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Could there once have been two stars in our solar system?

Could our sun have had a partner star during the early days of the solar system? A new study suggests our sun may have had a binary companion, like the system of the planet Tatooine from the original Star Wars movie.

Twin suns seen from the fictional planet Tatooine in Star Wars

A team of researchers from Harvard put forth the theory that our region of space may have had another star present during the formation of the solar system. That would explain the presence of the Oort cloud, a collection of icy bodies orbiting the sun beyond Neptune. Scientists aren’t sure exactly how this cloud formed, and the presence of another star early could help explain it.

“Previous models have had difficulty producing the expected ratio between scattered disk objects and outer Oort cloud objects,” lead author Amir Siraj explained in a statement. “The binary capture model offers significant improvement and refinement, which is seemingly obvious in retrospect: Most sun-like stars are born with binary companions.”

Artist’s conception of a potential solar companion, which theorists believe was developed in the Sun’s birth cluster and later lost. If proven, the solar companion theory would provide additional credence to theories that the Oort cloud formed as we see it today, and that Planet Nine was captured rather than formed in place. M. Weiss

Not only would the presence of another star help explain the Oort Cloud, it could even provide a clue to the origin of life on Earth. “Objects in the outer Oort Cloud may have played important roles in Earth’s history, such as possibly delivering water to Earth and causing the extinction of the dinosaurs,” said Siraj. “Understanding their origins is important.”

This potential companion also has links to another mystery of our solar system: The possible presence of Planet Nine, a hypothetical planet some believe orbits beyond Neptune.

“The puzzle is not only regarding the Oort clouds, but also extreme trans-Neptunian objects, like the potential Planet Nine,” co-author Avi Loeb said in the statement. “It is unclear where they came from, and our new model predicts that there should be more objects with a similar orbital orientation to Planet Nine.”

The research is published in The Astrophysical Journal Letters.

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