Titan's 5-micron lightcurve
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.
- Publication:
-
Icarus
- Pub Date:
- March 2004
- DOI:
- 10.1016/j.icarus.2003.12.001
- Bibcode:
- 2004Icar..168..209L
- Keywords:
-
- planets;
- Titan;
- Infrared observations