Astronomers Pin Mysterious Repeating Radio Bursts to Accreting White Dwarf Binary

Astronomers have identified the origin of one of the most puzzling signal classes in modern radio astronomy, providing the first confirmed source for what researchers call long-period radio transients -- repeating bursts of radio waves that pulse on timescales of minutes to hours, far slower than any known pulsar.

The findings, published June 2 in Nature Astronomy, center on a source designated ASKAP J1745-5051. <cite index="25-1">The breakthrough began when researchers led by graduate student Kovi Rose at the University of Sydney used the Australian Square Kilometre Array Pathfinder (ASKAP) radio telescope to detect powerful bursts of radio waves repeating every 1.4 hours.</cite> <cite index="25-2">Observations with multiple telescopes suggested the signals were coming from a binary star system containing a white dwarf, a dense stellar remnant roughly the size of Earth but with a mass comparable to the Sun, and a low-mass red dwarf companion.</cite>

<cite index="21-7">"For the first time we have pinpointed the origin of these signals, confirming the source to be a 'cataclysmic variable', or an accreting white dwarf star," said Rose.</cite> The classification matters because the field has been genuinely stuck: <cite index="23-6">to date, astronomers have only found a dozen of these sources, and researchers are still trying to understand exactly what they are.</cite>

What makes ASKAP J1745-5051 unusually tractable as a case study is the multi-wavelength coverage the team assembled. <cite index="23-1">For the first time, researchers combined observations from radio, X-ray and optical telescopes to find that ASKAP J1745 produces both X-ray and radio bursts with each orbit of its two stars.</cite> <cite index="20-4,20-5">The international team included astronomers from the United States, China, Canada, Spain, Israel and Australia, using CSIRO's ASKAP and the Australia Telescope Compact Array, the MeerKAT radio telescope in South Africa, the SOAR and Magellan optical telescopes in Chile, and the space-based Swift and Einstein Probe X-ray observatories.</cite>

The physics being invoked is relatively well-understood in other contexts. <cite index="23-12">In these rapidly orbiting systems, the X-ray light is thought to come from the material heating up as it streams onto the white dwarf.</cite> <cite index="23-15">The type of pulsed radio light detected is typically caused by energetic particles interacting with strong magnetic fields.</cite> The team's interpretation, then, is that accretion -- the gravitational siphoning of gas from the red dwarf onto its compact companion -- is the engine driving both emission channels simultaneously.

The name "Rosetta stone" the authors attach to this system is doing real scientific work, not just rhetorical work. <cite index="21-11">The researchers say that ASKAP J1745-5051 could act as a reference point for understanding other long-period radio transients</cite> -- specifically, it may help distinguish which of the remaining dozen sources are more like pulsars (neutron stars) and which are more like white dwarf binaries. Those two physical regimes produce similar-looking light curves but imply very different population statistics and emission mechanisms.

Caveats are worth naming here. The sample is small by any standard. <cite index="26-3">The team cannot rule out that ASKAP J1745, which remains hard to pin down, is unique when it comes to these transient signals.</cite> One confirmed source does not constitute a solved taxonomy. The ASKAP survey that turned up this object is still running, and what it finds next will matter considerably for whether this binary-accretion model generalizes or turns out to describe a rare edge case.

The paper is also notable as a demonstration of what wide-field radio surveys can now do. <cite index="21-9,21-10">ASKAP is owned and operated by CSIRO, Australia's national science agency, and its mix of coverage, resolution, and sensitivity is allowing unusual signals to be detected that would otherwise be missed.</cite> Long-period transients were themselves discovered by chance when astronomers were scanning large portions of the sky for other targets -- a recurring pattern in radio astronomy where the most interesting objects are not the ones you went looking for.

Rose and colleagues say the next step is catching more signals across multiple wavelengths before they fade. The window for X-ray follow-up tends to be narrow, which is part of why the full multi-wavelength picture proved so difficult to assemble for the other eleven known sources in this class.

Sources cited:
- Nature Astronomy (via phys.org) (https://phys.org/news/2026-05-student-astronomer-rosetta-stone-mysterious.html)
- CSIRO News Release (https://www.csiro.au/en/news/All/News/2026/June/Student-astronomer-discovers-mysterious-cosmic-signals)
- The Conversation (Kovi Rose) (https://theconversation.com/mysterious-signals-keep-coming-from-space-we-have-found-their-rosetta-stone-281753)
- UNC-Chapel Hill News (https://uncnews.unc.edu/2026/06/02/unc-chapel-hill-astronomers-help-crack-cosmic-radio-mystery/)
- ScienceDaily (https://www.sciencedaily.com/releases/2026/06/260602021631.htm)