Juno observations of spot structures and a split tail in Io-induced aurorae on Jupiter

Lo strumento a bordo della sonda Juno svela il segreto delle impronte lunari nel sistema gioviano: invece di proiettare una singola ombra sulle aurore di Giove, la luna "Io" ne lascia una lunga serie altalenante, mentre la più grande luna di Giove, "Ganimede", proietta una doppia ombra aurorale la cui forma precisa non era mai stata osservata in precedenza

A. Mura, A. Adriani, J. E. P. Connerney, S. Bolton, F. Altieri, F. Bagenal, B. Bonfond, B.M. Dinelli, J-C. Gérard, T. Greathouse, D. Grodent, S. Levin, B. Mauk, M.L. Moriconi, J. Saur, J. H. Waite Jr., M. Amoroso12, A. Cicchetti1, F. Fabiano, G. Filacchione, D. Grassi, A. Migliorini, R. Noschese, A. Olivieri, G. Piccioni, C. Plainaki, G. Sindoni, R. Sordini, F. Tosi, D. Turrini
Juno observations of spot structures and a split tail in Io-induced aurorae on Jupiter
Science  05 Jul 2018: eaat1450 DOI: 10.1126/science.aat1450

Abstract

Jupiter’s aurorae are produced in its upper atmosphere when incoming high-energy electrons precipitate along the planet's magnetic field lines. A northern and a southern main auroral oval are visible, surrounded by small emission features associated with the Galilean moons. We present infrared observations, obtained with the Juno spacecraft, showing that in the case of Io, this emission exhibits a swirling pattern that is similar in appearance to a von Kármán vortex street. Well downstream of the main auroral spots the extended tail is split in two. Both of Ganymede’s footprints also appear as a pair of emission features, which may provide a remote measure of Ganymede’s magnetosphere. These features suggest that magnetohydrodynamic interaction between Jupiter and its moon is more complex than previously anticipated.