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Kuiper Belt and Centaur Objects
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Title: 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

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 summarise 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 summarise 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 visible colour (for Centaurs). Interestingly, if the colour 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.

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Kuiper Belt Objects
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Title: On the Dynamics of Resonant Kuiper Belt Objects
Authors: Ing-Guey Jiang (1), Li-Chin Yeh (2) ((1)Department of Physics, National Tsing-Hua University, Hsin-Chu, Taiwan; (2)Department of Applied Mathematics, National Hsinchu University of Education, Hsin-Chu, Taiwan)

We propose a new mechanism of drag-induced resonant capture, which can explain the resonant Kuiper Belt Objects in a natural way. A review and comparison with the traditional mechanism of sweeping capture by the migrating Neptune will be given.

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RE: Kuiper Belt
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(134340) Pluto 1930 01 23 C. W. Tombaugh, Flagstaff
(134568) 1999 RH215 1999 09 07 C. A. Trujillo, D. C. Jewitt, J. X. Luu, Mauna Kea
(134860) 2000 OJ67 2000 07 29 M. W. Buie, S. D. Kern, Cerro Tololo
(135024) 2001 KO76 2001 05 23 M. W. Buie, Cerro Tololo
(135182) 2001 QT322 2001 08 21 M. W. Buie, Cerro Tololo
(135571) 2002 GG32 2002 04 08 M. W. Buie, Cerro Tololo
(135742) 2002 PB171 2002 08 05 Mauna Kea
(136108) 2003 EL61 2003 03 07 F.J. Aceituno, P. Santos-Sanz, J. L. Ortiz, Sierra Nevada
(136120) 2003 LG7 2003 06 01 W. Buie, Cerro Tololo
(136199) 2003 UB313 2003 10 21 M. E. Brown, C. A. Trujillo, D. Rabinowitz, Palomar
(136472) 2005 FY9 2005 03 31 M. E. Brown, C. A. Trujillo, D. Rabinowitz, Palomar

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Researchers say they have found the first evidence that the frozen outer reaches of our solar system could be littered with many more objects than we think.
Astronomers have been trying to get a picture of the region, known as the Kuiper belt, because it is believed to contain debris from the birth of our solar system and so could tell us how planetary systems form.
About 1000 large bodies, including Pluto and the recently discovered Xena, have been located in the Kuiper belt so far.
But smaller objects have evaded detection as they are about 15 billion kilometres from the Sun, making it impossible to see them even with a powerful instrument like the Hubble Space Telescope.
An Australian team from the University of New South Wales (UNSW) and the Anglo-Australian Observatory (AAO) has used optical fibre technology to detect signs of smaller Kuiper belt objects for the first time.
They did this by observing split-second 'winking', or darkening, of stars which suggests a Kuiper belt object is passing in front, or occulting the star.
UNSW student George Georgevits presented his research at a recent workshop attended by international Kuiper belt experts in Italy.
His colleague Associate Professor Michael Ashley of UNSW says the observations offer the first evidence the Kuiper belt contains many more relics of the infant solar system than estimated.

"Basically our observation showed that that are many more, maybe five or 10 times as many, of the smaller objects than theory predicted" - Michael Ashley .

Ashley says Georgevits and fellow researcher Dr Will Saunders of the AAO found evidence of many objects ranging in size from 300 metres to one kilometre across using a 6DF instrument on the UK Schmidt telescope at Siding Spring.
The 6DF, which uses fibre optics, monitored 100 stars simultaneously over two weeks, the equivalent of 7000 star hours, or watching a single star every night for 3 years.

"We've got 100 fibres, each one of which is positioned on a star and then we feed the fibres into a high speed camera" - Michael Ashley .

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