论文标题
内部小行星带的动态演化
Dynamical evolution of the inner asteroid belt
论文作者
论文摘要
小行星带的动态演化的确定很困难，因为小行星带从小行星形成以来已经通过包括：（1）灾难性碰撞，（2）旋转破坏，（3）混乱轨道进化和（4）yarkovsky radiation drive驱动的旋转轨道进化。这些损失机制的时间尺度不确定，需要更加观察性约束。在内部主带中，非家庭小行星的平均大小随着倾向的增加而增加。在这里，我们使用该观察结果表明，所有内部主要的小行星都来自已知家庭或鬼家庭，即具有分散轨道元素的老家庭。我们估计，幽灵家族中小行星的平均年龄比Yarkovsky Orbital Evolution Evolution Timesscale少1/3倍。但是，这种轨道演化时间尺度是长期平均值，必须允许小行星的碰撞演化以及其自旋方向的随机变化。通过将这些约束应用于轨道演化的时间尺度上，即Vesta小行星家族的尺寸频率分布的演变，我们估计该家族的年龄大于1.3 $ gyr $，并且可以与太阳系的年龄相提并论。通过估计幽灵家族的数量，我们计算出是陨石的根源和源自内部主带的近地小行星的小行星数量约为20。
A determination of the dynamical evolution of the asteroid belt is difficult because the asteroid belt has evolved since the time of asteroid formation through mechanisms that include: (1) catastrophic collisions, (2) rotational disruption, (3) chaotic orbital evolution and (4) orbital evolution driven by Yarkovsky radiation forces. The timescales of these loss mechanisms are uncertain and there is a need for more observational constraints. In the inner main belt, the mean size of the non-family asteroids increases with increasing inclination. Here, we use that observation to show that all inner main belt asteroids originate from either the known families or from ghost families, that is, old families with dispersed orbital elements. We estimate that the average age of the asteroids in the ghost families is a factor of 1/3 less than the Yarkovsky orbital evolution timescale. However, this orbital evolution timescale is a long-term average that must allow for the collisional evolution of the asteroids and for stochastic changes in their spin directions. By applying these constraints on the orbital evolution timescales to the evolution of the size-frequency distribution of the Vesta asteroid family, we estimate that the age of this family is greater than 1.3 $Gyr$ and could be comparable with the age of the solar system. By estimating the number of ghost families, we calculate that the number of asteroids that are the root sources of the meteorites and the near-Earth asteroids that originate from the inner main belt is about 20.
