Detection of shocked atomic gas in the Kleinmann-low nebula

We have mapped the 63 ..mu..m /sup 3/P/sub 1/..-->../sup 3/P/sub 2/ fine-structure line emission of neutral atomic oxygen at the center of the Orion nebula with a resolution of 30''. There are three main emission peaks. One is associated with the region of strongest thermal radio continuum radiation close to the Trapezium cluster and probably arises at the interface between the H II region and the dense Orion molecular cloud. The other two (O I) line emission peaks, associated with the Kleinmann-Low nebula, are similar in both distribution and velocity to those of the 2 ..mu..m S(1) line of molecular hydrogen and of the high-velocity wings of rotational CO emission. The (O I) line profiles in the KL region are resolved at a resolution of 45 km s/sup -1/ and have an intrinsic width of about 50 km s/sup -1/, while the line profile in the vicinity of the Trapezium is unresolved. We show that the (O I) emission from the KL nebul can be produced in the shocked gas associated with the mass outflows in this region and is an important coolant of the shocked gas.