Conjugate observations of Saturn's northern and southern H3+ aurorae
| Autor: | O'Donoghue, James, Stallard, Tom S., Melin, Henrik, Cowley, Stan W. H., Badman, Sarah V., Moore, Luke, Miller, Steve, Tao, Chihiro, Baines, Kevin H., Blake, James S. D. |
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| Rok vydání: | 2013 |
| Předmět: | |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1016/j.icarus.2013.11.009 |
| Popis: | We present an analysis of recent high spatial and spectral resolution ground-based infrared observations of H3+ spectra obtained with the 10-metre Keck II telescope in April 2011. We observed H3+ emission from Saturn's northern and southern auroral regions, simultaneously, over the course of more than two hours, obtaining spectral images along the central meridian as Saturn rotates. 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 H3+ spectra, 10 for each hemisphere, providing H3+ 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. Comment: 31 pages (single column), 4 figures, 1 table. Accepted in Icarus 7th November 2013 |
| Databáze: | arXiv |
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