Configuration of Single Giant Planet Systems Generating `Oumuamua-Like Interstellar Asteroids

TL;DR

This study uses long-term simulations to explore how single giant planet systems can produce `Oumuamua-like interstellar objects through tidal fragmentation, highlighting the role of planetary eccentricity and mass.

Contribution

It demonstrates that specific orbital configurations of giant planets can generate elongated interstellar objects via tidal fragmentation, a novel insight into their origin.

Findings

Eccentric giant planets with e~0.2 are most effective.

Higher semi-major axes increase ejection rates of planetesimals.

Approximately 3% of interstellar objects may be elongated due to tidal fragmentation.

Abstract

The first discovered interstellar small object, `Oumuamua (1I/2017 U1), presents unique physical properties of extremely elongated geometric shape and dual characteristics of an asteroid and a comet. These properties suggest a possible origin through tidal fragmentation, which posits that `Oumuamua was produced through intensive tidal fragmentation during a close encounter with a star or a white dwarf, resulting in its shape and ejection from its natal system. According to this mechanism, a high initial orbit eccentricity and a small pericentre of the parent body are necessary to produce `Oumuamua-like objects. To verify whether this mechanism can occur in single giant planet systems, we conduct long-term numerical simulations of systems with a low-mass ($0.5M_\odot$) host star and a giant planet in this study. We determine that an eccentric orbit ($e_\mathrm{p}\sim0.2$) and a Jupiter-mass ($M_\mathrm{p}\sim M_\mathrm{J}$) of the planet appears to be optimal to generate sufficient perturbations for the production of `Oumuamua-like objects. When the planetary semi-major axis $a_\mathrm{p}$ increases, the proportion of planetesimals ejected beyond the system $P(\mathrm{ej})$ increases accordingly, while the possibilities of ejected planetesimals undergoing stellar tidal fragmentation $P(\mathrm{tidal}|\mathrm{ej})$ remains relatively constant at $\sim0.6\%$. Focusing on stellar tidal fragmentation alone, the ratio of extremely elongated interstellar objects to all interstellar objects is $P_\mathrm{e}\sim3\%$.