标题： 撞击体通量和谷神星与灶神星的撞击坑：对早期太阳系的意义 显示英文标题

标题： Impactor flux and cratering on Ceres and Vesta: Implications for the early Solar System

摘要： 我们研究由小行星主带的碰撞和动力演化引起的撞击体通量和谷神星与灶神星上的撞击坑。 我们开发了一个基于经过验证的模型的统计代码，用于同时演化主带和近地天体（NEA）的尺寸分布。 该代码包括灾难性碰撞以及非碰撞移除过程，如雅科夫斯基效应和轨道共振。 该模型假设早期主带的动力耗竭非常强烈，因此大部分主带粉碎发生在其动力结构类似于现在的时候。 我们的结果表明，在太阳系历史上，直径大于1公里的主带小行星撞击谷神星和灶神星的数量分别约为4600和1100。 预计撞击谷神星和灶神星的最大主带小行星的直径分别为71.7公里和21.1公里。 谷神星上直径大于0.1公里的撞击坑数量为\sim 3.4\times 10^8，而灶神星上为6.2\times 10^7。 直径大于100公里的撞击坑数量在谷神星上有47个，在灶神星上有8个。 我们的研究显示，观测到的灶神星上直径为460公里的撞击坑必须是由直径\sim 66.2公里的弹丸撞击形成的，这在太阳系历史中发生的概率为\sim 30%。 如果在我们关于谷神星和灶神星撞击坑的结果与来自黎明号任务的数据之间发现显著差异，那么这些差异应归因于早期主带更高的碰撞演化程度和/或晚期重轰炸的存在。 早期阶段碰撞活动的增加可能由与尼克斯模型一致的巨行星初始配置提供。 由此，黎明号任务能够为我们提供关于早期太阳系初始配置及其后续动力演化的重要线索。 显示英文摘要

摘要： We study the impactor flux and cratering on Ceres and Vesta caused by the collisional and dynamical evolution of the asteroid Main Belt. We develop a statistical code based on a well-tested model for the simultaneous evolution of the Main Belt and NEA size distributions. This code includes catastrophic collisions and noncollisional removal processes such as the Yarkovsky effect and the orbital resonances. The model assumes that the dynamical depletion of the early Main Belt was very strong, and owing to that, most Main Belt comminution occurred when its dynamical structure was similar to the present one. Our results indicate that the number of D > 1 km Main Belt asteroids striking Ceres and Vesta over the Solar System history are approximately 4 600 and 1 100 respectively. The largest Main Belt asteroids expected to have impacted Ceres and Vesta had diameters of 71.7 km and 21.1 km. The number of D > 0.1 km craters on Ceres is \sim 3.4 \times 10^8 and 6.2 \times 10^7 on Vesta. The number of craters with D > 100 km are 47 on Ceres and 8 on Vesta. Our study indicates that the D = 460 km crater observed on Vesta had to be formed by the impact of a D \sim 66.2 km projectile, which has a probability of occurr \sim 30% over the Solar System history. If significant discrepancies between our results about the cratering on Ceres and Vesta and data obtained from the Dawn Mission were found, they should be linked to a higher degree of collisional evolution during the early Main Belt and/or the existence of the late heavy bombardment. An increase in the collisional activity in the early phase may be provided for an initial configuration of the giant planets consistent with, for example, the Nice model. From this, the Dawn Mission would be able to give us clues about the initial configuration of the early Solar System and its subsequent dynamical evolution.