Peak emission altitude of Saturn's H3+ aurora

Tom S. Stallard, Henrik Melin, Steve Miller, Sarah V. Badman, Robert H. Brown, Kevin H. Baines

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Abstract

[1] Here we present the first detailed measurement of the altitudinal profile of H3+ emission within Saturn's ionosphere, made using images taken by the VIMS instrument on Cassini on 11–12 October 2006, during a chance alignment between the visible limb of the planet and the position of the main auroral emission. Using this, we show that the emission profile of H3+ can be fitted to a reasonable accuracy with a Gaussian, producing a calculated peak emission altitude at 1155 (±25) km that differs significantly from previous observations of the UV emission profile, and also from the predictions of models that calculated the H3+ emission profile, which suggested that there would be extended emission above the peak emission altitude. This lack of extended emission is most simply explained by differences in the scale height of H and H2, suggesting that models overestimate H2 at high altitudes, with little H2 from 2000 km above the 1 bar level.
Original languageEnglish
Article numberL15103
Number of pages5
JournalGeophysical Research Letters
Volume39
Issue number15
Early online date7 Aug 2012
DOIs
Publication statusPublished - 16 Aug 2012
Externally publishedYes

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