Interstellar Objects Outnumber Solar System Objects in the Oort Cloud

TL;DR

The paper suggests interstellar objects are more numerous than Solar System objects in the Oort cloud, with implications for galactic composition and future observational tests.

Contribution

It introduces the idea that interstellar objects dominate the Oort cloud and links this to galactic heavy element budgets and observational strategies.

Findings

Interstellar objects outnumber Solar System objects in the Oort cloud.

Detection of Borisov supports the prevalence of interstellar objects.

Approximately 1% of galactic carbon and oxygen may be in interstellar objects.

Abstract

Here, we show that the detection of Borisov implies that interstellar objects outnumber Solar system objects in the Oort cloud, whereas the reverse is true near the Sun due to the stronger gravitational focusing of bound objects. This hypothesis can be tested with stellar occultation surveys of the Oort cloud. Furthermore, we demonstrate that $\sim 1 \%$ of carbon and oxygen in the Milky Way Galaxy may be locked in interstellar objects, saturating the heavy element budget of the minimum mass Solar nebula model.