Rotating Ring of Complex Organic Molecules 2

Velocity structure of methyl formate observed along the A-B axis. The abscissa is the position along the A-B axis shown in Figure 1, while the ordinate is the line-of-sight velocity of methyl formate. Positive velocity means that the gas is going away from the observer, while negative velocity means that the gas is approaching the observer. The velocity on the A side is the opposite of that on the B side. (Lower Left) The above features can be interpreted as the rotating ring shown here schematically. Based on molecular velocity information, methyl formate is found to exist in the rotating ring. The size of the ring is about 50 AU, which corresponds to the boundary between the infalling gas and the disk structure. (Upper Right) Velocity structure of H2CS (thioformaldehyde) observed along the A-B axis shown in Figure 1. The H2CS emission is seen farther away from the protostar than the methyl formate emission, indicating its existence in the infalling gas. The velocity increases as it approaches the protostar. Furthermore, the emission is also visible within the ring boundary, and the velocity is higher than that observed for methyl formate. (Lower Right) A schematic illustration of the distribution of H2CS. Both the infalling gas and the disk structure can be seen. Credit: ALMA (ESO/NAOJ/NRAO), Oya et al.