Astronomy Colloquium (2016 Fall Semester)

* Date

Oct. 27

* Speaker

Heeyoung Oh (SNU)

* Title

IGRINS spectroscopy toward outflows from young stellar objects

* Abstract

Outflows from young stellar objects (YSOs) are essential process in the formation of stellar and planetary systems. I present the observations of outflows in the intermediate-mass and massive star forming regions using Immersion Grating Infrared Spectrograph (IGRINS). The near-IR, high-resolution spectroscopy allows us to study multiple outflows in the dense molecular clouds. Furthermore, the spectral mapping enables to probe the three-dimensional structure of outflows.

I report the results from two observational studies. First, I present the multiple-outflows around Herbig Be star LkH_alpha 234. This star formation region is complicated with several optical and IR outflows and embedded YSOs. Using the [Fe II] 1.644 micron line, we revealed that the radio source VLA 3 emanates a high-velocity (V_LSR = -120

km/s) outflow. Second, we conducted a spectral mapping toward the Orion KL, explosive outflow. At the H_2 peak 1 area, we identified a total of 31 outflow fingers using datacube of H_2 1-0 S(1) 2.122 micron line. We constructed a three-dimensional map of fingers by estimating the inclination angles. The extinction difference (Delta A_V > 10 mag) between blue shifted and redshifted fingers indicates high internal extinction. The extinction and overall angular spread of the flow argue for an ambient medium with high density (10^5 cm^-3).