The possibility of life outside Earth has received a boost from a new discovery: an exoplanet that emits a “coherent” radio signal. This signal could indicate that the planet has a magnetic field, which is essential for protecting life from harmful radiation.
The exoplanet, named YZ Ceti b, is a rocky world that orbits a star about 12 light years away from Earth. It is one of three planets in the system, but the only one that shows signs of radio emission.
This emission is believed to be caused by the interaction between the star and the planet’s magnetic field, creating a phenomenon similar to the aurora borealis or northern lights on Earth.
Astronomers detected the radio signal using a radio telescope called the Very Large Array (VLA) in New Mexico. They observed two bursts of radio waves from YZ Ceti b that repeated after about 3 hours, suggesting a regular pattern. The signal was also “coherent”, meaning that it had a constant frequency and phase.
“We saw the initial burst and it looked beautiful,” said Sebastian Pineda, an astrophysicist at the University of Colorado and one of the researchers who saw the signal. “When we saw it again, it was very indicative that, okay, maybe we really have something here.”
The discovery, published in Nature Astronomy journal, is important because it could provide a new way to search for habitable planets. Magnetic fields are thought to be crucial for shielding life from cosmic radiation and charged particles released from stars. They also help maintain a stable atmosphere and climate on a planet.
“Magnetic fields are one of the key ingredients for habitability,” said Jackie Villadsen, an astronomer at the National Radio Astronomy Observatory and another author of the paper. “They can protect life from harmful radiation and also prevent atmospheric escape.”
Until now, astronomers have struggled to confirm whether distant rocky planets have magnetic fields of their own, and therefore have found it difficult to say how likely a planet might be able to support life.
The radio signal from YZ Ceti b could be a sign that it has a magnetic field similar to Earth’s, which is generated by the movement of molten iron in its core.
However, having a magnetic field does not guarantee that a planet is habitable. YZ Ceti b is very close to its star, which is a red dwarf that emits frequent flares and high-energy radiation. The planet’s surface temperature could be too hot for liquid water to exist, and its atmosphere could be stripped away by stellar winds.
Therefore, more observations are needed to determine if YZ Ceti b is truly a potential home for life. The researchers plan to use other radio telescopes, such as the Low Frequency Array (LOFAR) in Europe and the Murchison Widefield Array (MWA) in Australia, to confirm and study the radio signal in more detail.
They also hope to find more exoplanets that emit radio signals, which could reveal new information about their magnetic fields and habitability. “This research shows not only that this particular rocky exoplanet likely has a magnetic field but provides a promising method to find more,” said Joe Pesce, program director for the National Radio Astronomy Observatory.