DPS 34th Meeting, October 2002
Session 9. Centaurs and Kuiper Belt Objects II
Oral, Chair(s): D. Jewitt and R. Millis, Monday, October 7, 2002, 4:30-6:00pm, Ballroom

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[9.06] The population size distribution of the Kuiper Belt

D. E. Trilling (U Penn)

The physical properties of Kuiper Belt Objects are determined by both the accretional and erosional histories of the Kuiper Belt. These two physical processes produce different slopes in the distribution of KBO sizes. We have used the orbital elements and magnitudes for the 219 designated/numbered KBOs discovered in the large-scale, relatively uniform Deep Ecliptic Survey (Millis et al.) to determine a population size distribution for a subset of the Kuiper Belt. This population size distribution is relatively free from biases that are unavoidable when data from more than one observing program are combined, although biases are still present in this data set. The observed population size distribution obeys a power law with a slope of -4 for bodies with radii 350 km > r > 150 km. This slope is consistent with that expected from KBO accretion models. The very largest KBOs (e.g., 28978 Ixion, radius around 600 km) do not obey the population size distribution power law; this behavior is reminiscent of signatures of oligarchic growth. An upcoming HST program (Bernstein et al.) will determine the population size distribution down to 20-40 km bodies. This HST program will test for a break in slope to a collisionally evolved, erosional KBO population (with a predicted slope of -3.5) at smaller sizes.

This work is supported by grants from the AAS and from STScI.

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Bulletin of the American Astronomical Society, 34, #3< br> © 2002. The American Astronomical Soceity.