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Published November 20, 2009 | Published
Journal Article Open

The Collisional Divot in the Kuiper Belt Size Distribution

Abstract

This paper presents the results of collisional evolution calculations for the Kuiper Belt starting from an initial size distribution similar to that produced by accretion simulations of that region—a steep power-law large object size distribution that breaks to a shallower slope at r ~ 1-2 km, with collisional equilibrium achieved for objects r ≾ 0.5 km. We find that the break from the steep large object power law causes a divot, or depletion of objects at r ~ 10-20 km, which, in turn, greatly reduces the disruption rate of objects with r ≳ 25-50 km, preserving the steep power-law behavior for objects at this size. Our calculations demonstrate that the roll-over observed in the Kuiper Belt size distribution is naturally explained as an edge of a divot in the size distribution; the radius at which the size distribution transitions away from the power law, and the shape of the divot from our simulations are consistent with the size of the observed roll-over, and size distribution for smaller bodies. Both the kink radius and the radius of the divot center depend on the strength scaling law in the gravity regime for Kuiper Belt objects. These simulations suggest that the sky density of r ~ 1 km objects is ~10^6-10^7 objects per square degree. A detection of the divot in the size distribution would provide a measure of the strength of large Kuiper Belt objects, and constrain the shape of the size distribution at the end of accretion in the Kuiper Belt.

Additional Information

© 2009 The American Astronomical Society. Received 2009 February 17; accepted 2009 October 1; published 2009 October 28. A special thank goes to J. J. Kavelaars and Mike Brown without whose guidance this work would have never come to fruition. I also thank David Trilling for his useful advice on what I should be looking for. Finally, I thank Parker, Raggozzine, Schwamb, and Bannister for humoring me during my rants. This project was funded in part, by the National Science and Engineering Research Council and the National Research Council of Canada. Support for this work was provided in part by NASA through a grant from the program HST-GO-11644 from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc. under NASA contract NAS 5-26555. This research used the facilities of the Canadian Astronomy Data Centre operated by the National Research Council of Canada with the support of the Canadian Space Agency.

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August 21, 2023
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