Astronomers Spot a Rare Quadruple Star System in the Milky Way, Shedding Light on Mysterious Brown Dwarfs

The discovery can help astronomers better understand these little-known objects nicknamed “failed stars”

Sara Hashemi | Daily Correspondent

August 29, 2025

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Astronomers have discovered a first-of-its-kind quadruple star system in our own Milky Way, a surprising find that could help scientists better understand mysterious objects called brown dwarfs.

Also known as “failed stars,” brown dwarfs form like normal stars but fail to gain enough mass to properly fuse hydrogen. These objects—something between a planet and a star—are notoriously difficult to study. They’re small, cold and faint, making them hard to detect. And determining a brown dwarf’s age also poses a challenge. That’s because, unlike stars, brown dwarfs continuously cool throughout their lifespan, so their characteristics are constantly changing.

To find these strange objects, astronomers might look for brown dwarfs when they’re young and still burning brightly, or seek out ones that are relatively close to us.

Zenghua Zhang, an astronomer at Nanjing University in China, and his team were initially searching for brown dwarfs by seeking out their bright stellar companions. The scientists sifted through data from the European Space Agency’s Gaia telescope and NASA’s Wide-field Infrared Survey Explorer (WISE) and were rewarded when they identified a brown dwarf orbiting a bright star.

They soon realized, however, that there wasn’t just one brown dwarf, but two. Then, they discovered there were also two of the bright, stellar companions.

“I like to call this a double-double,” says Adam Burgasser, an astrophysicist at the University of California, San Diego, and a member of the research team, to Katrina Miller at the New York Times. The discovery was highlighted in a recent study published in the Monthly Notices of the Royal Astronomical Society.

The system, named UPM J1040−3551 AabBab, is located about 82 light-years from Earth. The two pairs—the brown dwarfs and the bright stars, identified as red dwarfs—are separated by 1,656 astronomical units, making them 1,656 times farther apart from each other than the Earth is from the sun.

This unusual quartet can provide a “unique cosmic laboratory for studying these mysterious objects,” says co-author Maria Cruz Gálvez-Ortiz, an astrophysicist at the Center for Astrobiology in Spain, in a statement.

Because the objects likely formed around the same time from similar materials, the companion stars offer a benchmark from which researchers can uncover certain characteristics about the brown dwarfs, such as their ages and compositions. The brown dwarfs in this system appear similar in size to Jupiter, but they contain 10 to 30 times more mass.

With the help of the Southern Astrophysical Research (SOAR) telescope in Chile, scientists observed the red dwarf stars in visible light and the brown dwarfs in near-infrared. They found that the system is between 300 million and 2 billion years old, making it relatively young. They also concluded that the two brown dwarfs have temperatures of about 1,016 degrees Fahrenheit and 782 degrees Fahrenheit, while the brighter companions have temperatures of approximately 5,300 degrees Fahrenheit.

“This system offers a dual benefit for brown dwarf science,” Burgasser adds in the statement. “It can serve as an age benchmark to calibrate low-temperature atmosphere models and as a mass benchmark to test evolutionary models, if we can resolve the brown dwarf binary and track its orbit.”

And the fact that this star system has two pairs of objects is even better for scientists. It “helps twice as much,” Burgasser tells the New York Times.

Sara Hashemi | Read More

Sara Hashemi is a science writer and fact-checker currently based in New York City. Her work has appeared in Sierra, The Body, Maisonneuve magazine and more.