Spectral Diagnostics, Kinematics and Abundances Based on a New Population of Planetary Nebulae Discovered in the LMC

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We report our discovery of 460 planetary nebulae (PNe) in the central 25 deg 2 region of the Large Magellanic Cloud (LMC). Candidate emission sources were discovered using a deep, high resolution UKST stack of 6 Short Red (SR) and 12 Hα images which go respectively 1 and 1.5 magnitudes deeper than a single exposure. The two digitized stacks were then assigned false colours and merged to reveal emission sources. Confirmatory spectroscopy was largely performed using 2dF on the AAT, with low and high resolution gratings. Additional follow-up in selected regions was also performed using FLAMES on the ESO VLT2 and Gemini South [2]. Optical spectroscopy not only allowed us to identify PNe from our large sample but results are allowing physical conditions to be determined. The new PNe have implications for the LMC PN luminosity function, kinematics, abundance gradients, chemical evolution and the initial to final mass relation for low to intermediate mass stars via the AGB halos revealed on the Hα map [3]. All the previously known PNe in the survey area have also been spectroscopically observed, resulting in a sample of 629 PNe. These have now been used to produce nebula diagnostics including temperatures, electron densities and masses [4]. Together with newly derived excitation classes [5], these diagnostics and fluxes have led to the discovery of new evolutionary tracks for LMC PNe [4]. Luminosity gradients have been compared to masses and densities for different excitation classes. Newly derived dynamical ages have also been estimated. PN abundances have been determined, comprising the largest sample ever obtained in any galaxy beyond the Milky Way, allowing clear trends to be graphically displayed for the first time. A new luminosity function has been constructed, providing the first clues to the shape of the faint end. This is compared to a new luminosity function constructed from a very complete sample of local PNe. Radial velocities from the complete LMC sample have been used to compare PN kinematics to that of the H i disk. The resulting transverse velocity and angle of inclination for PNe in the central 25 deg 2 region of the LMC have been found [3].