In our study we have done photometry for open cluster M67. Photometric results are plotted in the color-magnitude diagram. The number of stars in each evolutionary phase has been estimated. The existence of blue stragglers in our result requires further research about stellar evolution and interacting binary stars. | JOURNAL OF SCIENCE OF HNUE Mathematical and Physical Sci. 2012 Vol. 57 No. 7 pp. 65-70 This paper is available online at http USING APERTURE PHOTOMETRY TO STUDY MESSIER 67 Doan Duc Lam and Nguyen Anh Vinh Hanoi National University of Education Abstract. Studying star clusters is a way to test theories of stellar evolution in astronomy. Using current theories the mass age and components of a star are affected and decide the position of star in the Hertzsprung-Russell color-magnitude diagram. To study the role of mass in stellar evolution we need to look at star clusters of which all stars were formed at the same time and are located at the same distance from planet Earth. In our study we have done photometry for open cluster M67. Photometric results are plotted in the color-magnitude diagram. The number of stars in each evolutionary phase has been estimated. The existence of blue stragglers in our result requires further research about stellar evolution and interacting binary stars. Keywords Photometry Messier 67 astrophysics. 1. Introduction A star is a physical entity which evolves over time and changes in phase. The stellar phase is indicated by parameters such as the temperature pressure generation and transportation of energy within a star. Stars having different initial masses evolve through different stages over time. A cluster is a system of stars which were formed from a single gas cloud. There are two types of clusters open cluster and global cluster. All stars in a cluster are presumed to have been born at the same time so the current phase of the stars is decided by their initial mass. Messier 67 M67 or NGC 2682 is an open cluster that is located in the Crab constellation. This is one of the oldest clusters and is of importance in the study of stellar evolution. Within it are at least 500 stars 1 and among them are about 150 white dwarfs 100 solar-type stars some blue stragglers and some giant stars. The age of M67 is about Received .
