A new population of planetary nebulae discovered in the Large Magellanic Cloud (IV): The outer LMC

Abstract

We have extended our planetary nebulae (PNe) survey to the outer ~64 deg2 of the Large Magellanic Cloud (LMC) using maps from the Magellanic Cloud Emission Line Survey (MCELS) and the UK Schmidt Telescope (UKST) Hα survey. Although the MCELS survey has poorer ~5 arcsec resolution than both the UKST Hα survey and the original Hα median stacked map in the LMC's central 25 deg2, it has the advantage of additional narrow-band filters at Hα, [OIII] and [S II] providing improved diagnostic capabilities. Using these data to uncover new emission line candidates we have so far spectroscopically confirmed an extra 61 LMC PNe which we present here for the first time.We have also independently recovered and spectroscopically confirmed 107 of the 109 (98 per cent) PNe that were previously known to exist in the outer LMC. The majority of our newly discovered and previously known PNe were confirmed using the AAOmega, multi-object fibre spectroscopy system on the 3.9-m Anglo-Australian Telescope (AAT) and the 6dF multi-object spectrograph on the UKST. These newly identified PNe were cross-checked against extant multi-wavelength imaging surveys in the near- and mid-infrared in particular and against the latest emission-line ratio diagnostic plots for improved confidence in PNe identification. © 2013 The AuthorsPublished by Oxford University Press on behalf of the Royal Astronomical Society.