Are Hyperion and Phoebe linked to Lapetus?

Narrowband reflectance spectra of the saturnian satellites S VII Hyperion a nd S LY Phoebe were obtained across the 0.4- to 0.8-mu m spectral region, T he spectrum of Phoebe shows an absorption feature centered near 0.43 mu m s uperimposed on the UV/blue intervalence charge transfer transition present in the spectrum, similar to absorptions identified in the spectra of C-clas s asteroids (Vilas et al. 1993b. Icarus 105, 67-78), We use a linear mixing model to separate the reflectance spectrum of the dark material on Hyperio n from the icy material. A distinct absorption feature centered at 0.67 mu m is present. A slight inflection suggesting an absorption feature near 0.4 -0.6 mu m, and change in slope near 0.73 mu m suggesting the lower waveleng th edge of an absorption, are also present. These absorptions are very simi lar to those identified in the spectrum of the dark material on the surface of Iapetus (Vilas et al, 1996. Icarus 124, 262-267), suggesting that the d ark material on these two satellites is compositionally similar and has a s imilar origin. We attribute these absorption features to the (6)A(1) --> T- 4(2)(G) and (6)A(1) --> T-4(1)(G) ferric charge transfer transitions in iro n alteration minerals such as goethite and hematite that are products of th e aqueous alteration of anhydrous silicates. (C) 2000 Academic Press.