An exoplanet is generating radio waves from its red dwarf sun

Space 17 February 2020
Red dwarf and planet
An artist’s impressions shows how the exoplanet acts as an electric dynamo

Danielle Futselaar

Radio waves blasting out of a red dwarf star have an unusual source – an orbiting planet.

Astronomers using the Low Frequency Array radio telescope in the Netherlands have discovered that red dwarf star GJ1151 is emitting fluctuating radio signals that are consistent with the star possessing a roughly Earth-sized planet completing a full orbit every few days.

A planet orbiting at this distance would probably be in a star’s habitable zone, the region in which temperatures allow for liquid water to flow on the planet’s surface.


However, the star is generating radio waves because the orbiting planet acts like an electric dynamo. The strength of the waves shows that substantial electrical power is flowing between the star and the planet, which will provide additional heat to the planet’s atmosphere. It could even be boiling the atmosphere away into space, rendering the world uninhabitable.

Harish Vedantham at the Netherlands Institute for Radio Astronomy, who led the work, says there is considerable uncertainty about the size and mass of the planet, so it is hard to say what is happening with the atmosphere. But he thinks this could be a promising method for exoplanet detection in the future.

“This is the first baby step. We now know this path exists and we know how to walk it,” says Vedantham.

The next step is to attempt to detect the planet through its gravitational pull on the star, which would cause it to wiggle slightly. This would provide better estimates of the planet’s mass and orbit, and let the researchers figure out the condition of its atmosphere.

The team is also looking at radio data for other stars to look for other planets. Other detection methods have found numerous planets around red dwarfs, and the stars generally have strong magnetic fields.

Hannah Wakeford, an exoplanet scientist at the University of Bristol, UK, says the new work could be important. “This is a fascinating study and has profound implications in our understanding of exoplanets, if corroborated,” she says.

Journal reference: Nature Astronomy, DOI: 10.1038/s41550-020-1011-9

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