Kovi Rose, a Ph.D. student at the University of Sydney, was scanning radio waves from distant space when his telescope picked up something no astronomer had clearly seen before: a white dwarf star, no larger than Earth but packing the mass of our sun, actively stealing material from its companion star and unleashing perfectly timed bursts of radio and X-rays every 1.4 hours.
For years, astronomers had detected about a dozen of these mysterious cosmic pulses—called "long-period radio transients"—originating from scattered regions of our galaxy, but their origin remained one of the field's most perplexing puzzles. Scientists had initially suspected they were slow-spinning neutron stars called pulsars, but that theory kept falling apart: neutron stars rotating at such speeds shouldn't be able to produce these signals at all. Now, using CSIRO's ASKAP radio telescope in Western Australia, Rose's international team has finally provided the answer, revealing in Nature Astronomy that at least some of these transients originate from rare binary systems involving white dwarfs—a discovery that transforms one of space's lingering mysteries into what researchers are calling a "Rosetta Stone" for future discoveries.
The newly identified system, named ASKAP J1745−5051, is a cosmic dance of extremes. The white dwarf—a collapsed stellar remnant roughly the size of Earth—orbits its companion red dwarf, which is larger but only about one-tenth the sun's mass. These two stars are locked in an extraordinarily tight embrace, completing a full orbit in just over an hour. As the white dwarf's gravity rips material away from its companion, that stolen gas spirals inward, heating up and releasing X-rays. Meanwhile, something equally remarkable happens: the magnetic fields of both stars collide and interact with the charged material being shredded from the red dwarf, generating tightly beamed bursts of radio waves that fire with clockwork precision every 1.4 hours.
What makes this discovery particularly striking is what it reveals about the system's inner workings. "The radio and X-ray signals don't peak at the same time, which tells us they're being produced in different regions of the system," Rose explained. The radio emission originates in the turbulent zone where the stars' magnetic fields meet and clash, while the X-rays emerge from the hotter material spiraling closest to the white dwarf. This spatial separation is the key that unlocked the mystery—each emission tells a different part of the same gravitational story.
ASKAP J1745−5051 holds another distinction: it is only the second known long-period radio transient to emit regular X-rays, and the first where the cause of that regularity has been confirmed. For astronomers, that confirmation matters enormously. The discovery strengthens what researchers call the "alternative explanation"—that at least some of these mysterious cosmic pulses originate not from exotic neutron stars, but from binary systems where white dwarfs actively feed on their companions. As Professor Murphy, Head of School at the University of Sydney School of Physics, noted, previous systems had hinted at this connection, but "this is the first one where we can clearly see both stars and the accretion process in action."
The implications ripple outward. By providing the first confirmed window into how these rare systems work, ASKAP J1745−5051 now serves as a reference point for understanding other long-period radio transients that may emerge from future surveys. For astronomers who have spent years chasing cosmic ghosts, Rose's discovery is a breakthrough that transforms puzzlement into understanding—and opens a pathway to many more answers ahead.