Irregular moons possibly injected from the outer solar system by a stellar flyby

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Hauptverfasser: Pfalzner, Susanne, Govind, Amith, Wagner, Frank
Format: Preprint
Veröffentlicht: 2024
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author Pfalzner, Susanne
Govind, Amith
Wagner, Frank
author_facet Pfalzner, Susanne
Govind, Amith
Wagner, Frank
contents The irregular moons orbit the giant planets on distant, inclined, and eccentric trajectories, in sharp contrast with the coplanar and quasicircular orbits of the regular moons. The origin of these irregular moons is still an open question, but these moons have a lot in common with the objects beyond Neptune (trans-Neptunian objects -- TNOs), suggestive of a common origin. Here, we show that the close flyby of a star may be the connecting element. A stellar flyby can simultaneously reproduce the complex TNO dynamics quantitatively while explaining the origin of the irregular moons and the colour distributions of both populations. This flyby would have catapulted 7.2% of the original TNO population into the region of the planets, many on retrograde orbits. Most injected TNOs would have been subsequently ejected from the solar system (85%). However, a considerable fraction would have had the potential to be captured by the planets. The exclusively distant origin of the injected TNOs may also explain the lack of very red irregular moons.
format Preprint
id arxiv_https___arxiv_org_abs_2409_03529
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Irregular moons possibly injected from the outer solar system by a stellar flyby
Pfalzner, Susanne
Govind, Amith
Wagner, Frank
Earth and Planetary Astrophysics
Astrophysics of Galaxies
Solar and Stellar Astrophysics
The irregular moons orbit the giant planets on distant, inclined, and eccentric trajectories, in sharp contrast with the coplanar and quasicircular orbits of the regular moons. The origin of these irregular moons is still an open question, but these moons have a lot in common with the objects beyond Neptune (trans-Neptunian objects -- TNOs), suggestive of a common origin. Here, we show that the close flyby of a star may be the connecting element. A stellar flyby can simultaneously reproduce the complex TNO dynamics quantitatively while explaining the origin of the irregular moons and the colour distributions of both populations. This flyby would have catapulted 7.2% of the original TNO population into the region of the planets, many on retrograde orbits. Most injected TNOs would have been subsequently ejected from the solar system (85%). However, a considerable fraction would have had the potential to be captured by the planets. The exclusively distant origin of the injected TNOs may also explain the lack of very red irregular moons.
title Irregular moons possibly injected from the outer solar system by a stellar flyby
topic Earth and Planetary Astrophysics
Astrophysics of Galaxies
Solar and Stellar Astrophysics
url https://arxiv.org/abs/2409.03529