Abundance Patterns in Extremely Metal-Poor Stars

“极端贫金属恒星的Abductile Patterns“AST-0098617历史上第一次有足够的恒星样本作为探测器来破译星系演化的初始阶段。在20世纪90年代进行的对极贫金属恒星的调查产生了这个样本。在本奖项颁发期间，大型望远镜及其摄谱仪将用于确定准确的化学丰度，从而追踪重元素合成自最早时期以来的进展情况。会有额外的好处。钍的丰度可以用来计算最古老恒星的放射性年龄，这将为宇宙的年龄设定一个下限。 将评估s-过程元素（在演化恒星内部产生）和r-过程元素（由前几代大质量恒星的超新星爆炸贡献）的不同贡献，并与核合成理论的预期进行比较。将搜索那些被预测显示出极端碳增强而不伴随s过程过度的第三星族恒星。还将观测外晕中属于银河球状星团的恒星和附近矮星系中的恒星，以寻找低质量星系化学演化的可能丰度特征。

" Abundance Patterns in Extremely Metal-Poor Stars"AST- 0098617For the first time in history there is an adequate sample of stars to use as probes in deciphering the initial phases of galactic evolution. Surveys for extremely metal-poor stars, carried out in the 1990s, produced this sample. During this period of the present award, large telescopes their spectrographs will be used to determine accurate chemical abundances and thus to trace how heavy element synthesis has proceeded since earliest times. There will be additional benefits. Thorium abundances can be used to compute radiogenic ages for the oldest stars, which will put a lower limit on the age of the universe. The different contributions of s-process elements (generated in the interiors of evolving stars) and r-process elements (contributed by supernovae explosions of earlier generations of massive stars) will be assessed and compared with expectations from nucleosynthesis theory. A search will be made for Population III stars that are predicted to show extreme carbon enhancements without accompanying s-process excesses. Observations will also be made of stars belonging to galactic globular clusters in the outer halo and of stars in nearby dwarf galaxies to search for possible abundance signatures characteristic of chemical evolution in low-mass galaxies.