Using the Low Frequency Radio Telescope (LOFAR) located in the Netherlands, a team of scientists has discovered several very distant stars that emit unexpected radio waves, possibly indicating the existence of hidden planets.
“We have discovered signals from 19 distant red dwarf stars, four of which could be better explained by the existence of planets that orbit them,” says Benjamin Pope, a researcher at the University of Queensland. “We have known for a long time that the planets in our own solar system emit powerful radio waves when their magnetic fields interact with the solar wind , but until now we have not picked up anything similar outside of our solar system.”
“This discovery is an important step for radio astronomy and could potentially lead to the discovery of planets throughout the galaxy, ” adds the scientist. Previously, astronomers could only detect the closest stars in a constant radio emission. Now, thanks to powerful new radio telescopes, it is possible to capture signals from old stars and, with that information, search for the planets that surround them.
In this case, the team focused on red dwarf stars, which are much smaller than the Sun and are known to have intense magnetic activity that drives stellar flares and radio emission. However, some old, magnetically inactive stars also appeared, challenging conventional understanding.
A spectacle light years away
The lead author of the discovery, a researcher at the University of Leiden and the Dutch National Observatory ASTRON Joseph Callingham, believes that these strange signals come from the magnetic connection of stars and invisible planets in orbit, something similar to the interaction between Jupiter and its moon, Io. “Our own Earth has auroras that also emit powerful radio waves, and this is due to the interaction of the planet’s magnetic field with the solar wind,” he says. “ Jupiter’s auroras are stronger, as its volcanic moon Io is launching material into space, filling its surroundings with particles that drive unusually powerful auroras. Our model for this radio emission from our stars is an enlarged version of Jupiter and Io, with a planet engulfed in a star’s magnetic field, feeding material in vast streams that equally fuel bright auroras. It is a spectacle that has attracted our attention from light years away ”.
Now the most difficult thing remains: to confirm the existence of these supposed hidden planets. ” We cannot be 100% sure that the four stars that we think have planets are in fact hosts of planets, but we can say that a planet-star interaction is the best explanation for the phenomenon we are capturing, ” Pope says. ” Follow-up observations have ruled out planets more massive than Earth, but there is nothing to say that a smaller planet is not capable of this. “
The discoveries with LOFAR are only the beginning, but the telescope ‘only’ has the ability to monitor stars that are relatively close, up to 165 light years away. With Australia and South Africa’s Square Kilometer Array radio telescope, which is under construction and expected to turn on in 2029, the team predicts they will be able to see hundreds of relevant stars at much greater distances.
The work has been published in the journals Nature Astronomy (Callingham et al; DOI: 10.1038 / s41550-021-01483-0) and Astrophysical Journal Letters (Pope et al; DOI: 10.3847 / 2041-8213 / ac230c).
