Analysis of faint absorption bands in the reflectance spectra of A-type asteroids

Abstract

Faint absorption bands detected in the visible range of the reflectance spectra of A-type asteroids suggest a various mineralogical composition of their surface. From the analysis of these bands, we conclude that, on some asteroids of this optical type, both olivine and pyroxene are present, while mostly clinopyroxene with minor admixtures of Cr-containing minerals, presumably chromites, is on the surface of others. A new esti- mate of the forsterite content in the olivine of the asteroids 289 Nenetta and 446 Aeternitas (Fo ∼ 50-60%) made by the absorption band near 500 nm in their spectra agrees with the estimate we obtained previously from the modeling of the reflectance spectra of the asteroid Aeternitas.