A Case Study of Interstellar Material Delivery: {\alpha} Centauri

TL;DR

This study models how interstellar material from the Alpha Centauri system could reach our Solar System, estimating current and future fluxes, and highlighting the low probability of direct detection of such material.

Contribution

It provides a detailed case study of interstellar material delivery from Alpha Centauri, including ejection dynamics and potential observational signatures, which was not previously analyzed in depth.

Findings

Interstellar particles from Alpha Centauri can reach our Solar System, especially near its closest approach.

The estimated number of large particles (>100 m) in the Oort Cloud from Alpha Centauri is about 10^6.

Approximately 10 meteors >100 μm from Alpha Centauri may enter Earth's atmosphere annually.

Abstract

Interstellar material has been discovered in our Solar System, yet its origins and details of its transport are unknown. Here we present $\alpha$ Centauri as a case study of the delivery of interstellar material to our Solar System. $\alpha$ Centauri is a mature triple star system that likely harbours planets and is moving towards us with the point of closest approach approximately 28,000 years in the future. Assuming a current ejection model for the system, we find that such material can reach our Solar System and may currently be present here. The material that does reach us is mostly a product of low ($<2$ km/s) ejection velocities, and the rate at which it enters our Solar System is expected to peak around the time of $\alpha$ Centauri 's closest approach. If $\alpha$ Centauri ejects material at a rate comparable to our own Solar System, we estimate the current number of $\alpha$ Centauri particles larger than 100 m in diameter within our Oort Cloud to be $10^{6}$, and during $\alpha$ Centauri 's closest approach, this will increase by an order of magnitude. However, the observable fraction of such objects remains low as there is only a probability of $10^{-6}$ that one of them is within 10 au of the Sun. A small number ($\sim 10$) meteors greater than 100 micrometers from $\alpha$ Centauri may currently be entering Earth's atmosphere every year: this number is very sensitive to the assumed ejected mass distribution, but the flux is expected to increase as $\alpha$ Centauri approaches.