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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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