论文标题
Ryugu撞击坑的空间分布
The spatial distribution of impact craters on Ryugu
论文作者
论文摘要
小行星162173 Ryugu有许多陨石坑。 Sugita等人对Ryugu的撞击弹药的初步测量。 （2019年），基于Hayabusa2 ONC图像在2018年6月到来的Hayabusa2到达后的第一个月获得的。使用直到2019年2月拍摄的新图像，我们构建了Ryugu的全球影响火山口目录，其中包括所有大于Ryugu表面上大于20 m的craters。结果，我们在Ryugu表面上确定了77个陨石坑。 Ryugu显示出陨石坑密度的变化，无法通过碎屑的随机性来解释；在较低的纬度地区，有更多的陨石坑，而在较高的纬度上，山瓣的量角较少，而西部凸起（160 e -290 e）的陨石坑比子午线周围的区域（300 e -30 e）少。这种变化意味着Ryugu的复杂地质历史。似乎火山口密度的纵向变化只是表明火山口年龄的变化。子午线周围的火山口似乎在地质上很旧，而西方凸起相对较小。火山口密度的纬度变化表明，龙古的赤道山脊是地质古老的结构。但是，这可以通过在Ryugu的短期旋转期间与许多裂变碎片发生碰撞来替代。
Asteroid 162173 Ryugu has numerous craters. The initial measurement of impact craters on Ryugu, by Sugita et al. (2019), is based on Hayabusa2 ONC images obtained during the first month after the arrival of Hayabusa2 in June 2018. Utilizing new images taken until February 2019, we constructed a global impact crater catalogue of Ryugu, which includes all craters larger than 20 m in diameter on the surface of Ryugu. As a result, we identified 77 craters on the surface of Ryugu. Ryugu shows variation in crater density which cannot be explained by the randomness of cratering; there are more craters at lower latitudes and fewer at higher latitudes, and fewer craters in the western bulge (160 E - 290 E) than in the region around the meridian (300 E - 30 E). This variation implies a complicated geologic history for Ryugu. It seems that the longitudinal variation in crater density simply indicates variation in the crater ages; the cratered terrain around the meridian seems to be geologically old while the western bulge is relatively young. The latitudinal variation in crater density suggests that the equatorial ridge of Ryugu is a geologically old structure; however, this could be alternatively explained by a collision with many fission fragments during a short rotational period of Ryugu in the past.
