Where the Solar system meets the solar neighbourhood: patterns in the distribution of radiants of observed hyperbolic minor bodies (1802.00778v2)

Abstract: Observed hyperbolic minor bodies might have an interstellar origin, but they can be natives of the Solar system as well. Fly-bys with the known planets or the Sun may result in the hyperbolic ejection of an originally bound minor body; in addition, members of the Oort cloud could be forced to follow inbound hyperbolic paths as a result of secular perturbations induced by the Galactic disc or, less frequently, due to impulsive interactions with passing stars. These four processes must leave distinctive signatures in the distribution of radiants of observed hyperbolic objects, both in terms of coordinates and velocity. Here, we perform a systematic numerical exploration of the past orbital evolution of known hyperbolic minor bodies using a full N-body approach and statistical analyses to study their radiants. Our results confirm the theoretical expectations that strong anisotropies are present in the data. We also identify a statistically significant overdensity of high-speed radiants towards the constellation of Gemini that could be due to the closest and most recent known fly-by of a star to the Solar system, that of the so-called Scholz's star. In addition to and besides 1I/2017 U1 (`Oumuamua), we single out eight candidate interstellar comets based on their radiants' velocities.

• The paper demonstrates that hyperbolic minor bodies exhibit marked anisotropies in their radiant distributions, suggesting diverse origins.
• The paper identifies additional interstellar candidates beyond ’Oumuamua based on significantly high inbound velocities and robust N-body simulations.
• The paper links an overdensity of radiants in Gemini to a stellar fly-by event, notably Scholz’s star, highlighting external cosmic influences.

Distribution Patterns of Hyperbolic Minor Bodies: A Study of Interstellar and Solar System Origins

The paper "Where the Solar system meets the solar neighbourhood: patterns in the distribution of radiants of observed hyperbolic minor bodies" provides a systematic examination of the trajectories and origins of hyperbolic minor bodies within the Solar system. Utilizing full N-body simulations and statistical analyses, the authors aim to discern the origins of these hyperbolic minor bodies, some of which may have originated from interstellar space, while others could be indigenous to the Solar system.

Methodology and Analysis

The authors employ a robust N-body approach to simulate the past orbital evolution of 339 known hyperbolic minor bodies, relying on data from JPL's SSDG SBDB and the MPC Database. The paper uses the Hermite integration scheme to compute the radiants and velocities of these bodies without considering non-gravitational forces. The Solar system model includes perturbations from the eight major planets, the barycentre of the Pluto-Charon system, and the three most massive main-belt asteroids. The geocentric equatorial coordinates and velocity distributions are computed to assess the origin and evolutionary patterns of these hyperbolic objects.

Key Findings

1. Distribution Anisotropy: The paper confirms the presence of significant anisotropies in the radiant distribution of hyperbolic minor bodies. This anisotropy suggests the influence of multiple mechanisms affecting their distribution.
2. Potential Interstellar Origins: Besides the well-known 1I/2017 U1 ('Oumuamua), eight additional candidates for interstellar interlopers are identified based on their inbound velocities, which exceed the median radiant velocity by a significant margin. These candidates include hyperbolic comets such as C/2008 J4 (McNaught) and C/2012 S1 (ISON).
3. Stellar Fly-by Influence: The research identifies a statistically significant overdensity of radiants in the direction of the constellation of Gemini. This concentration correlates with the trajectory of Scholz's star, a known stellar fly-by, suggesting a plausible connection between cosmic events and the observed radiant patterns.

Implications and Future Directions

The paper has profound implications for understanding the dynamical processes influencing the orbits of minor bodies in the Solar system. The identification of hyperbolic trajectories provides insights into the potential capture and ejection processes that can occur during stellar fly-bys. Furthermore, the potential discovery of additional interstellar objects challenges existing understandings of how the Solar system interacts with its galactic environment.

Future research could expand upon these findings by incorporating more comprehensive datasets and exploring the role of other potential stellar encounters. Advances in astronomical survey techniques may further elucidate the origins and trajectories of such hyperbolic objects, contributing to our understanding of solar-neighborhood dynamics and interstellar material exchange.

Conclusion

This paper rigorously identifies patterns in the distribution of hyperbolic minor bodies, presenting significant evidence for both interstellar and Solar system origins. The work emphasizes the complex interplay of local and external influences on the paths of such bodies, benefiting from detailed N-body simulations and statistical treatments. It paves the way for future investigations into celestial mechanics and the broader cosmic environment surrounding our Solar system.