Oral Presentation
Multiple Outflows Observed in the Protostellar System IRAS 15398-3359
Presenter: Jinshi Sai (ASIAA)
Understanding evolution of molecular outflows is essential for revealing angular momentum transfer mechanisms in the star formation process. Previous observations have suggested the presence of the secondary outflow around the single protostar IRAS 15398-3359, which is launched in a direction almost perpendicular to its primary outflow. In this talk, we report our discovery of the third outflow around the protostar. The 12CO 2-1 emission revealed by our mosaic observations with the ACA 7-m array shows a bipolar outflow toward the north and south at distances of ~3000 to 10,000 au from the protostar. The newly uncovered outflow is tilted from the other two outflows by ~20-70 degree. Its dynamical time is estimated to be ~10^4 yr, which is larger than that of the primary outflow by an order of magnitude. These results suggest that the outflow orientation significantly changes over time. Such dynamic evolution in the out?ow direction may happen if the rotational axis of the dense core and surrounding magnetic ?eld are misaligned or if the dense core is turbulent. We favor the second scenario as the origin of the multiple out?ows in IRAS 15398?3359, based on a comparison between the observational results and numerical simulations.
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