Researchers discover rare star system that emits radio signals every 8 minutes

Astronomers have identified GPM J071507−114153, a rare binary star system whose radio pulses recur every eight minutes. It contains a rapidly spinning white dwarf - the dense remnant of a dead star - and a G-type companion similar to the Sun. The discovery is significant because radio pulses of this kind, known as long-period transients, have previously been found mainly in systems with small, cool red dwarfs. Although about a dozen such systems have been detected since 2021, their signal-generating stars have often been difficult to identify.

In this system, the pulses are clear enough for researchers to track the white dwarf’s movement in its orbit, showing that the radio emission comes from near the white dwarf or possibly from the star itself. The signals also helped reveal flares on the Sun-like companion and a likely prominence, a large loop of plasma associated with a strong magnetic field. Researchers first detected the system in a survey with the Murchison Widefield Array, pinpointed it with MeerKAT, and confirmed the companion star using optical observations from the Keck Observatory. More than 100 hours of radio data were processed to verify the white dwarf’s motion. The finding advances understanding of long-period transients and demonstrates the capabilities of current telescopes, while pointing to the potential for many more discoveries with the future SKA observatories.