PLATEAU DE BURE OBSERVATIONS OF IRC- HIGH-SENSITIVITY MAPS OF SIC2, SIS, AND CS(10216 )

We have obtained high angular resolution (similar to 3''), and high se nsitivity maps of IRC+10216. SiC2 is found both in a spherical shell a nd in the very central region, indicating it is formed both in the inn er envelope close to the star, and in the outer shell. The molecules S iS and CS are mostly found in the inner parts of the envelope, but are still detectable in the outer region (r similar to 15'') where the pr oducts of photochemistry are found. The maps show that IRC+10216 has a very clumpy envelope, with strong departures from spherical symmetry; an axis oriented NS-SW (P.A. 20 degrees) can be seen in all maps. The radial brightness distribution of CS has secondary maxima, at the rad ius where the SiC2 shell has its peak emission. A preliminary map show s CN in the same shell, but also in a still larger outer shell. Time v ariations in the mass loss rate, could be invoked to explain the multi ple shell structure of this envelope.