This Earth-like rocky exoplanet likely has a magnetic field

Researchers have identified a prospective Earth-like exoplanet as a prime candidate for also having a magnetic field. Named YZ Ceti b, it is a rocky planet orbiting a small red dwarf star, YZ Ceti, about 12 light-years away from Earth.

Using the Karl G. Jansky Very Large Array, a radio telescope operated by the U.S. National Science Foundation's National Radio Astronomy Observatory, Sebastian Pineda, an astrophysicist at the University of Colorado, and Jackie Villadsen, an astronomer at Bucknell University, observed a repeating radio signal emanating from YZ Ceti in order to understand the magnetic field interactions between distant stars and their orbiting planets.

"The search for potentially habitable or life-bearing worlds in other solar systems depends in part on being able to determine if rocky, Earth-like exoplanets actually have magnetic fields. This research shows not only that this particular rocky exoplanet likely has a magnetic field but provides a promising method to find more," said NSF's Joe Pesce, program director for the National Radio Astronomy Observatory.

The researchers theorize that the stellar radio waves detected by them are generated by the interactions between the magnetic field of the exoplanet and the star it orbits. Detecting such radio waves over long distances requires them to be very strong. While magnetic fields have previously been detected on Jupiter-size exoplanets, doing so for a comparatively tiny Earth-sized exoplanet requires a different technique.

"We're looking for planets that are really close to their stars and are a similar size to Earth. These planets are way too close to their stars to be somewhere you could live, but because they are so close the planet is kind of plowing through a bunch of stuff coming off the star," says Villadsen.

According to the researchers, YZ Ceti b and the star it orbits provided an ideal pair because the exoplanet is so close to the star that it completes a full orbit in only two days. As plasma from the star careens off the planet's magnetic plow, it then interacts with the magnetic field of the star itself, resulting in the emission of radio waves strong enough to be observed on Earth.

Their interaction also produces an aurora, but with a significant difference - the natural light display is on the star itself.

Both researchers agree that while YZ Ceti b is the best candidate yet for a rocky exoplanet with a magnetic field, it's not a closed case. More details can be found here.