XMM-Newton: The Next Decade, Madrid, Spain, 9 - 11 May 2016, pp.111-112
T Tauri stars are in the pre-main sequence phase of stellar evolution. These stars convert their own gravitational potential energy to light, but their cores do not have enough temperature for nuclear reactions like a main sequence star. T Tauri stars are surrounded by a circumstellar disk, hot plasma and dust. Some T Tauri stars host protoplanetary objects in their circumstellar disk such as HL Tau. In this case HL Tau system is a good example for stellar evolution and planet formation. But HL Tau's protoplanetary objects were formed earlier than planet formation theories' expectations. With this purpose, this study will discuss "What triggered the early planet formation processes in HL Tau system?" with XMM-Newton and Chandra observations of HL Tau system.