An Earth-sized exoplanet detected by a repeating radio signal

(CNN) – Astronomers have detected a repeating radio signal coming from an exoplanet and the star it orbits, both located 12 light-years from Earth. The signal suggests that a planet the size of Earth could have a magnetic field and even an atmosphere.

Earth’s magnetic field shields the planet’s atmosphere, which life needs to survive, by scattering energetic particles and plasma emerging from the sun. The detection of atmospheres on planets outside our solar system could indicate the presence of other worlds potentially capable of supporting life.

Scientists detected strong radio waves coming from the star YZ Ceti and the rocky exoplanet it orbits, called YZ Ceti b, during observations using the Karl G. Jansky Very Large Array Telescope in New Mexico. Researchers believe that the radio signal was generated by interactions between the planet’s magnetic field and the star.

magazine natural astronomy A study published Monday detailed the findings.

“We saw the initial explosion and thought it was pretty cool,” Sebastian Pineda, lead author of the study and research in astrophysics at the University of Colorado at Boulder, said in a statement. “When we saw it again, it was a great indication that, well, maybe we really have something here.”

Magnetic fields can prevent the planet’s atmosphere from being depleted and essentially eroded over time as particles separate from and bombard the star, Pineda said.

How are radio waves produced?

According to the researchers, for radio waves to be detectable on Earth, they would have to be very intense. “Whether or not a planet stays in the atmosphere may depend on whether or not the planet has a strong magnetic field,” Pineda said.

Previously, researchers had detected magnetic fields on exoplanets similar in size to Jupiter, the largest planet in our solar system. But finding magnetic fields on smaller planets like Earth is much more difficult, because they are basically invisible.

“What we’re doing is looking for a way to see it,” Jackie Feldsen, study co-author and associate professor of physics and astronomy at Bucknell University in Pennsylvania, said in a statement.

“We’re looking for planets that are very close to their stars and that are similar in size to Earth,” he explains. “These planets are too close to their stars to be a place to live, but being so close, the planet is going through a lot of stuff coming out of the star. If the planet has a magnetic field and passes through enough stellar material, it will cause the star to emit bright radio waves.”

It takes YZ Ceti b only two Earth days to complete one orbit around its star. Meanwhile, the shortest orbit in our solar system is the planet Mercury, which takes 88 Earth days to complete one revolution around the Sun.

As YZ Ceti b orbits its star, the plasma collides with the planet’s magnetic field, bounces back and interacts with the star’s magnetic field. All of these energetic interactions create and emit powerful radio waves that can be detected on Earth.

The researchers measured the detected radio waves to determine the strength of the planet’s magnetic field. “This gives us new information about the environment around stars,” Pineda says. “This idea is what we call ‘extrasolar space weather’.”

In our solar system, the sun’s activity can create space weather that affects Earth. Active explosions from the sun can disrupt global satellites and communications and cause dazzling light shows near the Earth’s poles, such as the aurora borealis.

Scientists imagine that interactions between YZ Ceti and its planet also create the aurora, but this light show is happening on the star. “We’re already seeing the aurora borealis on the star, and that’s what this radio broadcast represents,” Pineda said. “There should also be aurorae on the planet if it had its own atmosphere.”

best candidate

Researchers believe that YZ Ceti b is the best candidate discovered so far for a rocky exoplanet with a magnetic field. “It’s very likely that this is the case,” says Feldsen. “But I think it will take a lot of follow-up work before there is a really strong confirmation of planet-induced radio waves.”

New radio telescopes due to come online this decade could help astronomers make further detections of signals indicating magnetic fields, researchers said.

“The search for potentially habitable or life-bearing worlds in other solar systems depends in part on being able to determine whether rocky, Earth-like exoplanets do indeed have magnetic fields,” said Joe Pesci, program director at the National Astronomical Observatory. statement. “This research shows not only that this particular rocky exoplanet likely has a magnetic field, but provides a promising way to find more.”