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‘Hellish’ exoplanet may have magnetic field, like Earth

Scientists don't know whether magnetic fields are the norm for Earth-sized exoplanets. The uninhabitable YZ Ceti b may hold answers.

(CN) — YZ Ceti b, a rocky exoplanet 12 light-years from Earth, would be a “hellish place to live” because it orbits its small red star YZ Ceti so closely. And yet the planet may help us find life-sustaining worlds outside our solar system if — as astronomers suspect — the messages it sent came from its magnetic field.

Bucknell University astronomer Dr. Jackie Villadsen and team revealed the news in a study published Monday in the journal Nature Astronomy.

Dr. J. Sebastian Pineda, co-author of the study and an astrophysicist at the University of Colorado, said the research team used a combination of radio interferometry, time series monitoring, and the Karl G. Jansky Very Large Array radio telescope to look for “significant changes in the radio brightness at the target location.”

According to the study, researchers typically detect magnetic fields from long-distance Jupiter-sized exoplanets rather than relatively tiny Earth-sized ones.

However, while YZ Ceti b's magnetic field does not prevent it from being totally uninhabitable — unlike Earth's magnetic field which regularly saves us by deflecting high-energy particles and plasma the sun blasts out — the exoplanet's closeness to the star causes it to plow “through a bunch of stuff coming off the star" which Villadsen said caused “the star to emit bright radio waves.”

Curiously, while learning more about YZ Ceti, the researchers found that it has a magnetic field stronger than Earth’s sun, so it can create its own aurora.

“The same physics that powers the aurora on the star would also allow energy to get dumped onto the planet, producing planetary aurorae if it has its own magnetic field and atmosphere," Pineda said. “We would need a different observing strategy and more sensitive facilities to look for that planet’s aurorae, but it could be there if this star and planet are really interacting magnetically. Our radio detections are for light originating from the stellar atmosphere.”

The researchers intend to continue their pursuit of potentially habitable worlds in other solar systems, but Villadsen stressed the importance of time. She said future studies need to spend a long time using radio telescopes such as the Square Kilometer Array in South Africa and the next-generation Very Large Array in the U.S. to confirm or defy the researchers’ findings, which includes if the two bursts of radio waves they detected follow a pattern.

If the radio bursts are part of a pattern, Villadsen hypothesized that YZ Ceti b’s magnetic field caused the radio waves. However, if future radio bursts from the star are actually random, then Villadsen believes that the researchers probably saw stellar flares which she described as magnetic “explosions” on the star’s surface, and that they don’t provide information on the planet itself.

As for what they do know, Villadsen wrote that the study “shows that YZ Ceti b could have a magnetic field like Earth's. So far, we really don't know whether to expect most extrasolar planets to have magnetic fields or not. So, this gives me hope that other extrasolar planets like Earth may have a protective magnetic field shielding them.”

Villadsen said that it will be a long-term project but she, Pineda, and the other researchers will continue to see what else they can find in other solar systems.

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