Collaborative Project: The 3-Helium Problem

合作项目：3-氦问题

• 批准号: 9731484
• 负责人: Thomas Bania
• 金额: $ 10.55万
• 依托单位: Trustees of Boston University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-05-01 至 2002-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9731484&HistoricalAwards=false
• 关键词: Collaborative; Project; Helium; Problem

AST-9731484 Bania Dr. Bania and Dr. Rood are collaborating to determine the abundance of the one of those light elements, an isotope of helium, 3He. The study of the origin and evolution of the elements is one of the cornerstones of modern astrophysics. The Big Bang theory predicts that significant amounts of the light elements (2H, 3He, 4He 7Li) are produced in the first few thousand seconds of the Universe. The relative abundances of these elements depends upon details of the initial conditions in the theory. In addition, over time, nuclear fusion reactions in stars will change the relative amounts of these elements. Observations of how these elements vary with space and time provide a crucial probe to the evolution of stars and galaxies since the first few thousand seconds. The PI and Co-PI have shown that it is feasible to detect and measure these weak 3He+ emission lines, and from those measurements to derive accurate 3He abundances. The PI's are making a systematic study of 3He through the Milky Way. This project extends that work by observing a larger sample of planetary nebulae (where reprocessing of stellar material is occurring), improving the accuracy of the current abundances, observing new H II regions (where there has been new star formation), obtaining improved spectra for selected H II regions, refining the models that predict how much 3He can be present, and searching for 3He+ emission from extragalactic sources. The 3He+ emission line at 3.5 cm is observed at a wavelength of 3.5 cm. The project uses the NRAO 140 ft, the NRAO VLA, the MP1fR 100 m, Arecibo and (when operational) the 3.5 cm receiver at Green Bank. ***

AST-9731484 Bania Bania 博士和 Rood 博士正在合作确定其中一种轻元素（氦同位素 3He）的丰度。 对元素起源和演化的研究是现代天体物理学的基石之一。大爆炸理论预测，在宇宙诞生的最初几千秒内会产生大量的轻元素（2H、3He、4He 7Li）。 这些元素的相对丰度取决于理论中初始条件的细节。 此外，随着时间的推移，恒星中的核聚变反应将改变这些元素的相对含量。 对这些元素如何随空间和时间变化的观察为恒星和星系自最初几千秒以来的演化提供了至关重要的探索。 PI 和 Co-PI 表明，检测和测量这些弱 3He+ 发射线并从这些测量中推导出准确的 3He 丰度是可行的。 PI 正在对银河系中的 3He 进行系统研究。 该项目通过观察更大的行星状星云样本（正在对恒星物质进行再处理）、提高当前丰度的准确性、观察新的 H II 区域（其中有新的恒星形成）、获得选定的 H II 区域的改进光谱、改进预测 3He 存在量的模型以及搜索河外来源的 3He+ 发射来扩展这项工作。 在 3.5 cm 波长处观察到 3.5 cm 处的 3He+ 发射线。 该项目使用 NRAO 140 ft、NRAO VLA、MP1fR 100 m、Arecibo 和（运行时）Green Bank 的 3.5 cm 接收器。 ***