[HOT] : Space: hidden exoplanets detected thanks to their radio signals

Some stars emit radio waves unexpectedly, a team of Australian and Dutch astronomers has found. Their careful study would allow the detection of previously hidden exoplanets.

Astronomers from the University of Queensland, Australia, and the Dutch national observatory ASTRON, the Netherlands, have reached to detect signals proving the existence of exoplanets thanks to radio broadcasts from distant stars. The results of their work have just been published in Nature Astronomy.

The disruption of the magnetic field of some stars would be a sign of the presence of hidden exoplanets

The international team used the world’s most powerful radio telescope, the Low Frequency Array (LOFAR) based in the Netherlands. She explains that these signals come from of the magnetic connection of these stars with their orbiting planets, invisible to the naked eye. This connection is similar, for example, to the interaction between Jupiter and its satellite Io. “We have known for a long time that the planets in the solar system emit powerful radio waves,” explains Dr. Benjamin Pope of the University of Queensland. But so far, we had not yet detected radio signals from exoplanets, located outside the solar system ”.

These unexpected signals have already been detected around 19 red dwarf stars. For four of them, astronomers are convinced that they can be explained by the existence of exoplanets in orbit – very distant planets that telescopes and classical detection methods cannot see.

The Pandora mission will be launched this month by NASA expected to break through the atmospheric mysteries of the exoplanets which are close to the Earth. But the new radio detection technique will make it possible to detect others much further. “This is an important step for radio astronomy, which could potentially lead to the discovery of planets throughout the galaxy,” says Dr. Pope.

A more powerful radio telescope will allow the detection of hundreds of exoplanets by 2029

Until then, it was only possible for radio astronomers to detect constant radio emissions: stars, interstellar gas, or exotic emissions like those from black holes. The technique they have developed now allows them to isolate single stars during their observations … and therefore to look for possible planets orbiting around them. Red dwarfs, smaller than our Sun, are favorite subjects because their small size combines with intense magnetic activity.

The magnetic field of the stars indeed feeds vast currents in space, that can be compared to the Northern Lights on Earth. They emit characteristic radio waves, and their disturbance could confirm the existence of hidden planets. These discoveries made with the LOFAR radio telescope are just the beginning, because its range, up to 165 light years, only allows it to monitor relatively nearby stars.

Fortunately, the future Square Kilometer Array radio telescope (in French, “Network of a square kilometer”) should be put into service in 2029 at two sites in Australia and South Africa. It will allow the observation of radio broadcasts hundreds of new stars – and spotting exoplanets – at distances unparalleled.