Multiple Outflows Observed around the Single Protostar IRAS 15398-3359

Jinshi Sai  (ASIAA)

Understanding evolution of molecular outflows is essential for revealing angular momentum transfer mechanisms in the disk 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 a 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 on a larger scale than the primary and secondary outflows, and also tilted from the other two outflows by ~20-70 degree. The dynamical time of the third outflow is estimated to be ~10^4 yr, which is larger than that of the primary outflow by an order of magnitude, suggesting that the outflow direction changes with time. Comparison of the turbulent energy of the dense core of IRAS 15398 with those in numerical simulations suggests that turbulence in the dense core could cause the variation in the outflow direction over time in this source.