Poster Presentation

Kinematical transition from an infalling envelope to a quiescent core around the protostar L1489 IRS

Author(s): Jinshi Sai (Univ. of Tokyo/ASIAA)

Presenter: Jinshi Sai (Univ. of Tokyo/ASIAA)

Revealing the kinematic structures on a disk (~100 au) to a core (~10,000 au) scales around protostars is essential to understand how material in the initial cores transfers into disks and protostars through star formation process. However, the kinematic structures on an envelope (~1,000 au) to a core scales are poorly understood. We have conducted mapping observations of ~2’x2’ area around the protostar L1489 IRS with IRAM-30m telescope in the C18O J=2-1 line to investigate the kinematics on ~1,000 to 10,000 au scales. The C18O moment 0 map shows a condensation with a radius of ~1,400 au centered at the protostellar position while the moment I map shows velocity gradient over ~8,000 au across from NE to SW, which is in the same direction as that due to its disk rotation. The velocity dispersion (mom2) map of C18O exhibits a drastic change of the velocity dispersion at a radius of ~2,000-3,000 au, which separates a highly dynamical and quiescent regions. To investigate the kinematic structure in more detail, rotational velocities are measured from the velocity gradient over the radius from ~1,000 to 7,000 au based on the present data combined with that previously obtained with ALMA. While the rotational velocities are mostly proportional to r^-1 up to r~2,400 au, they are almost flat or slightly increase at r>2,400 au, suggesting a transition from an infalling envelope to a quiescent core. A possible interpretation of the suggested transition is discussed comparing our observations with other protostars and theoretical predictions.