A determination of the composition of the Saturnian stratosphere using the IUE |
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| Authors: | Peter Winkelstein John Caldwell SJ Kim M Combes GE Hunt V Moore |
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| Institution: | Department of Earth and Space Sciences, SUNY at Stony Brook, Stony Brook, New York 11794, USA;Section d''Astrophysique, Observatoire de Paris, Meudon 92190, France;Department of Physics and Astronomy, University College London, London WCIE 6BT, England |
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| Abstract: | We reduced ultraviolet spectra of Saturn from the IUE satellite to produce a geometric albedo of the planet from 1500 to 3000 Å. By matching computer models to the albedo we determined a chemical composition consistent with the data. This model includes C2H2 and C2H6 with mixing ratios and distributions of (9 ± 3) × 10?8 in the top 20 mbar of the atmosphere with none below for C2H2 and (6 ± 1) × 10?6 also in the top 20 mbar with none below for C2H6. The C2H2 and C2H6 distributions and the C2H6 mixing ratio are taken directly from the Voyager IRIS model R. Courtin et al., Bull. Amer. Astron. Soc.13, 722 (1981), and private communication]. The Voyager IRIS model also includes PH3, which is not consistent with the uv albedo from 1800 to 2400 Å. Our model requires a previously unidentified absorber to explain the albedo near 1600 Å. After considering several candidates, we find that the best fit to the data is obtained with H2O, having a column density of (6 ± 1) × 10?3 cm-am. |
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