Bright, fleeting blasts of radio waves coming from the vicinity of a nearby galaxy are deepening one of astronomy’s biggest mysteries. The repeating bursts of energy seem to be coming from an ancient group of stars called a globular cluster, which is among the last places astronomers expected to find them.

Often originating billions of light-years away, the extremely bright, extremely brief bursts of radio waves known as fast radio bursts, or FRBs, have defied explanation since they were first spotted in 2007. Based on observations to date, scientists surmised that the bursts are powered by young, short-lived cosmic objects called magnetars.

But a fast radio burst discovered last year has now been traced to a globular cluster about 11.7 million light-years away, near the neighboring spiral galaxy M81, according to a paper describing the discovery posted on the scientific preprint server arXiv. Finding this burst among a cluster of aging stars is kind of like finding a smartphone embedded in Stonehenge—the observation doesn’t make sense. 

“This is definitely not a place fast radio bursts are expected to live,” Bryan Gaensler, an astronomer at the University of Toronto and a co-author of the new paper, posted on Twitter. “Just what is going on?”

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