Newfound binary system is a cosmic oddball, researchers say. 

Ohio State News Article, written by Tatyana Woodall

Stars die and vanish from sight all the time, but astronomers were puzzled when one that had been stable for more than a decade almost disappeared for eight months. 

Between late 2024 and early 2025, one star in our galaxy, dubbed ASASSN-24fw, dimmed in brightness by about 97%, before brightening again. Since then, scientists have been swapping theories about what was behind this rare, exciting event. 

Now, an international team led by scientists at The Ohio State University may have come up with an answer to the mystery. In a new study recently published in The Open Journal of Astrophysics, astronomers suggest that because the color of the star’s light remained unchanged during its dimming, the event wasn’t caused by the star evolving in some way, but by a large cloud of dust and gas around the star that occluded Earth’s view of it. 

“We explored three different scenarios for what could be going on,” said Raquel Forés-Toribio, lead author of the study and a postdoctoral researcher in astronomy at Ohio State. “Evidence suggests it is likely that there is a cloud of dust in the form of a disk around it.”

ASASSN-24fw is an F-type star — a star that is a little more massive than our sun and about twice as big —  and is located about 3,000 light-years away from Earth. Researchers estimate that the cloudy disk it’s surrounded by is about 1.3 astronomical units (AU) across, even bigger than the distance between the sun and our planet. (One AU is the distance between the center of the Earth and the center of the sun.)

Researchers suggest this disk is also likely made up of large clusters of carbon or water ice close in size to a large grain of dust found on Earth. This material is similar enough to planet-forming disks that studying it could give astronomers novel insights into stellar formation and evolution. 

Yet these findings alone don’t explain all of the system’s abnormalities, said Forés-Toribio. Instead, researchers think that a smaller, cooler star may also orbit ASASSN-24fw, which would make it a hidden binary system.  

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