Study on a formation and chemical evolution of the Galaxy based on spectroscopic observations of metal-poor stars

基于贫金属恒星光谱观测的星系形成和化学演化研究

基本信息

批准号：
13640246
负责人：
HIDAI Masahide
金额：
$ 1.98万
依托单位：
Tokai University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2004
项目状态：
已结题

项目摘要

1. Our spectroscopic studies of alpha- elements, O, Si, S, and Ca, in metal-poor stars were carried out to investigate their behaviors against metalicity [Fe/H]. As for O, the abundance derived from the triplet lines was found to show a flat trend. The behaviors of Si and Ca show a correlated trend and were found to be classified into three groups based on dynamical properties. As for S, our result of an increasing trend with decreasing [Fe/H] in a paper of 2002 was first derived from a large sample, and inspired other groups as well as us to make further studies of S behavior. Our result obtained in a paper of 2005 confirmed that S shows a flat trend in -4 <[Fe/H]<-1, which may be explained by chemical evolution models based on standard supernovae nucleosynthesis.2. Other light elements of Li, Na, and K were also studied and found to provide the new results being different from the previous ones.3. The behavior of Zinc in very metal-poor stars was found to show an increasing trend below [Fe/H]<-3, which gives an important constraints to supernova models.4. The behaviors of r-process elements were found to show a large star-to-star scatter and to be explained by r-process nucleosynthesis. However, an unknown process was needed for an explanation of behaviors of Sr and Ba.5. The most iron-deficient star was discovered. The star may be a population III, or even if not, it gives strong constraints to a nature of the first generation stars in the beginning of the Galaxy.

1。在金属贫困星中，我们对o，si，s和ca的字母元素的光谱研究进行了研究，以研究其针对金属性的行为[fe/h]。至于o，发现源自三重态线的丰度显示出平坦的趋势。 SI和CA的行为显示出相关的趋势，并根据动力学特性被发现分为三组。至于s，我们在2002年论文中随着[fe/h]的下降趋势的结果首先源自大型样本，并激发了其他群体以及我们对S行为进行进一步研究。我们在2005年的论文中获得的结果证实，S显示了-4 <[fe/h] <-1的平坦趋势，可以通过基于标准超新星核合成的化学演化模型来解释。2。还研究了Li，Na和K的其他光元素，并发现新的结果与以前的结果不同。3。发现锌在非常富有金属的恒星中的行为显示出低于[fe/h] <-3的趋势越来越大，这给超新星模型带来了重要的限制。4。发现R过程元素的行为显示出大型的恒星散射，并通过R-Process核合成来解释。但是，需要一个未知的过程来解释SR和BA.5的行为。发现了最不足的恒星。恒星可能是人口III，或者即使不是人口，它在银河系开始时对第一代恒星的本质产生了强烈的限制。