This image captures 2 high speed jets being ejected from the low mass protostar L1551-IRS5 embedded in a thick molecular cloud. It clearly shows the two jets parallel with each other, which are extending from the bright central part toward the lower left. The upper (northern) jet is 3 times faster than the lower (southern) jet, about 300 kilometers per second. It also turns out that two different kinds of gas flows exist in each jet. In other words, these double jets have two folded structures.

Velocity Structure and High Resolution Spectroscopy

As the first young stellar object where the presence of molecular bipolar outflow was confirmed, L1551-IRS5 is a historically important celestial object. This picture was taken by CISCO (Cooled Infrared Spectrograph and Camera for OHS) during the early period of the Subaru Telescope operation. Through low resolution spectrographic observations in the near infrared, we learned that the two jets shine brightly in the ionized forbidden iron ([Fe II]) emission lines by shock. To further elucidate the velocity structure of the jets, IRCS (Infrared Camera and Spectrograph) was used to perform a high resolution spectroscopy on the forbidden iron line. This showed that the northern jet has two velocity structures.

Text by: Tae-Soo Pyo (NAOJ, Subaru Telescope)
Translation by: Ramsey Lundock (NAOJ)