ALEXANDRIA, Va. — A distant, Earth-sized planet is emitting a radio signal which could point to it having a similar magnetic field to ours. American astronomers say rocky exoplanet YZ Ceti b is a prime candidate for having an Earth-like field, which could provide vital answers in humanity’s search for alien life. The researchers say the search for life on other planets depends in part on whether rocky, Earth-like exoplanets such as this one also have magnetic fields.
Using a radio telescope, the scientists found exoplanet YZ Ceti b – which is around 70.5 trillion miles away from Earth – is putting out a repetitive radio signal. They theorize that these waves may be the result of interactions between the magnetic field of the exoplanet and the small red dwarf star it orbits, called YZ Ceti.
The astronomers lauded the discovery as important not only in finding a planet that likely has a magnetic field, but also in providing a future method of finding more such planets. The researchers added it could also mean it would be possible to witness the northern lights phenomenon — an interaction between magnetic fields and solar weather — on distant planets and stars.
Earth’s magnetic field helps preserve our life-sustaining atmosphere by shielding us from and deflecting high-energy particles and plasma blasted from the Sun. It also keeps our compass needles pointing in the same direction. A planet’s magnetic field can prevent its atmosphere from being worn away over time by particles spewed from its star.
Now, researchers Dr. Sebastian Pineda and Assistant Professor Jackie Villadsen have discovered the faraway star is around 12 light years away from Earth. One light year is equivalent to 5.88 trillion miles.
This is a key part of finding alien life
The pair used the Karl G. Jansky Very Large Array, a radio telescope operated by the U.S. National Science Foundation’s National Radio Astronomy Observatory, to better understand the magnetic field interactions between distant stars and their orbiting planets. The research, published in the scientific journal Nature Astronomy, also received support from the National Science Foundation (NSF).
“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,” says NSF’s Joe Pesce, program director for the National Radio Astronomy Observatory, in a media release. “This research shows not only that this particular rocky exoplanet likely has a magnetic field but provides a promising method to find more.”
“We saw the initial burst and it looked beautiful,” adds Pineda, from the University of Colorado. “When we saw it again, it was very indicative that, OK, maybe we really have something here.”
“Whether a planet survives with an atmosphere or not can depend on whether the planet has a strong magnetic field or not.”
“I’m seeing this thing that no one has seen happen before,” notes Villadsen, an astronomer at Bucknell University.
While researchers believe the radio waves come from interactions between the magnetic field of YC Ceti b and its home star, for such signals to be detectable over such a distance, they must be very strong. Magnetic fields have been detected in the past on exoplanets the size of Jupiter, but finding those coming from a similar sized planet to Earth requires different techniques.
SInce magnetic fields are invisible, it can be a challenge to assert that a faraway planet has one. However, Villadsen explains that the team is searching for a way to detect them.
“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,” explains Villadsen. “If the planet has a magnetic field and it plows through enough star stuff, it will cause the star to emit bright radio waves.”
YZ Ceti and its exoplanet YZ Ceti b provide the ideal pair because they are so close to each other that the latter completes a full orbit in just two days. In comparison, the shortest planetary orbit in our solar system is Mercury’s 88 days.
As plasma from YZ Ceti careens off the planet’s magnetic “plow,” it then interacts with the magnetic field of the star itself, which generates radio waves strong enough for scientists on Earth to see them. The strength of those radio waves can then be measured, allowing the researchers to determine how strong the magnetic field of the planet might be.
High-energy particles and huge bursts of plasma from the Sun sometimes create solar weather around Earth. These ejections from the Sun can disrupt global telecommunications and short-circuit electronics in satellites and even on the Earth’s surface. The interactions between solar weather and the Earth’s magnetic field and atmosphere create the natural phenomenon of the aurora borealis, also known as the northern lights. Interactions between YZ Ceti b and its star also produce a similar aurora, but this phenomenon occurs on the star itself, equivalent to the northern lights occurring on the Sun.
“This is telling us new information about the environment around stars,” Pineda continues. “This idea is what we’re calling ‘extrasolar space weather.’”
“We’re actually seeing the aurora on the star — that’s what this radio emission is. There should also be aurora on the planet if it has its own atmosphere.”
Although both Villadsen and Dr. Pineda agree that YZ Ceti b is the best candidate so far for an exoplanet with a magnetic field, it’s not yet a cut-and-dry case.
“This could really plausibly be it,” says Villadsen. “But I think it’s going to be a lot of follow-up work before a really strong confirmation of radio waves caused by a planet comes out.”
“There are a lot of new radio facilities coming online and planned for the future,” Pineda concludes. “Once we show that this is really happening, we’ll be able to do it more systematically. We’re at the beginning of it.”
South West News Service writer James Gamble contributed to this report.