Galactic Evolution Of Oxygen As Traced By Open Clusters

在这个项目中，分析了以前获得的观测数据，以确定15个已知年龄和不同金属丰度(即重化学元素相对于氢的含量)的疏散星团的太阳型矮星中的氧和铁的丰度。这些样品的铁与氢的比例相差近十倍，星系团的年龄从大约3000万年到大约80亿年不等。这项研究将之前的丰度数据集扩展到大约三倍的星系团，每个星系团中的恒星样本更多，金属丰度和年龄范围更广。氧和铁的丰度跟踪了银河系的化学演化--恒星产生的化学元素中星际介质的浓缩。这项研究讨论了星系团中铁和氧的丰度是否取决于星系团的年龄，以及铁和氧的丰度是如何相互关联的。这很令人感兴趣，因为不同类型的大质量恒星以超新星的形式爆炸，产生的氧气和铁的数量不同。这里的另一项研究检查了阿尔法元素(如镁和硅)的产生与年龄的关系。这种关系可能会对恒星中的过程和大质量恒星释放到星际介质中的重元素的恒星核合成产额产生限制。这个项目提供了一个吸引许多本科生和研究生从事科学研究的场所，就像首席研究员之前的项目一样。

In this project, previously obtained observational data are analyzed to determined the oxygen and iron abundances in solar-type dwarf stars of 15 open clusters of known age and different metallicity (i.e., the contents of the heavy chemical elements relative to hydrogen). The samples range by nearly a factor of ten in their iron-to-hydrogen ratios and cluster ages span from about 30 million to about 8 billion years. This study expands previous abundance data sets to cover about three times as many clusters, a higher sample of stars in each cluster, and a wider range in metallicity and age.The abundances of oxygen and iron trace the galactic chemical evolution - the enrichment of the interstellar medium in chemical elements produced in stars. This study addresses whether the iron and oxygen abundances in clusters depend on cluster age and how iron and oxygen abundances relate to each-other. This is of interest because oxygen and iron productions vary among different types of massive stars that explode as supernovae. An additional study here checks on the relation of the alpha element (such as Mg and Si) production with age. Such relations may place constraints on the processes in stars and stellar nucleosynthetic yields of heavy elements that are released into the interstellar medium by massive stars.This project provides a venue to attract many undergraduate and graduate students to scientific research as have previous projects by the principal investigator.