Ejecta emplacement as the possible origin of Ryugu's equatorial ridge
Ejecta emplacement as the possible origin of Ryugu's equatorial ridge
复制标题
DOI：
10.1016/j.icarus.2021.114590
复制
发表时间：
2021-10
期刊：
影响因子：
3.2
通讯作者：
Ren Ikeya;N. Hirata
中科院分区：
文献类型：
--
作者：
Ren Ikeya;N. Hirata
日本航天器Hayabusa 2访问了小行星(162173)Ryugu，并提供了许多其表面的高分辨率图像，揭示了Ryugu具有旋转的顶部形状和突出的赤道脊，与报道的其他一些小行星的形状非常相似。在这项研究中，通过几十个数值计算，我们证明了在快速自转期间，从中低纬度形成的陨石坑喷出的物质可以沉积在赤道脊上。假设自转周期为3小时，我们估计主带小行星在128My 27+47My或近地小行星3.1Gy1.2+4.2Gy时可产生高度为50−的赤道脊线。因此，赤道脊可以在主带内一公里大小的小行星的平均碰撞寿命内形成，但不能在近地小行星上形成。此外，我们的模型可以解释为什么蓝色(年轻)物质出现在赤道脊上。
The Japanese spacecraft Hayabusa 2 visited the asteroid (162173) Ryugu and provided many high-resolution images of its surface, revealing that Ryugu has a spinning-top shape with a prominent equatorial ridge, much like the shapes reported for some other asteroids. In this study, through dozens of numerical calculations, we demonstrate that during a period of fast rotation, ejecta from craters formed at lower and mid-latitudes can be deposited on the equatorial ridge. Assuming a rotation period of 3 h, we estimate that an equatorial ridge with a height of 50 m can be generated in 128−27+47My for a main-belt asteroid, or 3.1−1.2+4.2Gy for a near-Earth asteroid. Therefore, an equatorial ridge can form within the average mean collisional lifetime of a km-sized asteroid within the main belt, but not for near-Earth asteroids. Furthermore, our model may explain why blue (younger) material occurs on the equatorial ridge.