Astronomers pinpoint origin of mysterious repeating radio bursts from space

Slowly repeating bursts of intense radio waves from space have puzzled astronomers since they were discovered in 2022.In new research, we have for the first time tracked one of these pulsating signals back to its source: a common kind of lightweight star called a red dwarf, likely in a binary orbit with a white dwarf, the core of another star that exploded long ago.A slowly pulsing mysteryIn 2022, our team made an amazing discovery: periodic radio pulsations that repeated every 18 minutes, emanating from space. The trouble is, our current theories say a pulsar spinning only once every 18 minutes should not produce radio waves.So we thought our 2022 discovery could point to new and exciting physics or help explain exactly how pulsars emit radiation, which despite 50 years of research is still not understood very well.More slowly blinking radio sources have been discovered since then. There are now about ten known 'long-period radio transients'.However, just finding more hasn't been enough to solve the mystery.Searching the outskirts of the galaxyUntil now, every one of these sources has been found deep in the heart of the Milky Way.This makes it very hard to figure out what kind of star or object produces the radio waves, because there are thousands of stars in a small area. When the wind hits the white dwarf's magnetic field, it would be accelerated, producing radio waves.This could be similar to how the Sun's stellar wind interacts with Earth's magnetic field to produce beautiful aurora, and also low-frequency radio waves.We already know of a few systems like this, such as AR Scorpii, where variations in the brightness of the red dwarf imply that the companion white dwarf is hitting it with a powerful beam of radio waves every two minutes.None of these systems are as bright or as slow as the long-period radio transients, but maybe as we find more examples, we will work out a unifying physical model that explains all of them.On the other hand, there may be many different kinds of system that can produce long-period radio pulsations.Either way, we've learned the power of expecting the unexpected and we'll keep scanning the skies to solve this cosmic mystery.