Small-scale structure and chemical differentiation in the central region of the Sagittarius B2 molecular cloud

Fifteen arcsec angular resolution observations of a number of molecular species in the center of the Sgr B2 molecular cloud, including HC3N in the ground and v7 = 1 vibrational states, SO, OCS,l and HNCO, have been performed. Emission from HC3N is fairly uniformly distributed over the region studied; SO and OCS have a spatially extended component but are strongly centrally peaked. HNCO and vibrationally excited HC/sub 3/N emission are essentially restricted to a very small region around the center of activity in the north. The difference between the spatial distributions are attributed to variation in the chemical abundances of the various clumps. The excitation requirements of the vibrationally excited HC/sub 3/N imply the presence of dust and gas at high temperatures. The results further heighten the apparent contradiction presented by the lack of infrared emission from this source. 53 references.