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Session 7 - Planetary & Other Nebulae.
Display session, Monday, June 09
South Main Hall,
We present high spectral and spatial resolution near-IR spectroscopy of the bipolar proto-planetary nebula M1-92. The spectra were obtained using the high resolution spectrograph, CSHELL, at the NASA Infrared Telescope Facility on Mauna Kea. The goal of this project was to spatially resolve the location of the H_2 emission present in this object and to determine its relative velocity as a function of nebular position. Previous optical spectropolarimetry of M1-92 revealed that the line emission seen in the bipolar lobes is indicative of shock heating with V_s = 40 - 100 km s^-1 (Trammell et al. 1993). Subsequent high resolution optical spectroscopy demonstrated that this shock emission is associated with a high velocity outflow (Solf 1994). Narrow-band HST images of this object show a highly collimated outflow originating near the central star and impacting the bipolar lobes (Trammell and Goodrich 1996). Using a 1\arcsec slit placed along the bipolar axis, we mapped the velocity field of the Br \gamma and H_2 2.122 \micron emission lines in M1-92. In both cases, high velocity components (> 100 km s^-1) of emission are evident. The high velocity components of emission are co-spatial with the collimated outflow seen in the lobes of M1-92 in the HST images. Further, the outflow velocities derived for the near-IR emission lines are consistent with those estimated from the optical emission line ratios and found using optical spectroscopy. These results suggest that the near-IR H_2 emission is associated with the collimated outflow seen in the lobes of M1-92. We discuss several mechanisms that could be responsible for producing the kinematic features observed in M1-92, in particular the action of a precessing, episodic jet.
