Saturn periodicities as revealed by energetic neutral atoms

The ion and neutral camera (INCA) is part of the MIMI instrument on the Cassini spacecraft. It images high-speed neutrals that are created when an energetic ion obtains an electron from a neutral. In this way, energetic neutral atom (ENA) images are diagnostic of neutral distributions and their dynamics. Previously, we have explained ENA periodicities in terms of two components: a symmetric background distribution, and an asymmetric corotating component. This latter is likely an injection of ions rotating through the magnetosphere emitting ENAs as it interacts with the neutral gas. We now extend our understanding of ENA periodicities by examining multiple case studies involving various projections of the ENA images. Periodicities can be quantified and compared directly to SKR periodicities. A simple model using the standard neutral background and injection is used to investigate the relationship between ENA and SKR periods. We also look into the perturbation to the system due to the asymmetric ring current (corotating ion distribution) that dominates our images.