Galactic Evolution Of Oxygen As Traced By Open Clusters

Indiana University, Bloomington IN

Investigators

Abstract

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.