Scientists discover a rebellious star family defying the cosmic order

Astronomers poring through a now-retired space telescope's data have spotted a bizarre family of fledgling stars breaking all the rules of how they're expected to behave.

The star group, which scientists have recently named Ophion, consists of more than 1,000 stars that formed together but are now scattering at high speeds. Stars that share the same birthplace usually migrate together for millions to billions of years.

But Ophion, just 20 million years old, is already flying apart in a fraction of the time it’d usually take to disperse. Researchers say all of these relatives are about to become estranged, completely removed from their ancestral home.

The discovery, made with the European Space Agency's Gaia star-surveying spacecraft, could change how astronomers find and study stellar groups — and reveal previously unknown ways they shape the Milky Way. 

"Ophion is filled with stars that are set to rush out across the galaxy in a totally haphazard, uncoordinated way, which is far from what we’d expect for a family so big," said Dylan Huson of Western Washington University in a statement. "It’s like no other star family we’ve seen before."

In this graphic, dots show the location of Ophion, a young star family discovered by the now-retired Gaia mission. Credit: ESA / Gaia / DPAC graphic

To find Ophion, scientists used a new machine-learning computer tool to analyze data from Gaia, which mapped the galaxy for more than a decade but recently retired because it ran out of fuel. Though the mission concluded this year, these new findings are a tease to another vast data release expected in 2026. 

Gaia has revealed long strings of stars that have stayed together for billions of years and even uncovered old star streams that helped shape the galaxy itself.

The tool, aptly named Gaia Net, has sifted through the massive amount of survey data and figured out basic traits of stars, such as their temperatures, sizes, ages, and ingredients. 

By searching for young stars, Gaia Net homed in on the young family about 650 light-years away, a relatively short distance in cosmic scales. The new paper, led by Huson, appears in The Astrophysical Journal. 

The exact reason for Ophion’s strange behavior is still unclear. One idea is that powerful events near the group — like explosions of old stars into supernovas — might have pushed the stars apart. Another idea is that nearby star groups may have disrupted Ophion with their energy and gravity.

Whatever the cause, Ophion seemingly escaped traditional methods of detection because they rely on spotting stars that move similarly through space. Because of that, there may have been a confirmation bias in only finding star families that behave in that specific way. Perhaps more star groups that don't fit the mold, previously eluding researchers, are waiting to be found, too.

"Previous methods identified families by clustering similarly moving stars together, but Ophion would have slipped through this net," said Marina Kounkel, a co-author based at the University of North Florida, in a statement. "Without the huge, high-quality datasets from Gaia, and the new models we can now use to dig into these, we may have been missing a big piece of the stellar puzzle."