On the Consequences of the Detection of an Interstellar Asteroid

TL;DR

The discovery of interstellar asteroid A/2017 U1 offers insights into planetary formation, suggesting a large population of similar bodies and possibly many undetected Neptune-like exoplanets in our galaxy.

Contribution

This paper links interstellar asteroid detection to the existence of numerous similar objects and undetected exoplanets, providing new implications for galaxy-wide planetary populations.

Findings

Galaxy contains substantial mass in interstellar objects.

A/2017 U1 likely had significant volatile components.

Presence of such objects implies many undetected Neptune-like planets.

Abstract

The arrival of the robustly hyperbolic asteroid A/2017 U1 has potentially interesting ramifications for the planet-formation process. Although extrapolations from a sample size of one are necessarily uncertain, order-of-magnitude estimates suggest that the Galaxy contains a substantial mass in similar bodies. We argue that despite its lack of Coma, A/2017 U1 likely contained a significant mass fraction of volatile components, and we argue that its presence can be used to infer a potentially large population of as-yet undetected Neptune-like extrasolar planets.