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Properties Of Dust Grains In Planetary Nebulae. I. The Ionized Region Of Ngc 6445, Peter A. M. Van Hoof, Griet C. Van De Steene, Douwe A. Beintema, P. G. Martin, Stuart R. Pottasch, Gary J. Ferland

Physics and Astronomy Faculty Publications

One of the factors influencing the spectral evolution of a planetary nebula is the fate of the dust grains that are emitting the infrared continuum. Several processes have been proposed that either destroy the grains or remove them from the ionized region. To test whether these processes are effective, we study new infrared spectra of the evolved nebula NGC 6445. These data show that the thermal emission from the grains is very cool and has a low flux compared to Hβ. A model of the ionized region is constructed, using the photoionization code CLOUDY 90.05. Based on this model, we …