Oral Presentation

Multiple Outflows around the Single Protostar IRAS 15398-3359

Author(s): Jinshi Sai (ASIAA)

Presenter: Jinshi Sai (ASIAA)

Understanding time evolution of molecular outflows is essential for revealing angular momentum transfer history in the disk formation process. A time variation of the outflow direction has been suggested around a single protostar IRAS 15398-3359 by finding of the secondary outflow that 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. Our mosaic observations with the ACA 7-m array covering ~2’ (or ~18,000 au) square region have revealed that the 12CO 2-1 emission shows a bipolar outflow toward the north and south at offsets of ~3000 to 10,000 au from the protostar. The outflow is on a larger scale than and tiled from both the primary and secondary outflows that are less than 1500 au in length. The estimated dynamical time scales are different between these multiple outflows, which suggests that the outflow direction changes with time. Comparisons of the observed turbulence level and B-field directions on a core scale with numerical simulations imply that turbulence is more likely responsible for the time variation of the outflow direction in this source. As the turbulence level of the protostellar core of IRAS 15398-3359 is similar to those of other dense cores, the dynamic change of the outflow direction might be common at the very early stage of protostellar phase.