Carbonaceous materials as components of cometary dust

Abstract

Recent exploration of comet Halley by space missions and ground-based observations have allowed to acquire a large amount of new information on cometary materials. In particular, IR spectroscopy has evidenced two pronounced and structured emission features at around 3.28 and 3.37 μm. Different kinds of gaseous molecules and/or solid grains including CH-X bonds have been proposed as possible carriers of the bands. In the past years, laboratory experiments have allowed to characterize the physical and optical properties of different classes of carbonaceous materials. The absorption properties measured for some of them are here used to fit the cometary features and to identify - if possible - the most probable carriers of these bands.