Five-planet Nice model
The five-planet Nice model is a recent variation of the Nice model that begins with five giant planets, the current four plus an additional ice giant, in a chain of mean-motion resonances. After the resonance chain is broken, the five giant planets undergo a period of planetesimal-driven migration, followed by a gravitational instability similar to that in the original Nice model. During the instability the additional giant planet is scattered inward onto a Jupiter-crossing orbit and is ejected from the Solar System following an encounter with Jupiter. An early Solar System with five giant planets was proposed in 2011 after numerical models indicated that this is more likely to reproduce the current Solar System.
A five-planet Nice model
The following is a version of the five-planet Nice model that results in a late instability and reproduces a number of aspects of the current Solar System. A number of recent studies indicate that the early Solar System may have evolved differently, however, with the instability occurring soon after the dissipation of the gas nebula, or with the giant planets beginning in another resonance chain.
The Solar System ends its nebula phase with Jupiter, Saturn, and the three ice giants in a 3:2, 3:2, 2:1, 3:2 resonance chain with semi-major axes ranging from 5.5 – 20 AU. A dense disk of planetesimals orbits beyond these planets, extending from 24 AU to 30 AU. Collisions between planetesimals in the outer disk produce debris that is ground to dust in a cascade of collisions. The dust spirals inward toward the planets due to Poynting-Robertson drag and eventually reaches Neptune's orbit. Gravitational interactions with the dust allow the giant planets to escape from the resonance chain roughly ten million years after the dissipation of the gas disk. After a series of distant planetary encounters the planets settle into an extended period of slow dust-driven migration. Their orbits slowly diverge over four hundred million years, until Neptune approaches the inner edge of the planetesimal disk.
The migration of the planets then accelerates and transitions to a planetesimal-driven migration as Neptune encounters and exchanges angular momentum with an increasing number of planetesimals. A net inward transfer of planetesimals and outward migration of Neptune occur during these encounters as most of those scattered outward return to be encountered again while some of those scattered inward are prevented from returning after encountering Uranus. A similar process occurs for Uranus, the extra ice giant, and Saturn resulting in their outward migration and a transfer of planetesimals inward from the outer belt to Jupiter. Jupiter, in contrast, ejects most of the planetesimals from the Solar System, and as a result migrates inward. After 10 million years the divergent migration of the planets leads to resonance crossings, exciting the eccentricities of the giant planets and destabilizing the planetary system when Neptune is near 28 AU.
During this instability the extra ice giant enters a Saturn-crossing orbit and is scattered inward by Saturn onto a Jupiter-crossing orbit. Repeated gravitational encounters with the ice giant cause jumps in Jupiter's and Saturn's semi-major axes, driving a step-wise separation of their orbits, leading to a rapid increase of the ratio of their periods until it is greater than 2.3. The ice giant also encounters Uranus and Neptune and crosses parts of the asteroid belt as these encounters increase the eccentricity and semi-major axis of its orbit. After 10,000–100,000 years, the ice giant is ejected from the Solar System following an encounter with Jupiter, becoming a rogue planet. The remaining planets then continue to migrate at a declining rate and slowly approach their final orbits as most of the remaining planetesimal disk is removed.
Solar System effects
The migrations of the giant planets and encounters between them have many effects throughout the Solar System. The gravitational encounters between the giant planets excite their eccentricities and inclinations. The planetesimals scattered inward by Neptune enter planet-crossing orbits, initiating the Late Heavy Bombardment. Impacts of these planetesimals leave craters and impact basins on the moons of the outer planets, and may result in the disruption of their inner moons. Some of those planetesimals with semi-major axes similar to Jupiter's new semi-major axis are jump-captured as Jupiter trojans when Jupiter's semi-major axis jumps during encounters with the ejected ice giant. One group of Jupiter trojans can be depleted relative to the other if the ice giant passes through it following the ice giant's last encounter with Jupiter. Later, when Jupiter and Saturn are near mean-motion resonances, other Jupiter trojans can be captured via the mechanism described in the original Nice model. Other planetesimals are captured as irregular satellites of the giant planets via three-body interactions during encounters between the ejected ice giant and the other planets. The irregular satellites begin with wide range of inclinations including prograde, retrograde, and perpendicular orbits. The population is later reduced as those in perpendicular orbits are lost due to the Kozai mechanism, and others are broken up by collisions among them. The encounters between planets can also perturb the orbits of the regular satellites and may be responsible for the inclination of Iapetus's orbit. Saturn's rotational axis may have been tilted when it slowly crosses a spin-orbit resonance with Neptune.
While Neptune migrates outward several AU, the hot classical Kuiper belt and the scattered disk are formed as some planetesimals scattered outward by Neptune are captured in resonances, undergo an exchange of eccentricity vs inclination via the Kozai mechanism, and are released onto higher perihelion, stable orbits. Planetesimals captured in Neptune's sweeping 2:1 resonance during this early migration are released when an encounter with the ice giant causes its semi-major axis to jump outward, leaving behind a group of low-inclination, low-eccentricity objects with semi-major axes near 44 AU. This process avoids close encounters with Neptune allowing loosely bound binaries, including 'blue' binaries, to survive. An excess of low-inclination plutinos is avoided due to a similar release of objects from Neptune's 3:2 resonance during this encounter. Neptune's modest eccentricity following the encounter, or the rapid precession of its orbit, allows the primordial disk of cold classical Kuiper belt objects to survive. If Neptune's migration is slow enough following this encounter the eccentricity distribution of these objects can be truncated by a sweeping mean-motion resonances. As Neptune slowly approaches its current orbit, objects are left in fossilized high-perihelion orbits in the scattered disk. Others with perihelia beyond Neptune's orbit but not high enough to avoid interactions with Neptune remain as a scattering objects, and those that remain in resonance at the end of Neptune's migration form the various resonant populations beyond Neptune's orbit. Objects that are scattered to very large semi-major axis orbits can have their perihelia lifted beyond the influences of the giant planets by the galactic tide or perturbations from passing stars, depositing them in the Oort cloud. If the hypothetical Planet Nine was in its proposed orbit at the time of the instability, objects would be captured in a cloud with semi-major axes centered on its semi-major axis.
In the inner Solar System, the rapid separation of the orbits of Jupiter and Saturn reduces the excitation of the eccentricities of the inner planets due to secular resonance sweeping. Modest changes in the asteroid's orbits also occur, potentially shifting the distribution of eccentricities from that of the Grand Tack model toward the current distribution. Asteroid collisional families can be dispersed due to interactions with various resonances and by encounters with the ice giant as it crosses the asteroid belt. Planetesimals from the outer belt are embedded in the asteroid belt as P- and D-type asteroids when their aphelion are lowered below Jupiter's orbit while they are in a resonance or during encounters with the ice giant, with some reaching the inner asteroid belt due to encounters with the ice giant. Roughly half of the asteroids escape the core of the asteroid belt (less than in the original Nice model) and an inner extension of the asteroid belt is disrupted when the planets reach their present positions, leading to a smaller, but extended, Late Heavy Bombardment of the inner planets by rocky objects.
Development of the Nice model
Four planet models
Current theories of planetary formation do not allow for the accretion of Uranus and Neptune in their present positions. The protoplanetary disk was too diffuse and the time scales too long for them to form via planetesimal accretion before the gas disk dissipated, and numerical models indicate that later accretion would be halted once Pluto-sized planetesimals formed. Although more recent models including pebble accretion allow for faster growth the inward migration of the planets due to interactions with the gas disk leave them in closer orbits.
It is now widely accepted that the Solar System was initially more compact and that the outer planets migrated outward to their current positions. The planetesimal-driven migration of the outer planets was first described in 1984 by Fernandez and Ip. This process is driven by the exchange of angular momentum between the planets and planetesimals originating from an outer disk. Early dynamical models assumed that this migration was smooth. In addition to reproducing the current positions of the outer planets, these models offered explanations for: the populations of resonant objects in the Kuiper belt, the eccentricity of Pluto's orbit, the inclinations of the hot classical Kuiper belt objects and the retention of a scattered disk, and the low mass of Kuiper belt and the location of its outer edge near the 2:1 resonance with Neptune. However, these models failed to reproduce the eccentricities of the outer planets, leaving them with very small eccentricities at the end of the migration.
In the original Nice model Jupiter and Saturn's eccentricities are excited when they cross their 2:1 resonance, destabilizing the outer Solar System. A series of gravitational encounters ensues during which Uranus and Neptune are scattered outward into the planetesimal disk. There they scatter a great number of planetesimals inward accelerating the migration of the planets. The scattering of planetesimals and the sweeping of resonances through the asteroid belt produce a bombardment of the inner planets. In addition to reproducing the positions and eccentricities of the outer planets, the original Nice model provided for the origin of: the Jupiter trojans, and the Neptune trojans; the irregular satellites of Saturn, Uranus, and Neptune; the various populations of trans-Neptunian objects; the magnitude of, and with the right initial conditions, the timing of the Late Heavy Bombardment.
However, sweeping secular resonances would perturb the orbits of inner Solar System objects if Jupiter's migration was slow and smooth. The ν5 secular resonance crosses the orbits of the terrestrial planets exciting their eccentricities. While Jupiter and Saturn slowly approach their 2:1 resonance the eccentricity of Mars reaches values that can result in collisions between planets or in Mars being ejected from the Solar System. Revised versions of the Nice model beginning with the planets in a chain of resonances avoid this slow approach to the 2:1 resonance. However, the eccentricities of Venus and Mercury are typically excited beyond their current values when the ν5 secular resonance crosses their orbits. The orbits of the asteroids are also significantly altered: the ν16 secular resonance excites inclinations and the ν6 secular resonance excites eccentricities removing low-inclination asteroids as they sweep across the asteroid belt. As a result, the surviving asteroid belt is left with a larger fraction of high inclination objects than is currently observed.
The orbits of the inner planets and the orbital distribution of the asteroid belt can be reproduced if Jupiter encounters one of the ice giants, accelerating its migration. The slow resonance crossings that excite the eccentricities of Venus and Mercury and alter the orbital distribution of the asteroids occur when Saturn's period was between 2.1 and 2.3 times that of Jupiter's. Theorists propose that these were avoided because the divergent migration of Jupiter and Saturn was dominated by planet–planet scattering at that time. Specifically, one of the ice giants was scattered inward onto a Jupiter-crossing orbit by a gravitational encounter with Saturn, after which it was scattered outward by a gravitational encounter with Jupiter. As a result, Jupiter's and Saturn's orbits rapidly diverged, accelerating the sweeping of the secular resonances. This evolution of the orbits of the giant planets, similar to processes described by exoplanet researchers, is referred to as the jumping-Jupiter scenario.
The encounters between the ice giant and Jupiter in the jumping-Jupiter scenario often lead to the ejection of the ice giant. For this ice giant to be retained its eccentricity must be damped by dynamical friction with the planetesimal disk, raising its perihelion beyond Saturn's orbit. The planetesimal disk masses typically used in the Nice model are often insufficient for this, leaving systems beginning with four giant planets with only three at the end of the instability. The ejection of the ice giant can be avoided if the disk mass is larger, but the separation of Jupiter and Saturn often grows too large and their eccentricities become too small as the larger disk is cleared. These problems led David Nesvorný of the Southwest Research Institute to propose that the Solar System began with five giant planets, with an additional Neptune-mass planet between Saturn and Uranus. Using thousands of simulations with a variety of initial conditions he found that the simulations beginning with five giant planets were ten times more likely to reproduce the orbits of the outer planets. A follow-up study by David Nesvorný and Alessandro Morbidelli found that the required jump in the ratio of Jupiter's and Saturn's periods occurred and the orbits of the outer planets were reproduced in 5% of simulations for one five-planet system vs less than 1% for four-planet systems. The most successful began with a significant migration of Neptune, disrupting the planetesimal disk, before planetary encounters were triggered by resonance crossing. This reduces secular friction, allowing Jupiter's eccentricity to be preserved after it is excited by resonance crossings and planetary encounters.
Konstantin Batygin, Michael E. Brown, and Hayden Betts, in contrast, found four- and five-planet systems had a similar likelihoods (4% vs 3%) of reproducing the orbits of the outer planets, including the oscillations of Jupiter's and Saturn's eccentricities, and the hot and cold populations of Kuiper belt. In their investigations Neptune's orbit was required to have a high eccentricity phase during which the hot population was implanted. A rapid precession of Neptune's orbit during this period due to interactions with Uranus was also necessary for the preservation a primordial belt of cold classical objects. For a five-planet system they found that the low eccentricities of the cold classical belt were best preserved if the fifth giant planet was ejected in 10,000 years. Since their study examined only the outer Solar System, it did not include a requirement that Jupiter's and Saturn's orbits diverged rapidly as would be necessary to reproduce the current inner Solar System, however.
A number of previous works also modeled Solar Systems with extra giant planets. A study by Thommes, Bryden, Wu, and Rasio included simulations of four and five planets beginning in resonant chains. Loose resonant chains of four or five planets with Jupiter and Saturn beginning in a 2:1 resonance often resulted in the loss of an ice giant for small mass planetesimal disks. The loss of a planet was avoided in four planet systems with a larger planetesimal disk but no scattering of planets occurred. A more compact system with Jupiter and Saturn in a 3:2 resonance sometimes resulted in encounters occurring between Jupiter and Saturn. A study by Morbidelli, Tsiganis, Crida, Levison, and Gomes was more successful in reproducing the Solar System beginning with a four planet system in a compact resonant chain. They also modeled the capture of planets in a five planet resonant chain and noted the planets had larger eccentricities and the system became unstable within 30 Myr. Ford and Chiang modeled systems of planets in a packed oligarchy, the result of their formation in a more massive dynamically cool disk. They found that the extra planets would be ejected as the density of the primordial disk declined. Simulations by Levison and Morbidelli, in contrast, showed that the planets in such systems would spread out rather than be ejected.
The giant planets begin in a chain of resonances. During their formation in the protoplanetary disk, interactions between the giant planets and the gas disk caused them to migrate inward toward the Sun. Jupiter's inward migration continued until it was halted, or reversed, as in the Grand Tack model, when it captured a faster migrating Saturn in a mean-motion resonance. The resonance chain was extended as the three ice giants also migrated inward and were captured in further resonances. A long-range migration of Neptune outward into the planetesimal disk before planetary encounters begins is most likely if the planets were captured in a 3:2, 3:2, 2:1, 3:2 resonance chain, occurring in 65% of simulations when the inner edge was within 2 AU. While this resonance chain has the highest likelihood of reproducing Neptune's migration other resonance chains are also possible if the instability occurred early.
A late instability may have followed an extended period of slow dust-driven migration. The combination of a late escape from a resonance chain, as described in the Nice 2 model, and a long-range migration of Neptune is unlikely. If the inner edge of the planetesimal disk is close an early escape from resonance occurs, if it is distant an instability typically triggered before a significant migration of Neptune occurs. This gap may be bridged if an early escape from resonance is followed by an extended period of slow dust-driven migration. Resonance chains other than the 3:2, 3:2, 2:1, 3:2 are unlikely in this case. Instabilities occur during the slow migration for tighter resonance chains and the distant disk is unrealistically narrow for more relaxed resonance chains. The rate of dust-driven migration slows with time as the rate of dust generation declines. As a result, the timing of the instability is sensitive to factors that determine the rate of dust generation such as the size distribution and the strength of the planetesimals.
Timing of the instability
The timing of the instability in the Nice model was initially proposed to have coincided with the Late Heavy Bombardment, a spike in the impact rate thought to have occurred several million years after the formation of the Solar System. However, recently a number of issues have been raised regarding the timing of the Nice model instability, whether it was the cause of the Late Heavy Bombardment, and if an alternative would better explain the associated craters and impact basins. Most of the effects of the Nice model instability on the orbits of the giant planets and those of the various small body populations from the asteroid belt outward to the scattered disk are independent of its timing, however.
A five-planet Nice model with a late instability has a low probability of reproducing the orbits of the terrestrial planets. Jupiter's and Saturn's period ratio makes the jump from less than 2.1 to greater than 2.3 required to avoid secular resonance crossings in a small fraction of simulations (7%–8.7%) and the eccentricities of the terrestrial planets can also be excited when Jupiter encounters the ice giant. In a study by Nathan Kaib and John Chambers this resulted in the orbits of the terrestrial planets being reproduced in a few percent of simulation with only 1% reproducing both the terrestrial and giant planets orbits. This led Kaib and Chambers to propose that the instability occurred early, before the formation of the terrestrial planets. However, a jump in the ratio of the orbital periods of Jupiter and Saturn is still required to reproduce the asteroid belt, reducing the advantage of an early instability. A previous study by Ramon Brasser, Kevin Walsh, and David Nesvorny found a reasonable chance (greater than 20%) of reproducing the inner Solar System using a selected five-planet model. The shapes of the impact basins on Iapetus are also consistent with a late bombardment.
Sufficient mass may not remain in the planetesimal disk after 400 million years of collisional grinding to fit models of the instability. If the size distribution of the planetesimal disk initially resembled its current distribution and included 1000's of Pluto mass objects significant mass loss occurs. This leaves the disk with under 10 Earth masses, while a minimum of 15 Earth masses is needed in current models of the instability. The size distribution also becomes shallower than is observed. These problems remain even if simulations begin with a more massive disk or a steeper size distribution. In contrast, a much lower mass loss and little change in the size distribution occurs during a early instability. If the planetesimal disk began without Pluto mass objects collisional grinding would begin as they formed from smaller object, with the timing depending on the initial size of the objects and mass of the planetesimal disk.
Binary objects such as Patroclus-Menoetius would be separated due to the collisions if the instability was late. Patroclus and Menoetius are a pair of ~100 km objects orbiting with a separation of 680 km and relative velocities of ~11 m/s. While this binary remains in a massive planetesimal disk it is vulnerable to being separated due to collision. Roughly ~90% of similar binaries are separated per hundred million years in simulations and after 400 million years its survival probabilities falls to 7 × 10-5. The presence of Patroclus-Menoetius among the Jupiter Trojans requires that the giant planet instability occurred within 100 million years of the formation of the Solar System.
Interactions between Pluto-massed objects in the outer planetesimal disk can result in an early instabilty. Gravitational interactions between the largest planetesimals dynamically heat the disk, increasing the eccentricities of their orbits. The increased eccentricities also lower their perihelion distances causing some of them to enter orbits that cross that of the outer giant planet. Gravitational interactions between the planetesimals and the planet allow it to escape from the resonance chain and drive its outward migration. In simulations this often leads to resonance crossings and an instability within 100 million years.
The bombardment produced by the Nice model may not match the Late Heavy Bombardment. An impactor size distribution similar to the asteroids would result in too many large impact basins relative to smaller craters. The innermost asteroid belt would need a different size distribution, perhaps due to its small asteroids being the result of collisions between a small number of large asteroids, to match this constraint. While the Nice model predicts a bombardment by both asteroids and comets, most evidence (although not all) points toward a bombardment dominated by asteroids. This may reflect the reduced cometary bombardment in the five-planet Nice model and the significant mass loss or the break-up of comets after entering the inner Solar System, potentially allowing the evidence of cometary bombardment to have been lost. However, two recent estimates of the asteroid bombardment find it is also insufficient to explain the Late Heavy Bombardment. Reproducing the lunar craters and impact basins identified with the Late Heavy Bombardment, about 1/6 of the craters larger than 150 km in diameter, and the craters on Mars may be possible if a different crater-scaling law is used. The remaining lunar craters would then be the result of another population of impactors with a different size distribution, possibly planetesimals left over from the formation of the planets. This crater-scaling law also is more successful at reproducing the more recently formed large craters.
The craters and impact basins identified with the Late Heavy Bombardment may have another cause. Some recently offered alternatives include debris from the impact that formed the Borealis Basin on Mars, and catastrophic collisions among lost planets once orbiting inside Mercury. These explanations have their own potential problems, for example, the timing of the formation of the Borealis basin, and whether objects should remain on orbits inside Mercury's. A monotonically declining bombardment by planetesimals left over from the formation of the terrestrial planets has also been proposed. This hypothesis requires the lunar mantle to have crystallized relatively late which may explain the differing concentrations of highly siderophile elements in the Earth and Moon. A previous work, however, found that the most dynamically stable part of this population would become depleted due to its collisional evolution, making the formation of several or even the last two impact basins unlikely.
According to Nesvorný, colleagues have suggested several names for the hypothetical fifth giant planet—Hades, after the Greek god of the underworld; Liber, after the Roman god of wine and a cognate of Dionysus and Bacchus; and Mephitis, after the Roman goddess of toxic gases. Another suggestion is "Thing 1" from Dr. Seuss's Cat in the Hat children's book.
Notes on Planet Nine
In January 2016, Batygin and Brown proposed that a distant massive ninth planet is responsible for the alignment of the perihelia of several trans-Neptunian objects with semi-major axes greater than 250 AU. Although the mechanism for the ejection of the fifth giant planet in the five-planet Nice model is reminiscent of the origin of Planet Nine, with a gravitational instability including an encounter with Jupiter, it is unlikely to be the same planet. The estimated timing of the capture of Planet Nine onto its distant orbit, three to ten million years after the formation of the Solar System, when the Sun was still in its birth cluster, is inconsistent with a giant-planet instability that was responsible for the Late Heavy Bombardment. A nearby star close enough to aid in Planet Nine's capture would also result in the capture of the Oort cloud objects on orbits much closer than has been estimated from the orbits of comets. However, Batygin and Brown remarked that there is possibility of retaining the ejected giant due to interactions with the protoplanetary disk. Also, in November 2017, Brown stated in a reply to a Twitter inquiry about the correlation between the five-planet Nice model and Planet Nine "i'd [sic] say it's a good chance that Planet Nine is Nice planet #5"
- Nesvorný, David (2011). "Young Solar System's Fifth Giant Planet?". The Astrophysical Journal Letters. 742 (2): L22. arXiv:1109.2949. Bibcode:2011ApJ...742L..22N. doi:10.1088/2041-8205/742/2/L22.
- Kaib, Nathan A.; Chambers, John E. (2016). "The fragility of the terrestrial planets during a giant-planet instability". Monthly Notices of the Royal Astronomical Society. 455 (4): 3561–3569. arXiv:1510.08448. Bibcode:2016MNRAS.455.3561K. doi:10.1093/mnras/stv2554.
- Nesvorny, David; Parker, Joel; Vokrouhlicky, David (2018). "Bi-lobed Shape of Comet 67P from a Collapsed Binary". The Astronomical Journal. 155 (6): 246. arXiv:1804.08735. Bibcode:2018AJ....155..246N. doi:10.3847/1538-3881/aac01f.
- Nesvorný, David; Vokrouhlický, David; Bottke, William F.; Levison, Harold F. (2018). "Evidence for very early migration of the Solar System planets from the Patroclus–Menoetius binary Jupiter Trojan". Nature Astronomy. 2 (11): 878–882. arXiv:1809.04007. doi:10.1038/s41550-018-0564-3.
- Quarles, Billy; Kaib, Nathan (2019). "Instabilities in the Early Solar System due to a Self-gravitating Disk". arXiv:1812.08710.
- Deienno, Rogerio; Morbidelli, Alessandro; Gomes, Rodney S.; Nesvorny, David (2017). "Constraining the giant planets' initial configuration from their evolution: implications for the timing of the planetary instability". The Astronomical Journal. 153 (4): 153. arXiv:1702.02094. Bibcode:2017AJ....153..153D. doi:10.3847/1538-3881/aa5eaa.
- Bottke, William F.; Vokrouhlický, David; Minton, David; Nesvorný, David; Morbidelli, Alessandro; Brasser, Ramon; Simonson, Bruce; Levison, Harold F. (2012). "An Archaean heavy bombardment from a destabilized extension of the asteroid belt". Nature. 485 (7396): 78–81. Bibcode:2012Natur.485...78B. doi:10.1038/nature10967. PMID 22535245.
- Tsiganis, Kleomenis; Gomes, Rodney S.; Morbidelli, Alessandro; Levison, Harold F. (2005). "Origin of the orbital architecture of the giant planets of the Solar System". Nature. 435 (7041): 459–461. Bibcode:2005Natur.435..459T. doi:10.1038/nature03539. PMID 15917800.
- Nesvorný, David (2015). "Evidence for Slow Migration of Neptune from the Inclination Distribution of Kuiper Belt Objects". The Astronomical Journal. 150 (3): 73. arXiv:1504.06021. Bibcode:2015AJ....150...73N. doi:10.1088/0004-6256/150/3/73.
- Brasser, Ramon; Morbidelli, Alessandro; Gomes, Rodney S.; Tsiganis, Kleomenis; Levison, Harold F. (2009). "Constructing the secular architecture of the solar system II: the terrestrial planets". Astronomy and Astrophysics. 504 (2): 1053–1065. arXiv:0909.1891. Bibcode:2009A&A...507.1053B. doi:10.1051/0004-6361/200912878.
- Roig, Fernando; Nesvorný, David (2015). "The Evolution of Asteroids in the Jumping-Jupiter Migration Model". The Astronomical Journal. 150 (6): 186. arXiv:1509.06105. Bibcode:2015AJ....150..186R. doi:10.1088/0004-6256/150/6/186.
- Morbidelli, Alessandro; Brasser, Ramon; Gomes, Rodney S.; Levison, Harold F.; Tsiganis, Kleomenis (2010). "Evidence from the Asteroid Belt for a Violent Past Evolution of Jupiter's Orbit". The Astronomical Journal. 140 (5): 1391–1401. arXiv:1009.1521. Bibcode:2010AJ....140.1391M. doi:10.1088/0004-6256/140/5/1391.
- Nesvorny, David; Vokrouhlicky, David; Roig, Fernando (2016). "The orbital distribution of trans-Neptunian objects beyond 50 au". The Astrophysical Journal. 827 (2): L35. arXiv:1607.08279. Bibcode:2016ApJ...827L..35N. doi:10.3847/2041-8205/827/2/L35.
- Morbidelli, Alessandro; Brasser, Ramon; Tsiganis, Kleomenis; Gomes, Rodney S.; Levison, Harold F. (2009). "Constructing the secular architecture of the solar system. I. The giant planets". Astronomy and Astrophysics. 507 (2): 1041–1052. arXiv:0909.1886. Bibcode:2009A&A...507.1041M. doi:10.1051/0004-6361/200912876.
- Gomes, Rodney S.; Levison, Harold F.; Tsiganis, Kleomenis; Morbidelli, Alessandro (2005). "Origin of the cataclysmic Late Heavy Bombardment period of the terrestrial planets". Nature. 435 (7041): 466–469. Bibcode:2005Natur.435..466G. doi:10.1038/nature03676. PMID 15917802.
- Rivera-Valentin, E. G.; Barr, A. C.; Lopez Garcia, E. J.; Kirchoff, M. R.; Schenk, P. M. (2014). "Constraints on Planetesimal Disk Mass from the Cratering Record and Equatorial Ridge on Iapetus". The Astrophysical Journal. 792 (2): 127. arXiv:1406.6919. Bibcode:2014ApJ...792..127R. doi:10.1088/0004-637X/792/2/127.
- Movshovitz, N.; Nimmo, F.; Korycansky, D. G.; Asphaug, E.; Owen, J. M. (2015). "Disruption and reaccretion of midsized moons during an outer solar system Late Heavy Bombardment". Geophysical Research Letters. 42 (2): 256–263. Bibcode:2015GeoRL..42..256M. doi:10.1002/2014GL062133.
- Nesvorný, David; Vokrouhlický, David; Morbidelli, Alessandro (2013). "Capture of Trojans by Jumping Jupiter". The Astrophysical Journal. 768 (1): 45. arXiv:1303.2900. Bibcode:2013ApJ...768...45N. doi:10.1088/0004-637X/768/1/45.
- Morbidelli, Alessandro; Levison, Harold F.; Tsiganis, Kleomenis; Gomes, Rodney S. (2005). "Chaotic capture of Jupiter's Trojan asteroids in the early Solar System". Nature. 435 (7041): 462–465. Bibcode:2005Natur.435..462M. doi:10.1038/nature03540. PMID 15917801.
- Nesvorný, David; Vokrouhlický, David; Deienno, Rogerio (2014). "Capture of Irregular Satellites at Jupiter". The Astrophysical Journal. 784 (1): 22. arXiv:1401.0253. Bibcode:2014ApJ...784...22N. doi:10.1088/0004-637X/784/1/22.
- Nesvorný, David; Vokrouhlický, David; Morbidelli, Alessandro (2007). "Capture of Irregular Satellites during Planetary Encounters". The Astronomical Journal. 133 (5): 1962–1976. Bibcode:2007AJ....133.1962N. doi:10.1086/512850.
- Bottke, William F.; Nesvorný, David; Vokrouhlický, David; Morbidelli, Alessandro (2010). "The Irregular Satellites: The Most Collisionally Evolved Populations in the Solar System". The Astronomical Journal. 139 (3): 994–1014. Bibcode:2010AJ....139..994B. CiteSeerX 10.1.1.693.4810. doi:10.1088/0004-6256/139/3/994.
- Nesvorný, David; Vokrouhlický, David; Deienno, Rogerio; Walsh, Kevin J. (2014). "Excitation of the Orbital Inclination of Iapetus during Planetary Encounters". The Astronomical Journal. 148 (3): 52. arXiv:1406.3600. Bibcode:2014AJ....148...52N. doi:10.1088/0004-6256/148/3/52.
- Vokrouhlický, David; Nesvorný, David (2015). "Tilting Jupiter (a bit) and Saturn (a lot) during Planetary Migration". The Astrophysical Journal. 806 (1): 143. arXiv:1505.02938. Bibcode:2015ApJ...806..143V. doi:10.1088/0004-637X/806/1/143.
- Brasser, R.; Lee, Man Hoi (2015). "Tilting Saturn without Tilting Jupiter: Constraints on Giant Planet Migration". The Astronomical Journal. 150 (5): 157. arXiv:1509.06834. Bibcode:2015AJ....150..157B. doi:10.1088/0004-6256/150/5/157.
- Nesvorny, D.; Vokrouhlicky, D.; Dones, L.; Levison, H. F.; Kaib, N.; Morbidelli, A. (2017). "Origin and Evolution of Short-Period Comets". The Astrophysical Journal. 845 (1): 27. arXiv:1706.07447. Bibcode:2017ApJ...845...27N. doi:10.3847/1538-4357/aa7cf6.
- Nesvorný, David (2015). "Jumping Neptune Can Explain the Kuiper Belt Kernel". The Astronomical Journal. 150 (3): 68. arXiv:1506.06019. Bibcode:2015AJ....150...68N. doi:10.1088/0004-6256/150/3/68.
- Fraser, Wesley, C; et al. (2017). "All planetesimals born near the Kuiper belt formed as binaries". Nature Astronomy. 1 (4): 0088. arXiv:1705.00683. Bibcode:2017NatAs...1E..88F. doi:10.1038/s41550-017-0088.CS1 maint: Explicit use of et al. (link)
- Wolff, Schuyler; Dawson, Rebekah I.; Murray-Clay, Ruth A. (2012). "Neptune on Tiptoes: Dynamical Histories that Preserve the Cold Classical Kuiper Belt". The Astrophysical Journal. 746 (2): 171. arXiv:1112.1954. Bibcode:2012ApJ...746..171W. doi:10.1088/0004-637X/746/2/171.
- Dawson, Rebekah I.; Murray-Clay, Ruth (2012). "Neptune's Wild Days: Constraints from the Eccentricity Distribution of the Classical Kuiper Belt". The Astrophysical Journal. 750 (1): 43. arXiv:1202.6060. Bibcode:2012ApJ...750...43D. doi:10.1088/0004-637X/750/1/43.
- Batygin, Konstantin; Brown, Michael E.; Fraser, Wesley (2011). "Retention of a Primordial Cold Classical Kuiper Belt in an Instability-Driven Model of Solar System Formation". The Astrophysical Journal. 738 (1): 13. arXiv:1106.0937. Bibcode:2011ApJ...738...13B. doi:10.1088/0004-637X/738/1/13.
- Morbidelli, A.; Gaspar, H. S.; Nesvorny, D. (2014). "Origin of the peculiar eccentricity distribution of the inner cold Kuiper belt". Icarus. 232: 81–87. arXiv:1312.7536. Bibcode:2014Icar..232...81M. doi:10.1016/j.icarus.2013.12.023.
- Kaib, Nathan A.; Sheppard, Scott S (2016). "Tracking Neptune's Migration History through High-Perihelion Resonant Trans-Neptunian Objects". The Astronomical Journal. 152 (5): 133. arXiv:1607.01777. Bibcode:2016AJ....152..133K. doi:10.3847/0004-6256/152/5/133.
- Nesvorný, David; Vokrouhlický, David (2016). "Neptune's Orbital Migration Was Grainy, Not Smooth". The Astrophysical Journal. 825 (2): 94. arXiv:1602.06988. Bibcode:2016ApJ...825...94N. doi:10.3847/0004-637X/825/2/94.
- Brasser, R.; Walsh, K. J.; Nesvorny, D. (2013). "Constraining the primordial orbits of the terrestrial planets". Monthly Notices of the Royal Astronomical Society. 433 (4): 3417–3427. arXiv:1306.0975. Bibcode:2013MNRAS.433.3417B. doi:10.1093/mnras/stt986.
- Deienno, Rogerio; Gomes, Rodney S.; Walsh, Kevin J.; Morbidelli, Allesandro; Nesvorný, David (2016). "Is the Grand Tack model compatible with the orbital distribution of main belt asteroids?". Icarus. 272: 114–124. arXiv:1701.02775. Bibcode:2016Icar..272..114D. doi:10.1016/j.icarus.2016.02.043.
- Brasil, P. I. O.; Roig, F.; Nesvorný, D.; Carruba, V.; Aljbaae, S.; Huaman, M. E. (2016). "Dynamical dispersal of primordial asteroid families". Icarus. 266: 142–151. Bibcode:2016Icar..266..142B. doi:10.1016/j.icarus.2015.11.015.
- Vokrouhlický, David; Bottke, William F.; Nesvorný, David (2016). "Capture of Trans-Neptunian Planetesimals in the Main Asteroid Belt". The Astronomical Journal. 152 (2): 39. Bibcode:2016AJ....152...39V. doi:10.3847/0004-6256/152/2/39.
- Levison, Harold F.; Stewart, Glen R. (2001). "Remarks on Modeling the Formation of Uranus and Neptune". Icarus. 153 (1): 224–228. Bibcode:2001Icar..153..224L. doi:10.1006/icar.2001.6672.
- Thommes, E. W.; Duncan, M. J.; Levison, Harold F. (2002). "The Formation of Uranus and Neptune among Jupiter and Saturn". The Astronomical Journal. 123 (5): 2862–2883. arXiv:astro-ph/0111290. Bibcode:2002AJ....123.2862T. doi:10.1086/339975.
- Kenyon, Scott J.; Bromley, Benjamin C. (2008). "Variations on Debris Disks: Icy Planet Formation at 30–150 AU for 1–3 Msolar Main-Sequence Stars". The Astrophysical Journal Supplement Series. 179 (2): 451–483. arXiv:0807.1134. Bibcode:2008ApJS..179..451K. doi:10.1086/591794.
- Bitsch, Bertram; Lanbrects, Michel; Johansen, Anders (2015). "The growth of planets by pebble accretion in evolving protoplanetary discs". Astronomy & Astrophysics. 582: A112. arXiv:1507.05209. Bibcode:2015A&A...582A.112B. doi:10.1051/0004-6361/201526463.
- Levison, Harold F.; Morbidelli, Alessandro (2005). "Interaction of planetesimals with the giant planets and the shaping of the trans-Neptunian belt". Dynamics of Populations of Planetary Systems, Proceedings of IAU Colloquium #197. 2004: 303–316. Bibcode:2005dpps.conf..303L. doi:10.1017/S1743921304008798.
- Fernandez, J. A.; Ip, W. H. (1984). "Some dynamical aspects of the accretion of Uranus and Neptune – The exchange of orbital angular momentum with planetesimals". Icarus. 58 (1): 109–120. Bibcode:1984Icar...58..109F. doi:10.1016/0019-1035(84)90101-5.
- Levison, Harold F.; Morbidelli, Alessandro; Gomes, Rodney S.; Backman, D. (2007). "Planet Migration in Planetesimal Disks". Protostars and Planets V. B. Reipurth, D. Jewitt, and K. Keil (eds.), University of Arizona Press: 669–684.
- Gomes, Rodney S.; Morbidelli, Alessandro; Levison, Harold F. (2004). "Planetary migration in a planetesimal disk: why did Neptune stop at 30 AU?". Icarus. 170 (2): 492–507. Bibcode:2004Icar..170..492G. doi:10.1016/j.icarus.2004.03.011.
- Hahn, Joseph M.; Malhotra, Renu (1999). "Orbital Evolution of Planets Embedded in a Planetesimal Disk". The Astronomical Journal. 117 (6): 3041–3053. arXiv:astro-ph/9902370. Bibcode:1999AJ....117.3041H. doi:10.1086/300891.
- Malhotra, Renu (1995). "The Origin of Pluto's Orbit: Implications for the Solar System Beyond Neptune". Astronomical Journal. 110: 420. arXiv:astro-ph/9504036. Bibcode:1995AJ....110..420M. doi:10.1086/117532.
- Gomes, Rodney S. (2003). "The origin of the Kuiper Belt high-inclination population". Icarus. 161 (2): 404–418. Bibcode:2003Icar..161..404G. doi:10.1016/S0019-1035(02)00056-8.
- Levison, Harold F.; Morbidelli, Alessandro (2003). "The formation of the Kuiper belt by the outward transport of bodies during Neptune's migration". Nature. 426 (6965): 419–421. Bibcode:2003Natur.426..419L. doi:10.1038/nature02120. PMID 14647375.
- Nesvorný, David; Vokrouhlický, David (2009). "Chaotic Capture of Neptune Trojans". The Astronomical Journal. 137 (6): 5003–5011. Bibcode:2009AJ....137.5003N. doi:10.1088/0004-6256/137/6/5003.
- Levison, Harold F.; Morbidelli, Alessandro; Van Laerhoven, Christa; Gomes, Rodney S.; Tsiganis, Kleomenis (2008). "Origin of the structure of the Kuiper belt during a dynamical instability in the orbits of Uranus and Neptune". Icarus. 196 (1): 258–273. arXiv:0712.0553. Bibcode:2008Icar..196..258L. doi:10.1016/j.icarus.2007.11.035.
- Agnor, Craig B.; Lin, D. N. C. (2012). "On the Migration of Jupiter and Saturn: Constraints from Linear Models of Secular Resonant Coupling with the Terrestrial Planets". The Astrophysical Journal. 745 (2): 143. arXiv:1110.5042. Bibcode:2012ApJ...745..143A. doi:10.1088/0004-637X/745/2/143.
- Fassett, Caleb I.; Minton, David A. (2013). "Impact bombardment of the terrestrial planets and the early history of the Solar System". Nature Geoscience. 6 (7): 520–524. Bibcode:2013NatGe...6..520F. doi:10.1038/ngeo1841.
- Stuart, Colin (2011-11-21). "Was a giant planet ejected from our solar system?". Physics World. Retrieved 16 January 2014.
- Nesvorný, David; Morbidelli, Alessandro (2012). "Statistical Study of the Early Solar System's Instability with Four, Five, and Six Giant Planets". The Astronomical Journal. 144 (4): 17. arXiv:1208.2957. Bibcode:2012AJ....144..117N. doi:10.1088/0004-6256/144/4/117.
- Batygin, Konstantin; Brown, Michael E.; Fraser, Wesly C. (2011). "Retention of a Primordial Cold Classical Kuiper Belt in an Instability-Driven Model of Solar System Formation". The Astrophysical Journal. 738 (1): 13. arXiv:1106.0937. Bibcode:2011ApJ...738...13B. doi:10.1088/0004-637X/738/1/13.
- Batygin, Konstantin; Brown, Michael E.; Betts, Hayden (2012). "Instability-driven Dynamical Evolution Model of a Primordially Five-planet Outer Solar System". The Astrophysical Journal Letters. 744 (1): L3. arXiv:1111.3682. Bibcode:2012ApJ...744L...3B. doi:10.1088/2041-8205/744/1/L3.
- Batygin, Konstantin; Brown, Michael E. (2010). "Early Dynamical Evolution of the Solar System: Pinning Down the Initial Conditions of the Nice Model". The Astrophysical Journal. 716 (2): 1323–1331. arXiv:1004.5414. Bibcode:2010ApJ...716.1323B. doi:10.1088/0004-637X/716/2/1323.
- Thommes, Edward W.; Bryden, Geoffrey; Wu, Yanqin; Rasio, Frederic A (2007). "From Mean Motion Resonances to Scattered Planets: Producing the Solar System, Eccentric Exoplanets, and Late Heavy Bombardments". The Astrophysical Journal. 675 (2): 1538–1548. arXiv:0706.1235. Bibcode:2008ApJ...675.1538T. doi:10.1086/525244.
- Morbidelli, Alessandro; Tsiganis, Kleomenis; Crida, Aurélien; Levison, Harold F.; Gomes, Rodney (2007). "Dynamics of the Giant Planets of the Solar System in the Gaseous Protoplanetary Disk and Their Relationship to the Current Orbital Architecture". The Astronomical Journal. 134 (5): 1790–1798. arXiv:0706.1713. Bibcode:2007AJ....134.1790M. doi:10.1086/521705.
- Ford, Eric B.; Chiang, Eugene I. (2007). "The Formation of Ice Giants in a Packed Oligarchy: Instability and Aftermath". The Astrophysical Journal. 661 (1): 602–615. arXiv:astro-ph/0701745. Bibcode:2007ApJ...661..602F. doi:10.1086/513598.
- Levison, Harold F.; Morbidelli, Alessandro (2007). "Models of the collisional damping scenario for ice-giant planets and Kuiper belt formation". Icarus. 189 (1): 196–212. arXiv:astro-ph/0701544. Bibcode:2007Icar..189..196L. doi:10.1016/j.icarus.2007.01.004.
- Masset, F.; Snellgrove, M. (2001). "Reversing type II migration: resonance trapping of a lighter giant protoplanet". Monthly Notices of the Royal Astronomical Society. 320 (4): L55–L59. arXiv:astro-ph/0003421. Bibcode:2001MNRAS.320L..55M. doi:10.1046/j.1365-8711.2001.04159.x.
- Walsh, K. J.; Morbidelli, A. (2011). "The effect of an early planetesimal-driven migration of the giant planets on terrestrial planet formation". Astronomy and Astrophysics. 526: A126. arXiv:1101.3776. Bibcode:2011A&A...526A.126W. doi:10.1051/0004-6361/201015277.
- Toliou, A.; Morbidelli, A.; Tsiganis, K. (2016). "Magnitude and timing of the giant planet instability: A reassessment from the perspective of the asteroid belt". Astronomy & Astrophysics. 592: A72. arXiv:1606.04330. Bibcode:2016A&A...592A..72T. doi:10.1051/0004-6361/201628658.
- Robuchon, Guillaume; Nimmo, Francis; Roberts, James; Kirchoff, Michelle (2011). "Impact basin relaxation at Iapetus". Icarus. 214 (1): 82–90. arXiv:1406.6919. Bibcode:2011Icar..214...82R. doi:10.1016/j.icarus.2011.05.011.
- Rivera-Valentin, E. G.; Barr, A. C.; Lopez Garcia, E. K.; Kirchoff, M. R.; Schenk, P. M. (2014). "Constraints on Planetesimal Disk Mass from the Cratering Record and Equatorial Ridge on Iapetus". The Astrophysical Journal. 792 (2): 127. arXiv:1406.6919. Bibcode:2014ApJ...792..127R. doi:10.1088/0004-637X/792/2/127.
- Kenyon, Scott J.; Bromley, Benjamin C. (2012). "Coagulation Calculations of Icy Planet Formation at 15-150 AU: A Correlation between the Maximum Radius and the Slope of the Size Distribution for Trans-Neptunian Objects". The Astronomical Journal. 143 (3): 63. arXiv:1201.4395. Bibcode:2012AJ....143...63K. doi:10.1088/0004-6256/143/3/63.
- Reyes-Ruiz, M.; Aceves, H.; Chavez, C. E. (2015). "Stability of the Outer Planets in Multiresonant Configurations with a Self-gravitating Planetesimal Disk". The Astrophysical Journal. 804 (2): 91. arXiv:1406.2341. doi:10.1088/0004-637X/804/2/91.
- Minton, David A.; Richardson, James E.; Fasset, Caleb I. (2015). "Re-examining the main asteroid belt as the primary source of ancient lunar craters". Icarus. 247: 172–190. arXiv:1408.5304. Bibcode:2015Icar..247..172M. doi:10.1016/j.icarus.2014.10.018.
- Bottke, W. F.; Marchi, S.; Vokrouhlicky, D.; Robbins, S.; Hynek, B.; Morbidelli, A. "New Insights into the Martian Late Heavy Bombardment" (PDF). 46th Lunar and Planetary Science Conference.
- Gråe Jørgensen, Uffe; Appel, Peter W. U.; Hatsukawa, Yuichi; Frei, Robert; Oshima, Masumi; Toh, Yosuke; Kimura, Atsushi (2009). "The Earth-Moon system during the late heavy bombardment period – Geochemical support for impacts dominated by comets". Icarus. 204 (2): 368–380. arXiv:0907.4104. Bibcode:2009Icar..204..368G. CiteSeerX 10.1.1.312.7222. doi:10.1016/j.icarus.2009.07.015.
- Kring, David A.; Cohen, Barbara A. (2002). "Cataclysmic bombardment throughout the inner solar system 3.9–4.0 Ga". Journal of Geophysical Research: Planets. 107 (E2): 4–1–4–6. Bibcode:2002JGRE..107.5009K. doi:10.1029/2001JE001529.
- Joy, Katherine H.; Zolensky, Michael E.; Nagashima, Kazuhide; Huss, Gary R.; Ross, D. Kent; McKay, David S.; Kring, David A. (2012). "Direct Detection of Projectile Relics from the End of the Lunar Basin-Forming Epoch". Science. 336 (6087): 1426–9. Bibcode:2012Sci...336.1426J. doi:10.1126/science.1219633. PMID 22604725.
- Strom, Robert G.; Malhotra, Renu; Ito, Takashi; Yoshida, Fumi; Kring, David A. (2005). "The Origin of Planetary Impactors in the Inner Solar System". Science. 309 (5742): 1847–1850. arXiv:astro-ph/0510200. Bibcode:2005Sci...309.1847S. CiteSeerX 10.1.1.317.2438. doi:10.1126/science.1113544. PMID 16166515.
- Rickman, H.; Wiśniowsk, T.; Gabryszewski, R.; Wajer, P.; Wójcikowsk, K.; Szutowicz, S.; Valsecchi, G. B.; Morbidelli, A. (2017). "Cometary impact rates on the Moon and planets during the late heavy bombardment". Astronomy & Astrophysics. 598: A67. Bibcode:2017A&A...598A..67R. doi:10.1051/0004-6361/201629376.
- Bottke, William F.; Vokrouhlický, David; Minton, David; Nesvorný, David; Morbidelli, Alessandro; Brasser, Ramon; Simonson, Bruce; Levison, Harold F. (2012). "An Archaean heavy bombardment from a destabilized extension of the asteroid belt: Supplementary Information" (PDF). Nature. 485 (7396).
- Johnson, Brandon C.; Collins, Garath S.; Minton, David A.; Bowling, Timothy J.; Simonson, Bruce M.; Zuber, Maria T. (2016). "Spherule layers, crater scaling laws, and the population of ancient terrestrial impactors". Icarus. 271: 350–359. Bibcode:2016Icar..271..350J. doi:10.1016/j.icarus.2016.02.023. hdl:10044/1/29965.
- Nesvorny, David; Roig, Fernando; Bottke, William F. (2016). "Modeling the Historical Flux of Planetary Impactors". The Astronomical Journal. 153 (3): 103. arXiv:1612.08771. Bibcode:2017AJ....153..103N. doi:10.3847/1538-3881/153/3/103.
- Bottke, W. F.; Nesvorny, D.; Roig, F.; Marchi, S.; Vokrouhlicky, D. "Evidence for Two Impacting Populations in the Early Bombardment of Mars and the Moon" (PDF). 48th Lunar and Planetary Science Conference.
- Bottke, W. F.; Vokrouhlicky, D.; Ghent, B.; Mazrouei, S.; Robbins, S.; marchi, S. "On Asteroid Impacts, Crater Scaling Laws, and a Proposed Younger Surface Age for Venus" (PDF). 47th Lunar and Planetary Science Conference.
- Minton, D. A.; Jackson, A. P.; Asphaug, E.; Fasset, C. I.; Richardson, J. E. "Debris from Borealis Basin Formation as the Primary Impactor Population of Late Heavy Bombardment" (PDF). Workshop on Early Solar System Impact Bombardment III.
- Volk, Kathryn; Gladman, Brett (2015). "Consolidating and Crushing Exoplanets: Did It Happen Here?". The Astrophysical Journal Letters. 806 (2): L26. arXiv:1502.06558. Bibcode:2015ApJ...806L..26V. doi:10.1088/2041-8205/806/2/L26.
- Andrews-Hanna, J. C.; Bottke, W. F. "The Post-Accretionary Doldrums on Mars: Constraints on the Pre-Noachian Impact Flux" (PDF). 47th Lunar and Planetary Science Conference.
- Raymond, Sean N.; Izidoro, Andre; Bitsch, Bertram; Jacobsen, Seth A. (2016). "Did Jupiter's core form in the innermost parts of the Sun's protoplanetary disc?". Monthly Notices of the Royal Astronomical Society. 458 (3): 2962–2972. arXiv:1602.06573. Bibcode:2016MNRAS.458.2962R. doi:10.1093/mnras/stw431.
- Morbidelli, A.; Nesvorny, D.; Laurenz, V.; Marchi, S.; Rubie, D. C.; Elkins-Tanton, L.; Jacobson, S. A. (2018). "The Lunar Late Heavy Bombardment as a Tail-end of Planet Accretion". Icarus. 305: 262–276. arXiv:1801.03756. Bibcode:2018Icar..305..262M. doi:10.1016/j.icarus.2017.12.046.
- Bottke, Wiliam F.; Levison, Harold F.; Nesvorný, David; Dones, Luke (2007). "Can planetesimals left over from terrestrial planet formation produce the lunar Late Heavy Bombardment?". Icarus. 190 (1): 203–223. Bibcode:2007Icar..190..203B. doi:10.1016/j.icarus.2007.02.010.
- A New Name for an Old Planet: New Scientist: 01.10.2011: 15, https://www.newscientist.com/article/dn20952-missing-planet-explains-solar-systems-structure/
- Batygin, Konstantin; Brown, Michael E. (20 January 2016). "Evidence for a distant giant planet in the Solar system". The Astronomical Journal. 151 (2): 22. arXiv:1601.05438. Bibcode:2016AJ....151...22B. doi:10.3847/0004-6256/151/2/22.
- Drake, Nadia (2016-01-22). "How can we find planet nine? (and other burning questions)". No place like home. National Geographic. Retrieved 30 January 2016.
- Raymond, Sean (2016-02-02). "Planet Nine: kicked out by the moody young Solar System?". PlanetPlanet. Retrieved 27 February 2016.
- Bromley, Benjamin; Kenyon, Scott (2014). "The fate of scattered planets". The Astrophysical Journal. 796 (2): 141. doi:10.1088/0004-637X/796/2/141.
- "Twitter". mobile.twitter.com. Retrieved 2017-11-26.