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

美日合作科学：彗星强X射线发射的起源

• 批准号: 0300708
• 负责人: Phillip Stancil
• 金额: $ 6.78万
• 依托单位: University of Georgia Research Foundation Inc
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-05-01 至 2007-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0300708&HistoricalAwards=false
• 关键词: U.S.; Japan; Cooperative; Science; Origin

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.

0300708Stancil该奖项支持佐治亚大学的菲利普·斯坦赛尔教授和日本东京都大学的冈野和彦教授之间为期两年的国际合作研究项目。他们将对彗星发出的强X射线的来源进行研究。长期以来，彗星的X射线发射一直令人费解，人们提出了各种理论来解释这些发射。事实上，重太阳风离子在与彗星中性粒子碰撞后将电子俘获到高激发态似乎是最可行的解释。目前的主题涉及从研究离子-原子到离子-分子碰撞的重新定向，并受到从1996年开始对彗星X射线发射(CXE)的观测的推动。目前支持的这些发射机制表明，它们来自高激发、高电荷态的重离子，其能级是通过太阳风离子与彗星中的中性分子(H2O、CO和CO2)的电荷变化碰撞而形成的。然而，现有的分子电荷转移(CT)数据的不足严重阻碍了对这一现象的理解，无论是完全选择性的还是状态选择性的。该项目将包括理论和实验研究人员，以研究与CXE相关的CT反应。高电荷态离子与分子碰撞的理论研究受到的关注很少，因此现在这类研究处于原子碰撞理论的前沿。实验工作将演变为状态分辨测量和对新的中性目标的研究，所有这些都将推进更广泛的原子碰撞领域。该项目汇集了具有互补专业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线捕获以及空间天气，如直接探测太阳风。该项目通过一些博士后的参与促进了国际人力资源的发展。通过思想和技术的交流，这个项目将扩大我们的基础知识基础，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。