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Determining proportions of lunar crater populations by fitting crater size distribution

Nan Wang, Ji-Lin Zhou

Abstract


We determine the proportions of two mixed crater populations distinguishable by size distributions on the Moon. A “multiple power-law” model is built to formulate crater size distribution N(D) ∝ D−α whose slope α varies with crater diameter D. This model is then used to fit size distributions of lunar highland craters and Class 1 craters. The former is characterized by α = 1.17 ± 0.04, 1.88 ± 0.07, 3.17 ± 0.10 and 1.40 ± 0.15 for D ranges ∼10 − 49, 49 − 120, 120 − 251 and ∼251 − 2500 km, while the latter has a single slope α = 1.96 ± 0.14 for about 10 − 100 km. They are considered as Population 1 and 2 crater size distributions, whose sum is then fitted to the global size distribution of lunar craters with D between 10 and 100 km. Estimated crater densities of Population 1 and 2 are 44 × 10−5 and 5 × 10−5 km−2 respectively, leading to the proportion of the latter being 10%. This result underlines the need for more thoroughly investigating Population 1 craters and their related impactors, the primordial main-belt asteroids, which dominated the late heavy bombardment.


Keywords


planets and satellites: surfaces — Moon — minor planets, asteroids: general

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DOI: http://dx.doi.org/10.1088/1674%E2%80%934527%2F16%2F12%2F185

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Print ISSN: 1674-4527

Online ISSN: 2397-6209