Astronomers detect magnetic fields on exoplanets for first time, key clue to habitability
Paris: For a planet to be habitable, it generally needs liquid water. To have liquid water, a planet needs an atmosphere. And to have an atmosphere, scientists say a world needs a magnetosphere. For the first time, a team of astronomers has found the strongest evidence yet of magnetic fields around exoplanets.
The discovery was made on 7 very hot, Jupiter-like exoplanets using observations from the European Southern Observatory’s Very Large Telescope and the Gemini North telescope. The planets are gas giants like Jupiter, but each is tidally locked to its host star and orbits very close to it, with one side always facing the star.
The researchers originally set out to measure wind speeds on these distant worlds. Instead, they found that the winds are most likely governed by magnetic fields, providing the first robust measurement of magnetism on planets outside the solar system.
Wind speeds measured on the 7 planets ranged from around 7,200 kmph to over 25,000 kmph. By comparison, the fastest winds on Jupiter reach about 1,500 kmph. The team noticed a counterintuitive pattern: the hotter the planet, the slower the wind.
“This breakthrough opens a completely new window on exoplanet research,” said Julia Seidel, astronomer at Laboratoire Lagrange, Observatoire de la Côte d’Azur, France, and lead author of the study published last week in Nature Astronomy. “It’s the first time we can compare the magnetic environments of other worlds—a key step toward ultimately understanding which planets can stay alive, keep their water, and perhaps even, one day, host life as we know it.”
Earth’s magnetic field influences the atmosphere in complex ways and is key to keeping the planet habitable. Mars lost its atmosphere and water after its magnetosphere departed, scientists believe. Magnetic fields are also present on Jupiter and Saturn, but for the past 15 years no one had succeeded in directly measuring magnetic field strength on exoplanets.
