Astronomers Detect First Radio Signal From Exoplanet

Astronomers detect the first radio signal from an exoplanet, Beta Pictoris b, revealing a magnetic field 200 times stronger than Jupiter's.

Astronomers say they have directly detected the first-ever radio emission from a planet outside the solar system, tracing repeating bursts to the gas giant Beta Pictoris b, 63 light-years from Earth. The signal is not evidence of intelligent life but of a colossal magnetic field producing auroras similar to Earth's northern lights. "I know radio signals are associated with searches for extraterrestrial intelligence," said Harvard astronomy professor Edo Berger, a coauthor. "But this is something very different." The finding, posted September 15 to ArXiv, still awaits peer review.

Earlier hints of radio emissions from exoplanets were never confirmed because the host star could not be ruled out as the source. According to the CNN report, Joseph Callingham of the University of Amsterdam, who was not involved, noted the team uniquely localized the emission to the planet itself, separate from the star. The surprise also defied expectations: astronomers had assumed exoplanet magnetic fields would resemble Jupiter's, producing emissions at lower frequencies. Berger called the result a matter of "going against the perceived wisdom in the field."

The team used MeerKAT, an array of 64 radio telescope dishes in South Africa, during what Berger described as a "fishing expedition." Lead author Kevin Ortiz Ceballos, a doctoral researcher at the Center for Astrophysics | Harvard & Smithsonian, brought the detection to Berger saying, "I don't think you're going to believe this." Berger said the signal was recorded multiple times at multiple frequencies and "it's there every single time." Both CNN and LatestLY report the magnetic field is at least 200 times stronger than Jupiter's.

Not all planets have a magnetic field; those that do benefit from a natural shield deflecting disruptive energy. Earth's field protects its atmosphere from being stripped away by solar wind. The detected emission, known as auroral radio emission, has previously been seen from Jupiter, Saturn, the sun, stars and brown dwarfs. Jonathan Nichols of the University of Leicester said such emissions allow scientists to infer planet properties that cannot otherwise be measured and to test solar-system theories in more extreme conditions.

If confirmed under peer review — expected to complete over the next few months — the result would show exoplanets can have far stronger magnetic fields than expected, a crucial learning Callingham highlighted. The Beta Pictoris system is astronomically young at about 23 million years old, and Beta Pictoris b, discovered in 2008, orbits alongside planets c and d. The authors have requested more telescope time to probe why the field is so strong. "I think that's going to be a question that occupies people for a while," Berger said.