The Origin and Evolution of the Light Elements

恒星的化学成分为我们的宇宙提供了许多最基本问题的答案。虽然像太阳这样的恒星的组成与太阳非常相似，但元素锂（Li）和铍（Be）的含量在太阳型恒星中显示出有趣的恒星间变化。这种不均匀性提供了一个独特的机会，通过它们的Li和Be含量来探测恒星的内部；不像大多数其他元素是由恒星内部的核反应形成的，Li和Be在那里被破坏了。这种破坏的程度，反映在表面的内容上，为恒星表面和内部混合的机制提供了线索。已经为这种“混合主”提出了几个模型；每个模型预测的Li和Be的耗竭量不同，因此需要两种元素的综合信息。在这项工作中，夏威夷大学的Ann Boesgaard博士将专注于Be，特别强调已知年龄和金属含量的星团中的Be。随着时间的推移，银河系中各种化学元素的富集揭示了大质量恒星的形成历史和超新星的早期产生。随着时间的推移，跟踪Be的增长可以提供关于前几代大质量恒星和超新星的敏感信息。对最早时期和中间时期进行更详细的探测将使我们对银河系的演化有更深入的了解。此外，对银盘星团中Be的研究有助于了解银河系盘成分的演化和混合。这项研究将利用世界上最大的两个望远镜，Keck-I 10米望远镜和位于夏威夷高海拔莫纳克亚天文台的斯巴鲁8.2米望远镜。他们配备了最先进的仪器和探测器。他们的高分辨率光谱仪将用于获得恒星光谱。最新的精密恒星大气模型将用于数据分析。在这项研究过程中获得的高质量数据的结果将更好地约束恒星内部和星系化学演化的模型。当这项工作完成后，我们应该对像太阳这样的恒星的内部结构有一个更全面的了解，以及这种结构如何随着时间、质量和金属含量的变化而变化。此外，我们将对银河系的化学历史有一个更完整的了解

AST 0097945BoesgaardThe chemical composition of stars holds the answers for many of the most fundamental questions about our Universe. Although the composition of stars like the Sun is very similar to that of the Sun, the amounts of the elements lithium (Li) and beryllium (Be) show interesting star-to-star variations among solar-type stars. This non-uniformity provides a unique opportunity to probe the insides of stars through their Li and Be content; unlike most other elements that are forged by nuclear reactions inside stars, Li and Be are destroyed there. The degree of this destruction, as reflected in the surface content, provides clues about the mechanism that does the mixing between the surfaces and the interiors of stars. Several models have been proposed for this "mix-master"; each model predicts differing amounts of depletion for Li and Be so information from both elements together is required. In this work, Dr. Ann Boesgaard, at the University of Hawaii, will concentrate on Be, with a special emphasis on Be in star clusters of known age and metal content.The enrichment over time of various chemical elements in the Galaxy reveals the history of formation of massive stars and the early production of supernovae. Tracking the increase of Be over time gives sensitive information about previous generations of massive stars and supernovae. Probing both the earliest times and the intermediate ages in more detail will result in a greater understanding of the evolution of the Galaxy. Furthermore, the study of Be in star clusters of the galactic disk help to discern the evolution and mixing in the disk component of our Galaxy.This research will take advantage of two of the world's largest telescopes, the Keck-I 10-m telescope and the Subaru 8.2-m telescope at the high-altitude Mauna Kea Observatory in Hawaii. They are equipped with state-of-the-art instruments and detectors. Their high-resolution spectrometers will be used to obtain the stellar spectra. Recent sophisticated models of stellar atmospheres will be used in the data analysis. The models of stellar interiors and of galactic chemical evolution will be constrained better by the results from the high quality data that is obtained during the course of this research. When this body of work is completed we should have a more comprehensive portrait of the internal structure of stars like the Sun and how this structure changes with time, with mass, and with metal content. Furthermore, we will have a more complete picture of the chemical history of our Galaxy.***