Shin-ichiro Okumura

SPICA Science Conference from Exoplanets to Distant Galaxies: SPICA's New Window on the Cool Universe (June 18-21, 2013. Ito Hall, the University of Tokyo), Bunkyou-ku, Tokyo, JapanWe built up a new observation system for investigation of massive star clusters. The tool is NIR imaging photometry by broad- and narrow-band filters installed in Atacama Near-InfraRed camera (ANIR). The observations of massive star clusters were carried out with mini-TAO 1m telescope. As the results, almost all of known Wolf-Rayet (WR) stars or luminous-blue variables (LBVs) were confined and new candidates of progenitors of supernovae (SNe) were detected. Color-color diagram (brackets N207/Ks brackets vs brackets N187/Ks brackets) made from the images clearly shows a zone of 1.87 micrometers excess due to He II and Paschen-alpha emission that indicates WN-type WR stars and LBVs, and a zone of 2.07 micrometers excess due to C IV emission from WC-type WR stars. In other words, we found that various types of massive stars can be classified as zones on the diagram. Furthermore we will be able to reveal not only buried WR stars but also the constituent, age and evolution of massive star clusters. Identification of the components of clusters with mini-TAO, TAO 6.5m and SPICA gives significant information to clarify the history of star formation (the birth and the evolution) of massive star clusters.Physical characteristics: Original contains color illustrations