천문우주과학과

일시:  2020년 10월 22일 목요일 오후 4시
       (ZOOM 회의 ID:932 6693 1767, PW:612443)

연사:  천상현 박사님(한국천문연구원)

제목: Star clusters as probes of formation and evolution of the galaxies

 초록:  

  Star clusters and their stellar populations are excellent laboratories to study the formation, assembly, and evolutionary history of their parent galaxies. We search for extratidal stars around two metal-poor Galactic globular clusters, M53 and NGC 5053. The extratidal stars around the clusters tend to be located along the leading direction of the cluster proper motion. Interestingly, we find that one extratidal star of NGC 5053 is located on the southern outskirts of M53, which is part of a common stellar envelope by the tidal interaction between two clusters. Our results support that M53 and NGC 5053 originated in dwarf galaxies and are surrounded by extended stellar substructures of more numerous populations of clusters. On the other hand, we find that the radial velocities of red supergiant stars (RSGs) in young massive star clusters (i.e. RSGC4) have a large scatter and offset compared to those of other RSGCs in the same Scutum-Crux arm. RSGC1 and  RSGC4  alsohave  different  dynamicalparameters  from  otherclusters, indicating external evolution effects or the potential different origin for RSGCs. Wediscuss  the  possibleexplanations  (e.g.,  galactictidal  interaction,  binary systemin  massive  clusters)for  peculiar  kinematicsand  spectral  absorption features of RSGs in RSGCs.