Scientists have discovered stars mysteriously sending out radio waves using the world's most powerful radio antenna.
Four red dwarf stars that should be silent in radio observations have been detected emitting radio signals within 160 light-years of the Solar System. According to an analysis of these signals, the presence of unseen exoplanets is the best explanation for this activity.
As described in a press release, researchers at the Dutch national observatory ASTRON have been scanning the skies for planets with the world's most powerful radio telescope, the Low Frequency Array (LOFAR).
To be clear, it's not a technosignature implying an alien civilization; rather, it appears to be the result of an interaction between the exoplanet's magnetic field and the star's magnetic field, resulting in intensely strong auroras detectable with the LOFAR.
The research suggests a new way of hunting for exoplanets in our solar neighborhood, following the publication of a similar discovery in 2020.
"This discovery is an important step for radio astronomy and could potentially lead to the discovery of planets throughout the galaxy," physicist Benjamin Pope of the University of Queensland in Australia said.
Previously, astronomers could only detect the very nearest stars in steady radio emission, with the rest of the radio sky consisting of interstellar gas or exotica like black holes.
When radio astronomers make observations, they can now see plain old stars, and we can use that information to look for planets orbiting those stars.
Red dwarf stars, which are much smaller than the Sun and known to have intense magnetic activity that drives stellar flares and radio emission, were the focus of the research.
Apart from the radio emissions, the team hasn't found any signs of the exoplanets suggested by the new method, but if they exist, future observations using the radial velocity method could help reveal them.
The discoveries made by LOFAR are only the beginning, as the telescope can only monitor stars that are relatively close by, up to 165 lightyears away.
The team predicts that once Australia and South Africa's Square Kilometer Array radio telescope is completed and operational in 2029, they will be able to see hundreds of relevant stars at much greater distances.