演講資訊

摘要：

How material transfers from the initial dense core to a disk in low-mass star formation processes is still unclear. This issue requires to understand the gas kinematics around protostars over a wide spatial range from a core scale (~0.05 pc) to a disk scale (~100 au). In this talk, I will present observational results that characterize the gas kinematics over the wide spatial range around a couple of protostars. In a case study of the Class I protostar L1489 IRS, I demonstrate a method to distinguish distinct velocity structures by measuring the radial dependence of the peak velocity of line emission. Using the method with observational data of C18O line emission obtained with ALMA, ACA 7 m array and IRAM 30 m telescope, I revealed three distinct structures around L1489 IRS; a rotationally supported disk, an infalling and rotating envelope surrounding the disk, and a velocity structure associated with the initial dense core outside the infalling envelope. These results give a rough size scale of the infalling envelope of ~2900 au in this source. I found similar kinematic structures in other two protostellar systems. Comparison of the estimated size scales of the infalling envelope between protostars suggests that the spatial extent of the infalling envelope could increase as the system evolves. I will also discuss a possibility that disks are forming in turbulent environments suggested from these observations.