The white dwarf steals material every 81 minutes, heating it to millions of degrees
For years, the Milky Way has whispered in an unfamiliar tongue — radio pulses arriving at intervals too slow and too strange for any known stellar voice. Now, a team of astronomers has traced at least one of these signals to its origin: a magnetized white dwarf locked in an 81-minute orbital embrace with a companion star, stealing material and converting it into synchronized bursts of radio waves and X-rays. The discovery, published in Nature Astronomy, offers not merely an answer to a single mystery, but a key to an entire hidden population of stellar systems scattered across the galaxy.
- Since 2022, roughly a dozen slow radio pulses have appeared across the galaxy, arriving at intervals of minutes rather than seconds — a rhythm that no existing model of stellar physics could explain.
- Each new detection deepened the unease: these long-period radio transients seemed to operate by rules astronomers hadn't yet written, defying the tidy categories of pulsars and magnetars.
- A team at the University of Sydney zeroed in on ASKAP J1745-5051, using a powerful Australian radio telescope to catch the system emitting both radio waves and X-rays in perfect 81-minute lockstep with its orbital period.
- The culprit turned out to be a magnetized white dwarf pulling matter from a companion star — material that superheats on impact, accelerating particles and generating the twin signals astronomers had been chasing.
- This system now functions as a Rosetta Stone, offering a unified framework that may explain dozens of other mysterious signals and reveal an entirely new class of cosmic objects hiding in plain sight.
For years, astronomers have been unsettled by strange radio pulses drifting out of the Milky Way's plane — signals that arrived far too slowly, at intervals of minutes rather than seconds, to fit any known model of stellar behavior. When radio telescopes first caught them around 2022, scientists gave them a name — long-period radio transients, or LPTs — but not yet an explanation. About a dozen were catalogued, each one an open question.
The answer, or at least a crucial piece of it, came from a system called ASKAP J1745-5051, identified by astronomer Kovi Rose and colleagues at the University of Sydney using the Australian Square Kilometre Array Pathfinder telescope. At the heart of this system sits a dense, magnetized white dwarf orbiting a companion star every 81 minutes. As the pair circle each other, the white dwarf's powerful magnetic field siphons material from its companion. That stolen matter crashes onto the white dwarf's surface at millions of degrees, producing both radio emissions and X-ray bursts — each arriving at precisely the same 81-minute rhythm as the orbital period itself.
That synchronization was the breakthrough. Radio signals, X-rays, and orbital timing all locked together, revealing the mechanism driving the phenomenon. The discovery builds on a trail of incremental findings since 2022, including earlier LPTs linked to white dwarf and red dwarf pairings, and a system that hinted at more energetic processes by emitting both radio and X-ray signals simultaneously.
ASKAP J1745-5051 appears to combine nearly every trait observed separately across other LPTs, making it an interpretive key for the whole class. What once looked like isolated cosmic oddities may instead represent a previously unrecognized population of stellar systems — one that astronomers are only now beginning to map.
For years, astronomers have been puzzled by strange radio signals emanating from the plane of the Milky Way—pulses that arrive at intervals far longer than anything predicted by conventional models of stellar behavior. Now, in a study published this week in Nature Astronomy, researchers believe they have finally cracked the code.
The mystery began around 2022, when radio telescopes first detected these anomalous signals. Unlike the rapid, regular pulses from known objects such as pulsars, these sources behaved differently: they pulsed slowly, at intervals measured in minutes rather than seconds. Astronomers began calling them long-period radio transients, or LPTs. About a dozen have been identified scattered across the galaxy, each one defying easy explanation and drawing intense scrutiny from the scientific community.
A team led by astronomer Kovi Rose at the University of Sydney has now traced at least one of these signals to its source—a system called ASKAP J1745-5051, located somewhere between 1,300 and 30,000 light-years from Earth. The discovery, made using the Australian Square Kilometre Array Pathfinder radiotelescope in Western Australia, reveals a system far more complex than initially imagined. At its heart lies a white dwarf—the dense, magnetized remnant of a dead star—locked in orbit with a companion star. Every 81 minutes, as the two stars complete an orbit around each other, the white dwarf's powerful magnetic field pulls material from its companion. This stolen material crashes onto the white dwarf's surface at temperatures of millions of degrees, producing both the radio waves and X-ray bursts that astronomers have been detecting.
The breakthrough came when researchers noticed that the radio emissions and X-ray pulses arrived at precisely the same 81-minute interval as the orbital period itself. Optical telescope data confirmed the timing: the two stars complete their dance in roughly 81 minutes, matching the rhythm of the signals. This synchronization was the key that unlocked the system's secrets. The magnetic field accelerates charged particles, generating the radio emissions, while the infalling material superheated against the white dwarf's surface produces the X-rays.
This discovery builds on years of incremental progress. In 2022, astronomers identified GLEAM-X J162759.5−523504.3, which emitted intense radio pulses every 18.18 minutes—a finding that sparked the search for similar objects. By 2025, another LPT was linked to a white dwarf and red dwarf system where intense magnetic interactions produced periodic bursts of radio waves. Then came ASKAP J1832-0911, which added another piece to the puzzle by simultaneously emitting both radio and X-ray signals, hinting at more energetic processes than scientists had initially supposed.
The ASKAP J1745-5051 system appears to be the Rosetta Stone of this emerging class of objects. It combines nearly every characteristic observed separately in other LPTs: the white dwarf, the companion star, the synchronized radio and X-ray emissions, the intense magnetic environment. For Rose and his colleagues, this system offers a framework for understanding dozens of other mysterious signals detected in recent years. The implication is profound: what once seemed like isolated oddities may instead represent an entirely new population of stellar systems, waiting to be catalogued and understood. As astronomers continue to scan the galaxy's plane, each new detection brings them closer to a complete picture of these strange and energetic cosmic events.
Notable Quotes
The new identification represents an important step toward understanding how these events are produced— Kovi Rose, University of Sydney
The Hearth Conversation Another angle on the story
So these signals have been puzzling astronomers for years. What made this particular system different enough to finally crack the case?
The timing. Everything aligned—the orbital period, the radio pulses, the X-ray bursts. They all arrived every 81 minutes. That synchronization was the thread that connected everything else.
And the white dwarf is doing what, exactly?
It's stealing. The magnetic field is so strong it's pulling material off the companion star with each orbit. That material gets accelerated and heated to millions of degrees, and that's what we're detecting as both radio and X-rays.
So this isn't some exotic new type of object. It's a known system behaving in a way we hadn't fully understood.
Exactly. Magnetic cataclysmic variables have been known for decades. But these slow radio transients showed us we were missing something about how they work—specifically, how the magnetic fields interact at these scales.
Does this mean the other mysterious signals are probably the same thing?
That's the working hypothesis now. Not all of them, necessarily, but many. This system seems to be a template. Once you understand one, you have a map for understanding the others.
What's the next question astronomers are asking?
How many of these systems are actually out there? And are there variations we haven't seen yet? This one is relatively nearby in cosmic terms. There could be hundreds more we haven't detected.