Surface materials on unusual planetary object chiron |
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| Authors: | William K Hartmann Dale P Cruikshank Johan Degewij RW Capps |
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| Institution: | Planetary Science Institute, 2030 E. Speedway, Suite 201, Tucson, Arizona 85719, USA;Institute for Astronomy, University of Hawaii, Honolulu, Hawaii 96822, USA;Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109, USA;Institute for Astronomy, University of Hawaii, Honolulu, Hawaii 96822, USA |
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| Abstract: | We present the first JHK near-infrared colorimetry giving some indication of the surface materials on the peculiar object 2060 Chiron. The colors appear to exclude relatively clean bright ice surfaces, such as those of Europa, Ganymede, Rhea, Dione, and theoretically studied micronscale clean ice particles. The colors are consistent with those of numerous outer solar system asteroids, which in all measured cases have: albedos of only a few percent, C?, RD?, or DM-type spectra, and no known H2O ice absorption features. The colors are also consistent with theoretical colors for certain size distributions of dirty ice grains. These and additional VJHK colorimetric data suggest that the spectrally dominant surface is C-type material, probably dark carbonaceous-like silicate dust, with a possible admixture of ice grains on a microscale. If Chiron has the low albedo common to such material on known interplanetary bodies, its diameter would be about 310 to 400 km, placing Chiron among the eight largest “asteroids”. Relationships to comet observations are discussed. |
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