A radio signal from an Earth-sized exoplanet alerts a research team. Is it a sign that planet YZ Ceti b may have a magnetic field?
Boulder – When researchers look for exoplanets that can support life, the question is usually whether the temperatures there are moderate enough for liquid water to be possible on the surface. But there are other key criteria that a livable planet should ideally meet. One of these is a magnetic field: it protects the planet’s atmosphere by blocking high-energy particles and plasma thrown into space by the star the planet orbits.
If there is no magnetic field, the atmosphere is eroded over time and disappears into space. “Whether a planet with an atmosphere survives or not can depend on whether or not the planet has a strong magnetic field,” explains astrophysicist Sebastian Pineda of the University of Colorado. Together with astronomer Jackie Villadsen (Bucknell University), Pineda has identified an Earth-sized planet outside our solar system that may have a magnetic field. The study was in the journal Nature Astronomy published.
| Rocky Exoplanet |
| 0.7 Erdmassen |
| 0.913 earth radii (estimated) |
| 2 Take |
| 2017 |
| Those: NASA |
Radio signal indicates 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 Villadsen spotted a repeating radio signal emanating from the star YZ Ceti. “I saw this thing that nobody has seen before,” Villadsen recalls of the moment she first discovered the radio signal. “We saw the first eruption and it looked beautiful,” Pineda describes, continuing, “When we saw it again, it was a strong indication that we might actually have something here.”
The research team’s theory: The radio waves they detected are interactions between the exoplanet’s magnetic field and the star. In order to detect these, they must be very strong over the great distance of twelve light years. Exoplanets with magnetic fields have been discovered before, but so far these have been Jupiter-sized exoplanets. To find magnetic fields around Earth-like planets, the research team had to think of a new approach because magnetic fields are invisible – making it extremely difficult to find out 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 are looking for planets that are very close to their stars and are similar in size to Earth. These planets are far too close to their stars to live on, but because they’re so close, the planet is sort of plowing through a bunch of material coming off the star.” If the planet flies through enough star material, “it will Make Stern emit bright radio waves,” Villadsen continues.
Exoplanet YZ Ceti b is very close to its star
The small red dwarf star YZ Ceti and its exoplanet YZ Ceti b are the ideal pair for this approach because the exoplanet is so close to its star that it takes only 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, among other things, to measure how strong the planet’s magnetic field might be.
We look for planets that are very close to their stars and are similar in size to Earth. These planets are far too close to their stars to live on.
“The search for potentially habitable or livable worlds in other solar systems depends in part on whether rocky, Earth-like exoplanets actually have magnetic fields,” explains Joe Pesce, program director of the National Radio Astronomy Observatory at the National Science Foundation (NSF), who is leading the research partially funded. “This research not only shows that this particular rocky exoplanet likely has a magnetic field, but 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 so far for a rocky planet with a magnetic field. “That could be really plausible,” says Villadsen in one communication. “But I think there will be a lot of follow-up work to be done before there’s really definitive confirmation of radio waves being made by a planet.” are planned. Once we have shown that this is really happening, we can approach it more systematically. We are still at the very beginning.” (tab)