HAT-P-11b was discovered using data from the Hubble Space Telescope (HST).

Astronomers have found and confirmed more than 5,000 planets outside our solar system, and 8,288 likely candidates remain. However, until now none of the magnetic fields of these exoplanets had been discovered. The findings were published in Nature Astronomy by astronomers from the European Space Astronomy Center (ESAC), NASA’s Jet Propulsion Laboratory (JPL), and many other organizations and universities.

HAT-P-11b is an exoplanet orbiting HAT-P-11, a K-type (orange dwarf) star located 123 light years from Earth. It is approximately the size of Neptune. They made the discovery using a technique called Transit Spectroscopy, or Transit Method, in which a star’s brightness periodically dims to indicate when a planet passes in front of it. It is used in the search for exoplanets and the study of their atmospheres.

In the ultraviolet spectrum, Hubble observed that HAT-P-11b made six transits around the star HAT-P-11. Additionally, it found carbon ions in the atmosphere, which scientists believe are likely caused by a magnetosphere.

This is the first time that an exoplanet’s magnetic field signature has been directly observed on a planet outside our solar system. On a planet like Earth, a strong magnetic field can protect the planet’s surface and atmosphere from the powerful particles of the solar wind. Because the magnetic field protects organisms from these energetic particles, these processes have a significant impact on the evolution of life on planets like Earth, according to co-author Gilda Ballester.