A research team including Professor Kazuhito Motogi (tenure track) of the Graduate School of Sciences and Technology for Innovation (Science) has successfully captured the rotation of a gas outflow jetting from a high-mass young stellar object.

A research team led by Kazuhito Motogi (tenure track) of the Graduate School of Sciences and Technology for Innovation (Science) and Tomoya Hirota of the National Astronomical Observatory of Japan / Graduate University for Advanced Studies used the ALMA Telescope to observe the high-mass young stellar object “Orion-KL Source I,” which is hidden inside the Orion Nebula, and succeeded in clearly identifying that the gas (outflow) that jets out violently from the young stellar object is rotating. The rotation is that same as that of the gas disk that surrounds the high-mass young stellar object, and the research can be said to be firm evidence that shows that the outflow is being pushed out into space by the disk's centrifugal force and the force of the magnetic field. In general, if the centrifugal force of the rotation is strong, gas in the disk cannot fall onto the star. Therefore, in order for a star to swallow up gas and grow, it was thought that it was necessary to remove the obstructive force of the rotation (angular momentum), but through the observations in this research, it has been possible to show that in fact, the outflow is taking most of the excessive angular momentum out of the disk. Although many mysteries still remain with regard to the birth mechanism of high-mass young stellar objects, these observation results, having provided a clear picture of a rotating gas, can be said to represent a big step toward unraveling them.

The findings were published in the online version of the scientific journal Nature Astronomy on June 13 (12 am Japanese time).



(Radio image of Orion-KL Source I observed using the ALMA telescope You can clearly see the high-temperature gas disk (red) and the outflow jetting out from the disk (blue) in both directions. The observations in this research succeeded in clearly capturing how the outflow jets out while rotating in the same direction as the disk at its base. Credit: ALMA (ESO/NAOJ/NRAO))