The Winds from HL Tau

Outflowing motions, whether a wind launched from the disk, a jet launched from the protostar, or the entrained molecular outflow, appear to be an ubiquitous feature of star formation. These outwards motions have a number of root causes, and how they manifest is intricately linked to their environment as well as the process of star formation itself. Using the ALMA Science Verification data of HL Tau, we investigate the high velocity molecular gas being removed from the system as a result of the star formation process. We aim to place these motions in context with the optically detected jet, and the disk. With these high resolution ($\sim 1"$) ALMA observations of CO (J=1-0), we quantify the outwards motions of the molecular gas. We find evidence for a bipolar outwards flow, with an opening angle, as measured in the red-shifted lobe, starting off at 90$^\circ$, and narrowing to 60$^\circ$ further from the disk, likely because of magnetic collimation. Its outwards velocity, corrected for inclination angle is of order 2.4 km s$^{-1}$.
Comment: 8 Pages, 8 figures, 3 tables. To appear in MNRAS