Program: GS-2007A-DD-9

We request T-ReCS observations of three southern planetary nebulae selected on the basis of their estimated N-band surface brightness, as part of a large, unbiased sample of N-band images of these objects. Comparison of these images to optical images will allow us to determine if there is hot dust beyond the ionized region and whether the dust is uniformly mixed in the ionized gas. We will also be able to produce detailed photoionization models of these objects including the effect of dust in the nebula based upon these observations and data available in the literatre (H beta fluxes, line intensities, radio brightnesses, and broad-band magnitudes). In addition to imaging we request N-band spectroscopy of the brightest of these objects, for which there is no information about the dust chemistry in the literature.