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W. F. Bottke (SWRI), A. Morbidelli (Obs. de la Cote d'Azur), R. Jedicke (U. Hawaii), J. S. Stuart, J. B. Evans, G. Stokes (MIT Lincoln Lab)
The remarkable progress made in finding near-Earth objects (NEOs) over the last decade by dedicated NEO surveys has been accompanied by substantial numerical and theoretical work. Together, these advances have given us a much more profound understanding of the NEO population than we have had at any time in the past. Recent models of the NEO orbital and size distributions have been made using different techniques (e.g., Bottke et al. 2000, 2002; Stuart 2001). In Bottke et al., an NEO model was produced by combining numerical integration work with computations of observational biases. This model was calibrated by fitting model parameters to a relatively small sample of 138 NEOs detected by Spacewatch. In Stuart (2001), a NEO model was computed more directly by debiasing the more extensive NEO observations provided by LINEAR. While the results from each model were similar overall, we found that the Bottke et al. model could not reproduce several features of the Stuart model (e.g., specific bumps in the NEO inclination distribution; its somewhat ``flat" shape). To explore this mismatch, we modified our NEO model in two important ways: (i) we added several high inclination sources of NEOs that were excluded by Bottke et al. (2002) (e.g., Hungarias, Phocaeas), and (ii) we joined forces with the LINEAR survey team to explore their extensive NEO data set within our model. While our new results are consistent with previous work, they also indicate that the high inclination asteroid sources contribute to the NEO population at the ~10% level; this may be enough to explain some of the features observed in Stuart (2001). Our latest results, as well as the implications of this work, will be discussed in our talk.
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Bulletin of the American Astronomical Society, 36 #4
© 2004. The American Astronomical Soceity.