Evidence for very early migration of the Solar System planets from the Patroclus–Menoetius binary Jupiter Trojan


The orbital distribution of trans-Neptunian objects provides strong evidence for the radial migration of Neptune1,2. The outer planets’ orbits are thought to have become unstable during the early stages3, with Jupiter having scattering encounters with a Neptune-class planet4. As a consequence, Jupiter jumped inwards by a fraction of an au, as required from inner Solar System constraints5,6, and obtained its current orbital eccentricity. The timing of these events is often linked to the lunar Late Heavy Bombardment that ended ~700 Myr after the dispersal of the protosolar nebula (t0)7,8. Here, we show instead that planetary migration started shortly after t0. Such early migration is inferred from the survival of the Patroclus–Menoetius binary Jupiter Trojan9. The binary formed at tt010,11 within a massive planetesimal disk once located beyond Neptune12,13. The longer the binary stayed in the disk, the greater the likelihood that collisions would strip its components from one another. The simulations of its survival indicate that the disk had to have been dispersed by migrating planets within 100 Myr of t0. This constraint implies that the planetary migration is unrelated to the formation of the youngest lunar basins.

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Fig. 1: Dynamical survival of binaries before their implantation onto Jupiter Trojan orbits.
Fig. 2: Collisional survival of binaries in the outer planetesimal disk.
Fig. 3: Size distribution of Jupiter Trojans.
Fig. 4: Survival of binaries in the case when the planet migration was initiated immediately after t0 (that is, tdisk = 0).

Data availability

The data that support the plots within this paper and other findings of this study are available from the corresponding author upon reasonable request.


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This work was funded by NASA’s SSERVI and Emerging Worlds programmes, and the Czech Science Foundation (grant 18-06083S). We thank A. Morbidelli for helpful suggestions.

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D.N. had the original idea, performed the simulations and prepared the manuscript for publication. D.V. developed the binary module in the collision code and the N-body code for planetary encounters. D.V., W.F.B. and H.F.L. suggested additional tests and helped to improve the manuscript.

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Correspondence to David Nesvorný.

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Nesvorný, D., Vokrouhlický, D., Bottke, W.F. et al. Evidence for very early migration of the Solar System planets from the Patroclus–Menoetius binary Jupiter Trojan. Nat Astron 2, 878–882 (2018). https://doi.org/10.1038/s41550-018-0564-3

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