Updated

Updated · WIRED · Jun 22

Sydney Team Identifies 1.345-Hour White Dwarf Binary as Source of Repeating Radio Bursts

Updated

Updated · WIRED · Jun 22

Sydney Team Identifies 1.345-Hour White Dwarf Binary as Source of Repeating Radio Bursts

Q: Why does this newfound stellar duo 'pulse' in hours, when typical pulsars flash every second?

It pulses in hours because the signal is tied to the **binary orbit**, not to the rapid spin of a neutron star. Typical pulsars are neutron stars whose lighthouse-like radio beams sweep past Earth as the star rotates. Because neutron stars are tiny, dense, and can spin extremely fast, their pulses usually arrive every milliseconds to seconds. ASKAP J1745-5051 is different. The new observations show it is a **magnetic cataclysmic variable**: a white dwarf pulling gas from a nearby red dwarf companion. Spectroscopy found hydrogen and helium emission lines from accretion, and radial-velocity measurements gave an orbital period of about **1.368 hours**, closely matching the **1.345-hour** radio repetition period. That near-match is the key evidence that the “pulse” clock is the stars’ orbital motion. The radio bursts appear to come from the region where the two stars’ **magnetic fields interact**, while the infalling gas produces the X-rays. Einstein Probe data also found X-ray variability near **1.32 hours**, reinforcing that the system’s regularity is linked to the orbit. So the object is not behaving like a standard pulsar at all. Its hours-long rhythm reflects the much slower timescale of two stars circling each other and repeatedly setting up the right magnetic geometry for a burst. That is why astronomers classify it as a **long-period radio transient** rather than an ordinary pulsar.

3 articles · Updated · WIRED · Jun 22

ASKAP J1745-5051 produced radio pulses every 1.345 hours, and researchers matched that cycle to a binary orbit of about 1.368 hours—pinpointing one long-period radio transient to a white dwarf accreting from a companion.
Spectroscopy found hydrogen and helium emission lines, including strong HeII, showing active accretion in a magnetic cataclysmic variable rather than a slowly rotating magnetar.
The companion appears to be an M6 red dwarf with about 0.096 solar masses and 0.13 solar radii, orbiting the white dwarf at extremely close range in just over an hour.
Einstein Probe data showed x-rays varying on a roughly 1.32-hour period, while radio and x-ray peaks did not align, indicating the two signals arise from different regions of the system.
Only about a dozen LPTs are known in the Milky Way, and the team says this is the clearest case yet linking one to a white dwarf binary, offering a template for sorting other transients between white-dwarf and neutron-star origins.

Sources

WIRED4h ago

University of Sydney Team Identifies White Dwarf Binary as Source of Mysterious Repeating Radio Signals

Yahoo! Voices4h ago

Scientists decode strange, repeating radio signal from space

spacedaily.com4h ago

In 2026, Kovi Rose traced a 1.3-hour radio pulse and matching X-ray flicker to ASKAP J1745-5051, a white-dwarf system so tight that the orbit itself appears to become the clock

Is a Jupiter-like magnetic interaction the real source of mysterious, long-period cosmic radio signals?

Why does this newfound stellar duo 'pulse' in hours, when typical pulsars flash every second?

Will this stellar 'Rosetta Stone' prove most cosmic flashes come from white dwarfs, not neutron stars?

Pinpointing ASKAP J1745−5051: The Breakthrough Discovery of a Long-Period Radio Transient Source

Overview

In June 2026, researchers made a breakthrough by identifying ASKAP J1745−5051 as the first confirmed source of Long-Period Radio Transients (LPTs), marking a pivotal moment in understanding mysterious, repeating cosmic bursts. This discovery was achieved through an extensive international collaboration, where pooling expertise and resources enabled a comprehensive approach to data collection and analysis. Pinpointing this source now offers scientists an unprecedented opportunity to study the origins and mechanisms of LPTs, opening the door to new insights into fundamental physics and the life cycles of exotic celestial objects.

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