Jumping-Jupiter scenario
The jumping-Jupiter scenario specifies an evolution of giant-planet migration described by the Nice model, in which an ice giant (an additional Neptune-mass planet) is scattered inward by Saturn and then ejected by Jupiter, causing their semi-major axes to jump, and thereby quickly separating their orbits.
[2] The jumps in the semi-major axes of Jupiter and Saturn described in the jumping-Jupiter scenario can allow these resonances to quickly cross the inner Solar System without altering orbits excessively,[1] although the terrestrial planets remain sensitive to its passage.
[12] The Grand Tack hypothesis, which posits that Jupiter's migration is reversed at 1.5 AU following the capture of Saturn in a resonance, is an example of this type of orbital evolution.
In a series of three articles Ramon Brasser, Alessandro Morbidelli, Rodney Gomes, Kleomenis Tsiganis, and Harold Levison analyzed the orbital evolution of the Solar System during giant planet migration.
[1][2] The jumping-Jupiter scenario replaces the smooth separation of Jupiter and Saturn with a series of jumps, thereby avoiding the sweeping of secular resonances through the inner Solar System as their period ratio crosses from 2.1 to 2.3.
[9] A separate study by Konstantin Batygin and Michael E. Brown found similar probabilities (4% vs 3%) of reproducing the current outer Solar System beginning with four or five giant planets using the best initial conditions.
[30][28] Their simulations differed in that the planetesimal disk was placed close to the outer planet resulting in a period of migration before planetary encounters began.
Jupiter's eccentricity is excited by resonance crossings and gravitational encounters with the ice giant and is damped due to secular friction with the planetesimal disk.
This can allow Jupiter's and Saturn's period ratio to jump beyond 2.3 during the planetary encounters without exceeding the current value once the planetesimal disk is removed.
Gravitational interactions with the dust causes the giant planets to escape from their resonance chain roughly 10 million years after the dissipation of the gas disk.
A slow and extended migration of Neptune into the planetesimal disk before planetary encounters begin leaves the Kuiper belt with a broad inclination distribution.
[5] During the giant planet migration the ν6 secular resonance first rapidly traversed the asteroid belt removing roughly half of its mass, much less than in the original Nice model.
[42] A recent work has found that the bombardment originating from the inner band of asteroids would yield only two lunar basins and would be insufficient to explain ancient impact spherule beds.
Noting the lack of direct evidence of cometary impactors, it proposes that leftover planetesimals were the source of most impacts and that Nice model instability may have occurred early.
[3] The jumping-Jupiter model used in this study was not typical, however, being selected from among only 5% with Jupiter and Saturn's period ratio jumped to beyond 2.3 while reproducing other aspects of the outer Solar System.
When relativistic effects are included, Mercury's precession rate is faster, which reduces the impact of this resonance crossing, and results in a smaller eccentricity similar to its current value.
[26] These may be the product of Jupiter's Grand Tack, provided that an excess of higher eccentricity asteroids is removed due to interactions with the terrestrial planets.
[56] However, if the ice giant spent a short time crossing the asteroid belt, some collisional families may remain recognizable by identifying the V-shaped patterns in plots of semi-major axes vs absolute magnitude produced by the Yarkovsky effect.
Numerical simulations of this process can roughly reproduce the distribution of P- and D-type asteroids and the size of the largest bodies, with differences such as an excess of objects smaller than 10 km being attributed to losses from collisions or the Yarkovsky effect, and the specific evolution of the planets in the model.
[6] The captured trojans have a wide range of inclinations and eccentricities, the result of their being scattered by the giant planets as they migrated from their original location in the outer disk.
This increases the size of Saturn's population relative to Uranus and Neptune when compared to the original Nice model, producing a closer match with observations.
If these encounters would lead to results inconsistent with the observations, for example, collisions between or the ejections of satellites or the disruption of the Laplace resonance of Jupiter's moons Io, Europa and Ganymede, this could provide evidence against jumping-Jupiter models.
This increases their velocities relative to the giant planets, decreasing the effectiveness of gravitational focusing, thereby reducing the fraction of planetesimals impacting the inner satellites.
Even in simulations where the final position of the giant planets are similar to the current Solar System, Jupiter's and Saturn's tilt are reproduced less than 10% of the time.
[85] The slow pace and extended distance of this migration provides sufficient time for inclinations to be excited before the resonances reach the region of Kuiper belt where the hot classical objects are captured and later deposited.
[86] If Neptune reaches an eccentricity greater than 0.12 following its encounter with the fifth giant planet hot classical Kuiper belt objects can also be captured due to secular forcing.
The kernel is a concentration of Kuiper belt objects with small eccentricities and inclinations, and with semi-major axes of 44–44.5 AU identified by the Canada–France Ecliptic Plane Survey.
The total mass deposited in the scattered disk is about twice that of the classical Kuiper belt, with roughly 80% of the objects surviving to the present having semi-major axes less than 200 AU.
Objects scattered outward to semi-major axes greater than 200 AU would have their perihelia raised by the dynamical effects of Planet Nine decoupling them from the influence of Neptune.
The outer Oort cloud, semi-major axes greater than 20,000 AU, forms quickly as the galactic tide raises the perihelion of object beyond the orbits of the giant planets.
