The Compositional Diversity of Comets

While the compositions of selected individual comets are well studied in terms of their composition, it is difficult to gain insight into the ensemble properties of comets with the current data. The largest survey to date (A'Hearn et al. 1995) has studied only ~10% of the known Jupiter Family comets (JFCs) - the progeny of Kuiper Belt objects (KBOs). The survey of 39 JFCs indicated the presence of two compositional groups within the dynamical family - the typical comets and the carbon-depleted comets. We propose to investigate the existence of sub-classes within the dynamical family by conducting a spectroscopic survey of JFCs. We aim to detect the CN emission line at 3889Aand the C_2 and C_3 bands between 4100Aand 5600Awhich together will confirm or deny the existence of compositionally-distinct groups of comets within one dynamical family.