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|Title:||Conjugate observations of Saturn’s northern and southern H[superscript + subscript 3] aurorae|
Stallard, Tom S.
Cowley, Stanley W. H.
Badman, Sarah V.
Baines, Kevin H.
Blake, James S.D.
|Publisher:||Elsevier on behalf of Academic Press|
|Citation:||Icarus, 2014, 229, pp. 214-220|
|Abstract:||We present an analysis of recent high spatial and spectral resolution ground-based infrared observations of H[superscript + subscript 3] obtained with the 10-m Keck II telescope in April 2011. We observed H[superscript + subscript 3] emission from Saturn’s northern and southern auroral regions, simultaneously, over the course of more than 2 h, obtaining spectral images along the central meridian as Saturn rotated. Previous ground-based work has derived only an average temperature of an individual polar region, summing an entire night of observations. Here we analyse 20 H[superscript + subscript 3] spectra, 10 for each hemisphere, providing H[superscript + subscript 3] temperature, column density and total emission in both the northern and southern polar regions simultaneously, improving on past results in temporal cadence and simultaneity. We find that: (1) the average thermospheric temperatures are 527 ± 18 K in northern Spring and 583 ± 13 K in southern Autumn, respectively; (2) this asymmetry in temperature is likely to be the result of an inversely proportional relationship between the total thermospheric heating rate (Joule heating and ion drag) and magnetic field strength – i.e. the larger northern field strength leads to reduced total heating rate and a reduced temperature, irrespective of season, and (3) this implies that thermospheric heating and temperatures are relatively insensitive to seasonal effects.|
|Rights:||Copyright © 2013 The Authors. Published by Elsevier Inc. All rights reserved. This is an open-access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.|
|Appears in Collections:||Published Articles, Dept. of Physics and Astronomy|
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