Radio waves, from a gas giant planet outside the solar system, would have been detected for the first time, indicating the presence of a protective magnetic field, according to a study.
The signal was observed by the European LOFAR radio telescope, a network of 50,000 antennas spread across Europe and with a very low frequency, an energy area that is still underused.
The emission comes from an already known system, Tau Bootis, located 50 light-years from the solar system. It contains a binary star and a gas giant exoplanet in close orbit: a “hot Jupiter” called Tau Bootis-b.
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Until now, the mass and orbit of many exoplanets were known, but not whether they had a magnetic field. This shield, which protects against radiation from stellar winds, is located around Earth and Jupiter.
However, the radio emission captured by LOFAR “is a very accurate signature of the magnetic field,” said Philippe Zarka, of the Paris Observatory, one of the lead authors of the study published this week in Astronomy & Astrophysics.
These waves are very difficult to detect as planetary magnetic fields are usually weak and their emission source is far away.
The international team of researchers observed three extrasolar systems (Tau Bootis, 55 Cancri and Ups) containing gas giants that, close to their star, are likely powerful ejectors. 2509-6217 / 16
Using Jupiter’s radio signal as a model, attenuated to the maximum, the analysis of one hundred hours of observation argued for the expected signature of Tau Bootis.
“There is a 98% probability that the signal is reliable,” said Philippe Zarka, indicating that some doubt remains about the possibility that the signal may have come from its star. “To be really sure, you need a probability of 99.9%. We will have to continue with the observations that are within our reach, ”added the astrophysicist.
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If confirmed, “it would be a first to validate the radio detection technique, and thus a step towards the characterization of exoplanets,” emphasized the researcher.
About 4,000 exoplanets have been detected since the first, 51 Pegasi-b, was found 25 years ago.
According to Philippe Zarka, the existence of a magnetic ‘bubble’ is an ingredient conducive to the development of a way of life. But there are other criteria, such as temperature, and in the case of Tau Bootis-b, hers would be too high to stay alive.