Physics Seminar: Saturn's Ring Rain

Luke Moore from Boston University will come to speak about Saturn's Ring Rain.

Recently H3+, a major ion in outer planet ionospheres, was detected at Saturn’s mid- and low-latitudes for the first time. These mid-IR ro-vibrational emissions were significantly structured in latitude, with local extrema in one hemisphere being mirrored at magnetically conjugate latitudes in the opposite hemisphere. Furthermore, the observed ionospheric minima and maxima were shown to map along magnetic field lines to regions of increased or decreased erosion in Saturn’s rings, implying a direct ring-atmosphere connection.

The most likely explanation of the observed H3+ structure is that charged water group particles from the rings are guided by magnetic field lines as they precipitate into the atmosphere, altering local ionospheric chemistry – hence, “ring rain”. Using a model of Saturn’s upper atmosphere, we reproduce the observed structure in H3+. Such model comparisons can be used to derive the global variations of water influx into Saturn’s atmosphere. Ring-derived water influxes have implications for ring mass loss, evolution and lifetime.