Observations of Dust in Planetary Nebulae

Abstract

This review summarises those observations which relate to the existence of dust in planetary nebulae. The most direct evidence for dust, namely infrared emission by grains, is considered in Section 2. Section 3 describes a variety of optical and ultraviolet observations which bear more indirectly on the properties of the dust, while Section 4 discusses the power sources of the observed infrared emission. The peculiar nebulae A 30 and A 78 are considered in Section 5, and Section 6 concludes with a discussion of the various infrared features which have been observed in emission from planetary nebulae.