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P.J. Huggins (NYU), P. Cox (IAS, Paris), J.-P. Maillard (IAP, Paris), C. Muthu, R. Bachiller (OAN, Madrid), T. Forveille (CFHT)
We report high resolution (0.5'' times 9 km s-1) spectro-imaging of the 2.12 micron H2 v=1-0 S(1) line in the proto-planetary nebula AFGL 618. The observations were made with the BEAR imaging Fourier transform spectrometer at the CFHT. The results provide a detailed picture of the structure and kinematics of the H2 emission in AFGL 618, and shed light on a long standing problem of the origin of high velocity H2 seen in the line wings of spatially unresolved spectra (Burton & Geballe 1986, MNRAS 223, 13p). At low expansion velocities the H2 distribution forms a tilted, bi-conical structure, which is typical of that seen in proto-PNe and young PNe. At high expansion velocities, the H2 emission is resolved into multiple, molecular outflows that align with the remarkable optical jets seen in HST images reported by Trammel and Goodrich (2002, ApJ in press). The H2 velocity increases along the jets away from the center, to as much as 200-350 km s-1 when corrected for inclination, although the line widths are quite narrow ~ 30 km s-1. The H2 emission signals shock interaction of the jets with the circumstellar gas, and likely arises from entrained envelope material. AFGL 618 is one of several proto-PNe and young PNe in which optical jets are seen: the structure and kinematics of the molecular outflows reported here illustrate how these jets interact with circumstellar gas and shape the environment in which planetary nebulae form. This work was supported in part by NSF AST-9986159.
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Bulletin of the American Astronomical Society, 34, #4
© 2002. The American Astronomical Soceity.