CCD PHOTOMETRY AND SPECTROSCOPY OF THE OUTER JOVIAN-SATELLITES

We present new charge-coupled device (CCD) photometry and spectroscopy of the eight outer Jovian satellites obtained from November 1987 to February 1989. The photometry consists of light curves for J7-J12, plus BVRI colors for J6, J8-J13. Spectroscopic data include reflectance spectra for J6, J8-J11. The satellites are spectrally diverse, with reflectivity gradients ranging from neutral (0.4% +/- 0.1%/10(3) angstrom) to red (12% +/- 1%/10(3) angstrom). The satellites thus resemble a mixture of C- and D-type asteroids. Similarities between the satellites and Trojan asteroids (diverse colors, low albedos) are consistent with the hypothesis that these two groups of objects share a common origin [Kuiper, Vistas in Astronomy, 2, 1631 (1956)]. However, the satellites seem to have less extreme shapes than the Trojans, perhaps due to the longer amount of time they spent in the proto-Jupiter nebula. Physical properties of the satellites are generally consistent with, but do not prove, the capture origin theory [Pollack et al., Icarus, 37, 587 (1979)].