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An Optical emission line survey of large planetary nebulae
International Astronomical Union Symposium (234th : 2006) (3 - 7 April 2006 : Hawaii)
Barlow, Michael J. and Méndez, Roberto H.. Planetary nebulae in our galaxy and beyond : proceedings of the 234th symposium of the International Astronomical Union held in Waikoloa Beach, Hawaii, USA April 3-7, 2006, Vol. 2, p.455-456
Accurate emission line fluxes from planetary nebulae (PNe) provide important constraints on the nature of the final phases of stellar evolution. Large, evolved PNe may trace the latest stages of PN evolution, where material from the AGB wind is returned to the interstellar medium. However, the low surface brightness and spatially extended emission of large PNe have made accurate measurements of line fluxes difficult with traditional long-slit spectroscopic techniques. Furthermore, distinguishing these nebulae from H II regions, supernova remnants, or interstellar gas ionized by a hot, evolved stellar core can be challenging. Here, we report on an ongoing survey of large Galactic PNe (r>5΄) with the Wisconsin H-Alpha Mapper (WHAM), a Fabry-Perot spectrograph designed to detect faint diffuse optical emission lines with high sensitivity and spectral resolution. Our sample includes newly revealed Hα enhancements from the AAO/UKST and WHAM Hα surveys of Parker et al. and Haffner et al. We present accurate emission line fluxes of Hα, [N II]λ6583, and [O III]λ5007, and compare our data to other measurements. We use the emission line ratios and kinematics of the ionized gas to assess, or in some cases reassess, the identification of some nebulae.