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Altitude of Saturn's aurora and its implications for the characteristic energy of precipitated electrons
Author(s) -
Gérard J.C.,
Bonfond B.,
Gustin J.,
Grodent D.,
Clarke J. T.,
Bisikalo D.,
Shematovich V.
Publication year - 2009
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2008gl036554
Subject(s) - saturn , physics , latitude , electron , altitude (triangle) , spectral line , atmospheric sciences , astrophysics , ionosphere , polar , range (aeronautics) , astronomy , planet , geometry , materials science , mathematics , quantum mechanics , composite material
Images of Saturn's aurora at the limb have been collected with the Advanced Camera for Surveys on board the Hubble Space Telescope. They show that the peak of Saturn's nightside emission is generally located 900–1300 km above the 1‐bar level. On the other hand, methane and H 2 columns overlying the aurora have been determined from the analysis of FUV and EUV spectra, respectively. Using a low‐latitude model, these columns place the emission layer at or above 610 km. One possibility to solve this apparent discrepancy between imaging and spectral observations is to assume that the thermospheric temperature in the auroral region sharply increases at a higher pressure level than in the low‐latitude regions. Using an electron transport code, we estimate the characteristic energy of the precipitated electrons derived from these observations to be in the range 1–5 keV using a low latitude model and 5–30 keV in case of the modified model.