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Table 1

Oort dynamical groups.

Oort group a0 (au) 1/a0 (au−1) P (yr)
New >10 000 0 to 10−4 >106
Intermediate 500 to 10 000 10−4 to 2 × 10−3 11 180 to 106
Old 25 to 500 2 × 10−3 to 4 × 10−2 125 to 11 180
Periodic <25 >4 × 10−2 <125

Notes. Dynamical groups (column 1) defined in Oort & Schmidt (1951), their original semi-major axis (column 2) and its reciprocal (column 3), and their range of orbital periods (column 4). Only the dynamically new, intermediate, and old groups are used throughout the paper.

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