Maps of the Molecular Emission Around 18 Evolved Stars

Abstract

We present maps at $20^{\prime \prime }$ 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.

28 pages, uses aaspp.sty file, submitted to ApJ. The full PostScript version with 19 figures can be obtained by the anonymous ftp from astro.princeton.edu, directory stanek/CO_maps, or through the WWW, htpp://astro.princeton.edu/~library/prep.html