NEAR-INFRARED SPECTROSCOPY OF LOW-ALBEDO SURFACES OF THE SOLAR-SYSTEM- SEARCH FOR THE SPECTRAL SIGNATURE OF DARK MATERIAL

We obtained I-J-H-K band spectroscopy of 18 low-albedo objects of the Solar System using the University of Hawaii 88-in. telescope equipped with the near-infrared spectrograph KSPEC, Most of our targets were se lected from among the population of the Cybele, Hilda, and Trojan grou ps of asteroids, based on their low albedos and the relatively steep s lopes of their reflection spectra at visible wavelengths. The outer jo vian satellite Himalia and the Apollo object 3200 Phaethon were also o bserved, None of the spectra show absorptions similar to those found i n the spectrum of 5145 Pholus, which remains the only asteroid-like ob ject whose H-K band reflection spectrum contains a few broad absorptio ns due to organics. The near-infrared slope and the (1.0- to 2.2-mu m) infrared color-index have been derived for each surface, This sample of primitive objects of the Solar System can be interpreted in terms o f cometary-like objects that have undergone different degrees of aging , (C) 1998 Academic Press.