Collisional Evolution of Asteroid Families
Collisional Evolution of Asteroid Families
复制标题
小行星家族的碰撞演化
DOI：
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发表时间：
1995
期刊：
影响因子：
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通讯作者：
V. Vanzani
中科院分区：
文献类型：
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作者：
F. Marzari;D. Davis;V. Vanzani
摘要大多数小行星动力学族被认为是母小行星与其他小行星高速碰撞破坏的结果。然而，随后的碰撞改变了家族成员的大小和轨道，因此我们今天看到的分布可能与母体分裂后的分布非常不同。我们研究了家庭小行星的postbreakup演化的数值模型，它保持跟踪的大小和轨道的碎片，因为它们碰撞相互作用的领域人口的小行星。使用这个模型，我们可视化家庭如何出现在不同的进化阶段。特别是，我们发现，家庭的规模分布变得不那么陡峭的时间。我们已经模拟了可能的进化历史的三个人口最多的平山家庭，Koronis，Eos和忒弥斯。通过匹配的大小和轨道的分布与观察到的家庭，我们得到显着的限制其母体的属性和一些碰撞响应参数，连同家庭的进化年龄。忒弥斯家族似乎是最大的小行星之一灾难性破坏的结果，这可能是太阳系历史上的一个独特事件。另一方面，Koronis和Eos家族似乎是由较小的母体形成的，但特殊的特征可能需要特定的过程或事件。科罗尼斯的大小分布在大直径一端有几个大小相当的天体，这可以解释为最初分裂的最大碎片随后发生了碎裂。Eos家族的“各向异性”轨道分布要么需要一个特殊的碎片速度场，要么需要对其成员轨道的知之甚少的动力学过程的作用。对于这两个Koronis和忒弥斯家庭，我们得出的估计年龄的顺序2 Byr。影响我们对家族年龄和母天体性质估计的不确定性主要是由于目前对数百公里大小天体的碰撞破裂过程了解有限，以及对小行星的大小分布了解不多。
Abstract Most asteroid dynamical families are thought to be the outcomes of collisional disruption of parent asteroids destroyed by high-velocity impacts with other astroids. However, subsequent collisions modify both the sizes and the orbits of family members, so the distributions that we see today may be very different from those following the breakup of the parent body. We study the postbreakup evolution of family asteroids with a numerical model which keeps track of both the sizes and the orbits of the fragments as they collisionally interact with the field population of asteroids. Using this model we visualize how the family appears at different evolutionary stages. In particular we find that the size distribution of a family becomes less steep with time. We have simulated the possible evolutionary history of the three most populous Hirayama families, Koronis, Eos, and Themis. By matching the distribution of sizes and orbits with those observed for the families, we obtain significant constraints on the properties of their parent bodies and on some collisional response parameters, together with the evolutionary ages of the families. The Themis family appears as the outcome of the catastrophic disruption of one of the largest asteroids, probably a unique event over the history of the Solar System. On the other hand, the Koronis and Eos families appear to have been formed from smaller parent bodies, but peculiar features may require specific processes or events. Koronis' size distribution has several bodies of comparable size at the large diameter end, which can be explained if the largest fragment of the initial breakup underwent subsequent fragmentation. The "anisotropic" orbital distribution of the Eos family requires either a peculiar fragment velocity field or the action of poorly understood dynamical processes on the orbits of its members. For both the Koronis and the Themis families we derive an estimate of the age of the order of 2 Byr. The uncertainties affecting our estimates of family ages and of the properties of the parent bodies are mainly due to the present limited understanding of collisional breakup processes for bodies hundreds of kilometers in size and to the poor knowledge of the size distribution of small asteroids.