Circumstellar Disk Systems in the LMC, SMC, and Milky Way Galaxy

摘要

Classical Be stars are rapidly rotating near main-sequence B-type stars which have gaseous circumstellar disks. Our understanding of these stars is incomplete, especially as regards two fundamental questions: 1) Is the Be phenomenon an evolutionary effect? and 2) What role does metallicity play in the formation of Be circumstellar disks? Initial attempts to address these questions have used 2-color diagram photometric techniques to determine the frequency of candidate Be stars in clusters of various ages and metallicities. These techniques classify all B type objects with excess Ha emission as classical Be stars, without accounting for the likelihood that other B-type stars, such as post main-sequence B[e] stars, YSOs, and B-supergiants, may also exhibit Ha emission and therefore contaminate the sample. We discuss our efforts to quantify the reliability of 2-color diagrams to identify classical Be stars.