Martin Cohen (University of California, Berkeley)

Multiwavelength studies of planetary nebulae - Martin Cohen Colloquium

ATNF Marsfield Lecture Theatre

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.