Signals from an alien planet

A radio signal from an Earth-sized exoplanet alerts a research team. Is it a sign that planet YZ Ceti b might have a magnetic field?

BOULDER — When researchers look for exoplanets that could support life, the question usually asked is whether temperatures there are mild enough to make liquid water possible on the surface. But there are other key criteria that an ideally livable planet must meet. One of these is a magnetic field: it protects the planet’s atmosphere by blocking high-energy particles and plasma ejected into space by the star around which the planet orbits.

If there was no magnetic field, the atmosphere would erode over time and disappear into space. “Whether or not a planet stays in the atmosphere depends on whether or not the planet has a strong magnetic field,” explains astrophysicist Sebastian Pineda of the University of Colorado. Together with astronomer Jackie Feldsen (Bucknell University), Pineda has identified an Earth-sized planet outside our solar system that might have a magnetic field. The study was in the journal natural astronomy published.

The radio signal indicates the magnetic field of exoplanet YZ Ceti b

YZ Ceti b is a rocky planet orbiting a star about 12 light-years from Earth. While observing the planet, Pineda and Veladsen spotted a repeating radio signal from the star YZ Ceti. “I saw this thing that no one had seen before,” Villaadsen recalls the moment she first detected the radio signal. “We saw the first eruption and it looked beautiful, and when we saw it again, it was a strong indication that we might actually have something here,” describes Pineda.

Research team theory: The radio waves they detected are interactions between the magnetic field of an exoplanet and the star. In order to detect these, they would have to be very powerful at a distance of twelve light years. Exoplanets with magnetic fields have been discovered before, but until now these exoplanets have been the size of Jupiter. To find magnetic fields around Earth-like planets, the research team had to think of a new approach because magnetic fields are not visible — making it very difficult to tell if a distant planet has one.

Planets are too close to their stars to live on

Villadsen describes the technique the team used to search: “We’re looking for planets that are very close to their stars and similar in size to Earth. These planets are too close to their stars to live on, but because they’re so close, the planet kind of slashes through a bunch of material coming in.” of the star.” If the planet flies through enough stellar material, “make Stern emit bright radio waves,” Feldsen continues.

Exoplanet YZ Ceti b is very close to its star

The tiny red dwarf star YZ Ceti and its exoplanet YZ Ceti b are the perfect pair for this approach because the exoplanet is so close to its star that it only takes two days to orbit it once. The radio waves that are generated are so powerful that they can be observed on Earth. The research team can use them to, among other things, measure how strong the planet’s magnetic field is.

We are looking for planets that are very close to their stars and similar in size to Earth. These planets are too close to their stars to live on.

“The search for potentially habitable or habitable worlds in other solar systems depends in part on whether rocky, Earth-like exoplanets do indeed have magnetic fields,” explains Joe Pesci, program director for the National Radio Astronomy Observatory at the National Science Foundation (NSF). . Who is leading the research is partially funded. “Not only does this research show that this particular rocky exoplanet likely has a magnetic field, but it also offers a promising way to find more.”

Exoplanet YZ Ceti b could be the first rocky exoplanet with a magnetic field

The research team is certain: YZ Ceti b is the best candidate yet for a rocky planet with a magnetic field. “That could be really reasonable,” Feldsen says in one communication. “But I think there will be a lot of follow-up work to be done before there is definitive confirmation of the radio waves being produced by a planet.” Once we establish that this is indeed happening, we can deal with it more systematically. We are still at the beginning. (tab)