Yi-Shan Tsai (ASIAA/NTU); Chin-Fei Lee (ASIAA)
How angular momentum is lost from a system in the core-collapse and disk formation process has been a long-standing problem in star formation. In order to investigate how angular momentum varies in an envelope surrounding a forming star, we explore the kinematics of HH111, a Class I protostellar system. Here we present the observations of HH111 system at ~0."2 resolution(80AU) in C18O(J=2-1) and SO(NJ=6(5)-5(4)) with Atacama Large Millimeter Submillimeter Array. The observations show a flattened envelope with constant specific angular momentum outside, a transition zone, and a compact Keplerian rotating disk innermost. Furthermore, we use radiation transfer code to reproduce the PV-diagrams of HH111 system under various circumstances(e.g., different angular momentum, infalling velocity and total energy). By comparing the results from radiation transfer code and the observations, we discuss about if there is really magnetic braking in the system and how angular momentum influences the kinematics of an envelope and also the formation of a Keplerian disk.