Trajectory of the stellar flyby that shaped the outer solar system

Abstract

Unlike the Solar System planets, thousands of smaller bodies beyond Neptune orbit the Sun on eccentric ($e>$ 0.1) and ($i>$ 3${}^{\circ }$) orbits. While migration of the giant planets during the early stages of Solar System evolution can induce substantial scattering of trans-Neptunian objects (TNO), this process cannot account for the small number of distant TNOs ($r_p>$ 60 au) outside the planets' reach. The alternative scenario of the close flyby of another star can instead produce all these TNO features simultaneously, but the possible parameter space for such an encounter is vast. Here, we compare observed TNO properties with thousands of flyby simulations to determine the specific properties of a flyby that reproduces all the different dynamical TNO populations, their location and their relative abundance and find that a 0.8${}_{-0.1}^{+0.1}$ $M_{\odot }$ star passing at a distance of $r_p=$ 110 $\pm$ 10 au, inclined by $i$ = 70${}^{\circ }$ ${}_{-10}^{+5}$ gives a near-perfect match. This flyby also replicates the retrograde TNO population, which has proved difficult to explain. Such a flyby is reasonably frequent; at least 140 million solar-type stars in the Milky Way are likely to have experienced a similar one. In light of these results, we predict that the upcoming Vera Rubin telescope will reveal that distant and retrograde TNOs are relatively common.

15 pages, 3 figures Open access version of original Nature Astronomy available under 10.1038/s41550-024-02349-x

References in corpus (14)

• Origin of the Structure of the Kuiper Belt during a Dynamical Instability in the Orbits of Uranus and Neptune
• The GENGA Code: Gravitational Encounters in N-body simulations with GPU Acceleration
• A tidal encounter caught in the act: modelling a star-disc fly-by in the young RW Aurigae system
• Sizes of protoplanetary discs after star-disc encounters
• Generation of Highly Inclined Trans-Neptunian Objects by Planet Nine
• Discovery of A New Retrograde Trans-Neptunian Object: Hint of A Common Orbital Plane for Low Semi-Major Axis, High Inclination TNOs and Centaurs
• Ongoing flyby in the young multiple system UX Tauri
• A Tail Structure Associated with Protoplanetary Disk around SU Aurigae
• Beyond the Kuiper Belt Edge: New High Perihelion Trans-Neptunian Objects With Moderate Semi-major Axes and Eccentricities
• Oort cloud Ecology II: Extra-solar Oort clouds and the origin of asteroidal interlopers
• A Near-coplanar Stellar Flyby of the Planet Host Star HD 106906
• Cradle(s) of the Sun
• The secular evolution of the Kuiper belt after a close stellar encounter
• Inclination Excitation of Solar System Debris Disk due to Stellar Flybys

Cited by in corpus (8)

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• Emergence of streamers in simulations of late infall
• Oort Cloud Ecology. III. The Sun left the parent star cluster shortly after the giant planets formed
• Limits on Stellar Flybys in the Solar Birth Cluster
• Implications for the formation of Oort cloud-like structures and interstellar comets in dense environments
• Distant TNO Inclinations as a Constraint on Primordial Cluster Perturbations in the Presence of Planet Nine