(CNN) Astronomers have detected a repeating radio signal from both an exoplanet and the star it orbits, 12 light-years away from Earth. The signal suggests that the Earth-sized planet may have a magnetic field and possibly an atmosphere.
Earth’s magnetic field protects the planet’s atmosphere, which life needs to survive, by deflecting energetic particles and plasma from the Sun. Finding atmospheres around planets outside our solar system could point to other worlds that could potentially support life.
Scientists using the Carl G. Jansky Very Large Array Telescope in New Mexico observed strong radio waves coming from the star YZ Ceti and the rocky exoplanet orbiting it, called YZ Ceti b. Researchers believe that the radio signal was created by the interaction between the planet’s magnetic field and the star.
The results were a detailed study Published in the Journal on Monday Nature Astronomy.
“We saw the explosion initially and it was beautiful to see,” said Sebastian Pineda, lead author of the study. astrophysicist at the University of Colorado Boulder, in a statement. “When we looked at it again, it was very suggestive that, OK, maybe we really have something here.”
Magnetic fields can prevent a planet’s atmosphere from subsiding and eroding over time as particles are ejected from the star and bombard it, Pineda said.
How strong are radio waves?
For radio waves to be detected on Earth, they must be very strong, the researchers said.
“Whether a planet survives with an atmosphere may depend on whether the planet has a strong magnetic field,” Pineda said.
Previously, researchers have detected magnetic fields in exoplanets the size of our solar system’s largest planet, Jupiter. But magnetic fields are more difficult to detect on planets the size of Earth because magnetic fields are essentially invisible.
“We’re looking for ways to make them see what we’re doing,” said study co-author Jackie Viladsen, an assistant professor of physics and astronomy at Bucknell University. Pennsylvania, in a statement.
“We’re looking for planets that are really close to their stars and about the same size as Earth,” he said. “These planets are too close to their stars to be habitable, but because they’re so close, the planet is plowing through a bunch of stuff from the star. Enough stellar material, it’ll make the star emit bright radio waves.”
YZ Ceti b takes just two Earth days to complete a single orbit around its star. Meanwhile, the shortest orbit in our solar system is that of Mercury, which takes 88 Earth days to complete one lap around the Sun.
As YZ Ceti b whips around its star, plasma from the star collides with the planet’s magnetic field, bouncing off and interacting with the star’s magnetic field. All of these powerful reactions create and release powerful radio waves that can be detected on Earth.
This illustration depicts plasma emitted by a star that is deflected by the magnetic field of an exoplanet orbiting it. The plasma then interacts with the star’s magnetic field, creating an aurora and radio waves.
The researchers measured the radio waves they detected to determine the strength of the planet’s magnetic field.
“This tells us new information about the environment around our star,” Pineda said. “We call this concept ‘outer space weather’.”
In our solar system, the sun’s activity can create space weather that affects Earth. Energetic bursts from the Sun can disrupt satellites and global telecommunications, and can cause bright lights like the aurora borealis or northern lights near Earth’s poles.
Scientists imagine that the interaction between YZ Ceti and its planet creates an aurora, but this light show actually takes place on the star itself.
“We actually see auroras in stars — that’s this radio emission,” Pineda said. “If the planet has its own atmosphere, it should also have auroras.”
Rocky exoplanet candidate
The researchers think that YZ Ceti b is the best candidate yet seen for a rocky exoplanet with a magnetic field.
“It could be really plausible,” Viladsen said. “But I think it’s going to take a lot of follow-up work before a really strong confirmation of radio waves caused by a planet comes out.”
New radio telescopes set to become operational this decade could help astronomers detect more signals that suggest a magnetic field, 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 actually have magnetic fields,” said Joe Pace, program director at the National Radio Astronomy Observatory. A statement “This study does not show that this particular rocky exoplanet likely has a magnetic field, but it does provide a promising method to find more.”
