Exploring the Collisional and Dynamical Evolution of Asteroids

AST-0909166该奖项由2009年美国复苏和再投资法案(公法111-5)资助。博特克博士领导的团队将利用最先进的数值模拟和当今的小行星特性，研究碰撞和动力演化如何塑造自吸积结束以来的小型天体种群。这部作品遵循三个主题。1)灶神星是一颗直径530公里的完整的分化小行星，目前在主带中是独一无二的，然而有证据表明，原始主带曾经拥有多达1000个类似灶神星的物体。他们神秘消失的关键线索可以在今天主带的玄武岩、橄榄石和金属碎片中找到，研究小组将利用这些幸存的残留物来收集对失踪的灶神星种群的性质和进化的洞察。2)外主带、希尔达和特洛伊小行星群分别包含15%、90%和90%的小行星类型，根据光谱数据被归类为D类或P类，这些原始天体非常类似于休眠的彗星，其起源存在争议。对这些种群的演化进行数值模拟，以得出D/P小行星的性质，将用于测试各种起源情景。3)小行星种群的历史受到不同小行星家族的存在和演化的严重制约。这里使用的研究工具包括Yarkovsky和YORP(科学家名字的首字母缩写)效应，它们分别是导致小行星经历轨道半长轴漂移和自旋矢量修改的热辐射力和扭矩。这项研究将追踪Yarkovsky/YORP力的耦合动力学效应以及碰撞效应，以模拟特定小行星家族的演化。对于单个家庭，研究小组将能够估计他们的初始速度分布、他们的年龄，以及他们过去是否产生过“小行星阵雨”。这一结果将影响对关键航天器数据的解释，并将有助于描述塑造和分散已知小行星、彗星和陨石的过程。这项研究将包括在科罗拉多州和怀俄明州的小学和高中的持续教育和公共推广工作中，并通过公共和业余天文学媒体。

AST-0909166BottkeThis award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).Using state-of-the-art numerical simulations and present-day asteroid properties, the team led by Dr. Bottke will investigate how collisional and dynamical evolution has shaped small body populations since the end of accretion. The work follows three main themes. 1) Vesta, a 530 km diameter intact differentiated asteroid, is currently unique in the main belt, and yet evidence indicates that the primordial main belt once held as many as one thousand Vesta-like objects. Critical clues to their mysterious disappearance can be found among the basaltic, olivine-rich, and metallic fragments in the main belt today, and the team will use these surviving remnants to glean insights into the nature and evolution of the missing Vesta population. 2) The outer main belt, Hilda, and Trojan populations contain 15%, 90%, and 90% of the type of asteroid classified from spectral data as class D or P, primitive objects that closely resemble dormant comets and whose origin is controversial. Numerical simulations of the evolution of these populations to derive the nature of D/P asteroids will be used to test various origin scenarios. 3) The histories of asteroid populations are critically constrained by the existence and evolution of different asteroid families. The research tools used here include the Yarkovsky and YORP (an acronym of scientists' names) effects, which are thermal radiation forces and torques that cause asteroids to undergo orbital semi-major axis drift and spin vector modifications, respectively. This study will track the coupled dynamical effects of Yarkovsky/YORP forces along with collisional effects, to model the evolution of specific asteroid families. For individual families, the team will be able to estimate their initial velocity distributions, their ages, and whether or not they produced "asteroid showers" in the past.The results will affect the interpretation of critical spacecraft data and will help to characterize the processes that shaped and scattered known asteroids, comets, and meteorites. The research will be included in continuing educational and public outreach work in Colorado and Wyoming elementary and high schools, and through the public and amateur astronomy media.