Oral Presentation
ALMA Observations toward the S-shaped Outflow and the Envelope around NGC1333 IRAS4A2
Presenter: Chen-Yu Chuang (NTU/ASIAA)
NGC1333 IRAS4A is a well-studied Class 0 protobinary system embedded in a circumbinary envelope. Each protostar of the binary, IRAS4A1 and IRAS4A2, ejects its own outflow toward the north and the south. In order to investigate the outflow envelope system in more detail, we analyzed ALMA archival data of SO (6_5-5_4), SO (7_6-6_5), and CO (2-1) lines. The high resolution images (90.4 au times 55.9 au) of SO (6_5-5_4) and CO (2-1) successfully separate the two northern outflow lobes connected to IRAS4A1 and IRAS4A2. The SO and CO images have revealed that the outflow from IRAS4A2 shows S-shaped morphology, consisting of an elongated structure around IRAS4A2 and two outflow lobes connected to the both edges of the elongated structure. The elongated structure that is considered to be a flattened envelope surrounding IRAS4A2 has an opposite velocity gradient to that of the circumbinary envelope. In order to reproduce the observed morphology and kinematics of the IRAS4A2 outflow, we have conducted the magnetohydrodynamic simulation with the protostar formation in the core whose magnetic field direction is misaligned to the rotational axis. Our simulation shows that the intensity of the outflow lobes is enhanced in one side, resulting in the formation of S-shaped morphology. The opposite velocity gradients in the flattened envelope and circumbinary envelope can be explained as the rotation and inflowing motion, respectively.
asiaa.sinica.edu.tw