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arXiv 1012.5770astro-ph.EP
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大倾角主带小行星的尺度分布

Size Distribution of Main-Belt Asteroids with High Inclination

Tsuyoshi Terai, Yoichi Itoh

摘要:

我们研究了大倾角主带小行星(MBA)的尺寸分布,以探索小行星在10 km/s左右的超高速碰撞下的碰撞演化。我们使用8.2米斯巴鲁望远镜和斯巴鲁Prime Focus相机(Suprime-Cam)对高倾角亚千米MBA进行了宽视场调查。还使用了Suprime-Cam存档数据。在SDSS r滤波器中,在9.0度^[2]的区域内总共探测到616个MBA候选者,其极限星等为24.0等。大多数候选直径估计小于1公里。我们发现一个稀缺的亚公里MBA与高倾向。累积尺寸分布(CSD)是使用斯巴鲁数据和公布的小行星目录构建的。在0.7-50 km直径范围内,低倾角(< 15度)MBA的CSD幂律指数为2.17 +/- 0.02,高倾角(> 15度)MBA的CSD幂律指数为2.02 +/- 0.03。高倾向的MBA有一个较浅的CSD。我们还发现,S型MBA的CSD有一个小的斜率与高倾角,而斜率不随倾角在C型组。超高速碰撞中,大倾角S型MBAs产生浅CSD的最可能原因是直径-冲击强度曲线中的大幂律指数。在行星形成的最后阶段的动力学激发阶段,MBA的碰撞演化可能已经推进了寡头生存。

英文摘要:

We investigated the size distribution of high-inclination main-belt asteroids (MBAs) to explore asteroid collisional evolution under hypervelocity collisions of around 10 km/s. We performed a wide-field survey for high-inclination sub-km MBAs using the 8.2-m Subaru Telescope with the Subaru Prime Focus Camera (Suprime-Cam). Suprime-Cam archival data were also used. A total of 616 MBA candidates were detected in an area of 9.0 deg^2 with a limiting magnitude of 24.0 mag in the SDSS r filter. Most of candidate diameters were estimated to be smaller than 1 km. We found a scarcity of sub-km MBAs with high inclination. Cumulative size distributions (CSDs) were constructed using Subaru data and published asteroid catalogs. The power-law indexes of the CSDs were 2.17 +/- 0.02 for low-inclination (< 15 deg) MBAs and 2.02 +/- 0.03 for high-inclination (> 15 deg) MBAs in the 0.7-50 km diameter range. The high-inclination MBAs had a shallower CSD. We also found that the CSD of S-like MBAs had a small slope with high inclination, whereas the slope did not vary with inclination in the C-like group. The most probable cause of the shallow CSD of the high-inclination S-like MBAs is the large power-law index in the diameter-impact strength curve in hypervelocity collisions. The collisional evolution of MBAs may have advanced with oligopolistic survival during the dynamical excitation phase in the final stage of planet formation.

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