The Universe is full of strange planets. Among the most puzzling are the so-called “ultra-hot Jupiters” – enormous gas spheres that orbit so close to their stars that their years can be shorter than a single day on Earth.
Since the environment in the immediate vicinity of stars is hostile to life, with extreme heat, radiation and swirling gases, planet formation there ought to be virtually impossible. Yet these searing gas giants exist, like enigmatic cosmic anomalies.
In a new study, an international team of researchers has measured wind speeds on seven ultra-hot gas giants in other solar systems, known as exoplanets, and made astonishing discoveries. By analysing how their atmospheres behave under extreme heat, the researchers have been able to infer the presence of magnetic fields from wind patterns in the planets’ atmospheres.
"What we are seeing is that the atmospheres of these gas giants are not driven solely by heat and rotation. There is an additional force at play pointing towards magnetic effects", says Adrien Simonnin, astrophysicist at Lund University.
Planetary magnetic fields
The study used both the European Southern Observatory’s Very Large Telescope and the Gemini North telescope in Hawaii. The discovery is based on an indirect method in which researchers study atmospheric motions in the gas giants. By analysing how light from their nearby stars is filtered through the atmosphere, the structure of the winds can be mapped with high precision.
"Our results suggest that the magnetic fields may be comparable in strength to those found among the planets in our Solar System. This gives us a new frame of reference for how planetary magnetic fields may form and evolve", says Brian Thorsbro, astrophysicist at Lund University.
Extremely Large Telescope
Studies of magnetic fields on exoplanets through atmospheric wind analysis mainly work for hot, Jupiter-like gas planets. However, with the next generation of telescopes – such as the European Southern Observatory’s Extremely Large Telescope, currently being built in Chile and expected to come into operation in 2029 – such research may soon extend to more types of exoplanets, including those similar to Earth.
"The next step is to understand how these magnetic fields vary between different types of exoplanets and how they affect their atmospheres over long periods. Ultimately, this could change how we assess which planets have a chance of maintaining stable environments and perhaps even hosting life", says astronomy researcher Bibiana Prinoth, affiliated with the European Southern Observatory, but working at Lund University when the study was conducted.
The study, led by astronomer Julia Seidel at the Observatoire de la Côte d’Azur, is published in the scientific journal Nature Astronomy: “Magnetic field strengths of hot giant exoplanets consistent with Solar System values.”
Link to the article on Nature Astronomy.
Adrien Simonnin’s profile in Lund University’s research portal.
Brian Thorsbro’s profile in Lund University’s research portal.