Joint AAO/ANTF Colloquium.
Wednesday 20th August 2008 - 3:30pm ATNF Lecture theatre
Multiwavelength Studies of Planetary Nebulae
Martin Cohen UC Berkeley, USA.
Abstract:
An approach to the study of planetary nebulae (PNe), both in the
Galaxy and the Magellanic Clouds, is described. This depends upon
new optical discoveries and confirmations of PNe, multi-frequency
radio imaging from the MOST, ATCA, and Parkes and ongoing mid-
infrared (MIR) observations by the Spitzer Space Telescope.
I describe the variety of tools utilized to recognize PNe, including
direct comparison of morphologies in H-alpha and MIR, the diagnostic
ratio of integrated MIR/radio fluxes, and the value of false
colour IR imaging. I present the first MIR luminosity functions
for a large sample of LMC PNe discovered by Reid & Parker (2006:Macquarie
University & AAO) and compare their features to optical
emission-line luminosity functions to explore whether PNe might be
viable MIR standard candles as they have been proven to be in
[OIII] emission. First efforts to discover MIR counterparts of H-alpha
halos are presented. These halos contain weakly ionized gaseous
ejecta from the AGB phase of the progenitors of PNe as well
as cool dust. Our goal is to combine halo masses from deep H-alpha
images and spectra with estimates of the mass in dust never previously assessed,
in order to address the "missing mass" problem in PNe.
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