Collaborative Research: The 3-Helium Problem

托马斯·巴尼亚：“合作研究：3氦问题”AST-0098047轻元素同位素丰度的测定是探索我们宇宙中最早的核合成的基础。在最初的1000秒内，产生了大量的轻元素2-H、3-He、4-He和7-Li。这次调查的重点是3-He同位素。原始丰度是一个最终目标，但首先必须评估普通太阳型恒星内通过核燃烧产生的这种同位素的贡献。我们预计，这种成分的污染会随着时间的推移而增加，在过去恒星形成率最高的地区也会更大。这些关联没有被看到，本提案的一个主要目标是理解为什么没有这些关联。该计划将继续对行星星云和H II区域进行调查，以确定银河系不同部分的3-He丰度。早期的工作揭示了行星状星云NGC3242中存在着少量但显著的3-He过量，这表明已经发生了浓缩。随着阿雷西博和绿岸设施的改善，预计现在可以观察到更多的物体。

Bania, Thomas" Collaborative Research: The 3- Helium Problem "AST- 0098047Determination of the isotopic abundances of the light elements is fundamental in probing the earliest nucleosynthesis in our universe. During the first 1000 seconds, significant amounts of light elements 2-H, 3-He, 4-He and 7-Li were produced. This investigation focuses on the 3-He isotope. A primordial abundance is an ultimate aim but the contribution by the generation of this isotope by nuclear burning within common solar-type stars must first be evaluated. We would expect the contamination from this component to increase with time and also to be larger in areas which have had the highest rates of star formation in the past. These correlations are not seen and a prime goal of the present proposal is to understand why they are absent. The plan is to continue a survey of planetary nebulae and H II regions to determine 3-He abundances in different parts of the galaxy. Earlier work had revealed that small but significant excesses of 3-He were present in the planetary nebula NGC 3242 showing that enrichment had taken place. With improved facilities at Arecibo and Green Bank, it is expected that many more objects can be observed now.