White dwarf and Sun-like star emit radio pulses every 7.9 minutes

Astronomers have connected a repeating radio signal to a binary system containing a white dwarf and a star similar to the Sun, according to research published in Nature Astronomy.

The discovery

The signal, identified as GPM J071507−114153, produces short flashes of radio waves every 7.9 minutes, according to The Conversation. The flashes were first spotted in late 2024 using the Murchison Widefield Array radio telescope in Western Australia.

The MeerKAT telescope in South Africa pinpointed the source to a tiny patch of sky containing a single faint star. Researchers then used the Keck telescope in Hawai’i to record the star’s spectrum.

The spectrum showed a G-type star almost the same mass and temperature as the Sun, rather than the small, cool red dwarf seen in other long-period radio transient systems.

What the timing shows

The pulses only appear during a window of about six hours, followed by 26 hours without pulses. The Conversation reports that the most natural explanation is a binary system with two stars orbiting each other once every 32 hours, with the radio pulses visible only when they are lined up in the right way.

As the pulsing object swings around its orbit, the pulses arrive up to four seconds earlier or later than expected, because the radio waves have further to travel at some points than others. That measurement tells researchers how large the orbit is.

The Sun-like star barely wobbles as the pulsing object orbits around it, meaning the Sun-like star must be much heavier than its partner. Combining the orbit size, the 32-hour orbital period, and the spectrum measurements, researchers calculated that the pulsing object is about two-thirds as heavy as the Sun. That means it is too light to be a neutron star.

Researchers believe the pulsing object is a white dwarf pulsar, the first found in orbit around a Sun-like star.

Why it matters

Long-period radio transients are objects that emit bright flashes of radio waves every few minutes to every few hours. Some have previously been traced to binary systems of a white dwarf and a red dwarf. This discovery marks the first time radio pulses have been detected from a white dwarf orbiting a Sun-like star.

The researchers think systems like this are probably common, but white dwarfs next to bright stars are very hard to see because the glare of the bright star hides the faint white dwarf. Radio pulses cut through the glare, so radio surveys could uncover a population that optical and X-ray telescopes miss.

Some white dwarf binaries are thought to be the ancestors of Type Ia supernovae, which astronomers use as “standard candles” to measure interstellar distances and the expansion of the universe. Finding these systems could reveal more about this process.

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Sources

• theconversation.com: A dead star is flashing radio waves every 8 minutes, and its partner looks a lot like the Sun
• discovermagazine.com: Rare Star Duo Flashes Radio Waves Every Eight Minutes, Shedding Light on Bright Space Phenomenon | Discover Magazine
• natureworldnews.com: White Dwarf in Sun-Like Star System Sends Radio Pulses Every 7.9 Minutes

This article was drafted with AI assistance and checked against the sources above. Company claims are reported as claims. Cover image is AI-generated.