Temporal variations in the cometary mass distribution

Abstract

The large majority of cometary mass is contained in the nucleus. This paper investigates the variation of the mass distribution of comets as they evolve. Theoretical predictions are compared with the observations of two specific cometary groups – first, comets which have orbital periods greater than 200 yr and which are assumed to have been recently perturbed into the inner solar system. They can be regarded from an evolutionary standpoint as ‘young’. Secondly comets which have periods less than 200 yr. These are members of the Jovian and Saturnian family and have been in the inner solar system for a considerable time. They can be regarded as ‘middle aged’. Middle aged comets have a lower mass distribution index than young ones, 1.49 as opposed to 1.74. Assuming that the rate of change of mass, m, is proportional to $$m^\alpha$$, the results presented in this paper indicate that α = 0.75 ± 0.04. The mass distribution variation also indicates that cometary break up is only a minor factor in cometary evolution.