A Radio Source Pulses Every 7.9 Minutes, and Its Companion Looks Like the Sun

Astronomers have identified a radio source that pulses every 7.9 minutes as a low-mass white dwarf, the burned-out core of a star, paired with a star much like the Sun. A team led by Samuel J. McSweeney of the International Centre for Radio Astronomy Research at Curtin University reports the system in Nature Astronomy.

The paper was published Nov. 12, 2026. Its authors conclude that the pulsed radio emission in such a pair depends on the white dwarf's interaction with its companion rather than on the white dwarf alone, and that the companion can be a G-type star like the Sun in an orbit lasting about a day.

Long-period transients are an emerging class of repeating radio sources with periods of minutes to hours. Optical follow-up has confirmed at least four of 12 of them as a white dwarf paired with an M dwarf, a small and cool star. The new source, designated GPM J071507-114153, also varies on a much longer cycle of about 1.3 days, which the authors read as the pair's orbital period.

Timing of the radio pulses constrains the orbit and suggests the G-type star does not fill its Roche lobe, meaning it is not swollen enough to spill gas onto the white dwarf. The twist the radio waves pick up on their way to Earth also changes quickly when the white dwarf is on the far side of its companion, consistent with the waves crossing the companion's corona, the hot gas of its outer atmosphere.

The paper records that the pulses were found in a survey of the Galactic plane, then followed up with the Murchison Widefield Array in Western Australia and with MeerKAT, run by the South African Radio Astronomy Observatory. The companion was identified from a spectrum taken at the Keck Observatory on Maunakea. Measurements of every detected pulse are posted on Zenodo, and the processing code is on GitHub.