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Interpretation of the near-IR spectra of the Kuiper Belt Object (136472) 2005 FY_9

Eluszkiewicz, Janusz and Cady-Pereira, Karen and Brown, Michael E. and Stansberry, John A. (2007) Interpretation of the near-IR spectra of the Kuiper Belt Object (136472) 2005 FY_9. Journal of Geophysical Research E, 112 (E6). Art. No. E06003. ISSN 0148-0227. doi:10.1029/2007JE002892.

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Visible 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.

Item Type:Article
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Brown, Michael E.0000-0002-8255-0545
Additional Information:© 2007 American Geophysical Union. Received 9 January 2007; revised 26 February 2007; accepted 5 April 2007; published 15 June 2007. Work at AER has been supported by the NASA Planetary Geology and Geophysics Program.
Group:UNSPECIFIED, Division of Geological and Planetary Sciences
Funding AgencyGrant Number
Subject Keywords:Kuiper Belt Objects; 2005 FY9; near-IR spectra; solid methane; sintering; slab model
Issue or Number:E6
Record Number:CaltechAUTHORS:20120925-113354526
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Official Citation:Eluszkiewicz, J., K. Cady-Pereira, M. E. Brown, and J. A. Stansberry (2007), Interpretation of the near-IR spectra of the Kuiper Belt Object (136472) 2005 FY9, J. Geophys. Res., 112, E06003, doi:10.1029/2007JE002892.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:34351
Deposited By: Ruth Sustaita
Deposited On:25 Sep 2012 18:47
Last Modified:09 Nov 2021 23:07

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