An international team of scientists have observed, for the first time ever, what they think is a multistar system in very early stages of formation. The implications of the findings, published in Nature, may help researchers understand why some star systems have only one star (like ours), and other have two or more stars.

ETH Zürich explains that the scientists found the four-star system emerging from a gas cloud in the Perseus constellation:

The star system consists of a young star still in an early development phase and three gas clouds which are rapidly condensing by gravitational forces. According the astrophysicists’ calculations, each gas cloud will develop into a star in 40,000 years. The stars may be relatively small and only reach around one-tenth the mass of our sun. The space between the individual stars amounts to more than a thousand times the average distance between the sun and Earth.

Jamie Pineda, the first author of the study who is now at the Max Planck Institute for Extraterrestrial Physics, expects that only the two stars closest together will form a star system, however. “Star systems with more than three members are unstable and prone to interference,” he said.

But even the two closest stars “aren’t very close to each other,” he told the Washington Post

“These potential stars aren’t very close to each other. They’re separated by several thousand times the distance between the Sun and the Earth,” he said. It’s generally assumed that binary systems have to form close together and then can later spread out across large distances. “But it seems that actually you don’t need to do all that,” Pineda said. “You can form them at very large distances from each other from the very beginning.”

Multistar systems are common in the Milky Way galaxy, notes Michael Meyer, professor at the Institute for Astronomy at ETH Zurich. But we know very little about them. University of Massachusetts Amherst astrophysicist Stella Offner, whose predictions about how multistar systems form match Wednesday’s findings, said of the findings, “Why is our sun a single star while the nearest star to us, Alpha Centauri, happens to be a triple system? There are competing models for how multiple star systems are born, but now we know a little more than we did before.”

(Image: B. Saxton, NRAO/AUI/NSF)