Dust Mineralogy, Volatiles, and Taxonomy of Comets

对彗星尘埃中有机和无机物质的测定提供了对原太阳系环境的洞察，并揭示了行星系统起源过程的线索。尘埃颗粒是可凝聚元素的储存库，在它们从演化的恒星、新星和超新星的星际风进入ISM云的过程中，产生了新的恒星和行星系统。在所有太阳星云中，彗星含有最少加工的物质，包括冰和尘埃。当太阳辐射增加了挥发性气体的产生速率，导致尘埃从原子核释放并使耐火材料暴露在紫外线(UV)通量下时，可以研究近日点通过过程中彗星物质的化学成分和演化。这项研究计划是对两个不同的动力学群体--木星族(JF)和奥尔特云(OC)彗星--进行全面、系统的调查。这项对彗星尘埃性质和物理特征的研究将：(1)有助于评估结晶硅酸盐作为太阳星云演化和湍流混合模型诊断的重要性；以及(2)探索彗星尘埃矿物学是否与观测到的有机挥发性生成率有关。对于天体物理界来说，理解行星是如何在原行星盘中形成的是一项科学挑战。这一举措有助于广泛的跨学科调查领域。首先，OC和JF彗星中颗粒性质的测定和相互比较使研究决定太阳系中天体特征的过程以及这些过程的运行和相互作用成为可能。其次，彗星提供了对早期太阳星云中行星小聚集和行星形成的初始过程的洞察。具体地说，存在于早期太阳星云中的尘埃颗粒的热历史可以通过限制彗星尘埃的性质来探索。最后，该计划将检验新的假设，该假设源于研究人员对深度撞击目标9P和分裂彗星73P的观察与最近对彗星气相有机体的研究进行比较后产生的新假设，即基于当前轨道(动力学)分类的彗星分类应该被基于尘埃矿物学和颗粒特性以及有机成分和超挥发生成率的物理特征的分类所取代。该计划为拥有不同学生群体和人才基础的大型公共机构的实验技术和观测天体物理学方面的教育指导活动创造了一个环境。研究机会提供了促进学生发展为科学家和批判性思考者的基础设施，同时使个人接触到科学话语、智力交流和公共宣传是如何在当代天体物理学的动态环境中进行的。研究人员的学生将利用各种设施收集观测数据，并直接参与科学分析和传播。这些活动有助于劳动力发展，并向有抱负的天文学家(和/或有科学/技术职业目标的学生)传授观测和技术专长、计算机编程技能和分析方法。天文学，部分是因为它令人惊叹的图像，为公众参与科学讨论提供了一个天然的门户，并有助于培养人们对科学和技术影响的广泛认识。研究人员将通过一些教育和公共推广活动和场所向公众传播研究亮点。*

AST 0706980WoodwardDetermination of organic and inorganic materials in cometary dust provides insight into the protosolar system environment and reveals clues to the process of planetary systems origins. Dust grains are reservoirs for condensable elements during their transport from the circumstellar winds of evolved stars, novae, and supernovae into ISM clouds that give rise to new stellar and planetary systems. Of all solar nebula bodies, comets contain the least processed materials, both ices and dust. The chemical composition and evolution of comet material can be studied during perihelion passage when solar irradiation enhances the production rate of volatile gases leading to the release of dust from the nucleus and the exposure of refractory material to ultraviolet (UV) flux. This research program is a comprehensive, systematic investigation of two distinct dynamical populations, Jupiter-family (JF) and Oort Cloud (OC) comets. This study of comet dust properties and physical characteristics will: (1) facilitate assessment of the importance of crystalline silicates as a diagnostic of solar nebula evolution and turbulent mixing models; and (2) explore whether comet dust mineralogy is correlated with observed organic volatile production rates. Understanding how planetary formation occurs in protoplanetary disks is a scientific challenge for the astrophysical community. This initiative contributes to broad cross-disciplinary areas of inquiry. First, the determination and inter-comparison of grain properties in OC and JF comets enable study of the processes that determine the characteristics of bodies in the Solar System and the operation and interaction of these processes. Secondly, comets provide insight into the initial processes of planetesimal aggregation and planet building in the early solar nebula. Specifically, the thermal history of dust grains extant in the early solar nebula can be probed by constraining the properties of dust from comets. Lastly, this program will test the new hypothesis, arising out of comparison of the investigators' observations of the Deep Impact target 9P and the split comet 73P with recent studies of comet gas-phase organics, that comet taxonomy based on current orbital (dynamical) classification should be supplanted by a taxonomy based on physical characteristics of dust mineralogy and grain properties and organic composition and super-volatile production rates.This program creates an environment for educational mentoring activities in experimental techniques and observational astrophysics at large public institutions with diverse student populations and talent bases. Research opportunities provide an infrastructure to promote student development as scientists and critical thinkers while exposing individuals to how scientific discourse, intellectual exchange, and public outreach are conducted in a dynamic environment of contemporary astrophysics. The investigators' students will utilize a variety of facilities to collect observational data, and participate directly with scientific analyses and dissemination. These activities contribute to workforce development and imparts to aspiring astronomers (and/or students with scientific/technical career objectives) observational and technical expertise, computer programming skills, and analysis methodology. Astronomy, in part because of its stunning imagery, provides a natural gateway for engaging the public in scientific discussions, and helps to foster a broad appreciation for the impact of science and technology. The researchers will disseminate research highlights to the public through a number of education and public outreach activities and venues.***