Astronomers traced radio flashes repeating every 7.9 minutes to a white dwarf orbiting a star much like the Sun, identifying the first known long-period radio transient in such a pair.
The system, called GPM J071507−114153, lies more than 5,000 light-years away. It belongs to a rare class of cosmic sources that switch radio signals on and off over periods ranging from minutes to hours. The discovery was reported in Nature Astronomy.
It adds a new kind of companion star to a group of systems that has often included white dwarfs paired with smaller, cooler red dwarfs. The team first spotted the brief pulses in late 2024 with the Murchison Widefield Array in Western Australia. They then used South Africa’s MeerKAT telescope to pinpoint the source.
Researchers found that the bursts appeared during a roughly six-hour window, followed by about 26 hours of silence. This pattern is consistent with the stars orbiting each other about every 32 hours. By tracking changes in when the pulses arrived, the team could follow the white dwarf’s motion.
The team concluded that the radio emission comes from near the white dwarf, or possibly from the white dwarf itself. The pulses also helped reveal magnetic activity around the Sun-like companion, including a likely loop of plasma. What powers these unusual radio sources remains unsettled.
Astronomers say more observations will be needed to determine whether this system explains other long-period transients.