Dust in Planetary Nebulae and in Post-AGB Objects

Abstract

Developments in the field since the review of Roche (1989) are discussed. Section 1 describes the results from detailed models of the dust emission from planetary nebulae and summarises the derived dust-to-gas mass ratios. The properties of the remarkable gas-poor planetary nebula IRAS 18333–2357, located in the globular cluster M22, are discussed in Section 2. The use of thermal infrared imaging to map the distribution of different dust components is reviewed in Section 3, and two recently applied optical probes of nebular dust properties are described: emission line spectropolarimetry, and spectroscopy of the Extended Red Emission (ERE). The final section describes recent results from infrared spectroscopy. The spectra of carbon-rich post-AGB objects have provided valuable new insights into the nature and evolution of the materials responsible for the UIR bands, while unusual oxide grains and crystalline ice emission have been detected around oxygen-rich post-AGB objects. The spectra of a small number of objects show evidence for the simultaneous presence of both oxygen-rich and carbon-rich material.