Large-Scale Interaction of the Outflow and Quiescent Gas in Orion

The detection of widespread high-velocity molecular gas in the Ori A molecular cloud is reported. The high-velocity emission occurs over a range of + or - 40 km/sec. This high-velocity gas is more extended (up to 150 arcsec from IRc2) than the very compact (40 arcsec) and well studied molecular outflow around IRc2. The terminal velocities of the CO wings decrease from 100 km/sec (corresponding to the very fast molecular flow) to the typical terminal velocities of the extended high-velocity gas when the distance to IRc2 changes from 40 to 60 arcsec. The origin of the large-scale high-velocity gas is discussed: it is very likely the link between the very compact and energetic molecular outflow around IRc2 and the ionized high-velocity gas and the HH objects.