All comets are born equal: infrared emission by dust as a key to comet nucleus composition

The infrared emission of various comets can be matched within the framework that all comets are made of aggregated interstellar dust. This is demonstr ated by comparing results on Halley (a periodic comet), Borrelly (a Jupiter family short period comet), Hale-Bopp (a long period comet), and extra-sol ar comets in the beta Pictoris disk. Attempts have been made to generalize the chemical composition of comet nuclei based on the observation of cometa ry dust and volatiles and the interstellar dust model. Finally, we deduce s ome of the expected dust and surface properties of comet Wirtanen from the interstellar dust model as applied to other comets. (C) 1999 Elsevier Scien ce Ltd. All rights reserved.