Astronomers first detect a radio signal from an exoplanet

(ORDO NEWS) — In our endless quest for life in the universe and our place in it, precious bursts of radio emission may point to new worlds.

Decreasing the brightness of a star could betray the presence of planets in orbit – and now astronomers have taken the first steps towards using the peaks of radio emission to uncover new planetary mysteries.

“Observing the planet’s aurora is a promising method for detecting exoplanetary magnetic fields,” explained Cornell University astronomer Jake Turner and colleagues in a new paper.

When a stellar wind — charged particles emanating from a star — hits the planet’s magnetic field, the change in speed can be detected as a startling change in radio emission, statistically described as “explosive.”

The Earth’s own magnetic field makes sounds as it collides with the solar wind. We have also heard similar sounds from other planets in our solar system.

Several years ago, scientists developed the BOREALIS program. They tested it on Jupiter and then calculated what the radio emission from Jupiter would look like if it were much further away.

There have already been several preliminary discoveries of new planets using radio emission, including earlier this year, when astronomers linked radio wave activity to interactions between the magnetic field of the star GJ 1151 and a potential planet the size of Earth. But all this has yet to be confirmed by further radio observations.

So Turner’s team decided to test the method they had developed using a low frequency radio telescope (LOFAR) in 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 “peaks” in the radio data that match the predictions made by the researchers in their tests with Jupiter. It manifests itself as 14-21 MHz pulsed emissions and is within approximately three standard deviations of confidence (3.2 sigma).

In 1996, an exoplanet was discovered in 3.3128-day orbit around a scorching young F-type star and a smaller red dwarf that make up the Tau Boötis binary.

“We are arguing for the radiation of the planet itself,” Turner said. “Based on the strength and polarization of the radio signal and the planet’s magnetic field, this is consistent with theoretical predictions.”

If their measurements are correct, the strength of the magnetic field on the planet’s surface ranges from 5 to 11 gauss (for comparison, Jupiter ranges from 4 to 13 gauss, and measurements of its magnetic field showed that the planet has a nucleus of metallic hydrogen). The observed magnetic field emission strength is also in line with previous predictions.

“The magnetic field of exoplanets can contribute to their possible habitability, – explained Turner, – protecting their own atmosphere from solar wind and cosmic rays and protecting the planet from atmospheric loss.”


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