White dwarf pulsar flashes radio waves every 8 minutes with sun-like partner

Astronomers have uncovered a rare cosmic system featuring a dead star that emits regular flashes of radio waves every eight minutes, partnered with a companion star that closely resembles our own Sun. Researchers examining long-period radio transients have identified this unusual binary setup, which challenges previous assumptions about how these intermittent cosmic broadcasters operate. The findings shed new light on stellar evolution and offer fresh methods for detecting hidden objects in the galaxy.

The discovery began when investigators utilized the Murchison Widefield Array radio telescope in Western Australia to scan for new signals. Using a search methodology developed by PhD student Csanád Horváth, the team detected radio pulses arriving with clockwork precision every 7.9 minutes. After periods of silence, further observation revealed that the pulses follow a distinct rhythm, appearing during a six-hour window before vanishing for 26 hours. This behavior pointed toward a binary system with a 32-hour orbital period, visible only when properly aligned.

To pinpoint the exact origin, the MeerKAT telescope in South Africa isolated a tiny patch of sky containing a single faint star. Subsequent observations using the Keck telescope in Hawai’i captured the star’s light spectrum, delivering an unexpected result. Rather than finding a typical cool red dwarf, scientists discovered a G-type star matching the mass and temperature of our solar system’s central star.

Understanding the White Dwarf Binary System

Analyzing the timing of the radio pulses provided critical clues about the system's mechanics. As the pulsing object travels along its orbit, the signals arrive slightly early or late depending on its position, revealing the scale of the orbit. Furthermore, the spectrum of the sun-like companion indicates it experiences virtually no wobble, proving that it outweighs its pulsing partner. Calculations reveal that the pulsing object weighs roughly two-thirds the mass of the Sun, making it too light to be a neutron star and confirming it as a white dwarf pulsar.

This pairing likely formed when the progenitor of the white dwarf expanded into a giant star, engulfing its companion before shedding its outer layers into space. Because the blinding glare of bright stars typically conceals faint white dwarfs from optical and X-ray instruments, radio surveys offer a powerful alternative for uncovering hidden stellar populations. Researchers anticipate that future instruments, such as the SKA Observatory, will locate many more of these systems, deepening our understanding of stellar lifecycles across the universe.