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J.A. Stansberry (Univ. Arizona.), D.P. Cruikshank (NASA Ames), W.M. Grundy (Lowell Observatory), J.P. Emery (NASA Ames), D.J. Osip (Las Campanas Observatories), Y. R. Fernandez (U. Hawaii), J. vanCleve (Ball Aerospace), D.E. Trilling (Univ. Arizona)
We have detected the thermal emission from a sample of 14 Kuiper Belt Objects (KBOs) and 8 Centaurs using the Multiband Imaging Photometer (MIPS) on Spitzer. MIPS operates at wavelengths of 24, 70 and 160 \mum; observations were made in various combinations of those bands, with band selection depending on the predicted thermal spectrum of the target. The emission appears to be fairly well described by the Standard Thermal Model (STM) for most of the targets that were detected at 24 and 70 \mum. An exception to that is 2002 AW197, which was detected at a distance of 47 AU and appears to be spectrally cooler than would be predicted by the STM, consistent with it being a fast rotator (in the thermal sense). Our data suggest that the geometric albedos of KBOs and Centaurs may be somewhat higher than the typically assumed value of 4 or 5%, and confirm that albedo varies considerably, as might be expected based on their diverse colors. We will provide an overview of our results in terms of albedos and diameters of individual objects, correlation of albedo with visible colors and dynamical properties, and limits on cometary activity. (This work supported, in-part, by NASA contract 960785, issued by JPL/CalTech.)
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Bulletin of the American Astronomical Society, 36 #4
© 2004. The American Astronomical Soceity.