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We present low spectral resolution molecular interferometric observations at1.2 mm obtained with the Combined Array for Research in Millimetre-waveAstronomy (CARMA) towards the C-rich AGB star IRC+10216. We have mapped theemission of several lines of SiS, H13CN, SiO, and SiC2 in the ground and firstexcited vibrational states with a high angular resolution of 0.25 arcsec. Theseobservations have allowed us to partially resolve the emission of the envelopeat distances from the star <50 stellar radii (R*), where the stellar wind ismainly accelerated. The structure of the molecular emission has been modelledwith a 3D radiation transfer code. The emission of line SiS(v=0,J=14-13) isbest reproduced with a set of maser emitting arcs arranged between 5 and 20 R*.The abundance of H13CN with respect to H2 decreases from 8e-7 at 1-5 R* to 3e-7at 20 R*. The SiO observations are explained with an abundance <2e-8 in theshell-like region between 1 and 5 R*. At this point, the SiO abundance sharplyincreases up to (2-3)e-7. The vibrational temperature of SiO increases by afactor of 2 due North-East between 20 and 50 R*. SiC2 is formed at the stellarsurface with an abundance of 8e-7 decreasing down to 8e-8 at 20 R* probably dueto depletion on to dust grains. Several asymmetries are found in the abundancedistributions of H13CN, SiO, and SiC2 which define three remarkable directions(North-East, South-Southwest, and South-East) in the explored region of theenvelope. There are some differences between the red- and blue-shiftedemissions of these molecules suggesting the existence of additional asymmetriesin their abundance distributions along the line-of-sight.

The complex dust formation zone of the AGB star IRC+10216 probed with CARMA 0.25 arcsec angular resolution molecular observations