GIANT PLANETS AURORAE AND THE MYSTERIOUS CASE OF JUPITER'S MAIN EMISSION
Seminars
Semester 1
: Prof. Denis Grodent is a Full Professor in the Department of Astrophysics, Geophysics, and Oceanography at the University of Liège, where he has directed the Laboratory for Planetary and Atmospheric Physics since 2012. Prof. Grodent received his PhD in Planetary Sciences from the University of Liège in February 2000 and was a postdoctoral researcher at the University of Michigan, USA. Over his distinguished career, he has been the recipient of several awards, including multiple NASA Group Achievement Awards for his work on the Cassini and Juno missions, and an ESA award for his outstanding contribution to the JUICE mission. Prof. Grodent's research focuses on the observation and interpretation of auroral emissions from giant planets, modelling their auroral atmospheric structures, and studying the magnetosphere-ionosphere coupling of Jupiter, Saturn, and their moons.
Like Earth, the giant planets in our solar system exhibit a certain level of auroral emissions. These emissions provide us with information about the atmospheres of these planets, their interactions with their magnetospheres and the energetic processes that take place there, and finally with the solar wind. After a very brief presentation of current observations of these emissions, we focus on Jupiter, whose auroral emissions in the far ultraviolet exceed those of all other planets in the solar system. Jupiter's aurora consists of several components that may be related to various processes in the magnetosphere. Among these, the main emission, often mistakenly called the 'main auroral oval', the most obvious and permanent component, has been observed for several decades by various observatories on Earth or orbiting the Earth, such as the HST, and by in situ observatories such as the Juno spacecraft. Despite these numerous long-term observations at multiple wavelengths, it is still unclear what powers the main auroral emission and what influences its morphology. We present some recent auroral results obtained by HST and Juno that strongly suggest an Alfvénic origin and partial control of the size of the main emission by the changing magnetic field of the current sheet, which may itself be influenced by the level of compression of the magnetosphere by the solar wind.