Maps of the Molecular Emission Around 18 Evolved Stars

We present maps at ${20}^{\mathrm{\prime }\mathrm{\prime }}$ resolution of the molecular emission around 18 evolved stars (14~asymptotic giant branch stars, one supergiant, two proto-planetary nebulae and one planetary nebula), mostly in the ${}^{12}$CO(3-2) line. Almost all molecular envelopes appear to be at least marginally resolved at this resolution. A substantial fraction of the molecular envelopes show clear deviations from spherical symmetry in the form of elliptical or bipolar envelopes. This indicates that there is a need to implement non-spherical mass loss in current scenarios of the late stages of stellar evolution, in particular on the asymptotic giant branch.