Astronomers may have detected the first radio signal from an exoplanet

In our never-ending quest to understand the universe and our place in it, precious little mistakes in data can indicate entirely new worlds.

Decreases in a star’s light levels may reveal the presence of planets in orbit – and now astronomers have taken the first steps to use radio peeps to unveil new exoplanetary mysteries.

“Observing planetary auroral radio waves is the most promising method for detecting exoplanetary magnetic fields,” said Cornell University astronomer Jake Turner and colleagues in their new paper, “the knowledge of which will provide valuable insights into the planet’s internal structure. the atmospheric escape and habitability. “

When stellar winds – charged particles streaming from the host star – hit a planet’s magnetic field, the change in speed can be detected as striking variations in radio emissions, statistically described as ‘bursty’.

Earth’s own magnetic field vibrates and squeaks like alien birds as it channels solar winds. We have also heard similar cries from other planets in our solar system.

To detect a whisper of such radio signals from an exoplanet, we naturally first need a way to see beyond all the sound from Earth and elsewhere.

A few years ago, the team developed the BOREALIS pipeline program to do just that. They tested it on Jupiter and then calculated what Jupiter’s radio emissions would look like if it were much further away.

There have been some preliminary detections of new planets using these radio emissions, including early this year when astronomers linked radio wave activity to interactions between the magnetic field of star GJ 1151 and a potential planet the size of Earth. But all of these have yet to be confirmed by follow-up radio observations.

So Turner’s team decided to test the technique they developed using the Low Frequency Array Radio Telescope (LOFAR) of the Netherlands to look at three systems with known exoplanets: 55 Cancri, Upsilon Andromedae and Tau Boötis.

Only the Tau Boötis system, 51 light-years away, showed the beeps in radio data that matched the researchers’ predictions based on their tests of Jupiter. It came in the form of 14-21 MHz burst emissions and falls within roughly three standard deviations of certainty (3.2 sigma).

In 1996, a hot Jupiter exoplanet orbiting 3.3128 days around the scorching young F-type star and the smaller red dwarf that make up the Tau Boötis binary system was discovered.

“We advocate an emission from the planet itself,” said Turner. “Given the strength and polarization of the planet’s radio signal and magnetic field, it is compatible with theoretical predictions.”

If their measurements are correct, they suggest that the planet’s magnetic field strength ranges from about 5 to 11 gauss (Jupiter ranges from 4 to 13 gauss, for comparison, and magnetic field measurements have shown that the planet has a core of metallic hydrogen). has) . The observed emission strength of the magnetic field is also consistent with previous predictions.

“The magnetic field of Earth-like exoplanets may contribute to their possible habitability,” explains Turner, “by shielding their own atmosphere from solar wind and cosmic rays, and protecting the planet from atmospheric loss.”

The signal they detected is weak and has yet to be verified by other low-frequency telescopes before researchers can confirm the true origin of the detected radio emissions.

“We cannot rule out stellar flares as the source of the emissions,” the researchers warned, but emissions from the planet remain a possibility.

If other telescopes such as LOFAR-LBA and NenuFAR can confirm these findings, such radio-emission detections from exoplanets will open an exciting new area of ​​research, giving us a potential way to see further into distant, alien worlds.

This research is published in Astronomy and Astrophysics.