The chemical diversity of comets

TL;DR

This paper investigates whether different dynamical classes of comets have distinct chemical compositions by analyzing spectroscopic data, revealing deep chemical differences but no clear correlation with dynamical class.

Contribution

It provides a comprehensive analysis of spectroscopic radio observations of various comet classes, enriching the database with new data on Jupiter-family and Halley-type comets.

Findings

Deep differences in cometary ices' relative abundances.

No obvious correlation between chemical composition and dynamical class.

Enhanced database with recent observations of diverse comet types.

Abstract

A fundamental question in cometary science is whether the different dynamical classes of comets have different chemical compositions, which would reflect different initial conditions. From the ground or Earth orbit, radio and infrared spectroscopic observations of a now significant sample of comets indeed reveal deep differences in the relative abundances of cometary ices. However, no obvious correlation with dynamical classes is found. Further results come, or are expected, from space exploration. Such investigations, by nature limited to a small number of objects, are unfortunately focussed on short-period comets (mainly Jupiter-family). But these in situ studies provide "ground truth" for remote sensing. We discuss the chemical differences in comets from our database of spectroscopic radio observations, which has been recently enriched by several Jupiter-family and Halley-type comets.