New method estimates magnetic field of an exoplanet

Scientists have developed a new method that can estimate the magnetic field of a distant exoplanet.
An exoplanet is a planet, which is located outside the solar system and orbits a different star.
Kristina Kislyakova of the Space Research Institute of the Austrian Academy of Sciences in Graz and an international group of physicists for the first time ever have estimated the value of the magnetic moment and the shape of the magnetosphere of the exoplanet HD 209458b.
Planet HD 209458b (Osiris) is a hot Jupiter, approximately one third larger and lighter than Jupiter. It is a hot gaseous giant orbiting very close to the host star HD 209458.

Scientists used the observations of the Hubble Space Telescope of the HD 209458b in the hydrogen Lyman-alpha line at the time of transit, when the planet crosses the stellar disc as seen from the Earth.
At first, the scientists studied the absorption of the star radiation by the atmosphere of the planet.
Afterwards they were able to estimate the shape of the gas cloud surrounding the hot Jupiter, and, based on these results, the size and the configuration of the magnetosphere.
"We modelled the formation of the cloud of hot hydrogen around the planet and showed that only one configuration, which corresponds to specific values of the magnetic moment and the parameters of the stellar wind, allowed us to reproduce the observations," said Kislyakova.