Earth-sized exoplanets can have a magnetic field and produce aurora borealis

A pair of researchers has identified a rocky, Earth-sized exoplanet with a possible magnetic field. It orbits a star located just 12 light-years from the solar system and could answer a question about magnetospheres on distant worlds.

Magnetic fields are important for life-sustaining planets, as they protect the atmosphere from the solar wind. However, clues about these fields in rocky worlds orbiting stars other than our sun are slim.

The study’s authors observed a repeating radio signal emitted by the planet YZ Ceti b, which was analyzed using the Karl G telescope. The detection indicates possible magnetic field interactions of the planet and its star, more precisely with the stellar plasma.

It is difficult to find a magnetic field on a small exoplanet because the signal emitted must be strong to be detected. On gaseous exoplanets the size of Jupiter, magnetic fields are easy to notice, but small, rocky worlds require more effort — and clever technology.

The first thing to do is find Earth-sized planets that are much closer to their stars than Earth is to the Sun. Thus, these worlds could circulate among the stellar plasma, and if they had magnetic fields, they would emit a radio signal.

In the case of the red dwarf star YZ Ceti and its outer planet, YZ Ceti b, the distance is 0.01634 AU short enough for an orbit of just two days — 44 times shorter than Mercury around the sun, separated by 0.46 AU. Once close to the star, the planet passes through the interstellar plasma made up of electrically charged particles.

When this happens to any object with a magnetic field, the inevitable result is the production of radio waves strong enough to be observed by large ground-based radio telescopes. The next step is to analyze the signal and determine the strength of the planet’s magnetic field.

According to the authors, this radio signal is, in fact, similar to the aurora borealis that we see on our planet, but with a significant difference: there, the auroras occur in the star (if the detection is confirmed).

There is still work to be done to confirm that YZ Ceti b does indeed have a magnetic field, but the authors are confident that it is the best candidate found so far to receive confirmation. To strike the hammer, it will be necessary to wait for the next generation tools.

The study has been published in the journal natural astronomy.

source: natureAnd NSF