Tuesday, November 17, 2009, 11:00 am, 3rd Floor Conference Room, 160 Concord Avenue
Multiwavelength studies of Planetary Nebulae
Dr. Martin Cohen, UC Berkeley
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I present multiwavelength work on planetary nebulae over the past
decade, emphasizing the interplay of optical, infrared and radio
continuum observations. Tools developed from mid-infrared and radio
analyses of HII regions have proven useful when applied to planetary
nebulae. By use of multiwavelength techniques it has been possible to
eliminate a significant number of non-planetary nebulae that have
contaminated previous catalogues. I discuss the application of these
techniques to the nebulae discovered by the Macquarie-AAO-Strasbourg
Halpha survey (MASH) which has found about 1500 new planetary nebula
candidates. It is now clear that one must merge several different
approaches in a variety of spectral regions in order to assure the
purity of catalogued planetary nebulae. One can no longer rely solely
upon optical morphology and spectroscopy. Indeed, we now know of a
potential planetary nebula discovered purely by radio and mid-infrared
observations but lacking any optical counterpart. This suggests the
importance of developing non-optical criteria for planetaries.
I highlight the results of multiwavelength analyses of a sample of PNe that has been "cleaned" by the application of these techniques; the rare class of OH planetary nebulae in which an optical nebula surrounds a still-pulsating OH-IR star; the PN discovered in the radio and MIR regimes; and the first infrared PN luminosity functions in the LMC. |