Free Astronomy Magazine May-June 2019

47 MAY-JUNE 2019 SPACE CHRONICLES long time periods due to the preces- sion of the central star. But in this case, considering the extreme youth of the gas streams, researchers con- cluded that the misalignment is not due to precession but is related to the launching process. There are two competing models for the for- mation mechanism of the protostel- lar outflows and jets. Some researchers assume that the two streams are formed independ- ently in different parts of the gas disk around the central baby star, while others propose that the collo- cated jet is formed first, then it en- trains the surrounding material to form the slower outflows. Despite extensive research, astron- omers had not yet reached a conclu- sive answer. A misalignment in the two flows could occur in the ‘independent model,’ but is difficult in the ‘en- trainment model.’ Moreover, the team found that the outflow was ejected considerably earlier than the jet. This clearly backs the ‘indepen- dent model.’ “The observation well matches the result of my simulation,” said Masahiro Machida, a professor at Kyushu University. A decade ago, he performed pioneering simulation studies using a supercomputer op- erated by the National Astronomical Observatory of Japan. In the simu- lation, the wide-angle outflow is ejected from the outer area of the gaseous disk around a protostar, while the collimated jet is launched independently from the inner area of the disk. Machida continues, “An observed misalignment between the two gas streams may indicate that the disk around the protostar is warped.” “ALMA’s high sensitivity and high angular resolution will enable us to find more and more young, ener- getic outflow-and-jet-systems like MMS 5/OMC-3,” said Satoko Taka- hashi, an astronomer at the Na- tional Astronomical Observatory of Japan and the Joint ALMA Observa- tory and co-author of the paper. “They will provide clues to under- stand the driving mechanisms of outflows and jets. Moreover study- ing such objects will also tell us how the mass accretion and ejection processes work at the earliest stage of star formation.” A LMA image of the protostar MMS5/OMC-3. The proto- star is located at the center and the gas streams are ejected to the east and west (left and right). The slow out- flow is shown in orange and the fast jet is shown in blue. It is obvious that the axes of the outflow and jet are mis- aligned. [ALMA (ESO/NAOJ/NRAO), Matsushita et al.] !