Blue-stragglers in open clusters: when and how stellar mergers occur?

Blue stragglers are main-sequence stars that are more luminous and bluer than stars of the same age, and their existence has long defied standard stellar evolution. It is now believed that blue stragglers are the product of mass transfer and/or merger in close binaries. Since the fraction of close binaries is a strong function of metallicity, it is expected that the fraction of blue stragglers will vary with metallicity. In this study you will use a sample of open stellar clusters to study how the fraction of blue-stragglers changes as function of clusters' age and metallicity. This study will allow you to provide new insights on one of the great mysteries of stellar evolution.