Scientists have traced one of the strangest repeating signals in our galaxy to a compact star system where a small, dense white dwarf is pulling material from a nearby companion.
The finding helps explain a class of cosmic flashes that has puzzled astronomers because the bursts arrive at slow, regular intervals, not in the rapid rhythm usually expected from certain dead stars.
The source, known as ASKAP J1745-5051, sends out radio waves and X-rays in a cycle of about 84 minutes. No alien code had to be cracked. Instead, the signal appears to come from a tight stellar pair where gravity, heat, and magnetic fields are doing something powerful and very strange.
A signal that kept coming back
Long-period radio transients are bursts of radio energy that repeat after minutes or hours. That timing is what made them so odd, because astronomers have found only about a dozen of them, and for years their source was unclear.
Think of it like hearing a knock from a dark room every hour or so. You know something is there, but you do not yet know what is making the sound. In this case, the “knock” was a pulse from deep space, captured by sensitive telescopes rather than human ears.
What a white dwarf is
A white dwarf is the leftover core of a star that has burned through its fuel. It is roughly the size of Earth, but it can hold a mass close to that of the Sun, which makes it incredibly dense.
In ASKAP J1745-5051, that compact object is paired with a red dwarf, a star larger than the white dwarf but much less massive than the Sun. The two orbit each other very closely, completing a full trip around each other in just over an hour and a half.
How the star system works
The white dwarf is not sitting quietly. It is stripping material from its companion, and as that material spirals inward, it heats up and gives off X-rays. At the same time, the magnetic fields of the two stars appear to interact with charged material, creating tightly focused bursts of radio energy.
Kovi Rose, a PhD student at the University of Sydney and the Commonwealth Scientific and Industrial Research Organisation (CSIRO), said, “For the first time, we have pinpointed the origin of these signals.” This means astronomers can now connect the repeating radio pulse to a real physical engine instead of just guessing at what might be behind it.
Why astronomers were unsure
For a while, scientists suspected that long-period radio transients might come from slow-spinning neutron stars called pulsars. Pulsars are famous for sending out beams of radiation, almost like cosmic lighthouses.
However, there is a problem. Current models suggest neutron stars spinning that slowly should not be able to produce these signals, at least not easily. That is why a white dwarf binary, meaning two stars locked together with one feeding on the other, now looks like a stronger explanation for at least some of these mysterious bursts.
Other clues were already building
This discovery did not come out of nowhere. In 2025, researchers studying ASKAP J1832-0911 reported radio and X-ray pulses every 44 minutes, although they still lacked a clear explanation for what was driving the pattern.
Another 2026 study also pointed toward white dwarf systems as possible engines for long-period transients. The new work goes further because scientists can see both the two-star setup and the material transfer in action. That makes the case much harder to ignore.
Why this matters
The new system is important because it gives astronomers a working example of how one of these signals can be made. It is also only the second known long-period radio transient to emit regular X-rays, and the first where scientists say they have confirmed the cause of that regular timing.
That may sound distant from everyday life, and in many ways it is, but this is how astronomy often moves forward, one strange signal at a time. A mystery becomes a pattern, the pattern becomes a model, and the model gives scientists a better map of what is happening in the galaxy.
A natural laboratory in space
The system gives researchers a chance to study matter under intense gravity and strong magnetic fields. Those are conditions that cannot be recreated in a normal laboratory on Earth, no matter how advanced the equipment gets.
Rose has described the system as a kind of stellar Rosetta Stone because it may help decode other long-period radio transients. The metaphor fits. One solved signal can help translate a whole group of cosmic messages that once looked unreadable.
What comes next
The team plans more observations using radio, optical, and X-ray telescopes. The goal is to better understand how these emissions are produced and whether the same mechanism explains other long-period transients scattered through the Milky Way.
For now, ASKAP J1745-5051 has turned a strange repeating signal into something more concrete, a close stellar pair where a white dwarf is feeding, flashing, and helping scientists understand a newly recognized class of cosmic events.
The main study has been published in Nature Astronomy.
