An exoplanet just 12 light-years beyond our solar system is sending out radio signals, but before you get excited they’re thought to be evidence not of life, but of aurora—the Northern and Southern Lights—that may reveal an Earth-like magnetic field and atmosphere.
Earth’s magnetic field helps preserve a slim life-sustaining atmosphere by deflecting high energy particles from the Sun. A planet’s magnetic field can prevent its atmosphere from being worn away over time by these particles—known as the solar wind—spewed from its star. It’s this same “space weather” that causes aurora on Earth.
The discovery of aurora makes YZ Ceti b—an Earth-sized planet orbiting a red dwarf star about 12 light-years away from Earth in the constellation Cetus—the best candidate yet for a rocky exoplanet with a magnetic field.
“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,” said NSF’s Joe Pesce, program director for the National Radio Astronomy Observatory about a new paper published in Nature Astronomy this week. “This research shows not only that this particular rocky exoplanet likely has a magnetic field but provides a promising method to find more.”
Using the Karl G. Jansky Very Large Array of telescopes in New Mexico, the researchers detected strong radio waves believed to be created by the star YZ Ceti interacting with the planet YZ Ceti b’s magnetic field.
“This is telling us new information about the environment around stars,” said Sebastian Pineda, co-lead author on the new paper, calling the detection “extrasolar space weather.” “We’re actually seeing the aurora on the star—that’s what this radio emission is … [but] there should also be aurora on the planet if it has its own atmosphere.”
Detecting the presence of a magnetic field around a distant exoplanet is not easy. This is the first time a magnetic field has been found around a Earth-sized exoplanet, with previous detections at only Jupiter-size worlds.
For radio waves to be detected from 12 light-years away requires them to be very strong, which means the exoplanet has to be orbiting very close to its star. YZ Ceti b take just two days to orbit its star. “We’re looking for planets that are really close to their stars and are a similar size to Earth,” said Pineda. “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 … if the planet has a magnetic field and it plows through enough star stuff, it will cause the star to emit bright radio waves.”
Follow-up work is needed to confirm the findings, said the researchers.
Wishing you clear skies and wide eyes.