The international research team observed the young protostar L1527 in the Taurus molecular cloud at a high spatial resolution with ALMA, and discovered an unexpected chemical change in the transition zone between the infalling envelope and the gas disk. So far, it has been believed that interstellar matter is smoothly delivered to the gas disk around the protostar without any significant chemical changes. However, it is now found to be oversimplified. The infalling gas is jammed up due to centrifugal force at the outer edge of the gas disk, where local heating causes a drastic chemical change. This chemical change highlights the outer edge of the gas disk which is still growing.

This research highlights “chemistry in the formation of protoplanetary disks” which is not anticipated before. It is still unknown whether this sharp transition is seen around many protostars or not, and it will be uncovered by future observational studies. This is also important for understanding of the formation process of our own solar system.

Figure
Illustration of rotating-infalling gas toward a protostar. The abundance of sulfermonooxcyde is enhanced at the outer edge (colored blue) of a protoplenatry disk.
The scientific paper on which this article is based appears in the science magazine “Nature” published on February 12, 2014. (Sakai et al. “Change in the chemical composition of infalling gas forming a disk around a protostar”)

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