Galileo orbiter ultraviolet observations of Jupiter aurora

摘要

In 1996 during the first four orbits of the satellite tour the Galileo ultraviolet spectrometer (UVS) (1130-4320 Angstrom) and extreme ultraviolet spectrometer (EUVS) (540-1280 Angstrom) performed near-simultaneous observations of the Jupiter aurora in both the north and south polar regions. These observations are modeled to provide the absolute surface brightness of the aurora from the H-2 Rydberg Systems (B, B', B ", C, D, D' --> X band systems). The spectral distribution and brightness of the EUV aurora are sensitive to H-2 abundance, H-2 temperature, and CH4 abundance. Analysis of the emission spectra indicates that the EUV aurora (800-1200 Angstrom) are produced over a range of altitudes corresponding to slant column abundances of H-2 from 10(16) to 10(20) cm(-2) or greater. The UVS spectra of the far ultraviolet (FUV) from 1130 to 1700 Angstrom are optically thin in H-2, but highly sensitive to the CH4 column abundance and to the secondary electron energy distribution. The slant column abundance of CH4 absorbers found from models of the FUV spectra varied in the range 0 - 10 x 10(16) cm(-2), indicating the presence of both high altitude aurora, at or above the homopause, and deep aurora. The EW spectra show C2H2 absorption bands near 1520 Angstrom. The surface brightness of the aurora from the H-2 Rydberg Systems ranged from 100 to 600 kR and of H Lyman alpha was 60 to 130 kR for a 2000 km wide oval. The total power input to the atmosphere from particle deposition is estimated to be similar to 1 x 10(14) W. [References: 55]