IV. Envelopes Near-IR Emission Line Imaging of PN T.M.Hodge 1 , C.E.Woodward 1 , D.M.Kelly 1 , J.Fischer 2 , M.A. Greenhouse 3 , S. Satyapal , H.A. Smith , J.L. Pipher 4 and W.J. Forrest 4 1 U. Wyoming; 2 Naval Research Lab; 3 National Air & Space Museum; 4 U . Rochester Spatial studies of the emission line regions in planetary nebulae (PN) can provide in- sight into the physical and chemical environments across the nebulae. In a collaborative effort by the coauthors, a K-band Fabry-Perot talon has been coupled with an advanced 256x256 InSb focal plane array at the Wyoming Infrared Observatory 2.3m telescope. This system permits us to obtain spatially resolved, 0.24"/pixel, moderate spectral resolu- tion (R « 800), flux-density IR emission line images of astronomical sources. We obtained continuum-subtracted images of Br 7, Hel 2.06 , the 2- UIR features, and the 3.3 PAH dust feature in the PN NGC 6572, NGC 7027, and NGC 7662. One objective was to determine the spatial morphology of two unidentified emission lines, UIR1 - 2.199 , and UIR2 - 2.287 (Geballe et al. 1991). These UIR lines appear in the spectra of many PN (Hora et al. 1997) and in the Orion Nebula (Luhman & Rieke 1996). Geballe et al. suggested that the UIR lines are most likely forbidden transitions and showed that the parent ion ionization potential is « 30 - 40 eV, while the ionization potential for the ions themselves is 40 — 60 eV. Here we directly compare the distribution of the UIR emitters to that of the gas (H+,He+) and dust (PAHs). The UIR lines in these PN lie in a narrow shell on the outer edge of the II region, interior to the PAH-emitting region. The UIR shells are thinner in spatial extent than the limb-brightened Br7 shells. The UIR images of NGC 7027 are similar in morphology to the [ II] images (Robberto et al. 1995), supporting the idea that the UIR lines are atomic in origin. Spatially-extracted longslit spectra of the nebulae show the UIR lines to be sim- ilar in spatial extent to Br7 and significantly more extended than the He II emission. The He I emission tends to peak at positions where the UIR emission is at a minimum. Echelle spectroscopy of NGC 7027 shows clear similarities in the kinematic signatures of the two UIR features and differences compared to H 2 and He I (Kelly et al. 1997). Our current hypothesis is that the UIR lines are forbidden transitions in a two or three times ionized complex metal - possibly even fine structure transitions in the ground term of such an ion (cf. Hodge et al. 1997). This work has been supported in part by NSF grant AST94-53354. REFERENCES Geballe, T.R., Burton, M.G., & Isaacman, R. 1991, MNRAS, 253, 75. Hodge, T.M., et al. 1997, in preparation. Hora, J.L., Latter, W.B., & Deutsch, L.K. 1997, in preparation. Kelly, D.M., Woodward, C.E., & Latter, W.B. 1997, in preparation. Luhman, K., & Rieke, G.H. 1996, Astrophys. J., 461, 298. Robberto, M., et al. 1993, Astron. & Astrophys. 280, 241. 237 available at https://www.cambridge.org/core/terms. https://doi.org/10.1017/S0074180900130578 Downloaded from https://www.cambridge.org/core. IP address: 54.163.42.124, on 26 May 2020 at 12:09:56, subject to the Cambridge Core terms of use,