Laboratory investigation of the sublimation of comet nucleus models

Abstract

The results of the laboratory investigations of different versions of comet ice nucleus model sublimation under the conditions simulating 0.5–3 A.U. heliocentric distances are proposed. The sublimation constants of possible comet ices are experimentally studies, the laws for production and destruction of the dust matrix (mineral crust) on the nucleus model surface are investigated, and possible ejection of icy particles from the model surface is shown. The mineral crust properties of the nucleus model surfaces are studied and possible velocity of these crust fragments ejections are determined. The results of the experiments are used to interpret the observed of real comet desintegration, including the Halley comet. The possible mechanisms of dust and ice particles ejection out of the comet nuclei are given. On the basis of the observed dependence between the secular brightness decrease of short-period comets and perihelion distancrs of their orbits, and of nucleus model experiment data the conclusion were made of overgrowing the nucleus surfaces of some short-period comets with a mineral crust, and their further evolution into asteroid-like bodies. The perspective of laboratory modelling of the processes occuring on the comet nuclei and asteroid surfaces is considered.