Comet Taxonomy and Evolution

Abstract

Abstract.Measurements of physical and dynamical properties of comets have yielded considerable evidence for variations in the origin and evolution of these primordial objects. Given these findings, one might reasonably expect to observe differences in the chemical composition as well. This paper reviews our current state of knowledge of the similarities and differences in the composition of comets, and summarizes the recent findings by A'Hearn et al. (1994) for two taxonomic classes of comets and evidence of compositional variation due to origin and/or evolution.

Narrowband Filter Photometry of Five Comets

“…Also, based upon the overview of comet taxonomy by Schleicher (1993), Comet Bradfield is in the "normal" or "typical" class of comets, and Comet Furuyama probably is as well, although its production rate ratios are much less consistent. Bradfield is an old, long-period comet and Furuyama is a young, long-period comet, so they are expected to be in the "normal" category.…”

Molecular Abundances in Comets

“…The data for parent molecules are still very sparse, but a high comet-to-comet variability is suggested for methanol or formaldehyde. Schleicher (1994) (Fink 1992;see Greenberg et al 1993 for a discussion) and P/Wolf-Harrington, depleted in C2 and C3 compared to CN and OH (Schleicher et al 1993).…”