Release and fragmentation of aggregates to produce heterogeneous, lumpy coma streams

Abstract

The unpredicted heterogeneity in particle number density in the coma of Wild 2 is consistent with delayed fragmentation to produce small particles from larger aggregates initially ejected from the cometary nucleus. The resultant heterogeneous inner coma results in stochastic variations in particle number and size distribution. Fragmentation can be accelerated after aggregate release by enhanced heating and one or more additional factors such as abrupt depressurization, phase transitions, exothermic chemical reactions, centrifugal forces, and electrostatic repulsion. Certain predicted characteristics of such in-flight disaggregation in coma particle streams correspond to known cometary phenomena. Copyright 2004 by the American Geophysical Union.