A determination of the composition of the Saturnian stratosphere using the IUE |
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| Authors: | Peter Winkelstein John Caldwell S.J. Kim M. Combes G.E. Hunt V. Moore |
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| Affiliation: | 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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