A Dead Star Flashes Every 8 Minutes — and Its Partner Is Nearly the Sun

The MeerKAT telescope in South Africa pinpointed the source to a tiny patch of sky containing a single faint star. The team then turned to the Keck telescope in Hawaii to record the star's spectrum — the "fingerprint" of its light, which reveals its physical properties. The result surprised them. This was no tiny red dwarf. It was a G-type star, almost the same mass and temperature as the sun.

How do you weigh a star you cannot see?

The astronomers needed to rule out a neutron star after all. The clue was in the timing. As the pulsing object swings around its orbit, the pulses arrive up to 4 seconds earlier or later than expected, because the radio waves travel farther at some points in the orbit than at others. That timing reveals the orbit's size.

The spectrum of the sunlike star shows it barely wobbles as its partner circles it, which means the sunlike star must be far heavier than its companion. Combining the orbit's size, the 32-hour orbital period and the spectral measurements, the team calculated that the pulsing object weighs about two-thirds of the sun's mass.

That is too light to be a neutron star. The team concludes the object is a white dwarf pulsar — the first ever found in orbit around a sunlike star.

How did this odd couple form?

The researchers reconstruct a violent history. The star that became the white dwarf must first have swelled into a giant, engulfing its companion. The companion then spiraled inward, shrinking the orbit, before the giant's outer layers were ejected and the exposed core cooled into a white dwarf.

Systems like this are probably common across the universe, the team believes, but white dwarfs beside bright stars are extremely hard to see. The bright star's glare hides the faint remnant, like a match beside a floodlight. Radio pulses cut through that glare. If more long-period transients turn out to conceal white dwarfs around bright stars, radio surveys could expose an entire population that optical and X-ray telescopes miss.

Why does it matter?

The stakes reach beyond stellar oddities. Some white dwarf binaries are thought to be the ancestors of Type Ia supernovae — exploding stars that astronomers use as "standard candles," reference points for measuring interstellar distances and the expansion of the universe. Finding more of these systems could clarify how those explosions arise.

With next-generation radio telescopes such as the SKA Observatory, the team expects many more discoveries. If such objects turn up around many different types of stars, they will offer new insight into the lives and deaths of stars like our own sun, across the galaxy and beyond.

The findings come with the usual cautions. The sample of identified long-period transients remains small — only a handful have traced sources — and the evolutionary scenario, while consistent with the data, is a reconstruction rather than an observed sequence. Still, one system has already overturned an emerging rule. The dark, as the researchers note, may be hiding stranger things.

Publication details: Samuel J. McSweeney et al., "A long-period transient with a Sun-like companion," Nature Astronomy (2026). DOI: 10.1038/s41550-026-03016-z.