From a Different Star: 3I/ATLAS in the context of the \={O}tautahi-Oxford interstellar object population model

TL;DR

This paper assesses the interstellar object 3I/ATLAS within a Galactic population model, confirming its properties align with expectations and suggesting it likely did not originate from the same source as previous ISOs.

Contribution

It introduces a novel context for 3I/ATLAS using the f4tautahi-Oxford model, integrating Gaia data with disk chemistry and Galactic dynamics.

Findings

3I's velocity and radiant are within expected ranges.

Its age is estimated over 7.6 Gyr with high water content.

Unlikely to share origin with previous interstellar objects.

Abstract

The discovery of the third interstellar object (ISO), 3I/ATLAS (`3I'), provides a rare chance to directly observe a small body from another Solar System. Studying its chemistry and dynamics will add to our understanding of how the processes of planetesimal formation and evolution happen across the Milky Way's disk, and how such objects respond to the Milky Way's potential. In this Letter, we present a first assessment of 3I in the context of the \={O}tautahi-Oxford model, which uses data from Gaia in conjunction with models of protoplanetary disk chemistry and Galactic dynamics to predict the properties of the ISO population. The model shows that both the velocity and radiant of 3I are within the expected range. Its velocity predicts an age of over 7.6 Gyr and a high water mass fraction, which may become observable shortly. We also conclude that it is very unlikely that 3I shares an origin with either of the previous two interstellar object detections.