Maps of the Molecular Emission around 18 Evolved Stars

We present maps at 20 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 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. Subject headings: stars: mass loss – stars: late-type – stars: circumstellar shells – nebulae: structure