Rare star pair found pulsing radio signals every 8 minutes

Astronomers have identified an unusual pair of stars that sends out a radio pulse every eight minutes. The system, found by a team at the Curtin University node of ICRAR, consists of a white dwarf — the dense core left behind when a star dies — and a G-type star similar to our Sun. According to the report, it has been catalogued as GPM J071507−114153.

The pulses belong to a class of objects called long-period transients (LPTs), which switch radio signals on and off over intervals ranging from minutes to hours. Around a dozen have been detected since the first was found by the same ICRAR team in 2021. Earlier LPT systems also contained white dwarfs, but it was unclear which of the two stars was producing the radio emission. According to the paper, this time the pulses were clear enough to see the white dwarf moving in its orbit, so the emission comes from a region close to the white dwarf, or possibly from the star itself.

Lead author Sam McSweeney said the team processed more than 100 hours of radio data at the Pawsey Supercomputing Research Centre to confirm the motion. Co-author Natasha Hurley-Walker said the white dwarf's pulses also revealed stellar flares and a large loop of plasma on the Sun-like companion — the kind of activity that creates aurorae on Earth. According to the report, this shows radio wavelengths can reveal storms on a star over 5,000 light-years away.

The system was picked up in a survey with the MWA in Western Australia and pinpointed with South Africa's MeerKAT telescope, while the W.M. Keck Observatory in Hawaii confirmed the link to a G-type star through optical observations. Both telescopes are precursors to the upcoming SKA telescopes. According to McSweeney, if precursor instruments are already producing such finds, the completed SKA should reveal many more systems with far more detailed signals. The study was published in Nature Astronomy.