SF-06-0024

Revealing rotating signatures of low and high velocity outflows in HH270mms1 with ALMA

Mitsuki Omura, Kazuki Tokuda, Masahiro N. Machida

Protostellar outflows are theoretically predicted to have two components: wide-angle low-velocity, and collimated high-velocity flows. They are considered to be driven by different places of the protostellar disk and the region close to the protostar. However, objects for which both flows are clearly visible with ALMA are rare. Observing such objects is essential for a better understanding of angular momentum transport, i.e., outflow driving mechanisms. By studying ALMA archival data with a spatial resolution of ~ 230 au, we found that HH270mms1 in the region of Orion B L1617 is one of the ideal systems showing interesting observational signatures. The <sup>12</sup>CO(3-2) spectral map shows more than two velocity components within a relative velocity range of 0-50 km s<sup>-1</sup>. The lower velocity components have a wide opening angle. For the component, we also detected a marginal velocity gradient perpendicular to the outflow direction, implying the outflow rotation consistent with the rotation of the protostellar disk driving the flows. The high velocity ~50 km s<sup>-1</sup> components have a linewidth of ~10 km s<sup>-1</sup>, which is also expected due to rotation and comes from the vicinity of the protostar, i.e., the inner disk radii. In addition, there is a bridging feature between them on the position-velocity diagram, suggesting the existence of an intermediate velocity component entrained by the high-velocity flows. The number of complex systems showing various phenomena associated with mass ejection is limited. Further follow-up observations in multi-line/multi-scale observations will lead to a deeper understanding of the outflow process in an early phase of star formation.