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D. Fong, M. Meixner, E.C. Sutton (University of Illinois, Champaign-Urbana), W.J. Welch (University of California, Berkeley)
Mass loss on the Asymptotic Giant Branch (AGB) stage gives rise to a primarily molecular envelope. Over time the circumstellar molecules are dissociated through the hardening UV radiation field of the emerging central star and/or through shocks from the fast wind colliding with the slower AGB wind. To study the evolution of the molecular envelope, we imaged a small sample of sources with the Berkeley-Illinois-Maryland-Association (BIMA) Millimeter Array and the NRAO 12m in the 12CO J=1-0 line. Our sample ranges from the AGB to the planetary nebula stage including IRC +10216, MIRA, IRAS 17436+5003 (HD 161796), AFGL 2688, IRAS 22272+5435 (HD 235858), AFGL 2343 (IRAS 19114+0002) and NGC 7027. Full synthesis maps of these sources will be presented and some preliminary results will be discussed.
Fong, Meixner and Sutton have been partially supported by NSF AST 99-81363 and NSF AST 97-33697.