Physico-Chemical Modeling of Recent Comet Observations

AST 0507754 boicedr。丹尼尔·博伊斯和他的同事们将开展一个项目，分析最近发现的海尔-波普彗星和百武彗星的观测结果，以深入了解它们原子核的内在特性以及发生在它们彗发中的重要物理和化学过程。他们将使用他们在过去几十年里开发的两种计算工具；ComChem是一个彗星彗发化学的全球气体动力学模拟，ComFluo是一个具有非平衡态碰撞和叠加的随时间荧光模型，适用于彗星中感兴趣的分子。这些强大的工具的结合将带来一个创新和独特的机会，以提高我们对彗星母体分子的认识，从而获得了解太阳系和生命起源的线索，使这项工作与美国国家科学基金会和彗星航天器任务（星尘号，深度撞击号，罗塞塔号）高度相关。该奖项中概述的模型分析有望对来源、化学、S2、C2、C3、NS、HCN/HNC和CN的母星以及两颗截然不同的彗星内部彗发的热力学（气体速度分布、振动和旋转温度）（作为彗星中心和日心距离的函数）提供新的见解。例如，本课课组将测试S2的亲缘关系，它是原始物种还是仅仅是反应产物，这对冰彗星颗粒的热历史有直接的意义。NS自由基的化学性质将被研究，并与海尔-波普彗星的观测结果进行比较。该团队还试图提高对NS光解速率的了解，寻找光解产生NS的重要母体分子（X-NS），并更好地了解NS在内部昏迷中的化学反应。从我们对C2和C3起源的研究中推断出的复杂有机物相对于原始分子的化学性质，直接关系到彗星的相对年龄和它们形成的条件。这项研究的结果应该是彗星彗星的最佳反应网络，形成未来研究的标准模型。Boice和研究团队坚定地致力于教育和公众宣传。Boice博士将把这项工作的结果纳入几个正在进行的教育活动，涉及高中，本科生，研究生。Boice博士在过去的10年里一直担任青年工程师和科学家（YES）计划的主任。YES是一个屡获殊荣的社区合作项目，由SwRI、当地学区和德克萨斯州圣安东尼奥的慈善基金会合作，面向初中生和高年级学生。几名学生将在学年期间接受与该项目相关的独立研究指导。YES致力于从代表性不足的群体中招收学生。Boice博士与德克萨斯大学圣安东尼奥分校（UTSA）和圣安东尼奥社区学院有着密切的联系，他在过去的10年里一直在那里教授天文学课程。这项研究的要素将在他的课堂上呈现，每年影响约350名学生。UTSA的战略目标之一是成为西班牙裔研究生教育和研究机会的卓越中心。swri和UTSA物理系之间新形成的合作伙伴关系将允许PI教授博士课程的研究生课程，该项目的结果将用于生成高级课程的材料

AST 0507754BoiceDr. Daniel Boyce and colleagues will carry out a project to analyze observations of the recent comets, Hale-Bopp and Hyakutake, to gain insights into the intrinsic properties of their nuclei and the important physical and chemical processes that occur in their comae. They will employ two computational tools that they have developed over the past decades; ComChem, a global, gas dynamics simulation with chemistry of the cometary coma, and ComFluo, a time-dependent fluorescence model with collisions and superposition of non-equilibrium states, appropriate for molecules of interest in comets. The coupling of these powerful tools will result in an innovative and unique opportunity to advance our knowledge of parent molecules in comets, thereby gaining clues to understanding the origins of the solar system and life, making this work highly relevant to NSF and spacecraft missions to comets (Stardust, Deep Impact, Rosetta). The model analyses outlined in this award are expected to yield new insights into the sources, chemistry, and parents of S2, C2, C3, NS, and HCN/HNC, and CN, and the thermodynamics of the inner coma (gas velocitydistribution and vibration and rotation temperatures) in two very different comets as a function ofcometocentric and heliocentric distance. For example, this research group will test the parentage of S2, whether it is a primordial species or merely a reaction product, which has direct implications to the thermal history of icy comet grains. The chemistry of the NS radical will be investigated and compared to observations of comet Hale-Bopp. The team also seeks to improve the knowledge of the photodissociation rate of NS, search for important parent molecules (X-NS) which photodissociate to produce NS, and understand better the chemistry of NS in the inner coma. The chemistry of complex organics relative to primitive molecules inferred from our study of the parentage of C2, and C3 directly relates to issues concerning the relative ages of comets and the conditions from which they formed. The results of this study should be the best reaction network for cometary comae, forming the standard model for future studies.Dr. Boice and the research team are strongly committed to education and public outreach. Dr. Boice will incorporate the results of this work into several on-going educational activities to involve high school, undergraduate, graduate students. Dr. Boice has been the director of the Young Engineers and Scientists (YES) Program for the past 10 years. YES is an award-winning community partnership between SwRI, local school districts, and charitable foundations in San Antonio, Texas, for high school juniors and seniors. Several students will be mentored during the school year on independent research related to this project. YES has a strong commitment to recruiting students from underrepresented groups. Dr. Boice has close ties with the University of Texas SanAntonio (UTSA) and San Antonio Community College where he has taught classes in astronomy for the past 10 years. Elements of this research will be presented in his classes, affecting about 350students/year. One of UTSA's strategic goals is become a center of excellence in graduateeducation and research opportunities for Hispanics. A newly formed partnership between SwRIand the UTSA Physics Dept. will allow the PI to teach graduate classes in the Ph.D. programwith the results of this project used to generate material for advanced courses.***