H Stacked Images Reveal Large Numbers of PNe in the LMC Warren Reid1 Quentin Parker1,2 1Macquarie University, Sydney, Australia 2 Anglo-Australian Observatory

A Unique Set of Matching Images Deep Ha and equivalent R-band images of the entire 25.sq.deg. central LMC Monolithic, high quality Ha filter High-resolution Tech-Pan film SuperCOSMOS scanned and co-added exposures. 0.67 arcsec pixels after 15-bit digitized plate scanning. (SHASSA = 48 acrsec resolution WHAM = 1 degree resolution) Depth reaches R-equivalent ~22 for Ha and R ~21.5 for Red Advantages of the stacking process IAM data Red 9 x 15min Stack Hα 13 x 2hr Stack New PN!

SuperCOSMOS scanned UKST Images R-band, Tech-pan single exp. R-band, Tech-pan stacked R-band, IIIaF Ha, Tech-pan single exp. Ha, Tech-pan stacked

Colour combination of Red and Ha Stacked Images + = Red Stack Ha Stack + =

Method of Image Analysis 16 x 1.25 sq.deg. image cells Accurate WCS applied Image colouring and Intensity matching PSF matching on continuum sources Diameters recorded Magnitudes calibrated to bright photometry from the Tycho and Guide star Photometric catalogues. Faint calibrations are tied to CCD standards from: Groom et.al. (1999, MNRAS, 306, 592) Boyle et.al. (1995, MNRAS, 276, 33) Stobie et.al. (1985, A&AS, 60, 503) Large numbers of candidate PNe found

Previously Known PNe Re-identified SMP 90 SMP 89 Mo 35 Mo 39 Mo37 Mo 36

RP 105, a newly discovered and confirmed PN with an elliptical halo

SMP 27 HST bb 9” x 12” image revealing outer structure

SMP27

HST image of the central PN scaled to the UKST image SMP 93 with Extended Halo HST image of the central PN scaled to the UKST image

2dF Spectroscopic Follow-up New PNe discovered from our survey and confirmed with 2dF on the AAT within a 1.25 square degree area versus Previously known PNe within the same area

Images and Spectra PR 23 RP 25

Images and Spectra RP 85 RP 92

Difference in Ha magnitude between Central PN and Central PN plus Halo (with a sample of 71 PNe) Difference in Ha Magnitude between Emission-line Star and Ha Spread Function (with a sample of 39 ELS)

PNe halo radius beyond the Central PN vs PNe halo radius beyond the Central PN vs. the difference in Ha magnitude between the central PN and the whole PN including the halo Each diameter bucket contains an average magnitude for that Halo diameter

Newly Discovered PNe

Science Implications Comprehensive LMC PNe Luminosity Function To understand evolutionary types in the LMC To provide a probe into the structure and origin of the LMC As a distance probe when applied to other Hubble-type Galaxies Chemical Abundances and Ratios Shells provide a tool to study ejected material, giving insight into precursor evolution H-R Diagrams based on Diameters, Fluxes, Nebula Temperatures and Densities Specific line ratios can be used in conjunction with photoionization modelling to determine stellar parameters Parameters of AGB Halos Initial to Final Mass Relation An updated and comprehensive catalogue of LMC PNe

Conclusion Thus far 6/16 image cells have been carefully analysed to extract the position, magnitude and dimensions of every possible emission source. Detection rate increases 3-fold on the main bar Each source is added to the database with an estimate as to it’s probability as a PNe or Emission-line star. All previously known PNe have been re-identified independently. Of 262 candidate sources observed using 2dF on the AAT from spectroscopic follow-up of candidates in 3 cells we find: 136 are confirmed PNe, 57 are Emission-line stars, 33 require longer exposure times 33 are non-detections. From current estimates we expect to discover >1,000 new Pne within the 25 square degrees of the main LMC bar. A 5-night run allocated with 2dF on the AAT in December 2004 will confirm most candidates. A proposal to observe PNe for faint diagnostic lines on VLT/FLAMES is in. A proposal to observe PN Halos for chemical abundances, velocities and densities on VLT using IFUs.

Known PN with HST bb Images superimposed to scale SMP 88, Central PN dia = 1.5 arcsec. Halo dia = 8.1 arcsec SMP 89, Central PN dia

DSS SuperCosmos Stacked SuperCOSMOS

DSS SuperCOSMOS Stacked SuperCOSMOS