Abstract
A CO J=4-3 map of Orion-KL (size: 80 ''; beam (FWHM): 15 '') is presented which, for the first time, covers the extent of and spatially resolves an extreme high velocity outflow in a higher excited CO transition. The spike component is identified and shows that the bulk of the dense molecular ridge has a maximum kinetic temperature of similar to 150 K. The outflow has a bipolar structure observed nearly face-on. The distribution and kinematics of the highest velocity outflowing gas favours IRc2 to be its driving source. We interpret our observations in terms of a hierarchy of 'tubes' where the fastest gas proceeds through the narrowest innermost cone. The gas has an inhomogeneous temperature distribution, which can be expected for shock-excited regions, and must be highly clumped. Most of the properties derived fit well into the picture developed for the few known extreme high velocity outflows. However, the outflowing gas near IRc2 must be exceptionally dense (greater than or equal to 10(6) cm(-3)).