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Interpretation of the Near-IR Spectra of the Kuiper Belt ObjectVisible and near-IR observations of the Kuiper Belt Object (136472) 2005 FY(9) have indicated the presence of unusually long (1 cm or more) optical path lengths in a layer of methane ice. Using microphysical and radiative transfer modeling, we show that even at the frigid temperatures in the outer reaches of the solar system, a slab of low porosity methane ice can indeed form by pressureless sintering of micron-sized grains, and it can qualitatively reproduce the salient features of the measured spectra. A good semiquantitative match with the near-IR spectra can be obtained with a realistic slab model, provided the spectra are scaled to a visible albedo of 0.6, at the low end of the values currently estimated from Spitzer thermal measurements. Consistent with previous modeling studies, matching spectra scaled to higher albedos requires the incorporation of strong backscattering effects. The albedo may become better constrained through an iterative application of the slab model to the analysis of the thermal measurements from Spitzer and the visible/near-IR reflectance spectra. The slab interpretation offers two falsifiable predictions (1) Absence of an opposition surge, which is commonly attributed to the fluffiness of the optical surface. This prediction is best testable with a spacecraft, as Earth-based observations at true opposition will not be possible until early next century. (2) Unlikelihood of the simultaneous occurrence of very long spectroscopic path lengths in both methane and nitrogen ice on the surface of any Kuiper Belt Object, as the more volatile nitrogen would hinder densification in methane ice.
Document ID
20090001861
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Eluszkiewicz, Janusz (Atmospheric and Environmental Research, Inc. Lexington, MA, United States)
Cady-Pereira, Karen (Atmospheric and Environmental Research, Inc. Lexington, MA, United States)
Brown, Michael E. (California Inst. of Tech. Pasadena, CA, United States)
Stansberry, John A. (Arizona Univ. Tucson, AZ, United States)
Date Acquired
August 24, 2013
Publication Date
June 15, 2007
Publication Information
Publication: Journal of Geophysical Research - Planets
Volume: 112
ISSN: 0148-0227
Subject Category
Lunar and Planetary Science and Exploration
Funding Number(s)
CONTRACT_GRANT: NNH04CC40C
Distribution Limits
Public
Copyright
Other