Astronomers discover star system emitting radio signals every eight minutes

Astronomers in Australia have discovered an unusual star system that emits radio signals every eight minutes, located 5,000 light-years from Earth.

The discovery

The system, known as GPM J071507−114153, consists of two stars orbiting each other: a white dwarf and a G-type star similar to the sun. A white dwarf is the dense core left behind when a star dies.

It is the first time radio pulses have been detected from a white dwarf orbiting a sun-like star, according to a study published in the journal Nature Astronomy.

What the researchers found

Researchers at the International Centre for Radio Astronomy Research (ICRAR) in Perth, Western Australia, said such pulses are usually observed in systems with smaller and cooler red dwarf stars, meaning the discovery breaks new ground.

Dr Sam McSweeney, the study’s lead author, said: “This is the first time the pulses are clear enough to see the white dwarf moving in its orbit around its companion, so we know that the pulsations are coming from a region close to the white dwarf, or possibly even from the white dwarf itself.”

The team processed more than 100 hours of radio data at the Pawsey Supercomputing Research Centre to validate and understand the white dwarf motion.

How it was detected

The system was detected in a large survey using the Murchison Widefield Array to scan the entire Milky Way visible from Australia. Researchers then used the MeerKAT radio telescope in South Africa to determine its precise position. The W.M. Keck Observatory in Hawaiʻi confirmed its association with a G-type star through optical observations.

Study co-author Associate Professor Natasha Hurley-Walker said the pulses allowed the team to detect stellar flares on the sun-like star, similar to those that create aurorae on Earth. She added: “As a bonus, we also saw the white dwarf moving behind a region with a strong magnetic field, most likely a ‘stellar prominence’ – which is a large loop of plasma erupting from a star’s surface.”

Why it matters

These types of stellar pairs belong to a broader class of objects known as long-period transients (LPTs), producing radio signals that switch on and off over intervals ranging from minutes to hours. Around a dozen have been detected since the first was discovered by the same ICRAR team in 2021, and astronomers are still working to understand them.

Dr McSweeney said: “If we are already making such discoveries with precursor telescopes, just imagine how many more star systems we will be able to find, and what a beautifully detailed view of their signals we will have, once the SKAO telescopes are completely built.”

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Sources

• nypost.com: Star system that emits radio signals every eight minutes discovered in deep space
• eurekalert.org: Researchers discover rare star system that emits radio signals every eight minutes | EurekAlert!

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