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Here we present initial results of our search for extensive halos around the planetary nebulae (PNe) in our Galaxy based on imaging data from the Southern H-Alpha Sky Survey Atlas (SHASSA). A threshold surface brightness in H$alpha$ emission was used to help identify the spatially extended features of the PNe. We investigated a sample that included 10 PNe, the large majority of which were found to be surrounded by extensive outer halos. The formation of these halos might be closely related to the AGB phase mass loss and/or the interaction of the stellar outflows with the interstellar medium. Most of these outer halos are nearly spherical. Close investigation of some specific objects, such as He 2-111 and NGC 3242, indicate a kinematic age on the order of 10$^{5}$ yrs. The mass loss history can be traced back to the late AGB phase of the evolution of the progenitors. Two objects form the sample (He 2-111, NGC 3242), were found to have outer halos with fragmented arcs that are apparently the result of their interaction with the interstellar medium.
We compare H-alpha, radio continuum, and Spitzer Space Telescope (SST) images of 58 planetary nebulae (PNe) recently discovered by the Macquarie-AAO-Strasbo- urg H-alpha PN Project (MASH) of the SuperCOSMOS H-alpha Survey. Using InfraRed Array Camera
The discrepancy between abundances computed using optical recombination lines (ORLs) and collisionally excited lines (CELs) is a major, unresolved problem with significant implications for the determination of chemical abundances throughout the Unive
The Andromeda (M31) galaxy subtends nearly 100 sq. deg. on the sky, with severe contamination from the Milky Way halo stars whose surface density displays a steep gradient across the entire M31 field-of-view. Planetary Nebulae (PNe) are a population
We report H$alpha$ filter photometry for 197 northern hemisphere planetary nebulae (PNe) obtained using imaging data from the IPHAS survey. H$alpha$+[N II] fluxes were measured for 46 confirmed or possible PNe discovered by the IPHAS survey and for 1
We report the results of spectroscopic observations, obtained with the GEMINI Multi-Object Spectrograph, of 8 planetary nebulae (PNe) in the dwarf spheroidal (dSph) galaxy NGC147, a companion of M31. The physico-chemical properties of the six brighte