SPACE — Scientists have long believed that stars are born with at least one companion. Unfortunately, there hasn’t been much evidence to support this theory, until now.

Science Alert reports that a new study on star systems from the University of California at Berkeley and Harvard’s Smithsonian Astrophysical Observer has found that sunlike stars initially form as wide binaries. Some systems, like the Alpha Centauri, even form as triplets.

Over the next million years, these stars either come together to form a tight binary, or break apart.

Our sun would have been separated by a distance of 500 or more astronomical units from its twin star, before it was believed to have moved farther away.

The twin has been dubbed ‘Nemesis’, after scientists hypothesized that it had knocked an asteroid out of orbit and sent it hurtling toward Earth. They say that asteroid eventually collided with our planet and killed off the dinosaurs.

Still, Nemesis has never actually been found, and the idea that it may be responsible for catastrophic events on Earth has yet to be proved.