Collaborative Project: The 3-Helium Problem

巴尼亚博士和鲁德博士正在合作确定其中一种轻元素——氦的同位素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，大量的轻元素（2H, 3He, 4He, 7Li）是在宇宙形成的最初几千秒内产生的。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数量。对这些元素如何随空间和时间变化的观察，为了解恒星和星系自最初几千秒以来的演化提供了一个至关重要的探索。π和Co-PI表明，探测和测量这些弱3He+发射线是可行的，并从这些测量结果中得出准确的3He丰度。PI正在通过银河系系统地研究3He。这个项目通过观察更大的行星状星云样本（恒星物质的再加工正在发生）来扩展这项工作，提高当前丰度的准确性，观察新的H II区域（已经有新的恒星形成），获得选定H II区域的改进光谱，改进预测3He可能存在的模型，并寻找河外源的3He+发射。在3.5 cm波长处观测到3.5 cm处的3He+发射谱线。该项目使用了NRAO 140英尺，NRAO VLA， MP1fR 100米，Arecibo和Green Bank的3.5厘米接收器（运行时）。* * *

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. ***