  We present spectro-polarimetric observations of several molecular lines
obtained with the Submillimeter Array (SMA) toward the carbon rich AGB star
IRC+10216. We have detected and mapped the linear polarization of the CO 3-2,
SiS 19-18 and CS 7-6 lines. The polarization arises at a distance of ~450 AU
from the star and is blueshifted with respect the Stokes I. The SiS 19-18
polarization pattern appears to be consistent with a locally radial magnetic
field configuration. However, the CO 3-2 and CS 7-6 line polarization suggests
an overall complex magnetic field morphology within the envelope. This work
demonstrates the feasibility of using spectro-polarimetric observations to
carry out tomographic imaging of the magnetic field in circumstellar envelopes.
