Astronomers detect radio signals coming from an exoplanet for the first time - Astronomy & Space - Astronomy - Planetary Sciences

Radio detections of β Pic b in four observing sessions and at two frequency bands. Credit: arXiv (2026). DOI: 10.48550/arxiv.2609.16720

Exoplanets are exotic worlds orbiting distant stars far beyond our solar system. Ever since the first ones were discovered in the 1990s, astronomers have turned their attention to these distant worlds to understand more about them. Now, for the first time, scientists have detected radio signals coming directly from one of these planets, a massive gas giant named β Pictoris b.

Previous radio detections from exoplanetary systems couldn't be traced directly to the planet itself because astronomers couldn't tell whether the signal came from the star or the planet. And no, this isn't evidence of alien life communicating with each other. The radio waves come from auroras linked to the planet's powerful magnetic field.

Auroras can occur when high-energy charged particles travel along a planet's magnetic field lines and interact with its upper atmosphere. On Earth, for example, this produces the northern lights.

A team of scientists led by Kevin Ortiz Ceballos at the Center for Astrophysics | Harvard & Smithsonian used South Africa's MeerKAT radio telescope to study the β Pictoris planetary system, about 64 light-years from Earth.

Finding the source

They picked up faint, repeating bursts of radio signals originating from the β Pictoris system. At first, they didn't know whether the radio waves were coming from the star or one of its planets. To pinpoint the source, the researchers compared their radio images with precise positions of extremely distant background quasars, which acted as fixed markers.

This let them plot the exact positions of both the star and the planet. When they layered their radio images over that map, the radio signal lined up with the position of β Pictoris b rather than its parent star.

"Here, we report the first direct detection of auroral radio emission from an exoplanet, the giant planet β Pictoris b, with the MeerKAT array," wrote the team in their paper posted to the arXiv preprint server.

A window into the planet

The radio signals also revealed something about the planet itself. The researchers calculated that β Pictoris b has a magnetic field strength of at least 1,250 gauss where the radio waves are produced. That is far stronger than Jupiter's magnetic field. "This constitutes the first direct measurement of magnetic field strength for an exoplanet."

In their paper, the authors state that their result matches theoretical predictions for the strength of the magnetic fields generated by young, massive giant planets.

The discovery also gives scientists a new way to directly measure an exoplanet's magnetic field and test theoretical models of planetary interiors.

by Paul Arnold, Phys.org

edited by Lisa Lock, reviewed by Robert Egan 

Source: Astronomers detect radio signals coming from an exoplanet for the first time