Using China’s Five-hundred-meter Aperture Spherical Telescope (FAST), astronomers have found strong evidence that some fast radio bursts originate in binary star systems. Nearly two years of observations of a repeating burst revealed extreme Faraday rotation, pointing to a nearby companion star.

The data suggest a magnetar orbiting a sun-like star whose plasma periodically distorts the radio signal. This discovery offers one of the clearest clues yet to the origin of repeating FRBs, supporting the idea that interactions in double-star systems drive these powerful cosmic flashes.