Configuration of single giant planet systems generating ‘oumuamua-like interstellar asteroids

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⊙) host star and a giant planet in this study. We determine that an eccentric orbit (ep ∼ 0.2) and a Jupiter-mass (Mp ∼ MJ) of the planet appears to be optimal to generate sufficient perturbations for the production of ‘Oumuamua-like objects. When the planetary semi-major axis ap increases, the proportion of planetesimals ejected beyond the system P(ej) increases accordingly, while the possibilities of ejected planetesimals undergoing stellar tidal fragmentation P(tidal|ej) remains relatively constant at ∼0.6 %. Focusing on stellar tidal fragmentation alone, the ratio of extremely elongated interstellar objects to all interstellar objects is Pe ∼ 3 %.