"A Multi-wavelength Investigation of Newly Discovered Planetary Nebulae in the Large Magellanic Cloud

Monday, March 2, 2015 - 15:30
AURA Lecture Hall
WARREN REID, Macquarie University (Australia) and Gemini South Visitor (Tenure Track Astronomer Candidate)
Talk Abstract: 

We have recently completed our search for faint PNe in the LMC having included the outer 64 deg2 area not covered in the original UKST survey of the central 25deg2 region. Candidate PNe were selected using the [OIII], [SII] and H-alpha images provided by the Magellanic Cloud Emission Line Survey (MCELS). Four rounds of confirmatory spectroscopic observations using AAOmega on the Anglo-Australian telescope have yielded a further 110 new LMC PNe while confirming the 102 previously known PNe in the outer LMC. These observations, providing medium and high resolution spectra from 3650Ang to 6900Ang have been used to measure fluxes and derive central star temperatures for a series of research projects based on luminosity functions, chemical abundances, central star properties and kinematics.

The resulting [OIII]-based PN luminosity function, apart from providing an excellent standard candle, contains information about the parent population. Our PNLF, which extends down 9 magnitudes, finally allows us to investigate the faint end which holds clues to understanding the insensitivity of the PNLF cutoff, whatever the age of the population. With 766 spectroscopically confirmed bright and faint, highly evolved PNe, the shape of the function including the positions of its dips and peak provide new evolutionary insights, revealing evidence of low-mass cores and confirming simulated dynamical time scales.

To better understand the global properties of PNe I will present and compare PNLFs using H-alpha, IRAC (SAGE) and MIPS wavelengths from Spitzer and 2MASS J, H and K bands. We will also take a look at recent multi-wavelength plots comparing Miras to other giant and supergiant stars in the LMC. These stars provide a clue as to the chemical composition of stars that will eventually become PNe. Using the MCELS map I will display the LMC PNe as a function of their position in the LMC. These will then be shown as a function of their radial velocities and compared to the HI disk and other populations, both young and old. I will also show LMC PN positions according to their chemical abundances with particular reference to those PN high in He and N, commonly known as Type I PNe.