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Astronomers report the strongest evidence yet that planets beyond the Solar System possess global magnetic fields after measuring extreme winds on seven tidally locked “hot Jupiter” gas giants.
Using high-resolution spectroscopy from ESO’s Very Large Telescope (ESPRESSO) in Chile and the MAROON‑X instrument on the Gemini North telescope in Hawai‘i, the team led by Julia Seidel tracked atmospheric tracers and inferred wind speeds between roughly 4,470 mph (7,200 kph) and about 15,530 mph (25,000 kph). Counterintuitively, the hottest planets showed the slowest winds; researchers interpret this as magnetic braking of ionised atmospheric flows.
From the wind–temperature trend the team estimated planetary magnetic field strengths comparable to Solar System giants — roughly several gauss, about four times Saturn’s field up to around half of Jupiter’s.
Results are published in Nature Astronomy and co‑authored by Bibiana Prinoth and Vivien Parmentier.
The sample included planets from near Jupiter mass to over three times Jupiter’s mass, all orbiting very close to their host stars.








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