THE DISTRIBUTION OF MOLECULES IN THE CORE OF OMC-1

We have surveyed molecular line emission from five positions near the core of the Orion molecular cloud OMC-1, in the vicinity of Orion-KL, with 14'' spatial resolution. The frequency coverage of the survey was from 334 to 343 GHz. A maximum entropy analysis has been used to deco nvolve the double-sideband data into single-sideband spectra for each position. The rms noise levels in the single-sideband spectra are of o rder 0.2 K at 1 MHz resolution. A total of 291 resolvable lines have b een detected, corresponding to 26 different chemical species. There ar e 17 currently unidentified lines clearly present in at least one posi tion with peak T-R greater than 1 K. Some of these may be due to know n molecular species whose spectra have not been completely determined. An excitation analysis indicates that kinetic temperatures in these r egions are in a range of similar to 60-200 K with densities of 3 X 10( 5) cm(-3) to 3 X 10(6) cm(-3). Some highly reactive species, including free radicals, have peak column densities to the northeast of the Ori on core in the direction of the Orion ''extended ridge.'' Most other s pecies have maximum column densities about 8'' to the southwest of IRc 2, in the direction of the Orion ''compact ridge.'' Kinematic characte ristics are quite variable, with velocity dispersions ranging from 1.5 to 40 km s(-1). The chemistry of the extended ridge appears to be int ermediate between that of a typical cold dark cloud and a warm dense c loud core. Abundances of CH3OH and CH3CCH in the extended ridge probab ly reflect some evaporation of grain mantles. The chemistry of the cen tral regions near IRc2 are reasonably well represented by models of de nse cloud cores, although it appears to be somewhat difficult to expla in the large observed abundances of most complex molecules. Grain mant le evaporation seems to play a critical role in the chemistry of these regions. Substantial chemical differences exist between the ''hot cor e'' and ''compact ridge'' sources. It appears to be possible to explai n most of these differences in terms of physically distinct regions in a massive, collapsing protostellar source.