| タイトル | Cosmic-Ray-Exposure Ages of Diogenites and the Collisional History of the HED Parent Body or Bodies |
| 著者（英） | Schultz, L.; Scherer, P.; Lindner, L.; Welten, K. C.; vanderBorg, K.; Loeken, T. |
| 著者所属（英） | NASA Johnson Space Center |
| 発行日 | 1996-01-01
1996 |
| 言語 | eng |
| 内容記述 | Cosmic-ray-exposure ages of meteorites provide information on the collisional history of their parent bodies and the delivery mechanism of meteorites to Earth. The exposure-age distributions of ordinary chondrites show distinct patterns for H, L, and LL types, consistent with their origin on different parent bodies. The exposure-age distributions of howardites, eucrites. and diogenites (HEDS) show a common pattern with major peaks at 22 Ma and 38 Ma This provides additional evidence for a common origin of the HED meteorites, possibly 4 Vesta, although orbital dynamics calculations showed that the delivery of meteorites from Vesta to Earth is difficult. However, the discovery of several kilometer-sized Vesta-like asteroids in the region between Vesta and the 3:1 resonance suggested that these seem more likely parent bodies of the HEDs than Vesta itself. This implies that the exposure-age clusters may represent samples of several parent bodies. Therefore, the near-absence of diogenites with ages <20 Ma might be of interest for the composition of these kilometer-sized fragments of Vesta. Here we present cosmic-ray-exposure ages of 20 diogenites, including 9 new meteorites. In addition, we calculate the probability for each peak to occur by chance, assuming a constant production rate of HED fragments. |
| NASA分類 | Astrophysics |
| 権利 | No Copyright |
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