[FPSPACE] Physical Properties of Kuiper Belt and Centaur Objects: Constraints from Spitzer

[LARRY KLAES]

Astrophysics, abstract
astro-ph/0702538

From: John Stansberry [view email]

Date: Tue, 20 Feb 2007 18:49:52 GMT (396kb)

Physical Properties of Kuiper Belt and Centaur Objects: Constraints from 
Spitzer Space Telescope

Authors: John Stansberry, Will Grundy, Mike Brown, Dale Cruikshank, John 
Spencer, David Trilling, Jean-Luc Margot

Comments: 19 pages, 3 figures, 5 tables

Detecting heat from minor planets in the outer solar system is challenging, 
yet it is the most efficient means for constraining the albedos and sizes of 
Kuiper Belt Objects (KBOs) and their progeny, the Centaur objects. These 
physical parameters are critical, e.g., for interpreting spectroscopic data, 
deriving densities from the masses of binary systems, and predicting 
occultation tracks. Here we summarize Spitzer Space Telescope observations 
of 47 KBOs and Centaurs at wavelengths near 24 and 70 microns. We interpret 
the measurements using a variation of the Standard Thermal Model (STM) to 
derive the physical properties (albedo and diameter) of the targets. We also 
summarize the results of other efforts to measure the albedos and sizes of 
KBOs and Centaurs. The three or four largest KBOs appear to constitute a 
distinct class in terms of their albedos. From our Spitzer results, we find 
that the geometric albedo of KBOs and Centaurs is correlated with perihelion 
distance (darker objects having smaller perihelia), and that the albedos of 
KBOs (but not Centaurs) are correlated with size (larger KBOs having higher 
albedos). We also find hints that albedo may be correlated with with visible 
color (for Centaurs). Interestingly, if the color correlation is real, 
redder Centaurs appear to have higher albedos. Finally, we briefly discuss 
the prospects for future thermal observations of these primitive outer solar 
system objects.

http://arxiv.org/abs/astro-ph/0702538