) with completely different physical and dynamical properties. These properties have been explained in the framework of a sub-set of the simulations of the Nice Model, in which Neptune remained on a low-eccentricity orbit (Neptune’s eccentricity is never larger than 0.1) throughout the giant planet instability (Nesvorný 2015a,b). However, recent simulations (Gomes et al., 2018) have showed that the remaining Nice model simulations, in which Neptune temporarily acquires a large-eccentricity orbit (larger than 0.1), are also consistent with the preservation of the cold population (inclination smaller than 4°), if the latter formed in situ. However, the resulting a cold population showed in many of the simulations eccentricities larger than those observed for the real population. The purpose of this work is to discuss the dynamical effects on the Kuiper belt region due to an excited Neptune phase. We focus on a short period of time, of about six hundred thousand years, which is characterized by Neptune’s large eccentricity and smooth migration with a slow precession of Neptune’s perihelion. This phase was observed during a full simulation of the Nice Model (Gomes et al., 2018) just after the last jump of Neptune’s orbit due to an encounter with another planet. We show that if self-gravity is considered in the disk, the precession rate of the particles longitude of perihelion ϖ is slowed down, which in turn speeds up the cycle of ϖN−ϖ (the subscript N referring to Neptune), associated to the particles eccentricity evolution. This, combined with the effect of mutual scattering among the bodies, which spreads all orbital elements, allows some objects to return to low eccentricities. However, we show that if the cold population originally had a small total mass, this effect is negligible. Thus, we conclude that the only possibilities to keep at low eccentricity some cold-population objects