THREE-DIMENSIONAL SHOCK STRUCTURE OF THE ORION KL OUTFLOW WITH IGRINS

다국어 초록 (Multilingual Abstract)

<P>We report a study of the three-dimensional (3D) outflow structure of a 15 '' x 13 '' area around the H-2 peak 1 in Orion KL with slit-scan observations (13 slits) using the Immersion Grating Infrared Spectrograph. The datacubes have a high-velocity resolution (similar to 7.5 km s(-1)), provide high-contrast imaging within ultra-narrow bands, and enable the detection of the main stream of the previously reported H2 outflow fingers. We identified 31 distinct fingers in the H-2 1-0 S(1) lambda 2.122 mu m emission. The line profile at each finger shows multiple-velocity peaks with a strong low-velocity component around the systemic velocity at V-LSR = +8 km s(-1) and high-velocity emission (|V-LSR| = 45-135 km s(-1)), indicating a typical bow-shock. The observed radial velocity gradients of similar to 4 km s(-1) arcsec(-1) agree well with the velocities inferred from large-scale proper motions, where the projected motion is proportional to the distance from a common origin. We construct a conceptual 3D map of the fingers with estimated inclination angles of 57 degrees-74 degrees. The extinction difference (Delta A(v) > 10 mag) between blueshifted and redshifted fingers indicates high internal extinction. The extinction, the overall angular spread, and the scale of the flow argue for an ambient medium with a very high density (10(5)-10(6) cm(-3)), consistent with molecular line observations of the Orion Molecular Cloud core. The radial velocity gradients and the 3D distributions of the fingers together support the hypothesis of a simultaneous radial explosion of the Orion KL outflow.</P>