Ultraviolet Emission from Oxygen Precipitating into Jovian Aurora

The ultraviolet emission-line spectra of precipitating oxygen atoms and ions excited by charge transfer interaction with the molecular hydrogen in the auroral atmosphere of Jupiter are calculated using our computed cross sections of state-selective charge transfer. The charge transfer processes preferentially populate the ground states of neutral oxygen and low-charge ions and the highly excited states of high-charge ions, yielding low UV and high X-ray efficiencies, respectively. Much weaker than the underlying emission spectrum of H2 excited by energetic electron precipitation, the UV emission from oxygen is not expected to be discernible in the Jovian auroral spectrum. This reconciles the absence of UV emission with the presence of X-ray emission from the heavy ions precipitating in the Jovian aurora. (c) (c) 2000. The American Astronomical Society