U.S.-Japan Cooperative Science: The Origin of Strong X-Ray Emission from Comets

0300708 Stancil该奖项支持格鲁吉亚大学的Philip Stanford教授和日本东京都立大学的Kazuhiko Okuno教授之间为期两年的国际合作研究项目。 他们将对彗星强x射线发射的起源进行研究。 彗星的X射线辐射长期以来一直令人困惑，人们提出了各种理论来解释这些辐射。 事实上，与彗星中性粒子碰撞后，重太阳风离子被电子捕获到高激发态似乎是最可行的解释。目前的主题涉及从离子原子到离子分子碰撞的研究重定向，并在1996年开始的彗星X射线发射（CXE）的观测的动机。 目前对这些排放的有利机制表明，它们来自高激发，高电荷态的重离子，其水平通过太阳风离子与彗星中的中性分子（H2O，CO和CO2）的电荷变化碰撞来填充。 然而，在理解这种现象的进展，严重阻碍了可用的电荷转移（CT）数据的分子，总的和状态选择性的不足。 该项目将涉及理论和实验研究人员来研究与CXE相关的CT反应。 高电荷态离子与分子碰撞的理论研究很少受到关注，因此现在这类研究处于原子碰撞理论的前沿。 实验工作将发展到状态分辨的测量和新的中性目标的研究，所有这些都将推动原子碰撞的更广泛领域。 该项目汇集了具有互补专门知识和研究能力的实验室的努力。 这项研究将对理解太阳系天体的x射线发射现象产生影响。 它将有助于理解和解释越来越多的彗星X射线观测。 它还可能有助于更好地了解磁层中的异常宇宙射线捕获和空间天气，如直接探测太阳风。 该项目通过一些博士后的参与促进国际人力资源。 通过交流思想和技术，该项目将扩大我们的基础知识，促进国际理解与合作。 研究结果将在科学会议和科学期刊上传播。 这项研究还将有助于建立一个可在万维网上访问的电荷转移反应数据库。

0300708StancilThis award supports a two-year international collaborative research project between Professor Philip Stancil of the University of Georgia and Professor Kazuhiko Okuno of the Tokyo Metropolitan University in Japan. They will undertake a study on the origin of strong x-ray emission from comets. X-ray emissions by comets have long been puzzling, and a variety of theories have been put forward to explain these emissions. Indeed, electron capture of heavy solar wind ions to highly excited states following collisions with cometary neutrals seems perhaps the most viable explanation. The current topic involves a redirection from studies of ion-atom to ion-molecule collisions and is motivated by observations starting in 1996 of cometary x-ray emission (CXE). The currently favored mechanism for these emissions suggest that they originate from highly-excited, high-charge-state, heavy ions whose levels are populated through charge changing collisions of solar wind ions with neutral molecules (H2O, CO, and CO2) in the comet. Progress in understanding this phenomenon is, however, severely hindered by the deficiency of the available charge transfer (CT) data for molecules, both total and state-selective. The project will involve both theoretical and experimental researchers to investigate CT reactions relevant to CXE. Theoretical studies of highly-charged ion collisions with molecules have received very little attention so that now such investigations are at the forefront of atomic collision theory. Experimental work will evolve into state-resolved measurements and investigation of new neutral targets all advancing the broader area of atomic collisions. The project brings together the efforts of laboratories that have complementary expertise and research capabilities. The research will have an impact on the understanding of x-ray emission phenomena from solar system bodies. It will contribute to understanding and interpreting the increasing number of x-ray observations of comets. It may also contribute to a better understanding of anomalous cosmic ray capture in magnetospheres, and space weather such as a direct probe of the solar wind. The project advances international human resources through the participation of a number of postdocs. Through the exchange of ideas and technology, this project will broaden our base of basic knowledge and promote international understanding and cooperation. Results of the research will be disseminated at scientific meetings and in scientific journals. The research will also contribute to the production of a world wide web accessible database of charge transfer reactions.