Was Planet 9 captured in the Sun's natal star-forming region?

Abstract

The presence of an unseen `Planet 9' on the outskirts of the Solar system has been invoked to explain the unexpected clustering of the orbits of several Edgeworth--Kuiper Belt Objects. We use $N$-body simulations to investigate the probability that Planet 9 was a free-floating planet (FFLOP) that was captured by the Sun in its birth star-formation environment. We find that only 1 - 6 per cent of FFLOPs are ensnared by stars, even with the most optimal initial conditions for capture in star-forming regions (one FFLOP per star, and highly correlated stellar velocities to facilitate capture). Depending on the initial conditions of the star-forming regions, only 5 - 10 of 10000 planets are captured onto orbits that lie within the constraints for Planet 9. When we apply an additional environmental constraint for Solar system formation - namely the injection of short-lived radioisotopes into the Sun's protoplanetary disc from supernovae - we find that the probability for the capture of Planet 9 to be almost zero.

5 pages, 3 figures, 1 table, accepted for publication in MNRAS Letters (31.08.2017)

References in corpus (10)

• Astrophysics Source Code Library
• No large population of unbound or wide-orbit Jupiter-mass planets
• Origin and Evolution of Short-Period Comets
• OSSOS VI. Striking Biases in the detection of large semimajor axis Trans-Neptunian Objects
• Generation of Highly Inclined Trans-Neptunian Objects by Planet Nine
• Unveiling the Early-Stage Anatomy of a Protocluster Hub with ALMA
• Isotopic enrichment of forming planetary systems from supernova pollution
• Distributions of Short-Lived Radioactive Nuclei Produced by Young Embedded Stellar Clusters
• Supernova enrichment of planetary systems in low-mass star clusters
• Triggering Collapse of the Presolar Dense Cloud Core and Injecting Short-Lived Radioisotopes with a Shock Wave. V. Nonisothermal Collapse Regime

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• Tilting Uranus via Secular Spin-Orbit Resonance with Planet 9
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• Secular Eccentricity Oscillations in Axisymmetric Disks of Eccentric Orbits
• Prospects for localising Planet 9 with a future Uranus mission
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