Millions of years ago two massive stars circled each other in a cosmic dance. Then one of the stars went supernova. The blast likely flung the exploded star’s companion across space, setting it adrift in the cosmos for tens of thousands of years before it, too, succumbed to the same explosive end.

That, at least, is what astronomers believe may have happened to a newly identified pair of stellar remnants. Using observations from NASA’s Fermi Gamma-ray Space Telescope, researchers suggest that two clouds of supernova debris were once part of a binary star system—a pair of stars bound together by gravity and orbiting a common center.

“There are so many striking connections between the two remnants,” said Miltiadis Michailidis, a postdoctoral fellow at the physics department at Stanford University, in a statement. “They’re likely related, giving us the first known example of a binary system where both stars have undergone supernova explosions.”

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When a star explodes, it expels powerful shock waves that can accelerate charged particles to near-light speeds, creating cosmic rays. As these cosmic rays slam into nearby clouds of gas, they produce gamma rays—the highest-energy form of light. By detecting these gamma rays, astronomers can trace the lingering remnants of ancient supernovae long after the original stars have vanished.

Using 16 years of Fermi observations, researchers examined two remnants in the constellation Gemini: the well-known Jellyfish Nebula (IC 443) and a much fainter neighbor called G189.6+3.3. Both remnants appear to be interacting with the same dense gas clouds. Computer simulations further affirmed the observations. Together with estimates placing the objects at roughly the same distance from Earth, the data suggest that the two remnants share not only a neighborhood but potentially a common origin.

The researchers also calculated that the odds of the observed alignment having occurred by chance are less than 1 percent. “We can now connect the glowing remains of two massive stars to a powerful pair that evolved together over thousands of years,” said Elizabeth Hays, project scientist for Fermi at NASA’s Goddard Space Flight Center in Greenbelt, Md., in the same statement.

If confirmed, the interaction between the Jellyfish Nebula and G189.6+3.3 would provide a rare target for studying how massive binary stars evolve and die. The discovery could also help astronomers better understand the origin of some of the highest-energy particles in the universe.

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