First interstellar visitor likely came from binary star system: Study

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‘Oumuamua’, the rocky object identified as the first confirmed interstellar asteroid, very likely came from a binary star system, new research has found.

A binary star system, unlike our Sun, is one with two stars orbiting a common centre.

For the study, published in the journal Monthly Notices of the Royal Astronomical Society, Alan Jackson from University of Toronto Scarborough in Ontario, Canada and his co-authors set about testing how efficient binary star systems are at ejecting objects.

They also looked at how common these star systems are in the galaxy.

They found that rocky objects like ‘Oumuamua’ are far more likely to come from binary than single star systems.

They were also able to determine that rocky objects are ejected from binary systems in comparable numbers to icy objects.

“It’s really odd that the first object we would see from outside our system would be an asteroid, because a comet would be a lot easier to spot and the Solar System ejects many more comets than asteroids,” said lead study author Jackson.

Once they determined that binary systems are very efficient at ejecting rocky objects, and that a sufficient number of them exist, they were satisfied that ‘Oumuamua’ very likely came from a binary system.

They also concluded that it probably came from a system with a relatively hot, high mass star since such a system would have a greater number of rocky objects closer in.

The team suggest that the asteroid was very likely to have been ejected from its binary system sometime during the formation of planets.