A Case Study of Interstellar Material Delivery: α Centauri

Abstract

Interstellar material has been discovered in our solar system, yet its origins and details of its transport are unknown. Here, we present α Centauri as a case study of the delivery of interstellar material to our solar system. α Centauri is a mature triple star system that likely harbors planets, and is moving toward us with the point of the closest approach approximately 28,000 yr 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^‑1) ejection velocities, and the rate at which it enters our solar system is expected to peak around the time of α Centauri's closest approach. If α Centauri ejects material at a rate comparable to our own solar system, we estimate the current number of α Centauri particles larger than 100 m in diameter within our Oort Cloud to be 10⁶, and during α 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 (∼10) of meteors >100 μm from α 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 α Centauri approaches.