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The appearance of the Interstellar Objects (ISOs) Oumuamua and Comet Borisov in 2017 and 2019, respectively, created a surge of interest. What were they? Where did they come from? Unfortunately, they didn\u2019t stick around and wouldn\u2019t cooperate with our efforts to study them in detail. Regardless, they showed us something: Milky Way objects are moving around the galaxy.<\/p>\n
We don\u2019t know where either ISO came from, but there must be more\u2014far more. How many other objects from our stellar neighbours could be visiting our Solar System?<\/p>\n
<\/p>\n The Alpha Centauri (AC) star system is our nearest stellar neighbour and consists of three stars: Alpha Centauri A and Alpha Centauri B, which are in a binary relationship, and Proxima Centauri, a dim red dwarf. The entire AC system is moving toward us, and it presents an excellent opportunity to study how material might move between Solar Systems.<\/p>\n New research to be published in the Planetary Science Journal examines how much material from AC could reach our Solar System and how much might already be here. It\u2019s titled \u201cA Case Study of Interstellar Material Delivery: Alpha Centauri.\u201d The authors are Cole Greg and Paul Wiegert from the Department of Physics and Astronomy and the Institute for Earth and Space Exploration at the University of Western Ontario, Canada. <\/p>\n \u201cInterstellar material has been discovered in our Solar System, yet its origins and details of its transport are unknown,\u201d the authors write. \u201cHere we present Alpha Centauri as a case study of the delivery of interstellar material to our Solar System.\u201d AC likely hosts planets and is moving toward us at a speed of 22 km s?1<\/sup>, or about 79,000 km per hour. In about 28,000 years it will reach its closest point and be about 200,000 astronomical units (AU) of the Sun. According to Greg and Wiegert, material ejected from AC can and will reach us, and some is already here. <\/p>\n AC is considered a mature star system about five billion years old that hosts planets. Mature systems are expected to eject less material, but since AC has three stars and multiple planets, it likely ejects a considerable amount of material. \u201cThough mature star systems likely eject less material than those in their We know that macro objects like Borisov and Oumuamua have reached our Solar System, and we also know that interstellar dust has reached our system. The Cassini probe detected some, and researchers\u00a0reported on it in 2003. Existing models for material ejection from star systems are partly based on what we know about our<\/span> Solar System and how it ejects material, and Greg and Wiegert based their work on those models. <\/p>\n The research shows that there are potentially large quantities of material from AC. The authors write that \u201cthe current number of Alpha Centauri particles larger than 100 m in diameter within our Oort Cloud to be 106<\/sup>,\u201d or 1 million. However, these objects are extremely difficult to detect. Most of them are likely in the Oort Cloud, a long distance from the Sun. The pair of researchers explain that \u201cthe observable fraction of such objects remains low\u201d and that there is only a one-in-a-million chance that one is within 10 AU of the Sun. <\/p>\n \n
planet-forming years, the presence of multiple stars and planets increases the likelihood of gravitational scattering of members from any remnant planetesimal reservoirs, much as asteroids or comets are currently being ejected from our Solar System,\u201d the authors write. <\/p>\n