Astronomers have traced a mysterious radio signal repeating approximately every eight minutes to an unusual binary star system containing a white dwarf and a Sun-like star. The discovery, published in Nature Astronomy on November 12, 2026, marks the first time researchers have identified this type of repeating radio emission from a white dwarf orbiting a G-type star.
The system, designated GPM J071507−114153, is located more than 5,000 light-years from Earth. Its discovery provides new evidence about a rare category of astronomical objects known as long-period transients, which produce repeating radio signals over intervals ranging from minutes to hours. The observations also allowed scientists to detect stellar activity on the Sun-like companion, offering a new way to study distant stars.
A Mysterious Radio Signal Repeats Every 7.9 Minutes
The radio pulses were detected using the Murchison Widefield Array (MWA), a radio telescope located in Western Australia. Researchers identified the source during observations beginning in late 2024.
Between December 2024 and September 2025, the telescope recorded 214 pulses from the object. The signals repeated approximately every 7.9 minutes, making the system an example of a long-period transient.
Long-period transients are unusual astronomical sources that switch their radio emissions on and off over relatively long intervals. Unlike conventional pulsars, which are rapidly rotating neutron stars that can emit pulses many times per second, these objects have much longer repeating periods.
Astronomers have identified only around a dozen long-period transients since the first discovery in 2021. Their origins and physical mechanisms remain an active area of research.
The newly identified system is particularly important because it provides clearer evidence about which star in a binary system is producing the radio emission.
What Is GPM J071507−114153?
The newly studied system contains two stars orbiting each other:
- A white dwarf: A dense stellar remnant left behind after a star similar to the Sun exhausts its nuclear fuel and sheds its outer layers.
- A G-type star: A star broadly similar to the Sun in temperature and spectral classification.
White dwarfs are extremely compact objects. Although they no longer generate energy through the same nuclear fusion processes as ordinary stars, they can retain strong magnetic fields and exhibit complex interactions with nearby stellar companions.
Previously discovered long-period transients containing white dwarfs were commonly associated with smaller, cooler red dwarf stars. The new system demonstrates that a white dwarf can also produce these signals while orbiting a Sun-like companion.
The research therefore expands the range of known stellar environments associated with long-period radio emissions.
Scientists Identify the White Dwarf as the Likely Source
One of the biggest challenges in studying binary star systems is determining which object is responsible for a particular signal.
In earlier long-period transient discoveries, astronomers often found two stars in a system but could not confidently establish which one generated the radio pulses.
The observations of GPM J071507−114153 provided a breakthrough.
Researchers processed more than 100 hours of radio data at the Pawsey Supercomputing Research Centre to study the timing and movement of the signal. They found that the radio pulses changed in a way that revealed the white dwarf’s movement around its companion.
This orbital motion allowed the team to associate the radio emission with a region close to the white dwarf, or potentially the white dwarf itself.
Lead researcher Sam McSweeney, an astronomer at the International Centre for Radio Astronomy Research (ICRAR), said the pulses were sufficiently clear to track the white dwarf moving through its orbit.
The study also found that the radio pulses are modulated by a longer period of approximately 1.3 days, which researchers interpret as the orbital period of the binary system.
Radio Pulses Reveal Storms on a Sun-Like Star
The discovery offered another important scientific result: astronomers were able to observe activity on the system’s Sun-like companion using radio signals produced near the white dwarf.
As the radio pulses travelled through the environment surrounding the companion star, their properties changed. Researchers identified variations consistent with the presence of a stellar corona, the hot outer atmosphere surrounding the star.
The team also detected evidence of stellar flares. These powerful bursts of energy are comparable in broad terms to solar flares produced by the Sun.
Researchers additionally observed the white dwarf passing behind a region with a strong magnetic field, which they believe was most likely a stellar prominence.
A stellar prominence is a large loop of plasma extending outward from a star’s surface, shaped and influenced by magnetic fields. Similar structures occur on the Sun and can sometimes be observed during solar activity.
Associate Professor Natasha Hurley-Walker of ICRAR said the radio pulses allowed the researchers to detect stellar storms from more than 5,000 light-years away.
The findings demonstrate how radio astronomy can reveal activity that might otherwise be difficult to observe using conventional optical telescopes.
How Astronomers Located the Rare Binary System
The research combined observations from several major astronomical facilities.
| Observatory or facility | Role in the discovery |
|---|---|
| Murchison Widefield Array | Detected the repeating radio signals |
| MeerKAT radio telescope | Helped determine the source’s precise position and study its radio properties |
| W.M. Keck Observatory | Confirmed the association with a G-type star through optical observations |
| Pawsey Supercomputing Research Centre | Processed more than 100 hours of radio data |
The MWA scans large portions of the Milky Way visible from Australia, making it useful for discovering unusual and previously unknown radio sources.
MeerKAT, located in South Africa, provided additional observations that helped researchers investigate the signal’s characteristics. Optical observations from the Keck Observatory in Hawaii then confirmed the presence of the Sun-like companion.
Combining radio and optical observations was essential to identifying the nature of the system.
Why This Discovery Matters for Astronomy
The discovery helps astronomers understand the relationship between white dwarfs, magnetic fields and long-period radio emissions.
The researchers believe that interactions between a white dwarf and its companion star play an important role in producing the coherent radio pulses. The companion’s magnetic environment may influence how the emission travels through the system and how its properties change over time.
The study also suggests that long-period transients could provide a new way to identify white dwarfs that are difficult to detect through conventional observations.
If similar systems are discovered in larger numbers, astronomers may be able to investigate how frequently white dwarfs form close binary relationships with different types of stars.
The research was published in Nature Astronomy under the title “A long-period transient with a Sun-like companion.”
The Bigger Picture
The discovery highlights the growing importance of radio astronomy in understanding objects that are difficult to study through visible light alone. Radio signals can reveal magnetic activity, stellar interactions and orbital movements across enormous distances.
It also provides another reason for astronomers to investigate long-period transients. With only around a dozen known examples, every new detection can offer important clues about how these unusual systems work.
Looking Ahead
Future observations will help researchers determine exactly how the white dwarf produces its radio pulses and how its magnetic interaction with the Sun-like companion influences the emissions. Astronomers will also look for similar systems to establish whether this type of binary configuration is more common than currently understood.
The discovery could become particularly valuable as the Square Kilometre Array Observatory develops its next-generation radio telescopes in Australia and South Africa. Their greater observational capabilities are expected to help scientists detect more long-period transients and study their signals in much greater detail.
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