IMAGES OF AURORAE ON JUPITER FROM H-3+ EMISSION AT 4 MU-M

SINCE their discovery by Voyager 1, aurorae on Jupiter have been regularly observed over the past ten years, from space at ultraviolet wavelengths 2 and from the Earth in the thermal infrared band 3 (8-13-mu-m). The ultraviolet emissions originate from H and H-2 in the highest part of the atmosphere, whereas the thermal infrared emissions originate from the stratosphere. Here we present images of near-infrared H-3+ emission, recorded simultaneously with high-resolution spectra. Having both imaging and spectral data provides us with a much improved opportunity to study the spatial and spectral characteristics of the H-3+ emission. We find that northern and southern emissions show strong spatial variation at the wavelengths of H-3+ emission. We suggest that the appearance of the jovian auroral regions at these wavelengths may be explained by a combination of localized H-3+ emission, reflection of sunlight by polar haze and stratospheric CH4 emission in the 3.3-3.6-mu-m range.