Scientists Discover Mysterious Radio Pulses Every Eight Minutes
Astronomers in Australia have traced radio pulses arriving every eight minutes to a white dwarf orbiting a sun-like star 5,000 light-years away. The study in Nature Astronomy is the first to detect such pulses from that kind of pairing, researchers at ICRAR said.
Scientists discover mysterious radio signals arriving every eight minutes from a star system 5,000 light-years from Earth, according to a study published in the journal Nature Astronomy.
The source is a two-star system called GPM J071507−114153. One star is a white dwarf, the dense core left behind when a star dies. The other is a G-type star similar to the sun.
A first for sun-like companions
It is the first time radio pulses have been detected from a white dwarf orbiting a sun-like star. Researchers at the International Centre for Radio Astronomy Research (ICRAR) in Perth, Western Australia, said such pulses are usually seen in systems with smaller, cooler red dwarf stars.
The dead star spins once every eight minutes. The team says the system belongs to a class of objects called long-period transients, which produce radio signals that switch on and off over minutes to hours.
Around a dozen have been detected since the same ICRAR team found the first in 2021. Astronomers are still working to understand them.
Where the pulses come from
Several earlier systems of this kind also contain a white dwarf and a second star. It had remained unclear which of the two produced the radio pulses.
Study lead author Dr Sam McSweeney said this is the first time the pulses are clear enough to see the white dwarf moving in its orbit. "So we know that the pulsations are coming from a region close to the white dwarf, or possibly even from the white dwarf itself," he said.
The team processed more than 100 hours of radio data at the Pawsey Supercomputing Research Centre to validate and understand the white dwarf's motion.
Storms on a distant star
Associate Professor Natasha Hurley-Walker, a study co-author, said the white dwarf's pulses let the team detect stellar flares on the sun-like star. These are similar to the flares that create aurorae on Earth.
The researchers also saw the white dwarf pass behind a region with a strong magnetic field. Hurley-Walker said it was most likely a stellar prominence, a large loop of plasma erupting from a star's surface.
"It's amazing that by using radio wavelengths we can detect the storms on a star over 5,000 light-years away," she said.
How it was found
The team spotted the system in a large survey using the Murchison Widefield Array, which scans the entire Milky Way visible from Australia. They then used the MeerKAT radio telescope in South Africa to pin down its precise position.
The W.M. Keck Observatory in Hawaiʻi then confirmed the link to a G-type star through optical observations.
McSweeney said that if precursor telescopes are already making such discoveries, astronomers can expect many more star systems once the SKAO telescopes are completely built. "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," he said.
