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A. N. Sumerel, S. R. Trammell (UNC Charlotte)
We present STIS low and medium resolution optical spectroscopy of the proto-planetary nebula GL 618. This object is a compact, bipolar nebula that is currently undergoing the transition from AGB star to planetary nebula. Collimated outflows emanating from the central regions dominate the optical morphology of GL 618 and these outflows probably play an important role in its dynamic evolution. The optical spectrum is dominated by shock emission from these outflows. We have used line strengths derived from the spectra, and published shock models, to estimate shock velocities in the outflows to be in the range of 40 - 100 km s-1. Based on the shock velocities we estimate that the age of the outflows is less than 500 years. Gas densities range from about 2000 - 7000 cm-3 in the outflows. The outflows seen in the optical images of GL 618 are related to features seen in near-IR, CO and CS maps of this object. This relationship indicates that the outflows are playing a major role in the morphological evolution of this young planetary nebula, interacting with and shaping the neutral envelope surrounding GL 618.
This work was supported by NASA through a grant from the Space Telescope Science Institute.
Bulletin of the American Astronomical Society, 37 #4
© 2005. The American Astronomical Soceity.