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M. Meixner (STScI)
The asymptotic giant branch (AGB) star wind creates a predominantly molecular and dust rich circumstellar envelope which is the starting point for a proto-planetary nebula (PPN). We have been using BIMA imaging of the CO J=1-0 line to study the structure and kinematics of these circumstellar environments. The CO J=1-0 line emission is the best probe of the circumstellar molecular gas content, particularly the outer regions and millimeter interferometers, such as BIMA, provide the high angular resolution needed to resolve the compact structures of these PPN. Expanding molecular envelopes are found around all sources; however some PPN also have collimated bipolar outflows, such as the Egg Nebula and AFGL 618. For the collimated outflow sources, we compare the CO emission with near-IR imaging of the H2 and [FeII] taken with NIRIM at WIYN to identify shocked gas regions where these bipolar outflows are interacting with the slower AGB wind. We also compare the structures observed in CO with the dust shell structures that we have previously imaged in the thermal emission with the MIRAC3 and Berkcam mid-IR cameras and in scattered starlight with WFPC2/HST.
This research was supported by NSF AST 99-81363 and NSF AST 97-33679.
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Bulletin of the American Astronomical Society, 34, #4
© 2002. The American Astronomical Soceity.