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Titan's 5-micron lightcurve |
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| Authors: | E Lellouch B Schmitt J-G Cuby |
| Institution: | a LESIA, Observatoire de Paris, F-92195 Meudon, France b Laboratoire de Planétologie de Grenoble, F-38406 St Martin d'Hères, France c European Southern Observatory, Santiago, Chile |
| Abstract: | We report on repeated mid-resolution (R∼2000) spectroscopic observations of Titan, acquired between November 2002 and January 2003 with ISAAC at the ESO/VLT and covering the 4.84-5.05 μm range. These observations, which sample four different positions of Titan around Saturn, clearly indicate a variability of the 5-μm continuum albedo, with Titan's geometric albedo decreasing by ∼40% from Titan's leading side to the trailing side. This Titan 5-μm “lightcurve” appears to be in phase with the other near-infrared lightcurves. This can be understood in terms of a surface model in which water ice coexists in minor and variable proportions (13-25%, if pure) with a second, dark, component. |
| Keywords: | Surfaces planets Titan Infrared observations |
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