Astronomers have identified the first long-period radio transient driven by a white dwarf orbiting a Sun-like star, solving a mystery that began in 2022.
Later observations with the Murchison Widefield Array detected clock-work flashes every 7.9 minutes, appearing for about six hours before a 26-hour silence, a pattern that repeats every 32 hours.
Follow-up with MeerKAT and Keck telescopes showed the source is a tiny faint star surrounded by a G-type star nearly identical to our Sun, and spectroscopic analysis revealed the compact pulsar is about two-thirds the Sun's mass-far too light for a neutron star.
The researchers conclude the system is a white dwarf pulsar, the first found in orbit around a Sun-like star, and propose a formation scenario where the white dwarf's progenitor engulfed its companion, shrinking the orbit before shedding its outer layers.
Such binaries are thought to be precursors to Type Ia supernovae, and future radio surveys with telescopes like the SKA Observatory are expected to uncover many more hidden white dwarfs around bright stars.